# SSE 3 seat performance custom build



## dain254 (Oct 8, 2015)

I haven't conjured a name for this build yet, but I did a little design work this weekend working on the layout. I'm planning to build a 4-wheeled ariel atom type machine with borrowed seating layout from a McLaren F1. The idea is that I could potentially sell completed vehicles, kits, or plans!

As for chassis, the front end will be based heavily on Miata - the prototype will utilized everything from wheel to wheel including the K-member, much like the SSE CozE that I've already completed. 

Power and driveline, I will create a trailing link type suspension (not shown in the model yet) that will hold the motor and single chain reduction to the rear on each side, which may eventually be replaced by belts... I wanted to eliminate the CV's due to efforts of minimizing losses wherever possible. I'm planning to use a motenergy ME1507 to drive each rear wheel and a Kelly 96601 controller to feed power along with a pair of 4kwh Chevrolet Volt modules for energy storage. For simplicity of designing I plan on using seperate charging and battery management systems. 

Peak Power should be around 150hp... judging by the weight of the SSE CozE I've already built I believe I can keep this vehicle under 1000lbs pretty easily. Should be fun! Any comments or ideas feel free to post... I also thought if I need more range I could use Tesla lithium modules that were built for Toyta Rav 4 EV's.

I looked into using a large DC brushed motor as well... it would give me the same amount of power for about the same money but would require the need for a differential whereas running two motors eliminate the need - for a 4 wheel custom built vehicle to become street legal here in Iowa it is required to have some sort of differential. 

Attached are a couple quick snaps of what the design is looking like so far.


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## Duncan (Dec 8, 2008)

Drop the dopey two motor idea and you have the basis of a nice car!
Have you thought about using a Leaf power unit in the back?


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## ken wont (Jul 6, 2016)

Duncan said:


> Drop the dopey two motor idea and you have the basis of a nice car!


If you do use two motors you really should use two motor controllers and a traction controller.


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## dain254 (Oct 8, 2015)

I guess my wording above wasn't clear - this would require a pair of controllers. 

I definitely don't agree with "dopey" as a word to describe the dual motor setup... it can actually be done fairly streamlined and cheap. I've already worked out discounted prices for a pair of motors and controllers I intend to use. 

I have considered using a Leaf driveline, as well as a Smart, Focus, Bolt, 500e... one of the goals is to create something that is relatively repeatable, so relying on the majority of my drive to come from a salvage yard does not fit that bill. Batteries I can always pay double and source from CALB if I need to!

There is an electric MEV rocket I've seen being built on this forum that is also using a "dopey" 2 motor setup, I've seen nothing but praise to that gentleman. Sure the motors in that vehicle are connected, but they still feed a chain driven differential and CV axles, which are eliminated in my design. I'll post some more CAD snapshots as I progress... if it still seems dopey by the end I'll consider higher something else!

One cool aspect of dual motor is the ability to run 1 forward and 2 backwards, for insane donuts!!!


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## Yabert (Feb 7, 2010)

Nice model! I like the three seats configuration.
If I understand right, you don't have side windows... I can't wait to see the kind of mud guard you plan to protect the faces of passagers from anything comming from front wheels 

Waiting for 3D CAD details of your drive system.


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## dain254 (Oct 8, 2015)

Thanks Yabert! The front wheels will have fenders similar to those on the "CozE" vehicle I built a couple years ago, shoudln't be a ton of debris from the wheels making it into the passengers, although the seats are really there for more novelty than anything else. I may switch back to standard 2 seat... 

As for the drivetrain, I started modeling a few parts I couldn't find anywhere and laying them out. It is going to be tricky to integrate the motors into the trailing links but it looks doable. I want to keep them integrated so as the suspension moves it doesn't change the chain tension or create any torsion on it. I'm currently using chain drive for my 3 wheeler and it works perfectly for drive and regen - the motor is integrated into the rear swingarm on that design.


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## MalcolmB (Jun 10, 2008)

Hi Dain,

I like the layout so far, though personally I would go with simple drive shafts from each motor to the rear wheels. I don't think there would be much difference in efficiency between CV joints and chain drive, but that's just a matter of preference.

I'm curious where you got the figure of 75 hp per motor from? The few sources I can find for the ME1507 quote 85 Nm stall torque and 6000 max rpm, which give a theoretical peak of 71 hp, but I'm not sure if you can actually use the stall torque at max speed.


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## dain254 (Oct 8, 2015)

I'm probably being optimistic at 75hp/motor... if they even do 50 or 60 it should still be fun. The efficiency in eliminating the CV joints comes from eliminating them along with the gear reduction in a differential housing... but running 2 chains I get the efficiency loss once per side, but total loss would still be similar to a single bevel gear reduction in an oil bath (differential). 

