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Discussion Starter · #2 ·
Donor Vehicle:
2000 BMW 323i E46 w/ blown head gasket (maybe?) and 5-speed manual tranny

Range:
120 to 150 miles if possible.

Speed:
Nothing to set your hair on fire, just a runabout.

Ideas:
  • Go the EMW way and use a Warp 11 motor with a StepTronic tranny
  • Go the EVWest way and use 2 Warp 11s and a TorqueFlite tranny
  • Use a Tesla rear end and retrofit it.
  • Use a Leaf motor and battery pack.
  • Direct drive with a motor bolted on the different.
Seeing as I have absolutely no experience in this sort of thing, any advice or help would be greatly appreciated.
 

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Ideas:
  • Go the EMW way and use a Warp 11 motor with a StepTronic tranny
  • Go the EVWest way and use 2 Warp 11s and a TorqueFlite tranny
While EV West lists all sorts of old junk on their website, I don't think that brushed DC motors and converted automatic transmissions are "the EV West way" any more. They don't even list an automatic transmission or parts for converting with one on their site.

I don't recall anyone ever using TorqueFlite (Chrysler) transmissions in conversions, although antique Powerglides were common for a while.

Is "EMW" Electric Motor Werks (eMotorWerks)? They've been gone for a long time, absorbed into Enel X, which doesn't do or support conversions.

I can't imagine wanting to keep the weight and complication of any automatic transmission (such as the BMW's stock StepTronic) in a conversion.
 

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Thank you for your help. You are right. I knew that eMotor Werks has been out of business for years. I meant in their conversion that was in posted in the forums.
Starting new build: BMW 3-series (E46) -...
Wow, that's old. The car would be a museum piece now.

I only skimmed the thread looking for the word "transmission", but I didn't see any indication that they ever made the StepTronic work.

As for the transmission, would the 5- speed in my car work, or is it the same situation.
Assuming that you are capable of shifting a manual transmission, it would be lighter, simpler, and cheaper to convert than any automatic, although it would still have the extra weight and complication of five more gear sets (including reverse) than necessary.
 

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Im a little biased, But I say make it direct drive, Ideally a telsa motor, but with lots of modding skills you could use a leaf motor and transaxle too.
Once you remove the fuel tanks and diff, you have lots and lots of space for the new motor to go, lining up the driveshafts perfectly with the axle hubs. Modify the original diff cradle, which also holds the suspension mounts, to carry the motor and transaxle. You can extend the cradle to bolt to the chassis further back and all the soft mounts can be removed because the motors have their own rubber mounts.
Its a big job for sure, but at the end of the day you have an OEM motor and transmission that should mechanically last for a few hundred thousand kms of life without trouble. It'll drive essentially just like the car it came out of. It then also leaves the entire engine bay and transmission tunnel free to put your batteries. You could probably fit a whole Chev Volt battery pack in the tunnel and engine bay, that'd give you decent range, 100-150km or so depending on the life of your battery cells. It also balances all the weight through the chassis really nicely and evenly, really low for good center of gravity and between the axles so the car will handle really nicely.
 

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Would it be more cost and weight effective to do a direct drive then? And what would that entail?
That depends what you mean by "direct drive", but anything replacing the car's original multi-speed transmission with fixed-ratio reduction gear set would be lighter, simpler, and more compact.

Literally, it means that something drives something else, directly, with no intervening mechanism. In practice in an EV that could mean a motor driving a wheel without any gearing between them - that's only done with in-wheel motors, and no one is suggesting that (yet), because it's not likely to be a good idea.

Usually in this context, it means a motor driving the input of a final drive unit (diff) or axle without any reduction gearing between them. That can mean via a shaft (such as from a motor mounted where the transmission was) to the original final drive (perhaps with a different ring-and-pinion gear set in the final drive for an "axle ratio" with more reduction). It can also mean the motor mounted right onto the front of the final drive, if there is room there (and there usually isn't, but it has been done). Regardless of location, this can work well if the motor can produce enough torque for the result (after final drive multiplication) to be adequate at low speed, and if the motor speed corresponding to driving speeds allows the motor to produce enough power for those speeds. That's a really low-speed motor compared to what is normally used in modern EVs. You have only a single stage of reduction gearing (the BMW ring and pinion gears) with a ratio in the range of 3:1 to 5:1, instead of the two stages of reduction gearing in a typical EV transaxle with an overall ratio in the range of 7:1 to 10:1.

Im a little biased, But I say make it direct drive, Ideally a telsa motor, but with lots of modding skills you could use a leaf motor and transaxle too.
Using a complete drive unit (motor and transaxle) from a production EV makes a lot of sense. It's not "direct drive" in any sense, but it's still a good solution. ;) The Tesla "motor" would be a complete drive unit with transaxle, just like the Leaf unit.
 

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Discussion Starter · #13 ·
Thank you for explaining what direct drive really means. I do think using a Tesla or Leaf motor and/or transaxle on the rear with no diff is a great idea. Any idea how much it would cost to get a unit? And what about batteries? Any suggestions?
 
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