Broke diff. mount.

[LowR3V'in]

http://coupenut.blogspot.com/2017/09/randy-forbes-rear-subframe-reinfocement.html

The z3 bois look like they cut out the top and spot weld reinforcement plates as well.
This job is going to be super shitty..

[moatilliatta]

And definitely going to want to clean up all the cracked areas that will need to be welded. Not to mention you may discover other cracks to be welded. All cracks should have stop holes drill too to keep them traveling after welded. Slow welding, lowest heat possible as the metal is already fatigued and could just crack again later.

[Elysian]

you think this would fix it or na?

https://store.garagistic.com/e30-performance-parts/e30-secondary-diff-mount

Definitely a good idea.

[LowR3V'in]

you think this would fix it or na?

https://store.garagistic.com/e30-performance-parts/e30-secondary-diff-mount

[LowR3V'in]

i just welded the face of it because my car was catching on fire too much.
The diff mount broke again on a 2nd gear pull. What are men to do..

To do it right the the diff needs to come out so f it, it's staying hanging like that.

[moatilliatta]

I wonder how much worn subframe bushings play into this.

[e30davie]

Attack with wire wheel to remove all the paint and goop, weld it back together, inspect and replace bushes. Get back on the road and forget about it.

[e30austin]

We break them not uncommonly in racecars with solid subframe bushings

poly bushing, or solid bushings will make it even worst as the rotating torque has to go somewhere.

Quoted "dsphil" for total truth, but a new pair of poly bushings is better than a pair of completely roached, 350k mile, original subframe bushings. I'm pretty hard on my red shop rat, but luckily, I rebuilt the whole rear end, before the differential body mount failed.

[Ceeker]

e36 M cars were tearing their diffs off the mounts as well. We were welding re-inforcement plates to the floor then bolting the diff back to it. it was caused by too much dumping of the clutch and hard shifting.

[TobyB]

whut?

We break them not uncommonly in racecars with solid subframe bushings...

t

[dsphil]

The crack is mostly due to worn rear subframe bushings combine with hard driving and body rolling too much. 2 mount designs, poly bushing, or solid bushings will make it even worst as the rotating torque has to go somewhere. In some cases that is where the diff mount bolts start to tear off.

[JGood]

Agreed! I considered that as well, but it's more of a project than I want to dive into at the moment. Sure looks solid though.

[LowR3V'in]

this would be optimal

[JGood]

Mine cracked there as well. I was able to get in there with a wire wheel to clean it up, and mig weld it back together, without removing anything. It's held up for a few months so far behind an m60. My plan this winter is to drop the diff and weld a long piece of steel angle on both sides of that beam, and probably do the Garagistic 2nd diff mount.

[LowR3V'in]

in a way. but na, just street driving.