Brakes failing at high speed

[johnauckland]

I have an SE280 1981. Everythng is well except the brakes! At high speed or when the revs are high i.e. over 4,000 the brake pedal pushes down further before the breaks come on, a lot further. It does not do this around town. I thought it was the master cylinder or servo, but both have been replaced and it is still doing it. Are there any ideas out there of what it could be?

many thanks

JA

 

[Dieselman]

It sounds like the pads are being pushed back by the disks. Sounds silly but has the system really been bled of air and are the pads properly bedded into the disks?

 

[Ian B Walker]

It sounds like the pads are being pushed back by the disks. Sounds silly but has the system really been bled of air and are the pads properly bedded into the disks?

I was thinking along the lines of air locks too

 

[Dieselman]

Another idea is if the handbrake shoes are binding causing the rear brakes to overheat.
I've known two cars suffer complete failure due to this.