Last year I posted a thread about motor mounts because I had a vibration after I pulled the engine to repair oil leaks and paint it.
I have been living with this vibration which occurs around 55 to 60 mph. I have done numerous things that I wont go into but have now isolated it to the rear of the car. Had the driveshaft balanced and I have replaced wheels and tires.
With the car on a lift, wheels and drums removed the car doesn't vibrate when brought up to speed.
If I put the drums on with a few lug nuts (no wheels), car still vibrates. Warped or bad drum right? Nope. Bought new drums. Still vibrates.
So, with nothing bolted onto the axles, the car doesn't vibrate. When the slightest amount of resistance is applied, it vibrates. When road testing, I would bring it up to 80 mph, drop it to neutral and the vibration would NOT go away till speed dropped to under 55.
It must be coming from an axle or the diff?
I did read an old post of a similar problem that seemed to be the back-lash. The poster had the differential rebuilt and problem was resolved.
What do you guys think?