I am looking into the single larger motor design again for simplicity reasons as well as being able to keep the Miata rear suspension geometry, which will save me time and effort designing my own! Since I don't want to go over 24s due to my own personal knowledge of BMS and limitations associated to that, I limit my top speed with the miata differential (4.1) to 750RPM at the wheel (so.. 55-60mph if the ME1002 does 3100RPM at 96V. I'd need around a 30" OD tire to make my top speed 70mph. It would definitely rip off the line... 

I saw a cheap Azure electronics motor/transaxle/controller listed somewhere for 1500 bucks but it doesn't look like it has much power. I may end up chain driving a differential with the larger motor - we shall see!



MalcolmB said:


> Hi Dain,
> 
> I like the layout so far, though personally I would go with simple drive shafts from each motor to the rear wheels. I don't think there would be much difference in efficiency between CV joints and chain drive, but that's just a matter of preference.
> 
> I'm curious where you got the figure of 75 hp per motor from? The few sources I can find for the ME1507 quote 85 Nm stall torque and 6000 max rpm, which give a theoretical peak of 71 hp, but I'm not sure if you can actually use the stall torque at max speed.


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## Duncan (Dec 8, 2008)

Hi Dain
If you use swinging arms for your rear suspension then the tires will roll with body roll,

This is OK for a drag car but it will severely limit your cornering ability - the old minis had rear swinging arms but their rear tires didn't actually do a lot

Your model has nice wide wheels - the wider the wheel/tire the more important it is to keep it as flat with the ground as possible


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## dain254 (Oct 8, 2015)

Duncan - I am planning a type of "swinging arm" if I do not stick with Miata rear components. If I was using a rigid swingarm on each side you would definitely be correct in assuming adverse handling. 

The trailing link style I'm working on requires 2 tie rods which are used for camber and toe adjustment, where the wheel is not constrained to camber with the body. I am working on my CAD model and then I think all will become clear! It is kind of a cheater way of doing a "5 link" style suspension, where a forward/backward trailing link in this design will hold my motor, shock mount, and control the thrust/drag of the tractive force. Should be cool, might be a mess


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## Duncan (Dec 8, 2008)

I look forwards to seeing the design

I am unable to envision any way of having the wheels tilt relative to the main chassis that would not either twist the chain drive or involve the motor moving relative to the chassis

But maybe you can come up with something!

For use on a relatively smooth surface like a race track I always wanted to try front and rear beam axles 
Light rigid beam axles constrained to the chassis with something like a five link 
But that would require CV joints 

Why don't you like CV joints? - properly designed they are very long lasting and 99.9% efficient

If you wonder about the efficiency of a CV joint simply check the temperature - you can put hundreds of Kw through a CV joint for hours with almost no rise in temperature


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## dain254 (Oct 8, 2015)

I modeled up a quick design to check how the layout would work. The main "trailing link" is connected up front via heim joint to allow it to twist, and the motor is rigidly attached to the link so there is no relative movement between the sprockets. The motor will move along with the trailing link, but not a lot since it is close to the pivot point. The rear upright that holds the wheel bearing is also rigidly attached to the trailing link. 

The two rear links are simple tie rods with heim joints at each end. camber can be adjusted by shortening one and lengthening the other - toe can be adjusted by shortening or lengthening both equally. 

The shock could actually be attached a number of places... it could be placed between the motor and upright and lean forward aside from where I've got it in the model. Anywhere it is mounted will require a heim joint connection

Ideally the trailing link would be longer so there is minimal fore and aft movement of the tire during jounce and rebound... but I am really only looking to have 6" of travel or so... which will keep it somewhat minimal. The biggest hurdle of using this is having enough space for my big sprocket! Here is a pretty crude representation of what it would look like... please keep an open mind. 










Duncan - I don't have anything against CV joints, they are great! If I could direct drive my motor without a reduction or use a gearbox they would definitely be the way to go - but since I plan on using a chain drive in my opinion it is just extra mass in the sense of sprung, unsprung, and inertial! The chain drive I can transmit my power from motor to axle as well as accomplish a speed reduction. If I go single big motor I'll use the CV's.


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## ken wont (Jul 6, 2016)

Hopefully with light weight, fully enclosed, plastic chain guards!


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## dain254 (Oct 8, 2015)

ken wont said:


> Hopefully with light weight, fully enclosed, plastic chain guards!


Yes, I noticed on my other vehicle that covering the chain made a big difference in the noise... which wasn't terrible to begin with - but all you hear now is wind!


