who has had this problem? Amazes me! (brakes)

[gocallahan]

I am totally stumped...

I have a 1990 e34 with 150k miles on it... this summer when the air temprature was hotter than 90 degrees my right front caliper would totally lose its ability to brake. I replaced the entire brake assembly and flushed the whole system. Didn't work!!! Has anyone had this problem?

[BillionPa]

by replaced entire brake assembley, list parts.

your ABS unit could have a problem.

[92E34]

A while back I was working on a Chevy van that had sort of the same problem. You could be driving along, hit the brake, and the brakes would not work. Turns out it was a speed sensor had failed and was messing up another one.

[632 Regal]

is it overheating? Could be the brake line (rubber hose) is clogged inside and needs replacement.

I am totally stumped...

I have a 1990 e34 with 150k miles on it... this summer when the air temprature was hotter than 90 degrees my right front caliper would totally lose its ability to brake. I replaced the entire brake assembly and flushed the whole system. Didn't work!!! Has anyone had this problem?

[gocallahan]

is it overheating? Could be the brake line (rubber hose) is clogged inside and needs replacement.

I think the clogged brake line might be the problem.... the motor is not over-heating.... thanks for the reply!

[gocallahan]

by replaced entire brake assembley, list parts.

your ABS unit could have a problem.

The entire whole brake caliper was replaced. What is the ABS unit and where is it in the car? Thanks for the reply...

[BillionPa]

the brake system goes like this

Master Cylinder
|
ABS unit
|
metal brake pipes
|
rubber brake lines
|
calipers

for rear brakes there is an additional metal brake pipe on the trailing arm followed by another rubber line.

the brake pipes in the engine bay rarely have problems, but the rubber lines and metal ones under the car and on the trailing arms can corrode to nothing.

when you were bleeding the right front caliper did you notice any additional pedal pressure required to pump the fluid out? if it was easy like the other calipers then the lines could be ok, although vacuum flow testing is the best solution to find clogs.

the ABS unit next to the master cylinder is a series of high speed pumps that limit the pressure applied to the caliper, if one activates when hot it can reduce caliper clamping torque. the ABS unit gets HOT even when not operating, as it is close to the engine, and the metal brake pipes conduct heat away from the calipers.