# Has anyone modified a leaf gearbox to take power from the jackshaft?



## Zieg (10 mo ago)

I could have sworn I saw something about this once, but can't find it now. I thought it could be an interesting topic, though. 

I've been looking at motor options for my conversion and found (with no small amount of help from others on this forum) that a Leaf motor directly coupled to a rear differential isn't a good combination due to the reduction ratio involved. But what got me thinking was that the first stage of reduction in the Leaf gearbox is about 1.88:1 (depending on the year), and that opens up a lot of possibilities when paired with commonly available RWD differential ratios. 

Now I can't get much info online, but from watching Ben's teardown video it sure does look like the gears on the jackshaft (the intermediate shaft) are removable. You can just barely catch a glimpse of what looks like splines on the shaft. If anyone happens to have a torn down Leaf transmission that could confirm that, I would be very grateful. Here's a link to the page with the teardown videos and a handful of still shots so you can see what I am talking about. Nissan Leaf Transmission Tear Down - 300MPG.org

Since the main input shaft and the jackshaft both run on ball bearings and have reasonably close centerlines, I am considering designing a new case that would hold just those two gears, and perhaps the parking pawl mechanism. The motor side of the housing could be designed such that it would not only mount to the motor, but also serve as a mounting plate in the car. Then, I could whip up a new splined jackshaft that would accept the OEM gear, except instead of the grounding brush, the new shaft would end in either a keyway or maybe a yoke flange. If I do it right, it would even re-use the seals on each shaft. Possibly even the grounding brush.

Also worth considering is the fact that without modification, the direction of rotation would be reversed, but reversing the motor itself seems well documented, and if it's all going in a new case, it should be easy enough to design it to sling oil in the proper direction to keep it all lubricated. In theory, one could probably also modify the design to offset the output shaft to the left, right, above, or below the motor shaft.


Anyway, that's my latest crazy idea. Necessity is the mother of invention. Would love to hear your thoughts.


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## piotrsko (Dec 9, 2007)

If you're building a case, you can do any ratio you want from any maker of gears because you decide where the shafts are placed. You can do that somewhat with an existing case but ratios allowed are defined by the shaft spacings that the bearings allow minus the gear mesh. My Ranger 5 speed has 2 shafts and 5 sets of gears not including the reverse shaft and idler. Straight cut gears and ball bearings, so it whines, but EH......


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## Zieg (10 mo ago)

Yup, very true. I think the draw here is that a person could salvage parts from the OEM unit, to keep costs down. We already know the gear teeth can handle the power, the bearings can handle the RPM and so on. Since the teeth are helical cut, we also know the bearings can handle a bit of axial load, so the hope would be that they'd be fine transferring power to the front half of a two-piece driveshaft. 

I'm about this close to buying one just to tear it apart and start experimenting, haha.


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## piotrsko (Dec 9, 2007)

Find a place that repairs them and go visit. Afaik for playing, you don't necessarily need 100% functional. Might cost you a lunch and some time unless they are stupid cheap to own yourself.


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## TeZla (Feb 18, 2021)

Do it. Make one. But seriously, id keep it quiet until you've got a finished item. Get it all done up in cad so you can get a machine shop to process the cast blanks, then start talking to a foundry about a small volume run, 50 units maybe?
Next, start teasing the pics out from the beginning, building up momentum over a few weeks, before 'finishing' your prototype build just in time for the first 2 or 3 units to go on sale to anyone who wants to pay the money for the case, either supply their own leaf transmission and motor, or you'll sell the premium package all put together.
As those first few units sell, that'll fund the machining costs on the rest of the units.
include some mounting points that are expected to be useful in that mounting configuration and they'll get put in all sorts of cars.
Sell an extra unit that helps move the inverter off the top of the motor and then its begging to be put deep into the trans tunnel of a classic sports car, or a mx5...
There is nothing like that on the market. The DIY community will eat it up. Its essentially the evolution to the old DC forklift motor into a 5 speed rwd gearbox.

Edit.
If you're building your own casing, you could use any gearset you wanted, so long as you can connect it to the output shaft of the motor, preferably using the oem stub from the gearbox. that keeps the park brake. You could even maybe use a single gear selector and synchro from a diesel gearbox so the ratio is close and then you'd have a high/low gear, just like the awesome 80's arcade machines


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## brian_ (Feb 7, 2017)

piotrsko said:


> If you're building a case, you can do any ratio you want from any maker of gears because you decide where the shafts are placed. You can do that somewhat with an existing case but ratios allowed are defined by the shaft spacings that the bearings allow minus the gear mesh. My Ranger 5 speed has 2 shafts and 5 sets of gears not including the reverse shaft and idler. Straight cut gears and ball bearings, so it whines, but EH......


