Yet Another Diff Thread

rb1971

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I have looked through the archives and have yet to find a complete answer to my current diff dilemma. I welcome any thoughts.

The situation: I've destroyed two diffs now, likely due to high torque output and spirited driving. The first was a 40-year-old LSD - so failure was understandable and predicted - but the latter was a custom race diff and I was surprised to destroy it. (Maybe other folks on the Targa were surprised to have nasty diff oil all over their windshields, in which case I deeply apologize for any inconvenience.)

It seems to me there are three possibilities:

1. Get another rebuilt side loader.
2. Swap in the E28 subframe to get access to later diffs. I almost did this during my build process.
3. Swap in just enough pieces to allow use of the later diffs.

I would appreciate recommendations for #1, although Metric Mechanic is currently top of my list.

I would appreciate thoughts on 2 and 3 (and 2 vs. 3), as well as cautionary notes from anyone else that has done either of these swaps, or started down this path but quit due to difficulty or other problems (parts, etc.).

Thanks in advance,
John
 

bfeng

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Are they failing from heat or simply exceeding the stress

Rating on the materials and parts
If its just too much torque you could have it regularly rebuilt (ala race car style maintenance).

If its heat, why not run a diff oil cooler?
 

rb1971

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I think it's torque (although the first one was a stopgap while the second was being built and that's really on me for beating on a 40-year-old set of moving parts). The problem is that the expertise and parts to build these seem to be getting harder to find, while even when you've spent a lot of $$ to do so you end up with a product inferior to a modern style diff - which is why I'm interested in the last couple of options.
 

sfdon

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Have you spoken with Pete at Pete's Gear Shop?
He does a lot of the diffs and tranny's for the Bay Area BMW
groups. I just sent one of his diffs to Infineon last month.
I have LSDs in all of the hot engine cars I do and the only issue
Seems to be front seal leaks from other guys than Pete.
 

shanon

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Hi John,

Curious how much power you have at the wheels?
My brothers racer had 275hp at the wheels and never had issues with diffs.

The conversion to an e28 rear end is a huge undertaking. The Rogue/Cuffy Crabb cs racer runs an e28 set up, and said that it was a huge PITA of a conversion.

Sorry to hear of your mechanical in the Targa.

Mario at VSR seems to know his way around side loaders too.

-shanon
 
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