# Tesluar



## oudevolvo (Mar 10, 2015)

This is going a nice one to follow I expect.
Good luck with the project and I’m looking forward to further updates! Also photo’s and the battery box desings of which I’m curious what your approach is.


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## galderdi (Nov 17, 2015)

Hey Itchy

Great to see you starting to make some progress on the Tesluar (Personally I would have gone with Tesuar or Jaglar but no mind) 

Keep us informed of your progress. Many many photos please. It would be great to catch up again at some point soon.


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## Moltenmetal (Mar 20, 2014)

I will be following this project with interest, and wish you the very best of luck!


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## itchyback (May 28, 2014)

As i mentioned earlier, i have rigged up a dodgy setup to test the motor. theyre basically jumper cable wires. which are fine for a few hundred amps at 12v, if i can just spin the motor without load for less than 20amps ish they should be fine. Thats seems pretty low, so feedback welcome.

Monday night i was successfully able to get the 12v section of the VCU working. Via laptop I can communicate with the motor, set various parametres like max power, low voltage limit, regen, and read CAN messages from it. It took some fiddling, my computer didnt have the correct drivers to use a piece of software needed but Michal was very helpful and tolerant of my ignorance. Wiring the plugs yourself is a pain! my motor didnt come with a wiring harness for some reason. I bought the plugs and elected to wire it myself for the experience and save $120. It took me hours, next time i'll buy it complete. 

Frankly it was terrifying. I took on this project because i was interested in learning more about/ working with electricity. During the day i am a social worker and took to the project knowing nothing more than ambition and stupidity to help me. Having $10,000 sitting in front of my that could go up in smoke with one mistake. i was sweating. 

As if the 12v stuff wasnt scary enough, Next is the High voltage side. We've already had a run in. I was tightening a bolt on a bus bar, mindlessly i rotated the spanner too far and it touched the terminal of the next battery over. Sparks blew out at my face and the spanner was briefly welded between the two modules. The bolt did get welded in place and i needed to drill and tap the hole again. Which was also terrifying drilling nearly $2000. The battery voltage reads fine and i got the bolt out. Some molten metal did melt something underneath the terminal, i cant tell what that is, I cant reach the coolant pipes to check that so for now, i'm hoping its nothing important.

In order to test the high voltage side and motor, I'm waiting on some parts. The VCU calls for three contactors. I have two high performance ones capable of handling more amps. I've ordered a basic one which is solely for the precharge and a resistor accordin to the instructions. Then i should be hours away from testing the motor.


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## BuildMore (Oct 28, 2016)

Loving your project, mate! Beautiful model of a motorcar that needs to prevail long into the future! I still have an XJ Coupe on my short list of cars I want to convert in my lifetime. All the best of luck to you, my friend!


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## brian_ (Feb 7, 2017)

Since this thread has been revived...


itchyback said:


> The rear end will need to be redesigned entirely. The engineer didnt seem to worried about that so he has boosted my confidence. I'm thinking a trailing arm set up at this stage. Double wishbones could be tricky to fit around the motor.


You can go from ideas and problems straight to a suitable and fully developed design in one salvage purchase... of a complete Tesla Model S (or X) rear subframe with suspension. Yes, the same thing that motor came out of.

Chris did this in his Tesla Powered Nissan r32 skyline. It's a major project structurally, but doesn't require suspension design or fabrication.


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## itchyback (May 28, 2014)

Buildmore; when i received your message i was actually looking at an XJ coupe to buy. I really wanted it, but it was very rusty and i just couldnt take such a big step back now i've done so much work on the sedan. :/ 

Brian; yes it was tempting to get the whole setup but one regulation here in order to get the car registered is that you cant widen the car more than two inches. Tesla is much wider than the jag unfortunately. 

I've been grinding away at this but not as much as i would like. I've been wiring up the motor. That is damn scary i'm so afraid i'll connect something incorrectly. I am using an advantics VCU and that has bee difficult too. I expected the board to be sent back frmo them ready to spin the motor but i need to know how to do computer programming and work with CAN and i know neither. this wasnt made clear at the outset otherwise i may have chosen a different method. THe manual has limited information which doesnt help because everytime i take a step forward, i find out i need to get a piece of hardware or knowledge that takes me weeks if not longer to learn/ get. I could not recommend the advantics vcu to anyone unless you know how to computer program and have played with CAN before. Its not a skill that comes naturally too me so that complicates things. Michal has been working ok with me, i just wish he was more helpful given how little i know. If i ask something he doesnt want to answer, he just wont answer. for example i've asked he confirm the wiring of relays, recommend a program to work with CAN, asked if i can use arduino and CAN shield instead of arduino due, no response.

Last night i was working on it. I had made good progress but in the process blew up my contactors. I was testing the VCU's control of the contactors. I should have disconnected the HV wires but didnt. blew up both positive and negative contactors. bummer. 

These few months has been an exercise in persistence and motivation. Balancing my time between physical results, like i've been welding a battery mounting frame, and the wiring stuff, has been helpful. 

I have time off next week to keep building the battery frame. Will have to wait a few weeks to get some more contactors.


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## brian_ (Feb 7, 2017)

itchyback said:


> The rear end will need to be redesigned entirely. The engineer didnt seem to worried about that so he has boosted my confidence. I'm thinking a trailing arm set up at this stage. Double wishbones could be tricky to fit around the motor.


Independent suspensions are challenging, because the wide drive unit limits the length of the lateral arms. That can be worked around, but it means that any production multi-link suspension - other than the one built specifically to fit for Tesla - is unlikely to fit; double wishbone suspensions will be just as unlikely to fit.

Because the Tesla motor is behind the axle line, there is more space for suspension arms ahead of the axle line. That means that trailing and semi-trailing arm designs are most likely to fit. Trailing arms don't work very well and are only used in designs that link the arms with a twist beam, which is not easy to home-built properly and might be difficult to retrofit to a car not designed for it. While the semi-trailing arm design as been obsolete for decades (it was popular in the 1970's), it's the most common design used with Tesla drive units in projects in this forum... which are generally older BMWs and Porsches.

