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Rear end creak, 01 330i

6.1K views 12 replies 6 participants last post by  compcrasher86  
#1 · (Edited)
Hey guys, I've noticed with the warm weather lately my E46 will develop a creak from the rear when its warm. Didnt happen when ambient temp was in the 40's. Doesn't happen until car has been warmed up and driven several miles. Accelerating or braking or loading clutch has no effect. It seems to be only on uneven pavement at very low speeds under 10mph. I've gotten underneath and scrutinized the subframe mounts, but I can't find signs of any cracking so thats a relief. When I had the PPI done back in September they said the same. Shocks and upper mounts were replaced last month, no change in the sound at all. I can also hear the noise faintly when I get out of the car and the suspension unloads.

Should I be looking at the front-most RTABs, the two by the hub, am I in the wrong spot by looking at the trailing arm?
 
#6 ·
Waited it out to see if it became more obvious, and now from underneath I found it. Looking at replacing the upper trailing arm ball joint. Held my finger on the bolt while lowering the car and I could clearly feel the creaking. Everywhere else felt normal. Koch tools master set on the way and going to do a trailing arm overhaul.
https://www.youtube.com/watch?v=HNDM9qcfLgo
 
#8 ·
I honestly thought about doing that, and it would probably do the trick. Somebody over on M3forum had success with it. The Koch master kit I ordered looks like it'll make this a quick job with the right tools. I also needed to do the RTABs anyways because things are feeling a bit floaty sp while I'm in there why not upgrade the lower bushings to M3 style ball joints. Finish it up with a rear end allignment and I'll know everythings nice and tight.
 
#10 ·
I believe I have the same creak on my -03 330ci. During the PPI the mechanic also checked the subframe, no problems there. However he told me the rear bushings needed replacement. According to BMW, there are two types of rear bushings. I'm familiar with the RTABs, but which are the other ones? Are the RTABs the ones causing the creaks? Thanks!
 
#11 · (Edited)
I could try to explain it but Mango already has a pretty good thread covering the parts and locations: http://forum.e46fanatics.com/showthread.php?t=1006058

I am avoiding Poly in the back because it really only provides one axis of rotation so you might end up with binding with a lot of suspension travel. I do autox on stock springs so I would really notice it in some of the turns. Vorshlag has a nice snippet explaining:
Many racers just blindly install polyurethane into this and all bushing locations as a "fix" for a worn OEM rubber RTAB bushing. Polyurethane is a bad choice for a bushing material if it has to deflect - such as in a multi-axis suspension bushing location like the RTAB. Rubber bushings + limiters or a complete replacement with a custom steel spherical bearing are the only two textbook choices for this location. We have seen a number of RTAB failures on BMWs that were using poly in these areas - an expensive repair and a dangerous racing situation. At the very least poly will add bind during significant suspension movement, and this can make the handling feel odd (unexplained oversteer) as well as add significant stress to the suspension-to-chassis mounts (which is how they can fail over time).

That said, some folks with fully track prepared race BMWs have had OK results with polyurethane RTABs. This is due to the much higher spring rates and smoothness of tracks they tend to run with - higher spring rates and smooth tracks limit suspension travel, and thus limits the potential for bind from a polyurethane bushing at this bushing location. So even though you may hear good results from one racer, it doesn't necessarily mean that poly RTABs are the right choice for you. If you have a street car or dual purpose BMW you should always stick with OEM bushings and RTAB limiters, and even many race prepped BMWs use this setup with excellent results.
I've done a bit of research and personally I'm going with Z4M Lemfoerder bushings, vorshlag limiters, and Lemfoerder ball joints in the other two pivots on each trailing arm. With the Koch master kit I'm hoping it goes smoothly and then I'll get an allignment afterwards.