There is a Loud Bang right rear of car, sound like it is right forward of spring mount. It does it when the automatic transmission shifts from first to second or second to Drive. I just installed a Ford 8 third member Posi Track. Engine is 289 with about 300hp automatic transmission has a shift kit. I checked transmission mount and it is good. It doesn't do it as long as I drive it normal but who want to do that.

 

Did you check the torque on the axle/spring u-bolts? the whole thing might be banging the bottom of the car.

 

I will check, I just installed the springs when I put the new third member in. thanks

 

it may be a u joint

 

Fixed, It was the froward mounting bolt for the leaf spring, tightened it about a turn and a half. Thanks for the help.

 

I know you say it is fixed, but you might want to check to see if the pinion yoke has hit the bottom of the floorboard....

Old stock springs, differnet placement of the pinion, bigger than stock HP, and the springs can wrap up....

IMO, even if that front bolt was a little loose, the bushing would have to be out (torn/worn) in order for there to be enough play to make any noise, let alone a "bang"...

I think that your bushing is out....

 

They are new springs and bushings, I really got on it to make sure it was gone and it didn't come back. I thought is was kinda strange that a turn and half would make that much of a difference. You made me think about it I am going to take the bolt out and see if the holes on the frame are out of round, The bang has stopped for now but if that bolt loosens up it will be back.