A Ranger transmission might have a straight-cut reverse, but not the forward gears. The best selection of ratios in gear sets are probably straight-cut because they're sold for racing, but production vehicle transmissions have been helical for the past few decades.


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## remy_martian (Feb 4, 2019)

A pair of gears from a catalog costs half the price of a new transmission. 

Repurposing what's there is smart, since a couple of billets, & machining that includes a custom jackshaft will easily set you back about $5-$6k if not $10k. 

Many shops are also backed up for a couple of months.


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## Bratitude (Jan 23, 2020)

I’m working on a replacement set for the leaf gearbox. Mainly for 4x4 applications, as would allow to use the leaf gearbox to replace the transfer case. but with a spool or welded diff would work great for rwd application too.


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## remy_martian (Feb 4, 2019)

What kind of ratio from motor to spool?


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## Tremelune (Dec 8, 2009)

This would be a big deal, if the costs could be kept to a grand or two. Right now, RWD conversions involve keeping a manual transmission (heavy, complicated) or adapting to a $3,000 2:1 TorqueBox (which is overkill for a Leaf or Hyper9 that most use). I think most would want the output shaft to connect to a "standard" driveshaft yolk...or whatever could be easily adapted to a lot of driveshafts.

Right now the best alternative is to use a (giant) Lexus hybrid transmission instead of a motor...


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## Bratitude (Jan 23, 2020)

remy_martian said:


> What kind of ratio from motor to spool?


the first initial replacement gearset will result in a 4.41 reduction. Potentially more options in the future.



Tremelune said:


> This would be a big deal, if the costs could be kept to a grand or two. Right now, RWD conversions involve keeping a manual transmission (heavy, complicated) or adapting to a $3,000 2:1 TorqueBox (which is overkill for a Leaf or Hyper9 that most use). I think most would want the output shaft to connect to a "standard" driveshaft yolk...or whatever could be easily adapted to a lot of driveshafts.


I think I’ve come up with something that shouldn’t cost an arm and a leg. a few design tricks I’m keeping quiet about for now….

I have stubs shafts coming out shortly for the leaf gearbox, the outer splines fit VW flanges, so that’ll make drive shafts quite easy to adapt. Especially anything that uses a 108mm cv joint.


The next piece to the puzzle will be sorting out the open diff it self. 
a quaife ATB would be real nice!


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## remy_martian (Feb 4, 2019)

Tremelune said:


> This would be a big deal, if the costs could be kept to a grand or two. Right now, RWD conversions involve keeping a manual transmission (heavy, complicated) or adapting to a $3,000 2:1 TorqueBox (which is overkill for a Leaf or Hyper9 that most use). I think most would want the output shaft to connect to a "standard" driveshaft yolk...or whatever could be easily adapted to a lot of driveshafts.
> 
> Right now the best alternative is to use a (giant) Lexus hybrid transmission instead of a motor...


The GM "crate motor" appears to give what you are after.

You won't get a billet case for 2 grand. Using the existing case keeps costs down, but it's a lot of precious volume eaten up by a whole lotta nothing (spool).

Put your hand up if you're finding too much empty volume in your builds where you can't think of anything to stuff into it or if you're so bored you can't wait to chop up the driveshaft tunnel so you or your mistress can sit sideways in your conversion like old Corvette jockeys used to.

Therein lies the value of a torquebox. It may be "overkill", but it isn't unwieldy like a transaxle used to couple to a driveshaft.


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## Tremelune (Dec 8, 2009)

I'm confused. What I want is a Leaf motor with no axles and a single, somewhat centered output shaft at approximately 2:1 reduction, for the purpose of mating to a traditional driveshaft and rear differential. Is that what we're talking about here?

Turning the motor sideways to use existing axle outputs is...uncompelling.


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## remy_martian (Feb 4, 2019)

Agreed. But for some people it's acceptable so more power to @Bratitude for giving it a shot.

But to strip the primary reduction stage down to its panties, you need two new billet/cast case halves, or get really creative with a sawzall and patching the ensuing hole. My brother suggested a weldment of plates instead of original case when I was looking at hogging out a billet, but even that requires machining.

One thing that MAY work is taking a slice off the axle-end of the assembled case using a Bridgeport, then adding a cover plate to keep the slick wet stuff inside. There are some guys in Canuckistan that do that with Powerglides to get the monolithic bellhousing off.


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## Zieg (10 mo ago)

Ok, glad to have been able to start a conversation about this! 

