Why don't my rear brakes work?

[fronton]

I bought a new girling e34 M5 MC off ebay but you are correct, it was only $110. Came in the right box, had the right instructions, has the correct part number cast into it and everything fit and sealed correctly. Did I get scammed?

Also, I have now replaced the bias valve with an oem $75 replacement valve. It did not cure my rear braking issue. So to sum up, my issue is still that 50% of the time my brakes feel good and crisp, the other 50% the pedal is a little stiff and dull but still brakes, just not as effectively. However, the outer surface of the rear rotors is rusting over while the inner of the rears is clean.

What now?

[jeffnhiscars]

I'm not certain as to whats involved in an ABS delete, but I assume it involves re routing hard lines. Is it possible something is plugged, pinched or not re-routed correctly ?

Just thinking out loud here.

[fronton]

I'm not certain as to whats involved in an ABS delete, but I assume it involves re routing hard lines. Is it possible something is plugged, pinched or not re-routed correctly ?

Just thinking out loud here.

Possible, yes but I have new lines and triple checked that they are correctly connected. Todd88 is having the same issue as me with the ABS unit in.

[fronton]

Just letting those interested know, I replaced the rotors after trying new pads and now have normal biasing and all brakes working properly. Perhaps the new pads on the old rotors were not seating correctly but like the new oem rotors.

I believe the issue all along was failed calipers which the rebuild would have fixed but either the rotors were too thin (still in spec though) or were too rusty to seat the old pads again and even new pads. It wasn't until new rotors that new pads with the rebuilt calipers all came happily together.

The problem was not booster, MC, bias valve or ABS related. Thanks for all the advice gents.