Semi-trailing arm suspension geometry is crude and can be problematic, but there is a multi-link variation used by the Fiat Doblo which has better camber control and still puts all of the arms ahead of the axle line:








There have been other clever multi-link variations of the semi-trailing arm layout; this is just one that I have seen that I could think of offhand. Of course to use this from a production car you would need one which was rear wheel drive or four wheel drive (the Doblo is front wheel drive).

Building a good independent suspension from scratch is not easy. Certainly the easiest independent suspension which will fit around a Tesla drive unit would be semi-trailing arms. You could build a custom crossmember to mount the suspension of an older large BMW sedan (such as a 7-series up to the 1994 E32) to the mounting points in the XJ6 structure, although even that isn't guaranteed to fit.



itchyback said:


> ... yes it was tempting to get the whole setup but one regulation here in order to get the car registered is that you cant widen the car more than two inches. Tesla is much wider than the jag unfortunately.


For some cars it might be possible to use narrower and/or further inset wheels to reduce the overall width, but there are mechanical limitations on that, and the width difference in these cars is indeed substantial:
1969 Jaguar XJ6: 1768 mm / 69.6 in (from automobile catalog)
Tesla Model S: 77.3 in (1,964 mm) (from Wikipedia)​That's 204 mm, 154 mm more increase than allowed.

The Jag apparently came with 205/70R15 tires, so just using stock-width tires would knock off some width, but I don't know if the whole difference could be made up.


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## itchyback (May 28, 2014)

Thanks Brian, you've put a lot of thought into your response, I appreciate your wisdom. I dont underestimate the challenges involved in creating the suspension from scratch however at this point i have benefit of ignorance and optimism .
I understand Damian used some form of trailing arm suspension on his BMW. as you said Porsche has used it for years and thats a good performance car so i know its possible and performance can be good. what level i can achieve remains to be seen.

A rudimentary design i had in mind was what i'd seen in offroad camper trailers. Fitting something OEM would be my preference because than someone smarter than myself has designed it. then it would also have torsion bars and proper bushings etc. I've vaguely looked around at existing examples but only as a proof of concept. once the motor is going, then rear suspension is the next phase of the project.


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## brian_ (Feb 7, 2017)

itchyback said:


> I dont underestimate the challenges involved in creating the suspension from scratch however at this point i have benefit of ignorance and optimism .






itchyback said:


> I understand Damian used some form of trailing arm suspension on his BMW. as you said Porsche has used it for years and thats a good performance car so i know its possible and performance can be good. what level i can achieve remains to be seen.


Damien converted a BMW 8-Series (E31). Although this car came with a relatively modern multi-link suspension, he couldn't make that work with the Tesla drive unit, so he swapped in a semi-trailing arm suspension from an E34 car (a 5-Series up to the mid-1990's): *Tesla Powered BMW E31 8 Series* post #17

The history of Porsche is built on semi-trailing arm rear suspensions (because that's what an upgraded air-cooled VW had, and because it fits easily with a rear engine), but they haven't used it for about a quarter century. The 911 conversions in this forum are all older models. The multi-link systems in newer 911's would likely work, too, since they are designed to fit around the transaxle and rear engine, but that's not a cheap source of parts! On the other hand, the 993 generation of 911 (993 is the internal type identifier; 911 is the marketing model name) has the suspension mounted to an interesting aluminum subframe system which has separate right and left parts, which could be excellent for mounting to a tubular steel framework around an electric drive unit.



itchyback said:


> A rudimentary design i had in mind was what i'd seen in offroad camper trailers.


Excellent... for an off-road trailer. It can work for a car, but is no longer used in quite that configuration.

That's a pure trailing arm design, which means that the lines through the pivots run straight across the vehicle. With reasonable bushings this leads to the rear wheels steering undesirably when under cornering force; setting the pivot axis at an angle somewhat rearward toward the inboard end causes both toe inward and negative camber on the outside of the turn, which helps. Since the arms then don't purely "trail" (point rearward) the result is called a semi-trailing arm suspension.

Even for the trailer, semi-trailing would be better. There are lots of trailing arm trailer suspensions (almost all independent light trailer suspensions are of this type), but there are a few which are semi-trailing for better stability.



itchyback said:


> Fitting something OEM would be my preference because than someone smarter than myself has designed it. then it would also have torsion bars and proper bushings etc.


I agree - this sort of design is something that is best done by someone with more experience and resources than a typical DIYer, although the semi-trailing arm system is at a level which can be home-designed successfully.

Few modern suspensions use torsion bar springs; coils work better in most cases. If you mean a stabilizer bar... yes, having that already built is one of the advantages of using production pieces.


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## brian_ (Feb 7, 2017)

brian_ said:


> That's a pure trailing arm design, which means that the lines through the pivots run straight across the vehicle. With reasonable bushings this leads to the rear wheels steering undesirably when under cornering force; setting the pivot axis at an angle somewhat rearward toward the inboard end causes both toe inward and negative camber on the outside of the turn, which helps. Since the arms then don't purely "trail" (point rearward) the result is called a semi-trailing arm suspension.


In case this wasn't clear without an illustration:








(from _Autozine_ - Suspension Geometry)


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## brian_ (Feb 7, 2017)

brian_ said:


> Semi-trailing arm suspension geometry is crude and can be problematic, but there is a variation used by the Fiat Doblo which has better camber control and still puts all of the arms ahead of the axle line:
> ...
> There have been other clever variations of the semi-trailing arm design; this is just one that I have seen. Of course to use this from a production car you would need one which was rear wheel drive or four wheel drive (the Doblo is front wheel drive).


Okay, for those thinking that I've missed the obvious... the very common multi-link variation which looks like that one from Fiat, but is for rear wheel drive, is BMW's Z-axle. It appears in many BMW models starting with the E36 generation of 3-Series.








(from Brent Ford Racing)

Assuming that you would use a different subframe to mount the inner ends of the lateral links, it looks like this would leave the entire space behind the axle line clear, and would likely work well with a Tesla drive unit. It's not as good as more sophisticated multi-link designs, but at least it isn't just semi-trailing arms (which are inferior to the original Jag IRS).


