engine and drivetrain exhaust shake

[schnell944]

My exhaust seems to be shaking way too much. the tail pipe will tend to smack against the body of the car at certain engine speeds. I've had the car for a few months now. I didnt have this problem for the first few months of ownership, then it developed after '02 Fest East. I replaced both rubber hangers b/c one had broken, and I got new bushings for where the exhaust is supported by the mount on the transmission. None of this seemed to help. The engine doesn't seem to be rocking any more than it did before (which is a bit more than usual, I gather, because of the A4 setup). Any ideas of what could be wrong? As far as I can tell, there are only 3 points where the exhaust is supported after the manifold: transmission support and the two rubber hangers, correct? I adjusted the tranmission mount per the Haynes Manual recommendation. Not really sure what else to look at...all I know is it's annoying

[SteveJ]

Double check all the suspended points.

Muffler hangers and the motor mounts & tranny mount.

Check the alignment of the resonator. You may need to rotate it one way or the other to get a little more clearance above the rear subframe.

Last resort- hack it off and run a straight pipe out the side.

Oh, sorry...that remark was supposed to be for TJs Rat Rod look 02.

[bmw_jeff]

I have a fairly cheap solution for you. I had a similar problem where the muffler tip was too far to the right and kept bumping the body on startup/shutdwon and rattling, despite changin all the hangers and trying to adjust it out.

I took it to a muffler shop and the guy there used a generic straight bar/bracket with a stiff rubber joint at one end for a little give, that we bolted to the car body at the diff carrier's existing bolt location. Then I held the exhaust in the proper place while he welded this rod to a standard BMW exhaust U bracket (like the one attaching the muffler to the resonator) that we had pre-positioned and tightend down on the resenator pipe below the diff. This way I can easily unbolt the whole thing for removal of the exhaust w/o a welding again. No more exhaust movement = no more rattles! Cost was $30 from him, incl the one generic rod. I had the BMW U bracket already, like $5.

[zane]

I had the same problem. My exhaust was extremely loose at the tailpipe and would hit something when I was coasting downhill in gear. Take it to a muffler shop. My experience with the guys in Marin is that they are all really chill and will fix it for next to nothing. They guy who did mine unbolted everything, re-hung the system, bent the exhaust hangers correctly and only charged me $10. He was working on it for almost an hour and only $10. I've gone to some other guys in my area for exhaust leaks and they haven't charged me a dime to weld it up.

[schnell944]

good suggestions. I'm not sure where you all found such friendly exahust people, but I'll probably take it to a muffler shop and see if they are as helpful.

[Jack]

Did you replace the plastic inserts in the "rubber donuts" at the back? They will make a big difference in exh travel.

[schnell944]

do you mean the plastic pieces that fit on the metal hangers? I left them on because they looked fine.

[Jack]

I think we are talking the same thing. They kinda fill and give some body to the rubber donut hangers for the muffler. They show at realoem.com, if I'm not mistaken.

[schnell944]

is there supposed to be a plastic insert for both the top and bottom holes in the donut? if this is the case, I only have one at the top of each...i can see how that may cause play.

*edit* the diagram at real oem seems to show only one "base"

[Jack]

(nt)

[schnell944]

OK, so, I took it to the local muffler shop. He said everything looked to be in order and that I should probably try to bend the tail pipe. I took it home, took another look at the system, banged the rear muffler with a sledge hammer for a bit and got the connection to the center section to free up. All I had to do then was rotate the muffler a little to give it some more clearance. Steve, you were right about that. Problem solved