I'm trying to track down an annoying mild 'thump' from the rear left.

When the car was getting MOT'd recently I asked the friendly MOT man to poke around with his crow bar and he demonstated wear in the lower rear inner wishbone bushes. It was posssible to create movement between the chassis and the end of the W/B holding the bushes. The direction that he was levering would have simulated the load on the bushes under the forces of braking or acceleration and resulted in a change of the toe of the vehicle.

However, this movement could only be seen on both the front bushes but not either of the back bushes (Note: It could be the other way around!) and he concluded that this was most likely the cause of the thump. It's worth mentioning that during this test, the car was on a 4 post ramp so the suspension was loaded in its normal mode rather than on a 2 post lift in which case the suspension would not be loaded.

All set to order a pair of replacement lower arms but was then told by someone else that this type of movement was correct and that the bushes are designed to give the effect of changing toe under load in order to increase stability.

Looking at pictures of the bushes its clear that even though they are round, they need to be fitted in the correct orientatoin relative to the wishbone and this would presumably indicate that compliance is meant to be different depending upon the direction they are loaded ?

Any information would be appreciated. If anyone has new bushes fitted or even old ones and has the chance to poke around under thier car it would be usefull.