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## itchyback (May 28, 2014)

Porsche has served up a variety of useful designs and with the sports orientation i'm leaning towards (60% cruise, 40% sports). Yes I did mean a stabilise bar. Thanks for the link to the autozone page, the specifics of 50-70 degree pivot angle are useful to have and i've kept the link in my document of suspension information. If you have any other useful links/ info/ documents I would really appreciate them.
Looking at the car, I can imagine some sort of multilink design, but it fitting and performing well dont necessarily go hand in hand. The semi trailing arm was easy to fit and function adequately. The original jag suspension uses the half shaft as a axially loaded member which I cant do with the tesla unit. Complicating things, the chassis design and motor size dont lend themselves to the introduction of an upper control arm. Its possible to have one now but it would be ridiculously short resulting in wild changes in camber. It may be possible to have one roughly above the axle but the chassis limits travel. I'm not clear on the rules yet but am working on the assumption I cant cut and move the chassis rails.if I can, I think I can widen the car width and change wheel offset and make something of adequate size and function.

I'm certain of finding a solution and confident I can find a way that results in reasonable performance.


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## brian_ (Feb 7, 2017)

itchyback said:


> Thanks for the link to the autozone page, the specifics of 50-70 degree pivot angle are useful to have and i've kept the link in my document of suspension information.


The pivot axis may also be a bit off of horizontal, and that angle matters as well.



itchyback said:


> Looking at the car, I can imagine some sort of multilink design, but it fitting and performing well dont necessarily go hand in hand. The semi trailing arm was easy to fit and function adequately.


Very true!



itchyback said:


> The original jag suspension uses the half shaft as a axially loaded member which I cant do with the tesla unit.


Yes, that's a common characteristic of obsolete IRS designs, and not acceptable for modern components.



itchyback said:


> Complicating things, the chassis design and motor size dont lend themselves to the introduction of an upper control arm. Its possible to have one now but it would be ridiculously short resulting in wild changes in camber. It may be possible to have one roughly above the axle but the chassis limits travel.


The half shaft as suspension link does eliminate the need for a separate upper arm, and the body design takes advantage of that.

A common technique to improve this interference issue is to make the upper lateral arm boomerang-shaped, so it curved under the frame rail. This makes it less stiff, so careful design is required. This aftermarket upper A-arm for a Ford Mustang rear suspension shows a curved upper arm in tubular steel: IRS Rear Upper Control Arms for 1999-2004 Mustang SVT Cobra
Many curved upper links are cast and nearly a plate, such as the upper link in the rear suspension of Ford's "Control Blade" design used in the Ford Focus (and the many other cars of several brands which copied it) for many years. Ford built a display for the introduction of a new Mondeo generation showing very different old and new rear suspension designs... with a boomerang upper control link in both of them.


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## Duncan (Dec 8, 2008)

Hi itchyback

It may be worth thinking about Chapman Struts - used on all manner of cars and very effective - and I would advise getting a copy of 
Alan Staniforth's - Race and Rally Car Source Book


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## brian_ (Feb 7, 2017)

Strut suspensions are often incorrectly called Chapman struts when used in the rear, where they don't steer. A real Chapman strut uses the half shaft as a lateral suspension link, like the old Jag IRS... I don't think anyone wants that, for either the loads on the final drive, or the mandatory use of U-joints, or for the geometry limitations of the lateral link location controlled by the differential output height.

A MacPherson strut suspension, using some combination of lower links to locate the bottom of the strut and control toe, has been used at the rear on many vehicles, although not frequently with rear wheel drive. This design is now uncommon at the rear, although even the most recent Porsche Boxster/Cayman still uses it (likely to keep this model cheaper and less capable than the 911). It does avoid the need for a lateral upper link, but requires a tall strut. That strut usually carries the spring, making it bulky, but it is also possible to put the spring on the lower control arm... a design typically called a modified MacPherson strut. The spring for a modified MacPherson strut can be a torsion bar (as in Porsche and Honda designs) or a coil (as in the Ford Fox chassis); a coil spring on the lower arm could be positioned similarly to the coil-over shock of the original Jaguar IRS.


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## Emyr (Oct 27, 2016)

brian_ said:


> A MacPherson strut suspension... has been used at the rear on many vehicles, although not frequently with rear wheel drive.


World Rally Car regulations for the last decade have been based on the Super 2000 spec, which mandates MacPherson front and rear, despite WRC cars being 4 wheel drive. Super 2000 is also used for the World Touring Car Championship, where BMW were series winners several times with their E90 320si.


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## brian_ (Feb 7, 2017)

Emyr said:


> World Rally Car regulations for the last decade have been based on the Super 2000 spec, which mandates MacPherson front and rear, despite WRC cars being 4 wheel drive. Super 2000 is also used for the World Touring Car Championship, where BMW were series winners several times with their E90 320si.


I was aware of other racing applications, in which the suspension was unrelated to the production vehicle, but I had not looked at the details of these two series.

These are good examples of situations which are controlled by competition regulations, rather than technical design factors. A full-cage race car is a relatively easy structure in which to mount a MacPherson strut, and packaging around a rear seat and cargo compartment is not a factor (interfering panels are just cut away); in both respects, this is a very different situation from a street-use sedan with a production unibody and full interior.

I can see why these series might specify the design. They want a single design to level competition, an inexpensive but capable design to keep competitors cost down, and perhaps even spec parts from a sponsoring supplier. This is done with many parts of competition cars, which often have minimal relationship to any production car. Super 2000 is a good example mechanically, whether in WRC or WTCC, although production-related bodies are used. A WRC or WTCC car also doesn't keep a functional rear interior.

A real BMW E90 3-Series doesn't have MacPherson strut rear suspension (and probably none of the cars in these series do) - it has a modern multi-link.

None of this has much to do with a classic Jag conversion. If a strut suspension fits easily that's great, but it seems unlikely.


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## brian_ (Feb 7, 2017)

MacPherson struts in a non-steering application can be arranged a little differently from usual, to address the packaging problems. Normally the strut is nearly on the axle line, for the desired steering geometry, and with a driven axle that forces the strut to be very high, above the axle. In the rear (where it doesn't need to steer), the strut can be behind the axle line, so the bottom of the strut can be lower than the axle shaft. This approach is an option, if it helps, but I suspect that it won't help with the frame rail issue.


