1990 Z32 NA Rear Sub Frame Bushing

[peterpilot9]

My 1990 NA (270K miles) has developed a "thumping" noise in the right rear when driving over bumps both large and small. A muffled sound, not a sound of metal on metal or grinding.

Get underneath and everything seems tight enough. Only about 30K on the strut but all the rubber is original. Oddly enough, (maybe oddly) the right rear sub frame mount bushing appears to be "wet." Not sure where any fluid would come from unless they're infused with a lube or some such thing. Thought they were solid. The fluid has the viscosity of something like tree sap. Even a bit tacky.

Anyone have experience with bad rear sub frame bushings? I am self diagnosing the sound and there is perhaps a good chance I am wrong in this diagnosis. Wondering if these things going bad would result in such a noise.

Would post a pic but I seemed to be "challenged" in that area at the moment. Can't even seem to find instructions. My apologies.

Thanks

[evildky]

Rear subframe bushings aren't terribly uncommon as these cars age, we are talking about a 25 year old rubber bushing. Assuming like most you have a T top car, the drain tubes come out near the subframe bushings and thats likely the fluid you are finding. Plenty of repair or upgrade options, stock, poly, solid, take your pick.

[peterpilot9]

Thanks! Didn't know about the drain lines being in the vicinity of the bushing.

[peterpilot9]

I decided against replacing the bushings but opted instead to install the bushing collars. Bought mine from Z1 Motorsports; $44.00 ($60 with shipping). Installation was straightforward and is well documented here;

http://www.nicoclub.com/archives/instal ... 300zx.html

The only issue I found that might be out of the ordinary is that the right rear bushing insert had delaminated from the rubber and was stuck to the mounting stud such that it did not release and lower with the subframe. Just a push with the tip of the crowbar and it slid right down.

This product install did nothing to remove the thumping noise I am hearing over bumps (guess I'll have to look into that strut) and it doesn't seem to have worsened the ride quality, which I must admit would be difficult to worsen in any case. The car does seem to have a much tighter back end around corners with rough pavement. Moves around much less.