Terrible grinding noises from rear diff on L and R turns

[mshobe]

Recently acquired a '77 124 Spider (from the original owner!) – I am planning to convert it to a sportier EV version of its original self a la http://www.electricgt.com/electric-124-gte/. If I follow Electric GT's plan, I will reuse the original transmission and differential/driveline.

https://photos.app.goo.gl/QV4acyLm3WsyttjM2

I bought the car knowing full well the diff was in questionable shape; it makes some hilariously tragic grinding noises at any speed under power, when turning left or right. Presumably a spider gear problem. A fair amount of fluid on the casing, too:

Is the simplest solution for my '77 to acquire this rebuild and drop it in?
http://www.vickauto.com/newstore/index. ... ts_id=2038

I think the trans needs new seals as well, but that's a subject for a future post.

[Odoyle]

1) Pictures do not work
2) Don't bother trying to rebuild diff, find a donor axle from later car.
3) Unless you're an electrical engineer, or have a team of willing and trained people, an EV conversion project will likely consume YEARS of your life.

[focodave]

You may want to stock up on several gear boxes and several rear axles if your EV conversion has any amount of torque like the one in this video:
https://youtu.be/-ye1FVpT0N8

Good luck...

[mshobe]

Sorry about the photos; Google Photos fooled me into believing the URLs worked universally, but in fact they only work from 3rd party sites if I'm the one viewing them. Updated original post with this gallery link:

https://photos.app.goo.gl/QV4acyLm3WsyttjM2

As for a full donor axle - for sure I can do that, but I wondered if the pumpkin I linked to might be the drop-in replacement I most likely need (and it wouldn't require any special tools or calibration).

As for EV conversions, well, I realize I'm getting in the deep end of the pool. Fortunately I have a path to follow from those who've done it before as well some good consulting mechanics. It takes a village and all that. My goal really is to keep the spirit of what makes the Spider a great driving experience but massively improve the powertrain. That video is from the exact template I'm following, although we're going with a slightly less powerful motor and a newer gen battery solution.

[mshobe]

Turns out it wasn't the diff per se; instead, the forward section of the propeller shaft is abrading two bolts on either side. I think these bolts help secure the seat base/rails. The reason the shaft is traveling so much is because the panhard rod's frame connection bracket is cracked and loose, so the rear axle is all over the place in any turn. Definitely not open road-safe at the moment.

So: some metal work and welding, and then trimming those bolts back a bit for sure clearance, and I think I'm back to normal.

[baltobernie]

My goal really is to keep the spirit of what makes the Spider a great driving experience but massively improve the powertrain.

... then don't electrify it. The Spider driving experience is a light-weight, balanced, vintage ride. Power is modest, but in complete harmony with the brakes and suspension. Other posts about transmissions, axles, dollars and hours should be taken to heart. A couple of people per year begin posts like yours. One or two have succeeded.