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## Duncan (Dec 8, 2008)

IMHO
Strut suspension is easy to design and make - and is easy to set to achieve the suspension results
The fact that the angles are set by the position of the strut top means that you can get precise angles 

The only issue that I can see is that it prevents some body shapes - but only at the front - the back is almost always high enough to mean that you can fit your struts

Edit
I used Strut suspension on the front and rear of my "Device" - and decades ago I used Strut suspension on the front of my Twin Cam Mini


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## brian_ (Feb 7, 2017)

Duncan said:


> Strut suspension is easy to design and make - and is easy to set to achieve the suspension results
> The fact that the angles are set by the position of the strut top means that you can get precise angles
> 
> The only issue that I can see is that it prevents some body shapes - but only at the front - the back is almost always high enough to mean that you can fit your struts


It's no worse to design than other non-trivial (not single arm) suspensions, but Duncan wisely chose not to design or make one, but instead to incorporate a production Subaru suspension to the Device.

True, there's lots of height in most bodies, including the XJ6. Of course, there's that little detail of an existing body structure... 



Duncan said:


> I used Strut suspension on the front and rear of my "Device"...


The Device is a tube-framed vehicle designed to fit the components, including the suspension. That's a substantially different situation from the XJ6.


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## Duncan (Dec 8, 2008)

Brian
You are completely WRONG in this
A twin wishbone setup is very sensitive to the positions of all of the pivot points - and it feeds large loads into all of those joints

For my mini I designed the suspension with my own bottom wishbones

I did use complete Subaru subframes for my device as it was easy - and made certification a lot easier

But designing a strut type rear suspension for something like the jag would be relatively easy - you just need the two pivot points for the lower wishbone and a single high mounting point for the strut top - you could cut the turret off another car (like a Subaru - or almost any car with struts) and weld it into position a trivial task compared to any of the other types of suspension 

Almost all current production vehicles use Strut suspension - because it is easy to design and make AND works very well


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## brian_ (Feb 7, 2017)

Duncan said:


> Brian
> You are completely WRONG in this...


That's strange... because I didn't disagree with any of the points which followed this, except...


Duncan said:


> Almost all current production vehicles use Strut suspension...


No. A large fraction (probably the majority by sales volume) of current production cars (not light trucks) do use MacPherson strut front suspension, but few have used it at the rear in the last decade or two.

We're supposed to be discussing a suspension to make a Tesla drive unit work in the back of the Jaguar XJ6. In the current Jaguar lineup only the E-Pace (the smallest and least expensive model) uses a MacPherson strut front suspension, and none uses a MacPherson strut rear suspension. The rest of the front suspensions are all extended hub carrier double A-arms, while the rears are all multi-link (generally Jag's Integral Link design) or double A-arm.


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## Duncan (Dec 8, 2008)

_We're supposed to be discussing a suspension to make a Tesla drive unit work in the back of the Jaguar XJ6_

YES
And in that situation I would be designing and making a Strut type rear suspension

It is easier to design
Easier to make
There are a LOT more parts available
And - importantly - it requires lower level of precision to make it work

Finally - if at all sensibly designed it works very well indeed


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## itchyback (May 28, 2014)

I stopped getting updates for some reason and regret not being up to date with the conversation. I had looked at McPherson Struts (the difference between them and Chapman struts is not immediately obvious, perhaps how they mount to the wheel hub?, i'll look into it further). Holding all the wiggliness of a 400kw car with a single control arm and strut seemed like a lot to ask so I had perhaps incorrectly, dismissed the idea early on for lack of understanding. There us heaps and heaps of space for struts and a lower control arm is easy to find space for so I should reconsider this option. 

After our conversations so far, I had another look at the rear suspension today. The front upper control arm is about 20cm long, the lower, 30cm long, not as long as I thought. I had dismissed the idea double wishbone suspension would be possible in the rear. With some clever positioning, perhaps I could get something similarly long into the rear, I had expected it would need to be much longer to get reasonable wheel travel. The current rear lower control arm is about 45cm long and may need to be shortened, I imagine there is a sweet spot for the length of upper vs lower control arm. All that said, this train of thought has just landed me in the poo pile that is lining up u-joints and suspension pivots and I can feel a cold sweat coming on 

As I said I had not put much thought to suspension design and now i'm suffering some errors as a result. For now I should put all options back on the table and educate myself for all options their strengths and weaknesses. Regrettably there is no perfect, easy and cheap option for my handling/ performance goals.


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## Duncan (Dec 8, 2008)

The strut design on the back of my device is (each side)

Two in/out links - one with length adjustment - both effectively simple tubes with eyes for the rubber bushes

One fore/aft link - in the Subaru it goes forwards but I swapped the rear hubs right to left so that it went backwards 

These three nicely constrain the bottom of the strut - then all you need is the top of the strut

As a general rule the more that you can move the top of the strut towards the center of the car the more the suspension compensates for vehicle roll to keep the tyres square to the road

On the Subaru the strut ends in a bracket that goes either side of a bit sticking up out of the hub

These two parts are clamped by friction so you can enlarge the holes to get more adjustment if you want


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## brian_ (Feb 7, 2017)

itchyback said:


> I had looked at McPherson Struts (the difference between them and Chapman struts is not immediately obvious, perhaps how they mount to the wheel hub?, i'll look into it further).


The difference is that a Chapman struts use the axle shaft as a suspension link (so cornering force is carried through the differential bearings), while MacPherson struts have normal shafts with CV joints and separate suspension links. Few cars ever had Chapman struts, and none have had them for decades; they're a historical curiosity.



itchyback said:


> Holding all the wiggliness of a 400kw car with a single control arm and strut seemed like a lot to ask so I had perhaps incorrectly, dismissed the idea early on for lack of understanding.


