superfast

Guys, I have an 02 CL500. I have been taking great care of the car so it has been running well & in perfect shape except there's a rumbling/thumping noise when car is driven especially on rough surfaced roads. Initially, I thought the noise was coming from the rear so I've inspected & replaced both rear bottom strut's bushings per one of the forum member's recommendation. I've also replaced the 2 rear bushings on both rear knuckles but the noise still there so over the weekend, I went ahead & replaced all the upper & lower front control arms as I've noticed some of them have minor cracks in them. I've also inspected the 4 rear sub-framed mounts & shimmed all 4 front & rear top strut mounts & tried a different set of wheels from a friend's E320. All replacement upper & lower control arms are Lemforder & bushings from Meyle. Unfortunately, the noise is still there. Now with lots of new parts, I think I can hear the noise is coming from the rear but I'm running out of idea so any help would be greatly appreciated.

Jack_88

My brother had the same problem on his A8 and it turned out to be a loose mounting point on the belly pan. It may seem a silly suggestion, but make sure everything you can get your hands on is fully secured.

superfast

It's definitely coming from the rear & I've re-tighten everything that I could get my hands on but the noise still there. I'll look some more & hopefully find the noise source soon. Thanks

Jack_88

It's difficult from inside a car to locate a sound outside the cabin. If everything front and rear is totally secured, then it's likely something rubber in the suspension. Noises like that are very hard to find.

smartadze

Have your significant other ride in the trunk and you will locate the source of the noise FAR better than you can from the driver's seat.

Besides ... she'll love it.

superfast

I've recently inspected the 4 rear sub-frame mounts & noticed the 2 front ones were ripped so I've figured I've found the source of the rumbling/thumping noise. Went ahead & replaced both of them w/ Lemforder mounts. They're metal & covered w/ rubber so it was very difficult get them removed & replaced. It took me 2 half days to get the old ones out & the new ones in, however after all that, I hate to report the rumbling/thumping noise still there. I'm running out of idea so I'll just have to live w/ the noise ...for now

tusabes

Transmission mount , ExhAust system or drive shaft center support bearing (the last one is my guess)

superfast

Tusabes- I've also replaced the tranny mount, both drive shaft's flex discs & checked the exhaust system. I'll look into the drive shaft center support bearing next. Thanks