You guys are right that one huge CNC'd billet at commercial pricing would be cost prohibitive and this whole idea revolves around the premise of being a low cost DIY solution. I did think about cutting the oem case and welding it shut, and still may consider that. I also have a manual mill that I could use to hog out the better part of a billet, and a friend with a CNC that could take care of the important stuff. That would at least suffice for a proof-of-concept.


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## Bratitude (Jan 23, 2020)

Tremelune said:


> I'm confused. What I want is a Leaf motor with no axles and a single, somewhat centered output shaft at approximately 2:1 reduction, for the purpose of mating to a traditional driveshaft and rear differential. Is that what we're talking about here?
> 
> Turning the motor sideways to use existing axle outputs is...uncompelling.


then the torque box is for you.

I have thought about making a replacement input shaft for a borg Warner t5 transmission with female leaf splines. would make for a compact unit.


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## szac (Mar 11, 2021)

Bratitude said:


> I have stubs shafts coming out shortly for the leaf gearbox, the outer splines fit VW flanges, so that’ll make drive shafts quite easy to adapt. Especially anything that uses a 108mm cv joint.


So for example in a 4WD truck conversion, are you saying that this would replace the original transmission and transfer case, and the Leaf motor would be mounted under the vehicle?


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## piotrsko (Dec 9, 2007)

Plate should be sufficient and tons more available and lots cheaper for a one off experiment done on a bridgeport. If you have the time money and numerics then go ahead and use that but billet is wasting chips for no mechanical advantages. Precision pin it with dowells when youre done, tis what we did for space applications.


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## Zieg (10 mo ago)

Yeah, true that. It also depends on the dimensions of the gears, I guess. Does anyone happen to have any internal gears floating around? Even some basic dims would help me get started designing while I try to buy one for myself.



Tremelune said:


> I'm confused. What I want is a Leaf motor with no axles and a single, somewhat centered output shaft at approximately 2:1 reduction, for the purpose of mating to a traditional driveshaft and rear differential. Is that what we're talking about here?


Yeah, that's what I'm talking about anyway. I think Bratitude has an awesome idea for 4wd/awd applications though. It is a separate project with a separate use case.


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## Bratitude (Jan 23, 2020)

szac said:


> So for example in a 4WD truck conversion, are you saying that this would replace the original transmission and transfer case, and the Leaf motor would be mounted under the vehicle?


yes exactly



piotrsko said:


> Plate should be sufficient and tons more available and lots cheaper for a one off experiment done on a bridgeport. If you have the time money and numerics then go ahead and use that but billet is wasting chips for no mechanical advantages. Precision pin it with dowells when youre done, tis what we did for space applications.


This. I’m building out adapter plate “kits” done this way. Universal cnc’d adapter plates for motors (NEMA B-face). The rest thin plate for adjusting backspacing, etc. 

Maybe there’s a transmission subsection that wouldwork as a preliminary reduction, while maintaining the “inline” factor + diy/ cheap


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## Tremelune (Dec 8, 2009)

Ah, I understand! I don't mean to downplay these ideas—both have their applications—I was just getting lost in the discussion of two very different applications.


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## dedlast (Aug 17, 2013)

I know this is a bit late to the discussion, but here are two pictures that may help a tiny bit. One is the jackshaft and the input shaft next to each other at about the right alignment. For the super detail oriented, I have the bearings pulled off of the input shaft and the spacer on the jack shaft bearing is in a weird spot. The next picture is the transaxle housing clamped down to my little mill as I'm starting to shave off the parts I don't want any more. 

The jack shaft has a brush contact to ground (earth) making something of a nipple. That could make it difficult to use it as an output shaft. I'm pretty sure that whole thing is hardened, too.



















Just because, this is what the housing looks like now. I think I need to do some more shaving on the hole on the left
to make room for the hub I am going to use.









B


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## remy_martian (Feb 4, 2019)

For those who don't like brain contortions, lower pic is flipped:


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## remy_martian (Feb 4, 2019)

Interesting approach. 

You're still going to need to ground out the rotating assembly, somehow - Tesla didn't in the early days of the LDU and wound up killing the roller bearings with arcing.


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## Zieg (10 mo ago)

dedlast said:


> I know this is a bit late to the discussion, but here are two pictures that may help a tiny bit. One is the jackshaft and the input shaft next to each other at about the right alignment. For the super detail oriented, I have the bearings pulled off of the input shaft and the spacer on the jack shaft bearing is in a weird spot. The next picture is the transaxle housing clamped down to my little mill as I'm starting to shave off the parts I don't want any more.
> 
> The jack shaft has a brush contact to ground (earth) making something of a nipple. That could make it difficult to use it as an output shaft. I'm pretty sure that whole thing is hardened, too.
> 
> ...


