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-   -   E46 rear end stability/rebound help (http://www.maxbimmer.com/forums/showthread.php?t=161447)

mtnbiker 01-06-2014 06:41 PM

E46 rear end stability/rebound help
 
Hi guys,

Im trying to figure out why the rear end of my 01 330ci does not seem planted, I will try explain it as best as I can as I dont know the right terms.

Previously when I went over a bump at speed it felt like the rear end did not absorb much of the force and after the compression, it felt like it was all over the place. So I checked the rear shocks, and the rear right was blown. So I replaced both shocks.

This made the compression/absorption much better but it was still all over the place after the bump. I checked the RTAB as per the forums, and sure enough they were both in bad shape. After I replaced both of them it feels much much better, however I still feel like after a bump, the tire does not make contact back to the road quick enough or so. Almost feels like its skipping or just not pushing the tire back on to the road fast/hard enough.

I hope that makes sense. Could this be because of the rear springs? What are the symptoms of bad springs? IF not, what else could it be?

dbworld4k 01-06-2014 06:47 PM

E46 rear end stability/rebound help
 
Did you do an alignment after the trailing arm bushings?

mtnbiker 01-06-2014 06:53 PM

Yes I did get an alignment, would an alignment make that much of a difference?

mtnbiker 01-06-2014 06:56 PM

And when I say it feels like it doesnt make contact with the road fast enough, its probably just milliseconds, but its noticeable.

From my understanding the shocks help with the upward travel of the tire and the springs help push them down after the shock compresses?

dbworld4k 01-06-2014 07:54 PM

I experienced very similar issues once with my E46. Turned out to be blown RTABs, and that solved it. In your case, assuming the RTAB replacements were good quality and installed properly and the alignment was done properly, the next thing I would check are your tires. How old are they, and how's the tread? Have you had your rims balanced recently to check for bends/warping?

Worst case, bring it to a good independent shop (one of the sponsors on this forum) and have them take a look at it. I'd recommend Stance Factory as they're suspension specialists and should definitely help.

windwagen 01-06-2014 08:29 PM

What's the tire pressure?

mtnbiker 01-06-2014 10:29 PM

Quote:

Originally Posted by windwagen (Post 1635783)
What's the tire pressure?

On my summer tires (225/45/17 and 255/40/17) I run 36F and 40R. On the winter tires I have to check but I've experienced the same thing on both set of tires.

mtnbiker 01-06-2014 10:36 PM

Quote:

Originally Posted by dbworld4k (Post 1635778)
I experienced very similar issues once with my E46. Turned out to be blown RTABs, and that solved it. In your case, assuming the RTAB replacements were good quality and installed properly and the alignment was done properly, the next thing I would check are your tires. How old are they, and how's the tread? Have you had your rims balanced recently to check for bends/warping?

Worst case, bring it to a good independent shop (one of the sponsors on this forum) and have them take a look at it. I'd recommend Stance Factory as they're suspension specialists and should definitely help.

I got OEM RTAB's and got it installed at a reputable mechanic, not a sponsor, but a good BMW mechanic. Maybe I should get the alignment checked again. Any recommendations for alignment shops?

My summer tires were new Hankook v12's bought last summer and balanced at Simplytire and the winters are Pirelli Sottozero's about 3 years old now. The rear end behaves the same with both tires so I was thinking it wasn't the tires?

dbworld4k 01-06-2014 11:59 PM

E46 rear end stability/rebound help
 
I use Pan Auto in Markham for alignments. (905) 294-8838. Might even be worth mentioning the cause for your visit when you see him in person, perhaps he can take a peek while it's on the machine.

Tell him Anuk referred you.

It's a one man show, but the guy is meticulous and by far the best and most accurate alignment shop I've used, and I've been to several and most weren't good enough or charged obscure rates. I've had several cars done there and some with custom specs to my liking. Perfect job, every single time.

jabela 01-07-2014 02:52 AM

Are you shocks and springs OEM?
Your rear tire pressure is a little high. You could lower it to 33-35psi to see if that helps.

Have you checked to see if your subframe is torn? I've seen people complain of similar issues when theirs was torn.


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