There's no problem with strength at all. The strut does take bending stress (unlike the shock in other designs), but they have a larger rod diameter and this isn't a problem. Where MacPherson struts are currently used (at the front of unibody cars, particularly those with transverse engines), they're usually supporting the heavier end of the vehicle and they are often controlling the drive axle. The current 6- and 8-wheeled vehicles armoured vehicles used by the Canadian army have strut suspensions for the forward axle(s)... and they weigh 16 tons or more.



itchyback said:


> After our conversations so far, I had another look at the rear suspension today. The front upper control arm is about 20cm long, the lower, 30cm long, not as long as I thought. I had dismissed the idea double wishbone suspension would be possible in the rear. With some clever positioning, perhaps I could get something similarly long into the rear, I had expected it would need to be much longer to get reasonable wheel travel. The current rear lower control arm is about 45cm long and may need to be shortened, I imagine there is a sweet spot for the length of upper vs lower control arm. All that said, this train of thought has just landed me in the poo pile that is lining up u-joints and suspension pivots and I can feel a cold sweat coming on
> 
> As I said I had not put much thought to suspension design and now i'm suffering some errors as a result. For now I should put all options back on the table and educate myself for all options their strengths and weaknesses. Regrettably there is no perfect, easy and cheap option for my handling/ performance goals.


There are a lot of factors in suspension design. I wouldn't consider playing with arm lengths without a substantial understanding of the geometry, which is a good reason to use a production design. For instance, there is no ideal ratio of upper to lower control arm length.



Duncan said:


> The strut design on the back of my device is (each side)
> 
> Two in/out links - one with length adjustment - both effectively simple tubes with eyes for the rubber bushes
> 
> ...


This is a common design of the 1980's; I had a 1984 Toyota Tercel with the same design. The "in/out" links are usually called lateral links; the fore/aft link is usually called a longitudinal link.


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## Bry5on (Mar 14, 2016)

You should reconsider using a motor in the transmission tunnel and keeping the Jag IRS. You see why I ended up taking the route I did with mine, the rear suspension problem is quite difficult to solve!

Good news is that four Tesla modules fit in the spare tire well and probably 12 under the hood (I have ten)


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## itchyback (May 28, 2014)

Thanks Bry5on, I agree it is a shame to get rid of the original IRS. It appears difficult, but we have at our finger tips all of human knowledge in the internet. I am confident i can come up with something 95% what i want. 

The transmission tunnel will be housing four modules, plus another two stacks of four on the front suspension. Plus four on the shelf above the IRS. Could probably fit a few more in the front but im trying to even out weight distribution and having four identical boxes minimises engineering design and certificate work/ costs. The spare tyre well is shrinking to fit the motor but is probably enough room left for a charger.


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## Bry5on (Mar 14, 2016)

Have you measured out the space on the shelf already? I thought about doing this as well but because the seat back is reclined and not vertical, it looks like stacking four modules is not possible without eating into the trunk space a bit more. 

Very curious to see how it ask pans out! Wish it were easier for us to get together and share musings


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## brian_ (Feb 7, 2017)

The biggest challenge of using a strut suspension at the rear is that - completely unlike the original Jag IRS which is obviously designed to be low and flat across the top - it fundamentally requires two towers to accommodate the struts.


Duncan said:


> ...- you could cut the turret off another car (like a Subaru - or almost any car with struts) and weld it into position...


This is true, but those towers (or turrets) would go through the existing structure, and into the interior.



itchyback said:


> I'm not clear on the rules yet but am working on the assumption I cant cut and move the chassis rails.


This could be one problem with fitting in strut towers, depending on frame rail spacing and strut spacing.

The other problem is what strut towers would run into in the interior, but I noticed these comments:


itchyback said:


> The transmission tunnel will be housing four modules, plus another two stacks of four on the front suspension. Plus four on the shelf above the IRS...





itchyback said:


> There us heaps and heaps of space for struts...


I've driven an XJ6 (I think a Series III, rather than this Series I), but I didn't look behind the rear seat and I don't recall the details of the trunk. It sounded at first like this body had a feature which was common in the 1960's, in which the trunk is behind base of the rear window, the rear seat back near the leading edge of the rear window, and in between them is a wasteland of awkward "parcel shelf" over the rear axle and suspension, within the passenger compartment volume. Looking at online images of bare XJ body shells, it seems more likely that these are references to the forward section of the trunk, where the floor is stepped up over the rear axle and suspension, ahead of the trunk opening and below the rear window.
(an old bodyshell image is attached to the end of this post)

In either case, that's a great battery location for some cars (as long as you package the modules safely), and if strut towers (for MacPherson struts or just springs and shocks of another IRS design) were to poke into there it wouldn't interfere with seating space or the main trunk space (although of course now battery and suspension are competing for space). There are just those structural issues to consider... struts outboard of those frame rails (visible in the bodyshell image) would require a very wide track.

While looking for information on the XJ body, I discovered that if you have buckets of money Jaguar Classic might still produce a complete new bodyshell for you (although only for the Series III, not earlier).


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## Duncan (Dec 8, 2008)

If you look at the picture Brian attached you will see that there is plenty of room for the struts 

IMHO you do NOT want your batteries high up at strut level - the best place for all the heavy bits like batteries is down on the floor - as low as possible


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## brian_ (Feb 7, 2017)

Duncan said:


> IMHO you do NOT want your batteries high up at strut level - the best place for all the heavy bits like batteries is down on the floor - as low as possible


Ideally, yes. Unfortunately the reality of a car body not designed for an under-floor battery box is that low locations are not likely available. The engine compartment and transmission tunnel go to the bottom of the car, and are planned locations; even the top of the engine area stack will be higher than that over-axle shelf. For the rest, there is the portion of the spare tire well behind the Tesla drive unit, but that's well behind the axle and so it is undesirable as well. Stacking them on the floor in the rear seat space might not be popular with the rear seat passengers... 

The stock "saddlebag" fuel tank locations are not very low, either... and not shaped to accommodate big flat modules.


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## itchyback (May 28, 2014)

If i'm ever in the US bry5on i'll look you up, would be great to shoot the breeze with a fellow jag lover. 
I believe a strut tower would fit. The fuel tanks sit above the wheels so without them leave plenty of height. The bulge locates under the filler cap but there is still space forward of that. 

Battery location has been a compromise. I'm trying to get it as low as possible. however the cells are quite long. one method I have designed is mounting them lengthwise which means they fit closer to the middle of the car. however fitting a stack in the transmission is taking up some dash and theyre just a little too long to make that work without altering th cabin appearance which i dont want to do. 

Another option is Perpendicular, as Bry5on has done, leaves more engine bay room, better space for radiators if you need one. However one mounts almost entirely forward of the front axle, the other must be mounted 10cm higher than my original design to clear the chassis rails, as is visible in Bry5ons photos. 

