I noticed today that I've had a loud clunk that shakes the car a bit when I put it in reverse. It was about 32 degrees out, and hasn't been this cold yet this year. I hadn't noticed it before tonight (purchased the car recently). What could be causing it to make this loud clunk?... I sure hope the car isn't a lemon... it'* rather slight when going from reverse to drive, and there'* no problem upshifting. The engine was warm when this was happening.

It also seems kind of odd that the power locks operate when its put into reverse. I can put it from drive to reverse and do it again and again and each time they'll operate.

It would help a ton if we knew what year and model your Bonneville was. Please edit your profile and put that in your signature.

In simple terms, even if your engine is warm, your trans is not. On cold mornings, your trans fluid viscosity is high, so when you shift, you get that effect. Make sure your rpm'* are low if this continues to be a problem (to prevent damage to the stovepipe or reverse reaction drum).

With my shift kit installed and my adjustable modulator maxed out on one of my cars, I have this problem, but not as bad as before the rebuild. I've learned to roll out of the driveway, then shift halfway down, or simply take my foot off the brake quickly to prevent the reverse shift from impacting a non-moving set of axles and diff.

Check your trans and motor mounts as well. Put the car in reverse and powerbrake it slightly. If you see or feel the motor jump alot, then you may have a bad mount

Sorry, I have a 1996 Bonneville SE.