Does anyone have a source for hardened Drive (Output) Flanges for a Medium Case Differential?
I have busted 2 and really need to find a solution other than going to a larger Diff.
Dan "PbFut" Rose
Don’t bother. I tried cyro treating them and broke 2 of those. Butters ordered billet ones from The Driveshaft Shop and snapped one of those.
First make sure you have the better ones. There are some older posts showing how some are cast slightly hollow.
Smart thing is to go 210mm if you can find one reasonably priced. I paid $200 for mine but that was in 2014. No one breaks the 210mm output stubs.
You could look into a Ford rear. I think 22RPD is working in a kit but it will include a subframe and be expensive. Maybe a 210 is so expensive now that the 22RPD kit is competitive?
Agreed, there really is no good solution. The e36 ones are solid core, but they have the retainer clip groove cut into them, and they break at that stress point. The e46 moved the ring to the nose, but made them hollow. We've broken the e46 ones a lot. I don;t think we ever broke the e36 ones, but obviously you need a diff that works with those (we have a built e46 diffsonline that uses e36 flanges).
The one thing we did try on the e46 ones is we had a shop make an insert and epoxy/press it into the hollow. That flange seemed to hold up from what I remember.
Thanks for the reply. Not what I was hoping to see.
Looks like a 210 may be in my future.
Dan "PbFut" Rose
I assume you are aware of the Rally Road weld-on adapter plate for the E36 subframe that works with the E32 750il 3.15 LSD. That is what I use with about 700 rwhp. There may be other 210 LSD that fit; some might mount differently. There is also the Euro E36 M3 rear subframe that holds a 210 LSD but you have to import one of those.
Thanks for the Rally Road tip. The car is a Z3M so it has the e30 subframe. Their kit is for a e36 frame. I have enough other welded supports, one or 2 more won't be an issue.
It appears the top two bolts line up the same as the 188 Diff. I assume the Output centerline is the same? If so, the two bolts would give me a easy start for fab'ing up the other mounts. Can anyone confirm this assumption?
But.... I seem to recall someone telling me the output flanges on the 210 are actually weaker than the 188 because the 210 flange is hollow. Is that true? I'm not having issue with the Ring and Pinion, just the output Flanges.
Dan "PbFut" Rose
No, you won’t break the 210 output flanges. I have launched on drag radials at 600+ rwhp and they are fine. With less power, I snapped 188 output flanges. I know of people running high 9s with these diffs swapped into E36. I don’t know the E30 fitment. It’s a bigger, heavier diff but I think you are right that the centerline is the same because the rear boomerang bushings bolt to the same subframe mounts that the 188 diff cover ear bushings bolt to. You’ll likely need a new DS as well — shorter and with a different end flange.
Last edited by pbonsalb; 07-02-2020 at 08:20 PM.
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