Oh wow that's awesome, thank you for sharing! If you have the jack shaft handy, can you confirm if it is in fact splined for the gears?


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## brian_ (Feb 7, 2017)

Zieg said:


> ... If you have the jack shaft handy, can you confirm if it is in fact splined for the gears?


This video shows a teardown of a 2013 Leaf transaxle:




At 7:12 it looks like there are splines just below (toward the motor end of the shaft) the bearing; unfortunately, that's as far as the teardown of the intermediate shaft goes, so the construction is still not clear.
I wouldn't be surprised if the small gear is integral with the shaft, and the large gear (the one wanted for this single-stage gearbox modification) is splined onto it... but I don't know


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## brian_ (Feb 7, 2017)

it doesn't really help with the Nissan Leaf project, but I think it's interesting that this Leaf transaxle modification is essentially what BorgWarner did themselves with their 31-03 eGeardrive transaxle to make the SR-309 single-stage gearbox; both are available from Cascadia Motion. Although the SR-309 is "built using a pair of gears from the time-proven BorgWarner 31-03 gearbox" and bolts and couples to the same motors, it appears to use none of the 31-03 case - not even a truncated version of the same shape. I don't know if there are any shared internal components other than the gears themselves, although logically the complete input shafts could be shared.


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## dedlast (Aug 17, 2013)

"If you have the jack shaft handy, can you confirm if it is in fact splined for the gears?"

I took a wander back to the shop and I see what look like splines under the large gear on the jack shaft. I think the small gear is machined in place. I would have to pull the bearings off to know for sure.

B


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## Zieg (10 mo ago)

dedlast said:


> "If you have the jack shaft handy, can you confirm if it is in fact splined for the gears?"
> 
> I took a wander back to the shop and I see what look like splines under the large gear on the jack shaft. I think the small gear is machined in place. I would have to pull the bearings off to know for sure.
> 
> B


Awesome, just as I thought. Thank you very much! I am going to try to buy one next week and will update when I get my hands on it.


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## Bratitude (Jan 23, 2020)




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## remy_martian (Feb 4, 2019)

That splined gear is begging to have a flange bolted to its face. 

In fact, a "shortie" Powerglide output shaft might be a good place to start....


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## Greengear (Mar 27, 2019)

This is exactly what I dream of doing with my conversion project, repurpose a leaf gear box to run a traditional rwd drive shaft and diff. 
following intently.


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## Zieg (10 mo ago)

Well, my gearbox has arrived. The residual fluid looked kind of nasty, but thankfully everything looks fine internally. Thanks to all the teardown videos floating around, I had it apart in a couple minutes tops. There are pry points (and dowel pins, be careful) all around the case, and not a ton of sealant. A few whacks and a bit of prying was all it took.

Time to break out the measuring instruments and get to it...


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## Zieg (10 mo ago)

Started to CAD up the stock parts today. The large gear on the jackshaft is 32 teeth and about 106.0mm outside diameter. The mating gear on the input shaft is 17 teeth and about 62.4mm outer diameter. The center-center distance of the shafts looks to be 77.0mm.

That's pretty close but not exactly a match with a MOD 3.0 gear pitch. From an online calculator, MOD 3 gears would have a slightly smaller OD and the C-C distance is 75.2mm. I might have to do more research here. I don't think it's worth worrying about too much, but it would be nice to be able to mathematically verify the nominal C-C distance of the shafts. I'm also wondering if Nissan spaced them a bit further apart intentionally (we already know they adjusted the ratio slightly at one point, and may or may not have adjusted the casting accordingly).

What's more 'pressing' is the splines on the jackshaft. After removing the snap ring, I had to actually use a press to get the gear off the shaft, which I was not expecting. I'll have to be very careful to correctly spec these out for the new shaft. All I know for now is the OD of the splines on the shaft are about 38.2mm and there are 36 splines.


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## Zieg (10 mo ago)

Still plugging away. I don't have the tools I need to properly measure some of the features, so I'll set out to buy a couple things next week. Namely a set of gage blocks and a straight edge so I can pick up some of the faces on the stock housing (to locate the bearings relative to the motor front face etc).

Until then, I laid out what I could and just extruded a crude housing around everything to get the creative juices flowing. If I'm building it out of plate I will probably have a formed sheet in there to help catch and sling oil from the bottom gear up to the top gear/bearings. I used Bratitude's hole pattern for the motor plate, so thank you for that.

Presently shown is a 1.125" keyed shaft on the output end (just like a Hyper 9), which could accept a 1310 driveshaft end yoke such as a Spicer 2-4-503.


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## Oregonian (Aug 6, 2018)

Bratitude said:


> View attachment 129010


Would the corresponding input shaft gear happen to be removable as well?


