What can cause judder when backing up on a slight grade?

[atomicDog]

Sounds very similar to a Ford I had some years ago - turned out to be the handbrake shoes were simply adjusted too close to the drums and the mechanism allowed the shoes to 'grab' the drum when in reverse, in the manner of a real 'sprag-clutch' ... so maybe check handbrake ?

... but then again that was Ford engineering ... hmmm

Interesting thought. This car has rear disc brakes and not drum brakes. Could this still be an issue?

[zygoteer]

Interesting thought. This car has rear disc brakes and not drum brakes. Could this still be an issue?

Well my E34 535i SE has drum brakes in the middle of the rear discs exclusively for the handbrake function.

I had no idea the 525iT was different in this respect, as I thought all E34's were the same layout etc.