okay, so yesterday i was practicing my power brake burnout so i could do a good enough one to heat up the tires at the track, anyway about halfway through i hear a thudding sound coming from the back end. i stop and nothing lokks wrong so i go to drive away and the car make a fairly loud thud and kind of lurches when starting in gear. it does this whenever you shift gears. also while drving there is a constant thud thud thud. the thud gets much quieter whenever you push in the clutch. i jacked the car up and nothing looks boroken. i wiggles the halfshafts and the seem fairly stiff. i cant really look at the front u-joint because of the heat sheild but the rear one looks alright. anybody have any ideas. thanks and sorry this is so long

 

Put the rear on jackstands and with the tranny in neutral turn the rear wheels back & forth.
Then listen & trace the backlash sounds.

 

It almost sounds like you toasted your front diff mount. But that doesn't explain this:
Steve

 

hmmm. this whole thing make me much unhappy. i'll check the front diff mount and see how it looks

 

i think you might be right about the front differential mount. it sounds about right. also that would explain why the sound goes away when you push in the clutch becaus the differential is no longer trying to transfer all the power to the wheels. it's just rolling. is there any way to externally inspect this. thanks again

 

anyone????

 

A broken front diff mount will thud against the floorpan with forward torque on the axle.

 

is it a pain to change