In the rear, i am losing most of the spare wheel well to fit the motor might check space again though. The 4 module stack is 34cm high (14'). i think i'll put a coolant motor or something behind the stack so i dont lose the space because of the sloped seat. There is very nearly enough room to mount two modules in the original fuel tank location. but mounting vertically and in such a position prone to collisions, i thought better of it.


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## brian_ (Feb 7, 2017)

*Fuel tank spaces*



itchyback said:


> I believe a strut tower would fit. The fuel tanks sit above the wheels so without them leave plenty of height. The bulge locates under the filler cap but there is still space forward of that.


Just to be clear, with or without fuel tanks doesn't matter to struts, because the front of the tank is still well behind the axle line, and so behind even a large spring on a strut. The tanks are also behind the tires, and so mostly outboard of a strut location.

The tank locations look like good places for components such as chargers or coolant pumps, or even just storage bins. And one of the fill cap locations is just begging to become the charge port.


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## brian_ (Feb 7, 2017)

*Spare tire well*



itchyback said:


> In the rear, i am losing most of the spare wheel well to fit the motor might check space again though. The 4 module stack is 34cm high...


It appears that a 1969 XJ6 came with E70-15 tires, which are 26" or 660 mm in diameter. The spare tire well appears to be entirely behind the differential housing, so it must extend at least 26" or 660 mm past the diff. The front side of the Tesla motor will sit further forward that the back of the Jag diff, so the rear mount of the drive unit should end up about mid-way back in the spare tire well.

Does that leave enough space for modules (only stack of two due to height) in the spare well behind the motor? Is the spare well width (which looks like it is barely enough for the tire) enough for the length of a module? Both dimensions look tight, but especially the width, so I wouldn't be surprised if a module won't fit there.

This could be another space for various ancillary components (electronics, coolant pumps...), or just a storage cubby for the air compressor and tire puncture-repair stuff that one needs when one doesn't have a spare tire.


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## Bry5on (Mar 14, 2016)

There is not enough space in the trunk for a module to fit width-wise, it is about 1" shy of being doable without cutting into the old muffler compartment (which is not the end of the world if this much fabrication work is already happening). 

The old tank locations are indeed great spots for chargers and yes the gas door makes a great charge port 😉


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## brian_ (Feb 7, 2017)

Bry5on said:


> There is not enough space in the trunk for a module to fit width-wise, it is about 1" shy of being doable without cutting into the old muffler compartment (which is not the end of the world if this much fabrication work is already happening).


The mufflers flank the spare tire well, so I can see how cutting out one or both sides of the spare well would allow the use of the muffler space, but isn't there a structural ("frame") rail between them? The structure has to be somewhere, and forward around the axle it is in two rails essentially lined up with the sides of the spare tire well. Does the structure run outboard of the mufflers, or above them? The mufflers look like they might be under the fuel tanks.


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## Bry5on (Mar 14, 2016)

There's about two inches of space before you get to the frame rail, good thinking though!


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## itchyback (May 28, 2014)

14months, i thought it was worse. 
For all my spare time i now have a lovely new bathroom and renovated part of my house. Now thats done, i can get back to this. 

i have the battery boxes made and their mounting frames. You can see two of the three locations mocked up with cardboard boxes. I'm pretty excited to have a frunk. Although in Australia, it would be called a froot. 

I'm close to a solution for AC, i found a great company that lists all the individual parts with dimensions and that has been incredible to have when retrofitting something that never had AC! 

Today i mocked the motor up into position, you can see i've made a rough jig to hold the wheel hubs in place while i build everything around them. The engineer is coming in 4 days to discuss the rear suspension, i have something i think will work but it really needs his eye to review it, he's forgotten more than i'll ever know about suspension design.


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## Bry5on (Mar 14, 2016)

Awesome, looks great. Don’t forget to leave room in front of the engine compartment for the AC condenser. You might also want to make sure you box in the frame where the old radiator support was. 

Can’t wait to see this thing running. How many Tesla modules are you running again?


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## itchyback (May 28, 2014)

Some good progress recently. I’ve found a rear suspension solution and worked towards it and got some more parts and solved some future brake problems.

Suspension
The engineer changed my rear suspension design to be harder to make but stronger. I was hoping for a sexy space frame rear setup but he encouraged me to look for OEM parts I could adapt to fit. I found a tutor to walk me through autocad to design the parts but stumbled across another solution. I found out the tesla I have parts for uses 120x5 pcd similar to my jaguar. For shits and giggles I put the rear tesla hubs in my hub jig and with the motor roughly in place found the upper and lower control arms actually fit really well. Using the complete Tesla rear hub, brakes and control arms will save a lot of time and money, both of which I can better spend elsewhere. 
That makes a new problem that I either modify the rear brakes to be smaller (originally 355mm, Jag rotors are 280mm) or modify the front (which are 280mm). Seems stupid to downgrade brakes so I think I’ll put Tesla brakes on the front, 355mm rotors (which almost fit) and use an adapter to fit the tesla caliper. I think that will look good, I’m already using the Tesla brake booster so basically a whole system swap which is helpful for brake bias issues too. Briefly look at stand alone ABS (since the rears already have the hardware but quicly shelved the idea… well maybe in the future).

jig
This weekend I’ve made a ridiculous jig to align the wheel hubs and motor and copy the Tesla suspension mounting points to be able to translate them to the Jag. Its taken two weeks of brainstorming to make a workable design and another several hours to build. The suspension mounts need to be able to move inward to accommodate the smaller track width of the jag, as well as being able to move down because the jag is lower. The motor also needs to move up, I’ve raised it to improve clearance as directed by the engineer. I’m working on this build being really high quality so even though it’s a temporary jog, I paid a lot of attention to detail. I hope it pays off. I even added adjustable bolts so I can level the jig in two axis. The cars have also been levelled. Photos are of the completed ‘negative’ jig that fits within the chassis side suspension mounts. I need to add a ‘positive’ jig to locate it in the jag based on the control arms attached to the hubs in the hub jig. 

