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Discussion Starter · #1 ·
Dear DIY EV community,

I am working on a conversion to create a BMW 2002e in celebration of the first electric BWM from 1972. My aim is to meet the 50th anniversary of this visionary vehicle in 2022.

My story is that I believe in EV's and have a strong connection to the BMW 1602/2002. Last year I visited the Munich BMW museum and saw the 1602e. This was demonstrated in 1972 for the Munich Olympics.
See:

I would like to recognise @Tremelune in particular for his recent work and inspiration for me to start with the Nissan Leaf.

See below some photos of the current status:
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Current plans are to use the Leaf OEM parts (including possibly power steering, brakes, etc).

Fingers crossed I may have some assistance with getting the VCM re-programmed (watch this space .....) and re-use the charger/ inverter etc.

I am hoping to reuse the BMW gearbox with a simple converter (using Fiat/BMW clutch). I plan to reuse the display & gear selector from the leaf.

At the moment:

  • Nissan Leaf still works & is almost stripped of excess components. I have an I-key alarm but it seems Ok. I have not pulled the parts from the Leaf yet. The Leaf will provide the "heart and lungs".
  • BMW is stripped - ready for the transplant (heart and lungs).
  • Next steps are to plan the mounting motor in the BMW, work out where to mount the batteries, and strip as much as possible from the Leaf.

I would love to ask the community for experience in:

  • Dealing with wiring looms (and how to stripping what is not needed)
  • Battery housing (box or covers) to cope with "crash loading" so I can comply with transport regulations in Australia
  • Experience using Leaf power steering/ brakes in an EV conversion
  • Similar experience with BMW 2002/1602 EV's
  • What have I missed
  • Comments
 

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That looks like a good start :)

I am hoping to reuse the BMW gearbox with a simple converter (using Fiat/BMW clutch). I plan to reuse the display & gear selector from the leaf.
I'm not sure why you want to retain the whole BMW gearbox (the Leaf works with only a single gear ratio, and in 1969 BMW didn't use the gearbox), but it is the easiest setup to mount... and takes the most engine compartment space.

The Leaf shifter doesn't actually change gears - it won't work with the BMW transmission. Getting suitable messages for Park and Reverse to the rest of the Leaf system will be a challenge if you want to use the Leaf control systems intact. If you use the BMW transmission's reverse the Leaf stuff may not need to know it's not still going forward. There is no equivalent to "Park" in a manual transmission car, but the Leaf may need to think it's in Park as part of the shutdown and startup sequence. This has been solved by other builders, but they may be using various approaches to working with the stock Leaf controls.
 

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Discussion Starter · #3 ·
That looks like a good start :)


I'm not sure why you want to retain the whole BMW gearbox (the Leaf works with only a single gear ratio, and in 1969 BMW didn't use the gearbox), but it is the easiest setup to mount... and takes the most engine compartment space.

The Leaf shifter doesn't actually change gears - it won't work with the BMW transmission. Getting suitable messages for Park and Reverse to the rest of the Leaf system will be a challenge if you want to use the Leaf control systems intact. If you use the BMW transmission's reverse the Leaf stuff may not need to know it's not still going forward. There is no equivalent to "Park" in a manual transmission car, but the Leaf may need to think it's in Park as part of the shutdown and startup sequence. This has been solved by other builders, but they may be using various approaches to working with the stock Leaf controls.
Thanks Brian for the response. Much appreciated. You have got me thinking about the re-use of the gearbox. I understand the BMW (Getrag) gearbox ratio is 1st to 4th gear = 3.7/2.0/1.3/1. The differential is 3.6 ratio. Are you suggesting I use the output from the Leaf = 1:1 ie 4th gear straight to the differential? I see the low speed torque is great in the leaf.

The leaf performance (2012 model from ORNL) - page 12:

Compared with BMW 2002 ICE:
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My post was not clear re intentions for the Leaf gear selector. I was going to leave the BMW gearbox in a fixed gear(I was thinking 3rd or 4th) & then use the gear selector from the Leaf for actually driving day to day. In this case the BMW gearbox does not really do anything.
 

