i currently have a big milage S type (2500cc 2005) which drives very nicely but it has a rear end problem.

The car drives well up to about 48mph (1500rpm) and then a brake dragging noise occurs and the rev counter dips repeatedly. its as thought the brakes are being jabbed on and off very quickly. (rear only)

but... after 10 mins or so the noise stops and the car drives fine until it cools down and the problem starts again...

what I've done,

Rear brakes - pistons wound out and in and pads refitted. new(ish) pads and disc all around.
ABS / TC sensor removed and cleaned and ring gear cleaned on both rear wheels. With both sensors unplugged the speedo stops working and the ABS warning is on but the brakes do exactly the same at the same speed.

and the fault still happens so not quite so aggressively now its been cleaned.

any ideas ?

no error codes or warning lights on the dash.

I'm thinking it could be ABS or TC or an electrical problem as the brakes function just fine.

 

This is a very common and well understood issue. Nothing to do with the brakes or ABS.

It's the torque converter lock up system that is acting erratically when the transmission is cold. It's due to to a software glitch.

There's TSB S307-14 on the subject. You'll need to visit a dealer to have them update the TCM software accordingly.

 

thank you , thats great :-)