MikeG

iTrader: (33)

The last few days my car has been shimmying pretty bad at speeds over 55 MPH all of a sudden. I couldn't figure out what was wrong. Then today on the interstate when I had to slow down for traffic, I started hearing/feeling this banging coming from what sounded like the back or the underside of the car. It only clunks when I'm braking or when slowly coasting. It makes no noise under acceleration. Anyone got any ideas? I'm gonna crawl under the car tomorrow to check for obvious things, but any tips on something to look for in particular?

EPP

iTrader: (22)

The tranny mount breaks very easily, as a result of GM electing to mount the torque arm to the transmission. I would suspect the tranny mount is the source of your problems. Bob

MikeG

iTrader: (33)

Well, I got under the car and looked to see if I could find something and everything looked ok... I tried to wiggle the driveshaft and it would not budge a bit. I looked at the tranny mount and tried to see if I could move the tranny at all and I couldnt. What should I be looking for? Is there a way to reproduce the clunking sound when under the car?

EPP

iTrader: (22)

A broken trannyt mount can be very hard to notice. One time we didn't know what the problem was, we had the clunking noise going on, but couldn't see or find anything wrong. We ended up strapping the car down on our dyno, and while my brother drove the car with a load on the dyno (Mustang dyno with eddy current) I got under the car and checked it out while my brother was driving the car. Sure enough, when shifting the car, I could see that the mount was broken.
Try using a pry bar to see if you can get a gap to appear there. Bob

MikeG

iTrader: (33)

Well duh, I finally noticed that I was missing 2 lug nuts off of the drivers side rear wheel! 2 of the studs had snapped off! I'm so lucky that wheel stayed on. I have no idea how that happened. So me and a buddy replaced all the studs and lugs and all is well.