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Login to post Forums » Grassroots Motorsports » BMW E36 help! Clunk, drivers side rear.

Dec. 6, 2011 12:57 p.m. HunterJP Reader

Help me, oh great GRM board.

Clunk is coming from behind driver, on the outboard side of car. Very pronounced. Not specific to accel or decel. Large bumps don't always effect it. Typically, it happens more during small, quick undulations. Or even large, quick undulations. Seems to happen on downstroke, or as the suspension drops, rather then compresses.

Car has poly Rtabs, and they look fine. I can see no tears around the mounting points of the subframe. Rear sway is stock. Car is on Tein Basics, and lowered. (Came on car) Shock mounts look fine, as well. Have had the trunk emptied and seats down, still hasn't helped me locate sound. I have poked and prodded everywhere I can think of, and have yet to find culprit. Sound is definitely a clunk/thunk. And when it happens, whatever is causing it sounds very loose. Does seem worse, the colder it is. Can't say if the rear feels loose, as the car is on snow tires now. I can't recall if the noise started happening before I switched to them, or not.
Dec. 6, 2011 1:01 p.m. Giant Purple Snorklewacker SuperDork

Open the trunk and see if the jack is loose in the right rear well

That meets the exact criteria for a failed upper shock mount.

They look like this... (Fair, sorry for the stolen bandwidth)
Dec. 6, 2011 1:04 p.m. N Sperlo SuperDork

You mention the sway bar is stock, but make sure the bolts are completely tightened. You may not be able to physically budge it, but that doesn't mean its not loose.
Dec. 6, 2011 1:08 p.m. Brett_Murphy HalfDork

+1 something loose in the jack area.

Also +1 to a torn shock mount.
Dec. 6, 2011 1:12 p.m. Giant Purple Snorklewacker SuperDork

N Sperlo wrote:

You mention the sway bar is stock, but make sure the bolts are completely tightened. You may not be able to physically budge it, but that doesn't mean its not loose.

Yeah, this too - if the car was auto-x'd there is a good chance one of the mounts is busted or just had the rubber guts knocked out of it. The end-links too.
Dec. 6, 2011 1:22 p.m. GameboyRMH SuperDork

Is this the model that has the chassis tearing problem back there?
Dec. 6, 2011 1:23 p.m. bludroptop SuperDork

Dead hooker in the trunk that isn't quite dead yet?

My first guesses would be the upper shock mount or sway bar link as well.

Both are cheap and easy to replace.
Dec. 6, 2011 1:27 p.m. HunterJP Reader

I have had everything out of the trunk. Well, except the battery. Mount looks fine. I am going to switch the shocks from one side to the other to see if the sound moves. Was also going to try to simply remove the sway bar, as well.
Dec. 6, 2011 1:43 p.m. Strike_Zero HalfDork

I had the same thing going on my E36 M3. Turned out to be a subframe mount. I didn't find it until I dropped the subframe.
Dec. 6, 2011 1:55 p.m. HunterJP Reader

Was the sound concentrated on the side of the car? Sound is not just from behind, but from behind and to my left. I would have sworn it was the Rtab, but it is poly.

Just swapped the shocks. Have yet to drive. Tested the bolts for the sway. Passenger side tightened a bit, where it mounts to the body. Also used the jack to push up on the subframe. Mounts moved/stretched less than a 1/4 of an inch before the car started lifting as well.
Dec. 6, 2011 2:04 p.m. HunterJP Reader

Just test drove the car. Swapping shocks, and mounts, did not help.

Guess it is time to swap in the LSD dif. Should get a good look at everything else, at that point.
Dec. 6, 2011 4:01 p.m. Strike_Zero HalfDork

On mine, it was in the right rear. I traced it down by riding in the back seat and . . . in the trunk

In the back seat it almost sounded like the gas tank was loose. It was a pretty loud thud when I rode in trunk.
Dec. 6, 2011 4:17 p.m. HunterJP Reader

Speaking of gas tank, mine was kinda loose. Isn't the culprit, though.

So, was it the bushings, or that the mount was torn?
Dec. 6, 2011 4:27 p.m. motomoron HalfDork

Check the front diff mounting bolt. They break.

If yours is broken- after the ordeal of removing the swaybar and unbolting the CVs and drive shaft from the diff to drop it to get the broken bit out...

Cut a screwdriver slot in the pointy end of the new bolt so when it breaks you can get it out w/o dropping the diff again.
Dec. 6, 2011 5:19 p.m. Strike_Zero HalfDork

It was just the bushing that was fragged up pretty good.

I actually did the front diff bolt just in time on all my E36s. That's one of the nice surprises BMW left for us. No double shear equals borked bolt. MM is right about cutting a slot on the bolt!!
Dec. 6, 2011 10:07 p.m. motomoron HalfDork

Strike_Zero wrote:

It was just the bushing that was fragged up pretty good.

I actually did the front diff bolt just in time on all my E36s. That's one of the nice surprises BMW left for us. No double shear equals borked bolt. MM is right about cutting a slot on the bolt!!

Thanks - and in the process of pummeling the car off the curbing, 10 corners a lap, 20 laps a session, 5 sessions a day for a weekend in a concerted effort to break said bolt, the female threads in the metal hub of the front bushing disappear. This no doubt makes breaking the next one an easier job. Thanks, Fritz!

I hear the e46 part is teh betterz , but I just put in a new stock bolt and have 2 spares, so it'll never break again.
Dec. 7, 2011 8:02 a.m. nderwater SuperDork

While you're looking under the car, shake your exhaust pretty firmly to check the exhaust hangers.
Dec. 7, 2011 8:31 a.m. 7pilot Reader

How about the rear speaker/shelf?

m
Dec. 7, 2011 11:39 a.m. HunterJP Reader

It appears I do, infact, have some play in the Rtab. Just dropped it. Even though it is poly, with it dropped, I can wiggle it a bit. The bolt is being a bugger to loosen, too. Suppose this means new poly rtabs?
Dec. 7, 2011 12:26 p.m. Strike_Zero HalfDork

Depends on how much play you have . . . I have stock RTABs and the poly limiters on mine . . .
Dec. 7, 2011 1:08 p.m. EricM SuperDork

my exhaust pipe was loose and it made a ton of clunking noises. Just something to check.
Dec. 8, 2011 8:12 a.m. HunterJP Reader

So, I have UUC poly Rtabs. Dropped them down to inspect. Thought they might be the culprit. All was tight, however. I did rotate the bushing a little, however. I then buttoned it up, and drove home. To my amazement, there was no more clunk. I am thinking I found my issue. And I am thinking I will be switching to the OEM M3 Rtab with limiters, here soon.
Dec. 8, 2011 11:23 p.m. Strike_Zero HalfDork

Hopefully that's all . . .something simple would be welcomed!!!

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