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## Zieg (10 mo ago)

Afraid not. It's cut right into the shaft. It also appears to be a custom pitch, so I don't think any OTS gears are going to mesh properly. 

Current model state for what it's worth. Working on the oil splash path now, but it's challenging and I don't have any simulation software so it's all going off intuition.


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## Oregonian (Aug 6, 2018)

Does anyone know a good source for pre made helical gear sets that show dimensions and what the center spacing is?


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## remy_martian (Feb 4, 2019)

Boston Gear, Mitsui, Stock Gear Products, McMaster-Carr come to mind off the top of my head. 

It's almost as cheap to have them made by my observations. Am also interested if there are easy and inexpensive sources, bonus if they can reverse the custom modulus gears some dickhead OEMs like to spec out.

Center spacing is application and lube dependent, afaik. (PD1+PD2)/2 is a zero clearance starting point for centers.


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## Oregonian (Aug 6, 2018)

I was thinking of trying to find the proper gear set ratio, hopeful with the same spline to replace the larger gear that came off, then machine off the smaller gear to have the same spline and press both gears on. Probably won’t get the right inner spline AND also have the proper ratio with spacing. In that case, have the spline machined to match the new gear and the smaller gear machined off and splined ready for pressing of the new gears.


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## brian_ (Feb 7, 2017)

Oregonian said:


> Does anyone know a good source for pre made helical gear sets that show dimensions and what the center spacing is?


All I can think of - from the automotive world of my interest - are alternate ratio and racing gear sets for specific transmissions. An example would be the motorsport gearkits from Quaife. They're normally documented only by straight-cut versus helical, dog ring versus synchro hubs, ratios, and what transmission they fit.



Oregonian said:


> I was thinking of trying to find the proper gear set ratio, hopeful with the same spline to replace the larger gear that came off, then machine off the smaller gear to have the same spline and press both gears on. Probably won’t get the right inner spline AND also have the proper ratio with spacing. In that case, have the spline machined to match the new gear and the smaller gear machined off and splined ready for pressing of the new gears.


This is the problem of using gear sets for a specific transmission: the spacing between shaft centerlines, the spline or bearing that they ride on, width of the gear, etc. are all characteristics of the transmission. Shaft spacing is well known for common transmissions, but I doubt that's collected in a tidy table anywhere. Sometimes it is embedded in the transmission name: my Ford Focus had an MTX 75, which means 'manual transaxle 75 mm shaft spacing'.

In a conventional manual transmission, any gear set which is shifted in and out of the power path has one gear fixed to the shaft (machined integrally with it, or splined on) and the other spinning on a bearing with some dog ring or similar feature on the side to engage it. That makes drop or transfer gears (such as the pair which take drive from the input shaft to the layshaft - a.k.a. intermediate shaft, a.k.a. countershaft - in a conventional longitudinal gearbox) the most likely candidate, but those are typically integral with their shafts. Alternate ratio final drive sets (the ring gear and the gear driving it) are available for some transverse transaxles and could be used with a flange for the ring gear, but the ratios are high.

Traditional quick-change axle centre sections use a pair of gears to transfer drive from the input shaft (below axle centreline) up to the bevel gear pinion shaft. The gears sets are available in various ratios, they are identically splined on both shafts so they can be used in either reduction or overdrive configuration, and those splines are slip-fit to allow those quick changes. Unfortunately, it's unlikely that any match the Leaf shaft spacing, and they are only available in relatively low ratios.


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## Zieg (10 mo ago)

Yeah, I think it would require having a custom gearset machined. Would have to tell them the shaft spacing, spline dimensions and desired ratio, then they would have to calculate the pitch to match. Pretty sure that's what Nissan did with the OEM gears, since the pitch does not match any common off-the-shelf options that I can see.


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## Greengear (Mar 27, 2019)

This project could really open up rwd conversions using leaf parts. 
Thank you Zieg for doing foundational work.


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## Bratitude (Jan 23, 2020)

this is all looking like some real good fun! i finally have the time to start on my little end, a replacement input shaft and gear set. 

currently working with 2 different spline specialist, on another project, but this is right up their ally. my plan is to have a replacement gear on the original intermediate shaft, and the same male splines on the new input shaft. being that i don't need to mesh with the stock leaf gears at all, ill be going with a of-the-shelf tooth pattern.

if we could possibly all come to an agreement on what that tooth pattern should be, that would be the most ideal!


