[s-cars] cracked rear subframe - B5 A4

[Theodore Chen]

Both.  The main issue appears to be the subframe mounts, but I was under the 
impression that the antiroll bar mounting points were an issue, too.  If the 
latter happens only with stiffer antiroll bars then we don't need to worry about 
it.

The main question I have to worry about that the 330i has Bilsteins on it now 
(with stock springs), after the OEM shocks wore out, and whether this would 
cause BMW to deny coverage if there is indeed a problem.

Luckily, I haven't had any problems of the sort with either the UrS4 or the B5 
S4, although they seem prone to eating CV boots.




________________________________
From: JC <jc at j2c3.com>
To: Taka Mizutani <t44tqtro at gmail.com>; tedebearp at yahoo.com
Cc: s-car-list at audifans.com
Sent: Tue, July 27, 2010 7:58:13 PM
Subject: RE: [s-cars] cracked rear subframe - B5 A4


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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