i did a rear brake drum to disc conversion on a polo 6N and i instanly noticed the rears were running very hot 150C
The front discs were also new and noticed the discs were not shiny. the brakes force on the front is minimum. They are not that hot either 50C.

There is no brake pressure compensator or regulator as it has an ABS system.
The ABS system has always had the light on which I am going to sort out so that the system works but I woudnt have thought this would effect anything as the fronts were working fine before the rear disc conversion was done.

Have you checked that the rear wheels are free to rotate?

are you saying that the rears are binding?

The non shiny fronts, did you clean the rust protection coating off?

The non shiny fronts, did you clean the rust protection coating off?

the front discs are black diomand discs which i have always used in the past. the black has come off and can now see the silver but its not shiny like the backs are.

like i said after driving for 10 minutes the backs shoudnt be 150c and the front 50c

i can rotate the backs by hand. shall i check when there the engine is switched on. i didnt want to do any dangerous stuff but can keep car in neatural.

If I've read this correctly you converted from drum to disc at the rear.

What else did you change? I'm asking as the volume of fluid to move a drum may be different to disk, you may therefore have to much fluid heading backwards. If you slam on the brakes at 20mph which wheels lock up first to I'm guessing the treats when it should be the fronts.

On disc based cars do they have the same master cylinder / abs system as your car?

If you jack the back up and with the engine running, stamp on the brakes and then check if the rear wheels are releasing. If not it could be bad piston seals or collapsed hoses or dirt in the system. I had this with my volvo until I flushed the system a few times to clean it all out. I'd also check everything is free and not jamming.