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## electro wrks (Mar 5, 2012)

So, have we moved from marginally practical 3 wheelers to somewhat more practical 4 wheelers? Sorry. I'm actually working on marginally practical motorcycles myself!

As Bill Dube' and others have pointed out, having separate motor drives can produce a large yaw moment if one of the drives should fail. This might put the vehicle in the ditch or worse, into oncoming traffic. This reminds me of the yaw issues the SR 71 aircraft had with an engine flame-out at speed. Pilots variously described the events as "train wrecks" by the way they were thrown around in the cockpit! AIR the design fix was to have a system that automatically sensed a loss of power in one engine and quickly reduced power in the other engine.

Maybe something similar could be designed into vehicles with separate motor drives.


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## dain254 (Oct 8, 2015)

electro wrks said:


> So, have we moved from marginally practical 3 wheelers to somewhat more practical 4 wheelers? Sorry. I'm actually working on marginally practical motorcycles myself!
> 
> As Bill Dube' and others have pointed out, having separate motor drives can produce a large yaw moment if one of the drives should fail. This might put the vehicle in the ditch or worse, into oncoming traffic. This reminds me of the yaw issues the SR 71 aircraft had with an engine flame-out at speed. Pilots variously described the events as "train wrecks" by the way they were thrown around in the cockpit! AIR the design fix was to have a system that automatically sensed a loss of power in one engine and quickly reduced power in the other engine.
> 
> Maybe something similar could be designed into vehicles with separate motor drives.



In theory a person would think that a large amount of yaw would lead to adverse handling... but should one drive quit and the other still not break traction the driver wouldn't feel anything except sluggish performance and a slight tendency to pull in one direction. Think of it like driving along and hitting a patch of snow or ice with one of the driving wheels - same effect. The car will continue to track straight and that will will simply spin. Hitting a slick spot this way doesn't cause a veer into the ditch or traffic. 

The SR71 example doesn't really relate - if I were designing an electric vehicle that relied on roller blade wheels to keep me straight a foot in front of each tire then absolutely... on the blackbird the yaw controlling device being the vertical stabilizers nearly at the point where the thrust comes out - absolutely there would be some nasty yaw if you all of a sudden turned off 40k lbs of thrust (don't know the actual amount). 

I certainly admit practicality is marginal, but there is really no reason to compete with a FocusEV, Leaf, or Tesla as the big auto manufacturers are already doing a better job of that than I ever could... This vehicle is purely to offer the driver (and passengers) a fun experience.


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## dain254 (Oct 8, 2015)

Speaking of marginally practical motorcycles... I built an electric dirt bike a couple months ago to race in an endurocross - finished 3rd in the +30 class, 2kwh volt battery, ME1008 brushed motor, 550A 48V controller... runs about like a 250F for 45min-1hr. I completed the whole night of racing on 1/3 of the battery charge. Only improvement it needs is controller cooling!


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## dain254 (Oct 8, 2015)

Got a chance to do a little more design work last night - This is likely where the motor will end up if I choose to go with a large single. It would also serve as an elbow warmer for the passengers! I'm picking up the miata differential case from a friend this evening - after I get that modeled I will be able to determine where the motor will actually sit and design a coupler to mate it to the stock gearbox. 

At 100V, the ME1002 motor I've selected looks like it will spin 3300rpm lightly loaded. The lowest ratio Miata diff I've seen is a 3.9, so that leaves me with 850RPM axle speed at my top end. Doing some quick calcs with a 26" OD rear tire give me a top speed of 65.43mph. That will work fine for around town and back and forth to work! If I want to go faster I will add more voltage. Here is what it looks like:

















I'm speculating that I will be able to slide the motor back a little depending on how the Miata diff is oriented, I figure this scenario as worst case. The Miata diff has a nice 4 bolt flange that will be super easy to adapt the motor to.


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## electro wrks (Mar 5, 2012)

It's good to see you abandoned the goofy (dopey?) separate motor design. Dube' pointed out that many manufacturers have come up with SM designs and later, most quietly abandoned them for designs like your latest. Their legal departments must have assessed the higher liability issues from failures in the SM designs.


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## dain254 (Oct 8, 2015)

I still disagree that any adverse handling effects would be caused by the dual motor setup if it were done properly... anyway - my reason for leaning single at this point is the possibility to add more power later. the dual motors i had chosen would be at their peak starting off with no where to improve if I decided I need more power.


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## dain254 (Oct 8, 2015)

The model hasn't progressed too much, aside from putting in a windshield and some 17x7 wheels with tires. I did determine in the rules for my state that I will need a safety glass windshield that is 6" tall... so I may hide a piece behind the curved plexiglass in the model - maybe use it as a heads up display.

