[s-cars] cracked rear subframe - B5 A4

[JC]

Taka - 
 
Agreed, re: E46 subframe failures for which in fact there's even a class
action settlement as well as a BMW pre-emptive repair/recall policy. The
primary failure people are talking about with the subframe shows up as the
subframe mounting points tearing through the floor pan in the rear. I've got
the M3 cab which theoretically gets a beefed up subframe already so (he
prays) unlikely to fail especially if street driven vs. hard track driven.
Some think (hope/pray) that if you keep an eye on the also known-problem
Rear Trailing Arm Bushings (RTAB's)  you can preempt the subframe from being
damaged, I'm not so sure I believe it.   
 
But that's all different from the swaybar mounting points, which also do
fail on the E46 but I'd not heard from stock swaybars - only from beefy
aftermarkets that were driven hard.  If it's true for OEM bars it would
surprise me but I suppose it's possible, I've just never heard about any
complaints there at all unless its a very hard driven car with monster
Ground Control / UUC / H&R / TMS / etc. sways. 
 
@tedebearp - are you talking about the subframe mount tearing problem, or a
sway bar mount problem? 
 
(And re:E30's yeah I thought they had had the same issues with big
suspension mods causing tear-outs but freely admit I could be wrong on
that... )
 
[...he says awaiting mod execution for polluting an S-car list with E46
Bimmertalk...] 
 



  _____  

From: Taka Mizutani [mailto:t44tqtro at gmail.com] 
Sent: Wednesday, July 28, 2010 9:59 AM
To: JC
Cc: s-car-list at audifans.com
Subject: Re: [s-cars] cracked rear subframe - B5 A4


John-
I've not heard about this with an E30, but the E36, E46 and even E90 have
this issue of subframe mounting points failing. This is with stock cars
without any modification.

The fix for the suspension mounting points on the BMW is to weld in gusseted
reinforcement plates. Although it could be worse- my recent research into
the E36/7 and /8 is that the rear diff is mounted to the floorpan sheetmetal
in those cars- very bad failure mode for that one.

For Lee's problem, I agree- weld the crack, weld in some reinforcement
plates and call it a day.

Taka





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