Ive noticed when I roll about 3-6 mph, under my car somewhere, there sounds like there are rocks in a coffee can jingling around. Im thinking its a bad cat, but does anyone know what could cause this?

 

rocks in a hub cap/beauty rim, backing plate, brake drum, stone in tire(s), or something simple (I hope).

 

I had a problem in the past on a different 92 Z28 then what I currently have, when I put the sub-frame connectors on, the garage who installed them put them right up against the exhaust...at a slow roll i noticed what sounded to be a lifter knock..or something of the sort. What it turned out to be was "Block chatter" cuz the vibration of the motor running was connected to the exhaust which was bumped right against the subframe which was then transferred throughout the whole car. Obviously at higher speeds I wouldn't have noticed it. After I re-routed my exhaust away form the connector, noise went away. Somethin to look at.

 

Hit your cat a few times and see if you hear it.

 

Yep you'll just need to get under it and do a little banging and touching of differnt parts. Try to narow down location before getting dirty.


This might be way off the bat but Check your torque converter bolts make sure they didn't snap off and rattleing around. I've had some extreme shift kits it the past which snapped my bolt heads.

 

I had that problem with my 84 z28.. the heat shield of the cat would rust off a lil bit, and it would rattle a lil bit