135i Rear suspension clunk - video included

[Bmacfarl99]

Hello everyone, I would really appreciate getting some feedback on the source of the clunk in my rear suspension. This is a 2011 135i that was built in 6/2010 and does not appear to be in scope of the CV joint recall. I replaced the rear shocks after the clunking sound started because they were known to be bad. No other bushings or suspension, diff, or driveshaft work has been done with the car. It has an automatic transmission.

As you can see from the following video the clunk is most likely to occur in first gear as I apply the throttle. It's already been to the shop once and they could not isolate the problem. I told them that I would be back after I replaced the rear shocks.

Video posted on Youtube: https://youtu.be/djLe0w8SHmw

I have inspected the suspension and diff bushings and while they look old, none of them appear to be completely blown. I've shaken the muffler and it's not contacting anything. I can find no metal contact spots among the suspension links, driveshaft and diff.

Diff bushings?
Driveshaft?

I'd appreciate any suggestions. Oh, for those in Maryland I've already been to Scandanavian Motors in Rockville. Other suggestions are welcomed.

Thank you,
Bill in Maryland

[The Wind Breezes]

I'm probably talking out of my ass but that looks like an issue with the trans / engine mounts. Maybe the diff mounts. Not sure that much movement is normal on the driveshaft, and the noise follows.

Also this is the best camera setup / attempt at supplying evidence for a mysterious noise that I have ever seen. Everyone who makes a "mysterious noise" post should be directed here to see how it's done. Surely someone can give you a definitive diagnosis.

[Elderado82]

Sounds and looks like the rear sub frame bushings (RSFB) are bad? Paying attention to the split video portion it looks like you have way to much play around your diff. This is caused by bad RSFB's you have a few options. Take a look at you RSFB's and see if they look torn or look deteriorated if not you can get some inserts that may stop the excess play. This is your cheapest and easiest route. Easily a DIY. Also how many miles on the car? If you're pushing over 100K I would look into either replacing the RSFB's with solid rubber bushings or aluminum. More expensive and a lot tougher job but also a sure fire way to remove the play and clunking. Your car will handle and behave much better to.

Also since you have replaced the struts I would advise replacing all the necessary hardware and strut mounts as these too wear over time. There are some good kits out there for this around the $200 mark.

[dtla1]

Check your Guibo Aka Flex Joint.

[MightyMouseTech]

Originally Posted by dtla1

Check your Guibo Aka Flex Joint.

Our cars don't have a guibo at the rear. It is common for the nut where the shaft attaches to the rear diff to make a popping noise as you load and unload the drivetrain. Need to check it in a hoist. Need to replace the nut and collar if that is the case. Not that fun a job BTW. That nut is REALLY tight.

[Bmacfarl99]

Thank you everyone for the replies. My 135i is just short of 100k miles. So I wouldn't be surprised that I have worn bushings. I've looked at all of them and don't see any gross cracking.

While under the vehicle placing my Gopros, I tried jacking up the front of the diff. I'd think that would show some weak diff bushings? Well the diff did not budge. Whatever is causing the diff to move up and down like that, it's got some good torque behind it.

The car goes to Scandanavian Import Autos in Rockville, MD on Thursday. I've got my fingers crossed that the video helps them find the problem. I'm committed to following up on this thread. I hate it when I find just the posting I need to solve my problem but the original author doesn't follow-up.

For those looking to record issues in your driveline and suspension, I used some older GoPro Hero 4 cameras on Small Rig clamps (search Amazon for Small Rig). Because I'm a photographer I have access to equipment like a Lumecube (on a small rig) to light up the underside of the car. I think you can just use a flashlight with some kind of clamp.

I backed the care up on some ramps and place the cameras. Then I drove around the neighborhood with one eye on the rearview mirror to see if there were any GoPros bouncing in the street behind me. The Small Rigs did a good job clamping things down but you don't have a lot of clearance under the cars.

I am familiar with editing video. So syncing two cameras and editing the video to be side-by-side is something I am familiar with. That's not worth the effort if you haven't edited video before. Just publish a few 30-second clips on Youtube or Vimeo, and paste the link into your post.

Thank you,
Bill in Maryland
'11 135i with a clunk in the trunk

[dtla1]

Originally Posted by MightyMouseTech

Our cars don't have a guibo at the rear. It is common for the nut where the shaft attaches to the rear diff to make a popping noise as you load and unload the drivetrain. Need to check it in a hoist. Need to replace the nut and collar if that is the case. Not that fun a job BTW. That nut is REALLY tight.

I wonder if the one at the front would allow the driveshaft to torque upwards bringing the diff with it though? That's my justification for throwing that out there as a maybe...

[Bmacfarl99]

Hello, just following up on what turned out to be the problem. The garage (Scandanavian Auto, Rockville, MD) found that the suspension clunk was coming from the right rear bearing housing (knuckle?). See the attached suspension diagram with an orange arrow pointing to the corresponding left side component.

The problem was at the alignment adjustment bolt at the top. Where that bolt was tightened allowed it to knock against something else in the suspension. I don't think they meant it's the bolt itself or the eccentric thing, because that sets the alignment. There is something else on that fitting that isn't critical to the alignment, and under suspension loading it was colliding with another suspension component.

It turned out to be something simple but was hard to find. Sorry I haven't had a chance to get back under there with a camera. All I can say is the clunk is gone, gone, gone. Hallelujah.