[don_r6]

I just recently installed an Active Autowerke catback exhaust on my 2007 e90 335xi. Upon cold starts, I hear a rattle underneath the shifter/console area. I actually feel the shifter vibrate. When I drive it while still cold, I can still hear a rattle. The rattling sound eventually goes away once the car warms up. I've looked underneath the under carriage a couple of times and everything is tight. Any body have a similar experience or have an idea what it may be?

The rattling noise sounds faintly metallic. Sounds like a part of the exhaust is hitting against metal while it's trying to expand when warming up? One thing I'm positive is that it's not coming from inside the cabin. I just can't figure out what it is. This is driving me insane. Any help greatly appreciated. Thanks

dt

[mycoupe]

is the exhaust catless? if so, you could be hearing the wastegate rattle that the stock exhaust could have been muffling.

[don_r6]

still catted. still have the stock dp. i only replaced from the cat back.

[DJHess]

It's vibrating on the crossmember underneath. Mine does the same thing. I had some shims made to drop the crossmember/pan, but do not have them installed yet.

[don_r6]

are you referring to this? http://cdn.nexternal.com/aaw/images/Main51.jpg

are those the two bolts where you need to add shims to?

[DJHess]

It is a shim that goes between the chassis and the crossmember. 4 bolts each, and you need to get longer ones.

I called Mike Hugh from AA and he helped me out.

[don_r6]

Thanks for the info. As of right now it seems I may have solved my rattling noise. There were actually two places my exhaust was hitting. One was a single arm bracket that connects the chasis to the exhaust (underneath the console area). I just loosened it and readjusted it. The second place was the exhaust was touching the tranny. A tranny bolt was pressed against the exhaust. I wrapped that area (approx 4") with high temp exhaust wrap I was never able to locate the problem because I kept looking when the car was cooled off and the componented have contracted and werent touching anymore. I hope this solves my rattling noise. I'm going to let her cool off for a few hours and test it again.

[don_r6]

I just wanted to update this thread. Wrapping the exhaust by the tranny bolt did temporarily help but the rattle actually came back and it was worst than before. I ran the car hard so the exhaust components will stay warm longer. This time I was able to see the tranny bolt still touching the exhaust. I ended up unbolting the tranny bracket and was able to readjust approximately 1/4". In addition I had the exhaust heated and slightly dented on the area where there was contact to the tranny bolt. At the same time I pushed up the heat shield in the mid section as much as I can without interfering with the drive shaft. After reinstalling the adjusted tranny bracket I haven't heard any rattle noise. I'll keep driving the car for a few more days before I make my final determination. So far so good.

[crazydrummer]

Is this the version 1 with the clamps or the bolt on version. If it's the v1 le me save you a lot of time and headache...have it welded

[don_r6]

I'm assuming it's the clamp on version because I had to cut the stock exhaust right before the DP. I'm just curious -does welding the exhaust have anything to do with the rattle noise? thx.