Hardware Battery: I made a deal on a complete Volt battery from a 2014 for $1200, so I will be picking that up later this week. The idea as of right now is to run 2S2P on 2kwh modules (so [email protected], 88V nominal?) to get me moving and add more later. I noticed on my dirt bike project that not all modules are created equal as one pack dies faster, so I wanted to make sure all my volt cells were from the same car. The Volt had 57k miles on it. 

Hardware Controller: I was looking to use a Soliton JR, but after doing some reading on the forum as well as contacting them directly I checked out ZEVA's website, pretty impressed with their integrated solutions for controllers and BMS not to mention they are mostly recommended by forum members. I may get in contact with them and see if I can get a 1000A controller on the way! The ultimate goal of the project is to beat the fastest Tesla to 60, so I'll need at least 200kw for 2.27 seconds for that!


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## galderdi (Nov 17, 2015)

Hi, that looks awesome. I can't wait to see it in reality.

Where are you located?

I have the Zeva 1000amp controller. You won't get 200KW of power out of it. So far I have set mine at 750amps and 170v and the most I have managed is 70KW. So I think the most you can hope for is around 100KW.

Aside from that technicality I would still recommend the Zeva controller.

But is that 200KW allowing for your reduced weight? Maybe you won't need that much.


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## dain254 (Oct 8, 2015)

I'm located in Cedar Falls, Iowa

I have noticed that most controllers don't put out the kind of power that they are rated for... 200kw would be a worst case scenario to meet my ultimate goal, and I definitely couldn't draw that off of only 8kwh of volt modules (that'd be 1000A/piece. Even 70kw would get it moving at a nice pace for now. If everything works as it should I may be able to get there with 160-170kw. 100kw it will still be extremely quick!

Should be able to start building here in a few weeks once I get the battery disassembled and stored as well as get the model a little further along.


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## Duncan (Dec 8, 2008)

Hi Dain
_I have noticed that most controllers don't put out the kind of power that they are rated for
_
You need to understand how they work
Your controller will give you the current that you command (with the throttle) - and that will give you a certain amount of torque

That works by the controller increasing the motor voltage until the motor current is equal to the demand current

My car has a 1200 amp controller and a 340v battery

When I am stationary it will take about 20v to get 1200amps
As motor revs rise the back EMF rises so the voltage required to push the current across the motor rises

Rpm
0 rpm - 20v - 1200amps - 24Kw
500 rpm - 13 kph - 70v - 1200amps - 84Kw
1000 rpm - 27 kph - 140v - 1200amps - 168Kw
2000 rpm - 54 kph - 280v - 1200amps - 326Kw
3000 rpm - 81 kph - would be over 340v - so 100% and 340v - 1200amps - 408Kw
4000 rpm - 108 kph - 340v - I will only be able to push 800 amps - 272Kw

So when using full throttle at about 3000 rpm I am using the full power of my controller
Above or below that rpm I will get less power

That controller with a 150v battery would only let me use about 170Kw


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## dain254 (Oct 8, 2015)

I can certainly see the theory behind it... but doesn't really give an insight into a controllers actual vs theoretical power (kw) output as opposed to calling power amperage. I believe my experience with this is due to Kelly controllers exaggerated ratings... You are absolutely correct that amps provide the given torque depending on throttle, and power is torque at an rpm. Will just have to order what works well for forum members and see what it will do!


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## Duncan (Dec 8, 2008)

Hi Dain
Theoretical?

Well in my 805Kg (900kg with me in it) device with 55% of the weight on the rear tires I can spin the back tires at will 

http://www.diyelectriccar.com/forum...dubious-device-44370p15.html?highlight=duncan

And I'm finding that I get better times with less power available!

I do like Paul & Sabrina controller - it's simple and very powerful - but I think I will need to sort out some sort of traction control

I'm using Galderdi's throttle reduction resister system - so simple even I can understand it


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## dain254 (Oct 8, 2015)

I get myself pretty easily confused with the theory and have made quite a few assumptions that I'm relearning, obviously the "device" rips. 

I'll look into the Paul & Sabrina controller! I'm definitely open to suggestions.


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## galderdi (Nov 17, 2015)

I know our purposes are all slightly different. True traction control is against the rules in my category. But what I currenty implemented is in two parts. 
The first is a dial that allows me to lower the resistance range of the throttle resulting in a reduction of the maximum power available and a spreading of the throttle range over a smaller power range increasing controlability.
The second is a dial connected to a button. When I push the button it further lowers the resistance range. So I can push the button for launch get some momentum going and then release it to reveal 100% power. 