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The Leaf motor's torque is great, but not great enough to make 1:1 between the motor and the axle very satisfactory, whether that is the BMW transmission stuck in 4th gear (making the transmission just a space-consuming pile of ballast), or simply a shaft from motor to axle (omitting the transmission). The original 1602e omitted the transmission, but they probably had a motor which couldn't safely run fast enough to use much lower gearing, and they may have had a different axle ratio. The 1600 came stock with a 4.11:1 axle ratio, which would make 1:1 transmission ratio more acceptable, and even shorter gearing likely exists.

If you are not going to shift the BMW transmission you don't need a clutch; I assume the note about using a clutch meant just using the splined hub of a clutch plate to make a shaft adapter.

The stock Leaf runs around 7:1, so the BMW transmission in the 2:1 second gear (with the 3.6:1 axle) is comparable to the stock Leaf setup; first gear is too low to use all of the time (the speed of the car would be limited by the motor's maximum speed), third gear would give less torque at low speed (and thus less acceleration) but allow higher top speed if there is enough power (which is unlikely), and fourth gear is just pointless.

In any gearing comparisons, tire size must also be considered, but the 2002 and Leaf are not wildly different in that respect. Stock Leaf tires are about 10% taller (overall diameter) than stock 2002 tires, so the BMW would need 10% less gear reduction to get the same motor speed to road speed relationship.
 

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Discussion Starter · #5 ·
The Leaf motor's torque is great, but not great enough to make 1:1 between the motor and the axle very satisfactory, whether that is the BMW transmission stuck in 4th gear (making the transmission just a space-consuming pile of ballast), or simply a shaft from motor to axle (omitting the transmission). The original 1602e omitted the transmission, but they probably had a motor which couldn't safely run fast enough to use much lower gearing, and they may have had a different axle ratio. The 1600 came stock with a 4.11:1 axle ratio, which would make 1:1 transmission ratio more acceptable, and even shorter gearing likely exists.

If you are not going to shift the BMW transmission you don't need a clutch; I assume the note about using a clutch meant just using the splined hub of a clutch plate to make a shaft adapter.

The stock Leaf runs around 7:1, so the BMW transmission in the 2:1 second gear (with the 3.6:1 axle) is comparable to the stock Leaf setup; first gear is too low to use all of the time (the speed of the car would be limited by the motor's maximum speed), third gear would give less torque at low speed (and thus less acceleration) but allow higher top speed if there is enough power (which is unlikely), and fourth gear is just pointless.

In any gearing comparisons, tire size must also be considered, but the 2002 and Leaf are not wildly different in that respect. Stock Leaf tires are about 10% taller (overall diameter) than stock 2002 tires, so the BMW would need 10% less gear reduction to get the same motor speed to road speed relationship.
Some great points there. Thanks
 

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Discussion Starter · #6 ·
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Update: I now have what I think is the almost bare minimum system - interior wiring / control / body components. The car still drives and after some mistakes in disconnecting too much I think I have the parts I need.

Most external parts which are not needed also have been removed (lights, abs sensors, A/C - except heater and compressor).

The car is from Japan and imported to Australia. It came with an Electronic Tolling system which seemed to be hard spliced into the stock wiring looms. Does anyone have experience with removing that system?
 

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Discussion Starter · #7 ·
Some more progress over the weekend.

At the start:
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Lifting the motor. The drive shaft joints (CV's??) "pulled out" from the gearbox. I won't be using the gearbox so not an issue if I have damaged them.
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Lowering the battery. Note the furniture dolley's under the timber supports. 3 jack points.
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Battery out. I actually pulled it out frontwards after jacking the front of the car. It is on furniture dolley's.
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Engine bay wiring loom (very carefully labelling before removal). I can probably remove a few extra bits.
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Finally bits & pieces that will need to go into the BMW 2002. I have the body wiring loom in the box on the left and engine bay wiring on the right. Also the A/C compressor, brakes & dash components (including gear selector). I will try to reuse the brake booster if I can. The A/C compressor will need to go.
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Discussion Starter · #8 ·
After removing the gearbox I thought I would try a test fit of the motor.

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It is a very tight fit.
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Looking from above there is plenty of room front & back - but the steering box & water pipes are almost clashing.
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View from below. The old gearbox will bolt-on. The motor is sitting on the old engine subframe.
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This is the most worrying angle. The charger cover sits up too high. I am pretty certain it will clash with the bonnet. I think I can lower the engine subframe to get a little bit of extra height.
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The drive shaft joints (CV's??) "pulled out" from the gearbox. I won't be using the gearbox so not an issue if I have damaged them.
Yes, they are CV (constant-velocity) joints, and they normally pull out of the transaxle... but you have pulled them apart, leaving the stubs in the transaxle. These are of the tripod type. The transaxle should be fine, and even the joints and shafts may be okay if cleaned, repacked with grease, and reassembled with new boots.
 