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## Zieg (10 mo ago)

Bratitude said:


> this is all looking like some real good fun! i finally have the time to start on my little end, a replacement input shaft and gear set.
> 
> currently working with 2 different spline specialist, on another project, but this is right up their ally. my plan is to have a replacement gear on the original intermediate shaft, and the same male splines on the new input shaft. being that i don't need to mesh with the stock leaf gears at all, ill be going with a of-the-shelf tooth pattern.
> 
> if we could possibly all come to an agreement on what that tooth pattern should be, that would be the most ideal!


If you'd be willing to share your findings WRT the jackshaft splines, that would help me out a lot. I had to use a press to get the gear off the shaft, so I do know there is some kind of interference. I did a little reading and found that in some cases they intentionally machine a slight spiral into the splines of the gear or shaft as a way to add some interference and keep everything tight. Unfortunately I have no way of measuring these myself. If nothing else, I'll be referring to my copy of the Machinery's Handbook in hopes that I can identify some kind of standard.

As for the tooth pattern, I suppose module 3 might be a good standard, given how close the OEM gears are to that. Common helix and pressure angles. Of course it wouldn't match the shaft spacing but I assume that doesn't matter for your project.


And here is the latest on my model. So in keeping with the OEM housing, there are shims on the motor side bearings, and on the other side there are snap ring grooves with shims behind. I'm working on a way to fit the OEM parking pawl, but it will require an increase to the size of the box. Not a huge fan of that. So I am also mulling different ways to engage to the OEM parking teeth without adding to the size of the box.


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## remy_martian (Feb 4, 2019)

A module 3 for 17 teeth seems too small in diameter.


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## Zieg (10 mo ago)

Fair enough. I suppose it'd be better to go up than down. The 17t gear is about 62.4mm in outside diameter (not pitch diameter).


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## Bratitude (Jan 23, 2020)

more than happy to share spline details once i have it. from looking at mine, the splines are straight, but there's a "crimp" line deforming them to add the press fit.


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## Zieg (10 mo ago)

Ah, that makes sense. Should be easy enough to replicate, too. 

Also worth keeping mind is that for this design, the direction the gears are turning will mean that the axial component of the force on that gear will be in the opposite direction, trying to push it off the shaft. A heavier snap ring groove will be a must.


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## brian_ (Feb 7, 2017)

Zieg said:


> Also worth keeping mind is that for this design, the direction the gears are turning will mean that the axial component of the force on that gear will be in the opposite direction, trying to push it off the shaft. A heavier snap ring groove will be a must.


Sure, but unless torque is restricted in reverse and regenerative braking, the difference in axial directions is only in how often the force is in that direction, not whether there is ever force in that direction.


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## Zieg (10 mo ago)

Fair point. Not sure about torque, but speed is certainly limited in reverse. For all the effort it'll take, I'll feel better with something more substantial in there.


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## remy_martian (Feb 4, 2019)

The forward direction torque can be several times larger than the reverse or regen torque. Reverse should be limited in speed and torque by firmware.

So they can be very different.


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## Bratitude (Jan 23, 2020)

one thing i have noticed about the female splines on the intermediate gear is the 2 different spline geometries
this must have todo with the pressfit? or is the gear and shaft orientated in a certain way?

and i'm leaning toward using spur gears instead of a helical. just out of cost, for the 1:1. 
2 copies of the spur would be needed, instead of a left and right hand helix. reduces number of custom parts, and increases economies of scale


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## remy_martian (Feb 4, 2019)

Spurs are loud AF

Interesting that they have indexing grooves. I'd just omit them on the shaft 😈


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## Zieg (10 mo ago)

Wow, that is bizarre! Very curious as to why.

Trying to work out a way to fit the OEM parking pawl but it's not looking great. Might have to see if I can actuate it a different way. But once I sort this out (or abandon the idea) I think I'll be ready to produce fabrication drawings of the housing and send them out for quotes. Gonna leave these shots big so you don't need to squint.


















So my current thought is that I can make the lever work if I cut the top of it off and limit its travel in a different way. Then I could make a new actuator rod that comes straight out the top of the housing and uses some kind of ball detent to engage park or drive. The guide piece would just about work as-is, I might just have to grind it a bit (and/or clearance the housing...


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## Bratitude (Jan 23, 2020)

remy_martian said:


> Spurs are loud AF


 yup. but a much cheaper option for a functional prototype. once the new input shaft is done, what ever ratio and geartype could be done.
electric 4x4 with 2 spurs is still quieter than a 22re, let alone a straight piped one 


remy_martian said:


> Interesting that they have indexing grooves. I'd just omit them on the shaft 😈


ahh yes that makes sense


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## IronDingo (6 mo ago)

I want to do something similar to what bratitude was talking about and use the leaf motor and gearbox in place of the transfer case on a 4WD.
Swapping the gears on the input and layshaft would produce a pretty acceptable output ratio, ~ 1:2.3, but I understand the input shaft gear is machined on.
So I'm considering machining off the gear on the input shaft and machining a new spline that would accept a different gear, ideally the existing removable 32t gear from the layshaft, and then having a new corresponding 17t gear cut to go on the layshaft.