But what I am finding is the second component (launch control) works well from a stationary launch but is no good when trying to do a very tight corner. Technically it works equally well in that scenario. But the problem is being able to take a hand off the wheel and find the button in mid corner.

So today I thought of an enhancement. The ideal solution would be some sort of motion sensor. At speeds less than say 10KMPH it would apply the throttle limit (lets say to 80%, but it would depend on the dial). Then once the speed was achieved it would release 100%. This would avoid much of the wheel spin you can see in my latest videos.


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## piotrsko (Dec 9, 2007)

Why not old school? Logarithmic taper on your resistance and a second throttle return spring.


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## dain254 (Oct 8, 2015)

I also want no traction control whatsoever... I want this thing to be a tail happy driver's machine! I used to do quite a bit of dirt track racing in Iowa - on a dry track pretending an egg was between my foot and the gas pedal was my traction control!

I may not be doing this correctly but the way I have been measuring power is across a shunt on the battery side as opposed to the motor side. The folks at Kelly have argued that this is not the correct way to determine motor power (which I'd agree... motor power would be less due to losses in the controller, wiring, motor, etc...) and that the motor power is somehow higher than what I'm reading coming from the battery. But they seem to think it is more...

I looked at some of my notes on back EMF last night (from my college days) - read some of the theory posted on the internet - I still am not confident I could apply it correctly. 

piotrsko - YES! Just scale up an old slot car hand controller, done!


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## Yabert (Feb 7, 2010)

dain254 said:


> I may not be doing this correctly but the way I have been measuring power is across a shunt on the battery side as opposed to the motor side. The folks at Kelly have argued that this is not the correct way to determine motor power (which I'd agree... motor power would be less due to losses in the controller, wiring, motor, etc...) and that the motor power is somehow higher than what I'm reading coming from the battery. But they seem to think it is more...


If you read volt and amps from the battery under load to give you an idea of the motor power, you are absolutely right.
From your explanation, I suppose Kelly said pure bullshit about motor power...


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## dain254 (Oct 8, 2015)

Yabert - I'm glad someone is seeing it my way! Pure bullshit would be an appropriate description! It's just convenient to place it on battery side because then I know my exact energy consumption.. which is the real thing I care about that keeps me from being stranded


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## galderdi (Nov 17, 2015)

piotrsko said:


> Why not old school? Logarithmic taper on your resistance and a second throttle return spring.


 Logarithmic taper would work but you would need to get it right first time. It is way too hard to find a potentiometer with exactly the correct resistance range mapping to exactly the right movement range. I prefer to be able to adjust it to the conditions using my dials.

I like the egg method. I had a driving instructor recomend imagining the steering wheel is a Parrot to encourage lighter gripping. After a practice run I came in and he asked how it went. I replied "Fine except for all the Parrot shit everywhere".

I also agree measuring the current from the battery should be a fair indication of total power (after allowing for some losses through the controller etc. Controllers are good but I haven't heard of one that can magically increase power.......Flux capacitor?


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## dain254 (Oct 8, 2015)

HA I like the parrot joke! All of my racing experience with 4 wheeled vehicles is in a circle on dirt, but I did race in the top class in the area for a few years "IMCA Late Model". Decided that the enjoyment wasn't worth the constant weekly maintenance to the vehicle and bought a boat instead. 

I also always considered the draw from the battery is a pretty fair way to gauge the power output... what is surprising is that I see a pretty flat amount of KW output from low to high RPM which goes against the back EMF theory... So I'd conclude root cause is that the controller just kind of gives up once it is outputting so much. 

Deciding how much a controller can put out for peak, I also take the highest voltage times the highest amperage - is there sort of a constant (.6, .7, .8, .9?) that I could apply to this figure to determine what it might actually put out? Or are all manufactures so wildy different that there is no way to judge it other than what others have experienced?


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## Baratong (Nov 29, 2012)

galderdi said:


> .... I haven't heard of one that can magically increase power.......Flux capacitor?


Funny you should mention it. I noticed yesterday that O'reilly auto parts sells them. Go to their web site and search for product "121G". ( http://www.oreillyauto.com/flux-capacitor.html ).

When I ordered one they said it is back ordered but maybe I'll receive it sometime last week.


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## ishiwgao (May 5, 2011)

Baratong said:


> Funny you should mention it. I noticed yesterday that O'reilly auto parts sells them. Go to their web site and search for product "121G". ( http://www.oreillyauto.com/flux-capacitor.html ).
> 
> When I ordered one they said it is back ordered but maybe I'll receive it sometime last week.


dont forget this part 

"Plutonium not Available at O'Reilly Auto Parts. Please contact your local supplier."


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