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Nice. That thing looks great in there! Are you planning to fool the Leaf into thinking it's a Leaf? It's a somewhat all-or-nothing proposition.

I've had good luck using (clamped) metal elbows for the tight spots in the cooling...though you'll at least need room for the elbows.

For the PDC (the top box on the motor), you can gain some millis by pulling the cover off and replacing it with something thinner. one thought I had was to use the cover, but cut off the top so it was just over even with the highest electronics bit, then cover the whole thing back up with a simple piece of 2mm ABS plastic or aluminum. It doesn't hold coolant or anything; it's mainly there to keep out dirt and fingers. You could even angle it to slope with the hood if that makes the difference.

The PDC is also something you could pretty easily put in the trunk. It doesn't need to be close to the motor to charge and power 12V electronics (though I think it needs coolant). I would do one of these two things before modifying the hood or lowering the transmission. It looks like you're close.

I'm still not sure why you'd bother with Leaf brakes. I would just use the BMW stuff, and if there really isn't room for a vacuum pump, put one in the trunk and run a hose.

I've been ruminating about a front-engine, rear-wheel-drive conversion, and my plan has been to mate the motor to the transmission with no clutch, more or less only using 2nd and 3rd. It just doesn't seem like a big deal to come to a stop and shift from 2nd to 3rd at some point before getting on a highway, and then back at some point after getting off. You can also change the rear differential gears to kind of tune the revs and speed tradeoff...

I built a little gearing grapher...It's buggy and goofy, but helps me visualize with real numbers. I believe the EM57 gearbox is 8.19:


 

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Discussion Starter · #11 ·
Are you planning to fool the Leaf into thinking it's a Leaf? It's a somewhat all-or-nothing proposition.
Watch this space. I have some outside assistance that is looking positive ie I might be able to use key components and discard others. I will proceed with all-or-nothing in the interim.

For the PDC (the top box on the motor), you can gain some millis by pulling the cover off and replacing it with something thinner. one thought I had was to use the cover, but cut off the top so it was just over even with the highest electronics bit, then cover the whole thing back up with a simple piece of 2mm ABS plastic or aluminum.
Great idea. I had not thought about that. Do you know how much could be saved? I can probably gain 20 to 40 mm with some spacers between the body and engine subframe.

I'm still not sure why you'd bother with Leaf brakes. I would just use the BMW stuff, and if there really isn't room for a vacuum pump, put one in the trunk and run a hose.
I take your point. I was partly trying to get rid of the BMW vacuum boosters x 2. You can see one in the following photo. The other is below. It would be good to have it all in one system. The BMW actually had a neat removable panel where the existing master cylinder, clutch pedal is so it may actually be super easy to mount the Leaf booster there (along with the Leaf pedals).

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've been ruminating about a front-engine, rear-wheel-drive conversion, and my plan has been to mate the motor to the transmission with no clutch, more or less only using 2nd and 3rd. It just doesn't seem like a big deal to come to a stop and shift from 2nd to 3rd at some point before getting on a highway, and then back at some point after getting off
This is the current plan. My thinking is that I use the old clutch & the spline from the Leaf gearbox to make an adaptor. Or alternatively (as some other people have suggested on this forum) use a "Fiat clutch" and mate it with the BMW clucth to form an adaptor.
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I built a little gearing grapher...It's buggy and goofy, but helps me visualize with real numbers. I believe the EM57 gearbox is 8.19:
Cool - I will plug in the numbers & see how it looks.
 

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Great idea. I had not thought about that. Do you know how much could be saved? I can probably gain 20 to 40 mm with some spacers between the body and engine subframe.
It might only be a centimeter or two, depending on what's under the black plastic:


My main concern is the driveshaft angle. The angle at the differential has to precisely match the angle at the transmission or wear will accelerate greatly...so I've read. If you lower the transmission, you have to make sure it doesn't tilt at all.
 