@Bryson, Thanks for the tip, actually the lower radiator mount was dented when i got the car, i remade it from scratch with thicker steel. for batteries I’ll be using 16 tesla modules for a standard 400v Tesla battery pack. I’ve also got a Tesla charger I’ll hack with a Zero EV board. I got a bunch of coolant pumps, a radiator and condenser that may be too big but were free and a Astra power steering pump that I thought about swapping for electrically assisted steering but not convinced I want to. Would like to for efficiency but want to stay to keep road feel and I have the pump already… open to ideas.


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## Bry5on (Mar 14, 2016)

You're a mad man, nice progress. Two questions:
1) how much wider is the Tesla track than the jag track?
2) have you fit the Tesla brake booster yet? Keeping the original pedal linkage? How did you adapt them together if so? I have one in the garage that I’d like to install eventually as well but it’s low priority.


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## itchyback (May 28, 2014)

Thanks Bryson,
Jag wheel track is 146cm tesla is 168cm.
I'll take a photo of the brake booster. I've used the original jag brake pedal and linkage. The jag brake booster bolted to an aluminium box that housed the brake pedal pivot. 
Your options are to use an adaptor plate in the range of 15mm to bolt them to each other or cut the pushrod shorter in the Tesla brake booster. I've opted for the latter because in either case you'll need to cut a relief in the inner wheel arch and i wanted to minimise any intrusion into that space. Some modest die grinder action on the aluminium box clears enough space for some nuts.


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## Bry5on (Mar 14, 2016)

Awesome. Did you try flipping the booster to see if it fit upside down without cutting the wheel well? It should work in either orientation. I haven’t gotten to the point of that yet as my vacuum pump works just fine. The Tesla booster is ‘cleaner’ however 🙂


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## itchyback (May 28, 2014)

I recall thinking about it but didn't. My photos suggest it may work so now I don't know what I was thinking.


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## blwnhr (Apr 4, 2019)

In the first photo it looks like the master cylinder cap may hit the bonnet?


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## itchyback (May 28, 2014)

Thanks Blwnhr that's probably why i did it this way. I've checked and it clears the bonnet by 1cm or so.


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## earz (Sep 3, 2020)

itchyback said:


> Buildmore; when i received your message i was actually looking at an XJ coupe to buy. I really wanted it, but it was very rusty and i just couldnt take such a big step back now i've done so much work on the sedan. :/
> 
> Brian; yes it was tempting to get the whole setup but one regulation here in order to get the car registered is that you cant widen the car more than two inches. Tesla is much wider than the jag unfortunately.
> 
> ...


Wow, what project. I have been introduced to using the advantics VCU as well. Who is Michal? did he sell you the VCU?
I have a million questions. Are you willing to answer some? Lets start with Michal. Best Regards, Randall


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## itchyback (May 28, 2014)

Hi Earz,
sure, i'll try to help. Michal is the guy who designed the board at advantics, he sold me the VCU


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## earz (Sep 3, 2020)

Did you ever connect to the VCU with a computer? did you use Uniflash from texas instruments?


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## mtrehy (Nov 10, 2019)

Hi,

Did you complete this build? Would be interested to see where you ended up with the rear suspension and tesla drive...

Cheers


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## itchyback (May 28, 2014)

earz said:


> Did you ever connect to the VCU with a computer? did you use Uniflash from texas instruments?


Yes and yes. I have no computer or electronics skills. I did it, it was very challenging. 

Mtrehy
It's not finished yet. I'm trialling using the original tesla control arms and drive shafts and building a narrower subframe to mount it all. It sits too close to the ground currently. I want to double check I've set it up correctly and may move it around.


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## amsmntparks (Jan 4, 2018)

Did you make any progress with the custom subframe? I'm working through a similar concept and would love to see any of your measurements for where the suspension mounting points are relative to the motor mounting points in the stock Tesla subframe.


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## gregski (Sep 6, 2011)

not sure if you seen Roadstercycle build called Tesla Motor Swap Mustang GT Part 1 where he mates a Tesla motor into a modern Mustang GT, maybe it can give you some ideas, just trying to help


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## amsmntparks (Jan 4, 2018)

Thanks @gregski. I just watched that series recently. It was very cool, but unfortunately doesn't help with my project. He uses the complete Tesla subframe and I'm trying to narrow the track width significantly.


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## mtrehy (Nov 10, 2019)

amsmntparks said:


> Thanks @gregski. I just watched that series recently. It was very cool, but unfortunately doesn't help with my project. He uses the complete Tesla subframe and I'm trying to narrow the track width significantly.


I've got the tesla LDU and rear track of just 55" but it is completely custom design suspension, wishbones, uprights etc.


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## Evbeddy (Jan 5, 2020)

mtrehy said:


> I've got the tesla LDU and rear track of just 55" but it is completely custom design suspension, wishbones, uprights etc.



Any chance of some pictures, mtrehy?


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## gregski (Sep 6, 2011)

here's some more non helpful Tesla rear end swapping videos 

BMW E31 840CI EV Conversion 87 : Tesla Swap Day 6


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## mtrehy (Nov 10, 2019)

Evbeddy said:


> Any chance of some pictures, mtrehy?


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## Evbeddy (Jan 5, 2020)

Thanks mtrehy, looks good. 

Would be a little harder to do in an old car but still helps give people ideas. What are you building?

So am I correct in assuming there will be springs and shocks attached to the top arms and mounted to the vehicle body?


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## mtrehy (Nov 10, 2019)




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## brian_ (Feb 7, 2017)

mtrehy said:


> View attachment 123741


Looking good 
Custom-fabbed control arms and uprights... are you using Tesla hub-bearing-carrier units so that you can use (shortened) Tesla halfshafts (and brakes, and wheels)?


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## mtrehy (Nov 10, 2019)

brian_ said:


> Looking good
> Custom-fabbed control arms and uprights... are you using Tesla hub-bearing-carrier units so that you can use (shortened) Tesla halfshafts (and brakes, and wheels)?


No, I am having driveshafts made for my application. Tesla hubs/brakes/wheels are too big and I needed standard Jag wheel fitment


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## brian_ (Feb 7, 2017)

mtrehy said:


> No, I am having driveshafts made for my application. Tesla hubs/brakes/wheels are too big and I needed standard Jag wheel fitment
> View attachment 123771
> View attachment 123772
> View attachment 123773


Nice.
So what hub/bearing units are you using? An old Jag wouldn't have come with a unit like that.