I also understand that the input shaft is hollow, so this may mean there's not enough material on it to machine on a spline that matches the existing removable gear.

The thought has also occurred to me that it might be possible to acquire a second input shaft, bore it out to the layshaft spline ID, broach in a new spline to match the layshaft spline and part the gear off and use it on the layshaft. 
This seems like a long shot as I assume the motor shaft bore continues down as far as the gear, unless the motor shaft spline OD is smaller than the layshaft spline ID or they happened to use the same spline on the motor shaft and the layshaft, but I think the odds of that are fairly low.

I don't have a gearbox yet to do any measurements, I was hoping if someone currently has one pulled apart and a motor handy, they could tell me the following:

The ID and OD of the layshaft spline.
The OD of the input shaft beside the gear on the motor side.
If the motor spline continues all the way inside the gear, then it would be good to know the ID and OD of the motor spline (and if this happens to be the same spline as the layshaft)
otherwise just the ID of the inputshaft at the gear


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## remy_martian (Feb 4, 2019)

What's your plan for the open diff? Nobody makes a limited slip for the Leaf that I know of, unlike the Tesla mod used by the Land Rover guys.

If you don't take care of that, you'll have the opposite of the Subaru spiel:

The IronDingo transfer case "transfers power from the wheels that grip to the wheels that slip"


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## IronDingo (6 mo ago)

I haven't been able to look at the inside of the diff yet, but it might be possible to use / trim down an existing LSD kit with a similar shaft pin diameter. If it absolutely can't be made to work then LSDs or lockers front and rear would still give you two driving wheels in any situation.


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## Tremelune (Dec 8, 2009)

There is a somewhat mythological LSD for the Leaf:



Leaf gear box nismo LSD - openinverter forum


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## brian_ (Feb 7, 2017)

Tremelune said:


> There is a somewhat mythological LSD for the Leaf:
> 
> 
> 
> Leaf gear box nismo LSD - openinverter forum


In that discussion bratitude commented:


> sadly this nismo lsd is not the right kind for a 4x4 application, as it will not transfer torque when there is 100% slip. A ATB would be ideal...


In fact, Quaife's ATB is a helical gear diff, as is the Nismo unit. Neither one can transfer all torque to one output; the ratio of the higher output torque to the lower one is known as the "torque bias ratio", and about 5:1 is the highest that can be expected. Some drivers drag the brakes slightly to provide resistance when one wheel is completely without traction (usually off the ground) in extreme off-road conditions when using this type of differential at the axle (such as in the HMMWV/Hummer H1).


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## remy_martian (Feb 4, 2019)

IronDingo said:


> I haven't been able to look at the inside of the diff yet, but it might be possible to use / trim down an existing LSD kit with a similar shaft pin diameter. If it absolutely can't be made to work then LSDs or lockers front and rear would still give you two driving wheels in any situation.


Locking hubs front and rear won't do anything unless you run a permanently locked spool in the "transfer case". If you lock a rear hub and freewheel the front, you won't move, otherwise.


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## remy_martian (Feb 4, 2019)

The best approach is to diddle the ABS, but nobody I'm aware of in DIY has boldly gone where no one has gone before.


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## Zieg (10 mo ago)

Yeah if it's for a 4x4 system I'd just be welding the spiders and using air hubs in the front. 

As for those measurements, I probably have most of that already, save for the ID of the shaft. I was planning to do some drawings for all the parts I'm working on, but I've been a little sidetracked getting the house ready for a baby on the way. Give me a few days and I'll try to get at least those initial drawings posted. Can also give STEP files if that's useful.


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## IronDingo (6 mo ago)

Zieg said:


> Yeah if it's for a 4x4 system I'd just be welding the spiders and using air hubs in the front.
> 
> As for those measurements, I probably have most of that already, save for the ID of the shaft. I was planning to do some drawings for all the parts I'm working on, but I've been a little sidetracked getting the house ready for a baby on the way. Give me a few days and I'll try to get at least those initial drawings posted. Can also give STEP files if that's useful.


That'd be great, thank you. If you have the STEP files it'd be helpful, but don't do any additional work, sounds like you have more pressing issues.

A good point on just locking the centre diff and using free wheeling hubs to disconnect the front wheels.