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For the PDC (the top box on the motor), you can gain some millis by pulling the cover off and replacing it with something thinner. one thought I had was to use the cover, but cut off the top so it was just over even with the highest electronics bit, then cover the whole thing back up with a simple piece of 2mm ABS plastic or aluminum. It doesn't hold coolant or anything; it's mainly there to keep out dirt and fingers.
But isn't that top cover cast aluminum, as shown in the video posted later? While components within it are individually enclosed, I would still expect the top cover to have a shielding function, because Nissan probably would have used a plastic cover if they could.
 

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It is aluminum. My guess is that it's more about physical protection from crushing (based on the honeycomb reinforcement), but I don't know much about RF one way or the other.
 

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My main concern is the driveshaft angle. The angle at the differential has to precisely match the angle at the transmission or wear will accelerate greatly...so I've read. If you lower the transmission, you have to make sure it doesn't tilt at all.
Yes, mostly...

Traditionally a propeller shaft has universal joints (U-joints), which are used in pairs and mounted in phase. With U-joints, if the input (transmission output shaft in this case) and output (final drive pinion shaft in this case) are parallel, then the variations in angular velocity cancel out and the system runs smoothly; if they are not parallel the speed varies during each revolution causing vibration and increased wear. Despite this, they do tolerate some out-of-parallel, which happens with suspension travel in every live beam axle system.

Some cars don't use U-joints; at least at one end there is a flexible disk a.k.a. rubber doughnut a.k.a. giubo a.k.a. rag joint (known by brand names such as Rotoflex). With independent rear suspension the final drive doesn't move with the suspension, so the joints in this shaft need to accommodate only the minimal movement due to mounting bushing deflection. These joints need to run as straight as possible, and the angle at one end doesn't matter to the other end.

As is often the case with German cars, the 2002 shaft appears to add an unnecessary degree of complication: it has a shaft with a U-joint at each end, but the front joint is well behind the transmission, with an extra shaft section from transmission to this U-joint. There is a flex disk joint between the extra shaft and the transmission. If that's what you have, you want the flex disk to run straight, and the extra shaft section and the final drive's pinion shaft to be parallel. To be fair, it could be worse: some newer BMWs have all three types of joint (flex disk, U-joint, and CV joint) all in one two-piece shaft, for maximal complication and cost, minimal reliability, and inherent vibration. :rolleyes:

What all of this means is, if I have the right shaft design, lowering the transmission also requires lowering the intermediate bearing carrier (where the forward U-joint is)... as well as keeping the transmission at the same angle.
 

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Discussion Starter · #16 ·
There were 3 mounting points for the engine (2 mounts) and gearbox (1 mount). If the new Leaf motor is lower (and bolted to the gearbox) I can also put in a spacer to lower the gearbox mount as well (this is via a rubber mount). This will then lower all the components (shaft/ rubber doughnut) & with some care I should be able to get it all straight.
 

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If the new Leaf motor is lower (and bolted to the gearbox) I can also put in a spacer to lower the gearbox mount as well (this is via a rubber mount). This will then lower all the components (shaft/ rubber doughnut) & with some care I should be able to get it all straight.
That will keep it level (or at least parallel to what it was originally, but then there's this:
... if I have the right shaft design, lowering the transmission also requires lowering the intermediate bearing carrier (where the forward U-joint is)... as well as keeping the transmission at the same angle.
For the flex joint to stay straight, the intermediate bearing carrier must be lowered, or the motor and transmission assembly must be tilted (front end lower) as it is lowered.
For the U-joints to run at equal angles, if the motor and transmission are kept parallel to what they were originally, then the the intermediate bearing carrier must be lowered the same amount.
 

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Discussion Starter · #19 ·
Update: Very excited to say that I have proof of life!!!

Everything (needed I think) from the 2014 Nissan Leaf is reconnected.

It turned on ("brake pedal" on).

I got the "green car".

It went from Park to Drive & also Reverse. The motor was spinning.

Then it started to go wrong. The motor kept spinning and I could not put it in Park. I managed to get it into neutral but it still was spinning.

At this point in time the selector did not work.

My only option was to disconnect the 12 V and Leaf battery..... then it stopped.

Any suggestions for what may have gone wrong?
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Discussion Starter · #20 ·
After the need to cut power yesterday I was brave enough to reconnect the 12V and main battery (without putting into D or R). Thankfully it fired up and seems to be ready for action.

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I have not reserached the DTCs ...but this is what I have. It does not appear that these are critical.
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