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## mtrehy (Nov 10, 2019)

brian_ said:


> Nice.
> So what hub/bearing units are you using? An old Jag wouldn't have come with a unit like that.


Indeed, thankfully the germans decided to use a stud pattern that can be made to work with little (to zero) modification

33411093371


7316577660657


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## brian_ (Feb 7, 2017)

mtrehy said:


> Indeed, thankfully the germans decided to use a stud pattern that can be made to work with little (to zero) modification
> 
> 33411093371
> 
> ...


I was going to ask "which Germans?", meaning "which German car does the hub belong to, which has a bolt pattern that works for your car?"... but from the part numbers it looks like a common BMW hub, used for multiple models.

I had guessed it was a sealed hub-bearing-carrier unit, but it appears to be a strange (which shouldn't surprise me from BMW) sealed bearing in a carrier plus a separate hub... which means that the stub of the drive axle presumably retains the hub in the bearing. The all-in-one units (including Tesla) are typically staked together, so while they can't be rebuilt, they don't need the axle shaft to hold them together. Not a problem, just an assembly factor to keep in mind.

The BMW bolt pattern is 5x120mm, and it looks like the Jags were 5x4.75". 4.75" is 120.65 mm; while that's very close to 120 mm, it's not the same - I wouldn't settle for that. I would expect there to be a hub-bearing assembly for an older GM model that would actually be 4.75", given that this was a very common GM bolt pattern and that GM has used unit bearing assemblies for decades, and while they are most common as non-driven hubs for the rear of front wheel drive cars, GM part #7470005 (from the front of a Chevrolet S-10 or 1979-1985 Buick Riviera, for instance) is a driven hub-bearing-carrier unit with 5x4.75" bolt pattern. 1984 and newer Corvette rears might work, too. There are other 5x4.75 vehicles, but many would not use these bearing assemblies, and I don't think Aston Martin or Lamborghini parts help much.  At least they're European, which might be better than looking for parts for GM North American models in the UK.

Do the Jaguar and BMW centre bores match? I don't know exactly which Jaguar and which BMW are being mixed, but it looks like Jaguar used 73.8 mm bore while BMW used 72.6 mm. I don't know if a centering ring rigid enough to ensure concentricity (i.e. not plastic) is practical for that combination. The GM hubs won't match the Jaguar centre bore, either, but as long as the hub is smaller than the wheel a centering ring can be used.

It would be handy if the splines matched between the Tesla side and the hub, even though custom-length axle shafts are needed... but I have no idea what splines any of these bits have.


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## mtrehy (Nov 10, 2019)

brian_ said:


> I was going to ask "which Germans?", meaning "which German car does the hub belong to, which has a bolt pattern that works for your car?"... but from the part numbers it looks like a common BMW hub, used for multiple models.
> 
> I had guessed it was a sealed hub-bearing-carrier unit, but it appears to be a strange (which shouldn't surprise me from BMW) sealed bearing in a carrier plus a separate hub... which means that the stub of the drive axle presumably retains the hub in the bearing. The all-in-one units (including Tesla) are typically staked together, so while they can't be rebuilt, they don't need the axle shaft to hold them together. Not a problem, just an assembly factor to keep in mind.
> 
> ...


Think you're looking at an older BMW wheel. The E39 has 74.1 centre bore so actually larger than the Jag 73.8

Anyway, thankfully this is a tried and trusted route with thousands of modified and race Jags in the UK fitted with the cheaper and more readily available BMW wheels.

You'd think you'd have to turn down the hub to fit the smaller Jag centre bore but in reality they fit which shows the manufacturing tolerances used on the Jag... In my pic you can see I have turned down the hub centre slightly (to match the Jag hub size) but when I bought new hubs I tried them in the wheels and they fit without reduction

So you're left with the PCD discrepancy which depending on your preference is:

Ignore it - it will be fine (not recommended)
Redrill it (I'd weld up the existing holes)
Obtain a hub that hasn't been drilled and drill to suit (expensive but available)
Use wobble bolts (cheap, simple and proven reliability)

BMW also gives you easy access to brake discs etc. In my case needing something small enough to fit under a 16" wheel. 

Not many chevrolet and buicks over here


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## brian_ (Feb 7, 2017)

mtrehy said:


> Think you're looking at an older BMW wheel. The E39 has 74.1 centre bore so actually larger than the Jag 73.8


I just followed the applications for the linked part, but must have slipped a generation somewhere. Thanks for the correction.



mtrehy said:


> Anyway, thankfully this is a tried and trusted route with thousands of modified and race Jags in the UK fitted with the cheaper and more readily available BMW wheels.
> 
> You'd think you'd have to turn down the hub to fit the smaller Jag centre bore but in reality they fit which shows the manufacturing tolerances used on the Jag... In my pic you can see I have turned down the hub centre slightly (to match the Jag hub size) but when I bought new hubs I tried them in the wheels and they fit without reduction
> 
> ...


Of those options, only redrill would be acceptable to me; yes people do a lot of things, but that doesn't make them right. I don't see any purpose in welding up the original holes, and I wouldn't want the potential heat distortion or change in hardness due to the heat of welding. At least in this case the hub is not integral with the bearing so you wouldn't have heat damage to the bearing.

If wheels fit despite a mismatch in centre bore, the wheels may simply be stud-piloted rather than hub-piloted - that was common many years ago, and is still done with trailers.



mtrehy said:


> BMW also gives you easy access to brake discs etc. In my case needing something small enough to fit under a 16" wheel.


Brake disks don't locate on the studs; they locate on the centre bore. Since fit to the studs is not critical, a slightly different PCD isn't a problem. But once you machine the hub centre, safe compatibility with disks intended for that hub is lost.



mtrehy said:


> Not many chevrolet and buicks over here


I do understand using what you can get locally!


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## mtrehy (Nov 10, 2019)

There's obviously no need to machine the part of the hub spigot that supports the brake disk, you can see that on the old hub that I machined to match the Jag spigot that the machining stops before the flange face leaving the shoulder for the disk to locate on.


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