Okay, so I got my first car, an 86 IROC, and everything was fine. It needed a lot of work to be what I wanted it to be, but it ran normally... At least until one day when I shifted from park to reverse and BANG! Metal against metal. It happens when shifting from park to reverse, and from reverse to drive just about every time.
I thought it was the transmission at first until I took it in and found out that the sound was actually coming from the differential. So now I'm in the process of trying to figure out what the noise is and how to fix it. Right now the car is up on jack stands in the garage with the differential cover off. There was a little bit of metal on the magnet, but nothing too bad.
My theory is that there is too much lash between the axels and the differential gears. I can move the wheels a little bit with the car in park and if I jolt them suddenly there is a similar but quieter noise. I figure that when I shift the car into gear the gears are slamming up against the axels and making the noise.
So I was wondering if that sounds rational to anyone. If it does, what would cause that to happen, and what might the solution be? If I'm way off on my theory, does anyone else have any ideas? Thanks for any help offered

 

trans mount, buy an ES poly mount

 

Hmm.. I just checked. The mount seems fine to me, no movement from the transmission...
BTW the noise only happens between park and reverse, or reverse and drive. It never happens in the shifts from 1-2, 2-3, or 3-4. There's also a noise sometimes while braking. I'm really led to believe it happens as a result of a sudden change of direction (shifting) or speed (braking) in the differential... So anyone have any other ideas? Thanks again.

 

Oh come on, are you gonna tell me no body else has ever had this problem? Maybe it's just my own rotten luck. Could someone at least tell me how much room the axels should have to move within the differential? i.e. If you've ever had the car in park and tried to spin the back tires, how much room do they have to move around (without overcoming the clutch, of course)? I assume there should be very little if any at all... I just want to verify my theory before I start shopping for a whole new rear end if I don't need one...