I need a manual transmission from an 850. Ideas?

Post by **ThaddeusTheBold** » 26 Apr 2022, 13:58

Hi again,

I am looking for a manual transmission (transaxle) from an 850 for the electric conversion of my V70.

I have the traction motor and my motor controller is almost complete. I'd like to source the transaxle and mate it to the motor for development and testing. I'd like to get everything working right and then just drop the whole completed motor/transaxle unit into the car. I'm not having much luck finding a transmission, though.

Ideas?

Post by **hausmeister** » 26 Apr 2022, 15:58

Pretty sure you can find a manual in sweden or europe. Wrecking/salvage etc, I see some on ebay for 300-500€ checking quickly.
Not sure if that helps you though.

Post by **abscate** » 26 Apr 2022, 16:25

You don’t need a gas motor transmission with an electric motor. Just a final drive

Post by **ThaddeusTheBold** » 26 Apr 2022, 18:55

Yes you do, if you are using a DC motor with advanced/clocked brushes.

Post by **abscate** » 26 Apr 2022, 23:45

I’m not familiar with that. What does the torque curve look like?

Post by **ThaddeusTheBold** » 27 Apr 2022, 04:31

Flat. Total torque from bottom end to top end. Most people just start out in 2d or 3rd and drive the car around like that.

From what I'm told, You advance the brushes when you are going to overvolt the motor and over rev it because the flux 'smears' and you need to adjust the pulse timing. But by advancing the brushes, you lose the ability to reverse the motor by flipping polarity. So I need a transmission so I can have reverse. I also might like a top gear for highway work, although this is going to be a running-around-the-city errand car.

Post by **abscate** » 27 Apr 2022, 04:46

Couldn’t you return the brushes to a static mode for reverse? Putting in a lossy transmission into an electric is a “real toilet paper on the shoe “ solution.

What efficiency gain do you get with brush advance? Trans and diff losses are 15% or so.

454cid · Post by **454cid** » 27 Apr 2022, 05:07

abscate wrote: ↑27 Apr 2022, 04:46 Couldn’t you return the brushes to a static mode for reverse? Putting in a lossy transmission into an electric is a “real toilet paper on the shoe “ solution.

What efficiency gain do you get with brush advance? Trans and diff losses are 15% or so.

Reverse gear simplifies the electronics greatly I'm told. I recently watched a video where one of the electric conversion/parts companies built a race car (Beemer, I think) that they took to Pikes Peak. They were letting a guy demo it on the street and it was insanely fast/powerful. The guy was just giddy driving it. They bolted two motors together to a GM Powerglide transmisson, and reverse gear was one of the reasons they sited...much simpler electronics.

Edit:

I didn't realize till now how old these videos are.

Post by **volvolugnut** » 27 Apr 2022, 08:19

Regardless of the use of the any gears besides reverse, you still need the differential and mating parts to the drive axles. Sourcing a manual trans that works with the chassis sounds like a good solution.
Keep us updated. This is interesting.
volvolugnut

Post by **ThaddeusTheBold** » 28 Apr 2022, 13:22

Motor controller. Yes, simplicity in my electronics are a necessity.