Brake problem on my 89

[globalgrooves]

hey guys, i have a probelm on my 89 635. after driving for a few miles the brakes start to bind, it only happens after about 15 mins of driving, and you can feel a difference in the pedal, much less travel. i have 750 calipers up front and 540 on the rear. The master is stock Left drive car, is it possibly a fault with abs unit ?

[86_6series]

When you feel the binding, does the car yaw as only one or more caliper is sticking?

Or, when you feel the drag is it even on all 4 corners-- sticky master.

I would say it's the master since your pedal gets hard.

ABS would not cause this problem as far as I know.

[Brucey]

there is a know fault with the MC getting sticky and not returning fully under spring pressure, but only once it gets warm. The pedal gets firm and the brakes drag on the front. Depending on how the compensation ports are arranged on each circuit, the binding will be on one or both front calipers.

635CSi has bias valves on the rear brakes which stop them from dragging with this MC fault. M635CSi has no bias valves, so all four brakes can drag, or one diagonal pair if one circuit is affected.

I did a long post on the MC fault some time ago.

cheers

[daz635]

Good thread for information on Master Cylinder / Brakes dragging issue

http://bigcoupe.com/phpBB3/viewtopic.ph ... r+cylinder

[globalgrooves]

thanks guys, yes it seems to bind all wheels as the wheel faces are hot on all corners, i will read through that last post in detail as it seesm to be the problem i have.
neil