Upper Control Arm Bushings Bad

[TooManyHobbies]

OK, I think I found the problem. I dropped the diff and there was a witness mark above the right side of the diff on the rear cradle above the diff. It looks like the bushings are just not strong enough to keep it from bumping up into the cradle under hard acceleration. I wish I had taken pictures but I was in a hurry to get it back together as the hours were ticking by and it was getting late, but my solution was to take some 5/16" inch diameter steel rod and cut 12 pieces 1.4 inches long. I drove those pieces into the voids in the bushings on both sides of the diff to take up that space and effectively stiffen the bushing. It was about a $5.50 solution. I also replaced the A-arm bushings with the pieces from BMR as well as the bushings on the trailing arms at the chassis interface. Problem solved; no more bumping and the rear just feels much more solid under the car. Thanks for the input gents!

Your fix was the same thing Pedders (or their importer) was doing to fix their diff bushings.

[Eidolon]

Oh what tangled webs we weave when first we practice to modify our cars. I had the BMR upper control arm bushings in mine and they served me well.

[Doug Hilliard]

Oh what tangled webs we weave when first we practice to modify our cars. I had the BMR upper control arm bushings in mine and they served me well.

Thanks Kevin; good to know!

[BuildItYourSelf]

Weird that it made a "grinding noise" and not a clunk or tapping sound.
I was thinking it was the drive shafts coupler to make the grinding sound.

[Doug Hilliard]

Weird that it made a "grinding noise" and not a clunk or tapping sound.
I was thinking it was the drive shafts coupler to make the grinding sound.

You might be mixing threads; mine was more of a vibration or bumping sound. Your suggestion of looking at the diff was what got me onto the problem and solution. Thanks much!