Clunking in rear over hard bumps

[euroshark]

I had a very mild / soft clunk coming from what sounded like the rear of my E28. It turned out to be the front strut insert collar nut not being tight enough... I jacked up the RF corner, slapped a pipe wrench on it, and it's silent now. It might be a long shot, but I'd check them only because it seriously sounded like it was coming from the rear in my car.

[Jand3rson]

Josh, over hard bumps only? Is your battery tied down sir?

No, no it's not. I didn't even think of that. I will die laughing if that's what it is.

[BigFurryWhale]

No, no it's not. I didn't even think of that. I will die laughing if that's what it is.

I should go check this too

[AlpineIS]

I'm going through the same problem you are. The noise heard is very similar to a bad RSM. I actually replaced them both although they had less than 10k on them. Noise continued.

Best method to check the condition of the subframe bushings is to get under the car, take a small mirror and point it down towards the top of the bushing. Mine appear to have several deep cracks. I would say they are in very bad condition. My problem is so severe the diff clunks when I accelerate/decelerate.

Let us know what you find.

[AndrewBird]

I can't imagine the lower shock mount is loose. I was the one who put the RSM on and I tightened the bottom bolt up with an impact.

Are there bump stops in an e30? I don't recall seeing any, but I never looked. Maybe yours are shot Josh, causing metal to contact metal when the suspension is fully compressed.

Try wiggling/jerking on the subframe with the car up in the air. See if you can get it to move or make a noise.

This had better not be a major problem not allowing us to go to the picnic. Not 2 years in a row...

[erik325i]

Have you ever replaced your differential? If so, I would double check the 4 bolts that hold the diff to the subframe. Those bolts are notorious for coming loose and causing a clunk after the differential has been replaced.

-Erik

[Kruzen]

Hey Josh,

I have this problem too, i've had it for nearly 6-8 months now, i ordered new RSM's to replace them but found that they're fine. I've narrowed it down to my rear subframe bushings and sway bushings, both have not been replaced and there IS a small amount of play that has slowly getting larger that I can tell at certain speeds on the freeway. Its GOTTA be the subframe bushings, thats the only thing left back there that I can replace.

[Mike325]

Try wiggling/jerking on the subframe with the car up in the air. See if you can get it to move or make a noise.

When I did my subframe bushings, my old mounts would let the subframe rock quite a bit with not too much force. My Powerflex ones made it solid as a rock.

Don't rear subframes only make noises while cornering and accel/braking?

[Kruzen]

When I did my subframe bushings, my old mounts would let the subframe rock quite a bit with not too much force. My Powerflex ones made it solid as a rock.

Don't rear subframes only make noises while cornering and accel/braking?

My rear has been making clunky noises for months, just recently though its having trouble getting traction under heavy acceleration and the rear end is just 'skipping and bumping'. I'm pretty sure its due to my subframe bushings continuing to wear.

[ErykTheRead]

I am trying to track down a clunk. There seems to be some play in the rear half shafts/diff, but my subframe bushings are pretty shot. 250k miles. One of the symptoms is that if I drop the clutch to spin the rear wheels, the rear bucks and hops.

Is this the subframe bushings? I've never driven a RWD car before, so I am nto sure what spinning your rear wheels SHOULD feel like...

-E

[Mike325]

Should not feel like that.

[Jand3rson]

An update to this, I bought a battery hold-down kit from AutoZone and installed it, and while it's hard to tell, the noise seems to have gone away a little bit, but not completely. What I noticed in installing the hold-down kit is that the battery tray itself is only attached to the car at one end, next to the wheel well, allowing the tray even with the battery attached to it to swing up and down. Now while this COULD still be what's making the noise, I don't think that's actually what it is. My diff bolts are all fine, there's nothing down in the spare tire well, shocks are tight, shock mounts are tight, everything seems ok. The only thing I can think of at this point that I haven't ruled out is that it's the rear subframe bushings, which I have not done since I've owned it, and god knows when they were done last.

[xLibelle]

we're gonna have to ask you to come in on saturday and take care of those SFB's.... mmkay? i'd like to have the definitive answer on this.

[thereisnoyun]

pennies

look for pennies. haha or anything in the back crevice first, before determining it requires replacement. Had pennies in both my gf car and my in the back, and in the car... wierd :P

[AndrewBird]

Maybe the car is just bottoming out over hard bumps? I wouldn't think it would with IE's, but then again, it doesn't have to compress very far.