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## IronDingo (6 mo ago)

remy_martian said:


> Locking hubs front and rear won't do anything unless you run a permanently locked spool in the "transfer case". If you lock a rear hub and freewheel the front, you won't move, otherwise.


I meant a diff locker rather than locking wheel hubs, but a permanently locked centre diff and freewheeling hubs is definitely an option. The first thing to do is to figure out altering the ratio of the leaf gearbox without breaking the bank. That said there's quite a bit of room on price between altering a leaf box and using the tesla motor + reduction gears.


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## remy_martian (Feb 4, 2019)

If you can live with about half the peak horsepower (they can put out 300hp at high revs), you don't have to change a damned thing in the spool-locked Leaf xfer case other than maybe deeper ring and pinions in the diffs. You only need 30-50 hp on the highway...

Full torque is from almost zero...


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## IronDingo (6 mo ago)

remy_martian said:


> If you can live with about half the peak horsepower (they can put out 300hp at high revs), you don't have to change a damned thing in the spool-locked Leaf xfer case other than maybe deeper ring and pinions in the diffs. You only need 30-50 hp on the highway...
> 
> Full torque is from almost zero...


My understanding is that the leaf motor's max RPM is around 10,300, with a reduction of 8.19 further reduced by say 4.5 by the differential, that'd bring the vehicles top speed to about 40 kph / 25 mph on 30" tires.


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## remy_martian (Feb 4, 2019)

I guess I didn't say it clearly. Drive the transfer case with the motor, no gearbox. You should be able to get around 40-50hp that way at highway speed and keep the 4wd. Bob's your uncle for stump pulling if the tc has a low range.


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## IronDingo (6 mo ago)

remy_martian said:


> I guess I didn't say it clearly. Drive the transfer case with the motor, no gearbox. You should be able to get around 40-50hp that way at highway speed and keep the 4wd. Bob's your uncle for stump pulling if the tc has a low range.


That is quite a good point. Looking at the transfer case on the r50 terrano I'm looking at converting, it has a low ratio of ~1:2 which is pretty close to what I was trying to achieve with the leaf gear box, without having to get any gears cut. It seems I couldn't see the forrest for the trees.


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## Zieg (10 mo ago)

Here's an export of my current status if anyone is interested in taking a look. I was playing with adding a wedge to help direct the oil splash towards the bearings, but not sure if it's a great idea. I also wanted to add dowel pins in the corners but haven't got around to it yet. I uploaded the three housing pieces to one of those CNC instant quoting websites, and it was $1400 USD. Also it flagged the snap ring grooves and deep holes through the center section as potentially problematic. I wasn't able to input the actual tolerances for the bearings so not sure what those would actually come out at. I have to say that cutting up the stock housing is looking more and more appealing, haha.






Onshape


Sign in to Onshape, the #1 fastest growing CAD system in the world with over 2 million users.




cad.onshape.com





This link should let anyone view the model, and if you create an account you can copy and modify it. For some reason the top became the bottom - the actual top is where the breather is. The NPT hole on the side is for filling and the hole on the bottom is of course the drain. Don;t mind the backplate, it's just a rough approximation for visualization. 

The height of the fill port is somewhat arbitrary, I wanted the oil to be high enough to reach the bearings when at rest, but I don't know if it should be higher or lower. Too much and it could have frothing issues, too low and it could have overheating issues among other things.


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## dedlast (Aug 17, 2013)

I was really struggling with getting CAD drawings done on the Leaf parts I wanted to draw until the Mechanical Engineer at work pointed me to OnShape. I had all the parts I wanted done in less time than it took me to not finish one part in the program I was trying to use.

Let's see if my Leaf folder will link into here for those who might be interested. (Hmm. It may require an account to view at the folder level)
Onshape

I am working toward using part of the transaxle housing at this point in time. We'll see if I still think that way next month/year...

Bill


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## remy_martian (Feb 4, 2019)

Grabcad is a good place to distribute files. STEP format seems like it works most of the time. I've never had much luck with IGES.


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## Zieg (10 mo ago)

Yeah that link doesn't work @dedlast, even when logged in. It says I don't have permission. Are there too many documents to link individually? Really interested to see what you have. 

As for Onshape itself, I have mixed feelings. Coming from Inventor/Solidworks it felt like Onshape belonged in a happy meal or a cereal box, but over time it grew on me. It is at least a good tool to have and if you know how to exploit its advantages it can make certain things a lot faster. It's also great that it's free, as long as you don't mind your designs being public.


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## Stuey (6 mo ago)

If you want a straight drive off the idler gear this Tesla mod may give you some ideas








Tesla Small Drive unit modified


Esta es la solución perfecta para una transmisión de eje trasero, barco y todo tipo de aplicaciones.




evshop.fr


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