I'm really at my wits end here! I know there are some transmission people on this forum ! It's a ZF5hp19 box on a 530i.

Ill do bullet points for this :

- Previous owner has transmission rebuilt .

- The rebuilders do the box and TC exchange, do not open valve body.

- I get the car and it has a jerk going from 2-1 when slowing down really fast, it also jerks if I just sit on the brake pedal in drive, and go in manual mode from 2-1. I can feel the transmission shift it, its a really light jerk on idle. Theres also a jerk fromn 3-4.

- I think software, so I have it updated, no difference.

- I then take it to the people who originally did the rebuild, they have no idea and say its functioning fine, they're too far from me to go again so I just leave it, they do admit they didn't open or clean the valve body, just put it back in.

- I then have a reconditioned valve body put in. This fixes the 3-4 issue but the 2-1 jerk is still present.

So now whenever I brake hard I get a thump from the back.

The suspension has been checked a billion times, it's definitely transmission related this one.

Big sigh.