It's round 2 of everyone's favorite game: Diagnose that suspension noise!

[AllanS]

This is sort of a follow up of a previous post.

Basically, when I go over bumps at under 60mph, I can hear a loose rattling sound from the right front wheel.

This sound goes away when I use my brakes and go over said bumps- the amount of force that I use doesn't seem to matter.

When I hit a series of bumps while going around a turn, I get a really nasty, heavy shimmy.

Once again, when I do this while braking, even lightly... no violent shimmy or noise.

I checked out everything around that caliper, and it's all tight- no loose bolts, nuts, cables, anti-rattle clips, etc., which is very disconcerting. The shock tower nuts, including the top one, are also tight. So I'm stuck, basically. The brake rattling and the shimmy stopping under braking may not be related, as far as I can tell, because it has the normal 55mph shimmy, and that isn't effected by braking.

I checked out the wheel while up on jackstands, and I can slightly replicate the noise by twisting the wheel side to side. Using a stethoscope, the sound is strongest at the brake caliper itself.

Any help or suggestions would, of course, be much appreciated!

Allan

[Mr Project]

A friend had a nasty rattle on the back wheel of his 240sx. It would go away with any application of the parking brake or the regular brakes. We eventually figured out that the wheel bearing was going out, and had enough slop that the pads were getting pushed too far back into the caliper and rattling. Application of the brakes would 'true' things up temporarily and then it would quickly return.

Another issue that would have a similar effect is a warped brake rotor, but I think you'd feel that in other ways as well.

Something to check?

[AllanS]

And that might also explain why the wheel shakes so violently going around bumpy turns, unless I'm braking. The brake caliper might be straightening it out, in effect. I guess I'll replace it and see what happens.

[Robin-535im]

Hi Allan,

FWIW: My 91 535 would go "BONKA BONKA BONKA" around a bumpy, heavy curve (even at medium speeds) before I did the thrust arms, and ever since it's been smooth. My sway links also would clunk ever so slightly when turning from lock to lock with the wheels raised, and tightening the heck out of them fixed that.

If your thrust arms are still in need of replacement, I would try that first and make sure the collar nut and sway links are super-tight, then test it again. Since you have to do the arms anyway (assuming I read that correctly, that you do have the "55-mph-shimmy") you might end up finding your other problem in the meantime.

HTH

Robin

[T. Martin]

I would say it is the thurst arms also. I had the same problem on my car, but i didn't get the 55mph shimmy until they were really bad. Order the arms with the stronger 750i bushings they last longer I've heard. I ordered my arms from foreigncarparts.com, less than $70 each. You might want to have the sway bar links changed at the same time.

[AllanS]

Yep, the arms are already on their way as of the 18th... If that doesn't fix it I'll be looking in the direction of wheel bearings then, I suppose. I'm also replacing the shocks, upper mounts, spring pads, nuts, etc. ... basically everything that I didn't replace on the last swing. That should be next weekend, hopefully.