Just had a poly bush kit fitted all round and the car is making a strange whining noise from the back. It only appears when I back off the throttle. As soon as I apply the throttle it stops.

It is also clunking when I put the throttle on and off. It's not much but there is a definite clunk as the throttle takes up the drive and then releases it.

 

Any ideas?.

 

Cheers,

 

Harty.

Maybe try checking you've got some clearance between the front of the diff case, at the bottom, and the subframe bolt on bit.

It is difficult to see, so you'll need to put some string or wire thro the gap and pull it across to check it's clear.

Sounds like diff and prop noise being transmitted through the chassis. Like Keith says check that they havent closed up the subframe to chassis mounts.

most likely the sound you hear is coming from the diff.

 

in most cases it's nothing to worry about, it's just because the poly bushes won't absorb the vibrations/sounds as much as the old (and worn) rubber bushes.

When you accelerate, the nose of the diff lifts up due to the torque reaction of the wheels. When you lift off, the nose drops back down. If the diff case is touching the subframe at the front, just behind the propshaft yoke then you will get the whining noise from the gears, but as you accelerate, the diff may just lift clear of the subframe and quieten down, but return with a clunk when you lift off.

It's just a suggestion, but when I fitted mine and bolted it back together I noticed the diff was hard against the bottom of the subframe.