TR6 Brake caliper lock after some driving

[Temeculan]

Hello All,

My first posting here! I have a '76 TR6 that I have spent a small fortune on to get running well. I ma happy with the results(in spite of the expense), but am having issues with the fron brakes making noise/sticking after running the car for a bit. They seem fine at the start, but then start making noise and causing the car sweve slightly when applying brakes. I have had the system completely re-bled, but I still have the issue. The calipers are only a few years old as i had them replaced as soon as I bought the car. Would the pistons already be shot after such a short amount of time? There are no leaks and brake fluid all looks clean. Thanks in advance for any insight.

Temeculan

 

[Andrew Mace]

I would tend to suspect the flexible hoses to the calipers.

 

[Temeculan]

I have done some addtl reading and wonder if the booster servo may not be the culprit. It does not leak, but it has never been replaced or rebuilt as far as I can tell. it just seems odd to me that the condition does not start until having run the car for a bit. I'll check the hoses, but suspect it's probably the servo.

 

[TR3driver]

Another possibility (tho perhaps remote given your description) is the adjustment between the MC and booster. There is a push-rod between them, and if it is too long, it can hold the MC down just enough to close the return valve and cause strange problems as the brake fluid warms up. The fluid expands, and with the return valve closed, will push the pads against the rotors lightly. That causes more heat, which leads to more expansion and so on. Also check that the pedal moves freely, as a binding pivot can cause the same problem.

But a squealing noise would tend to indicate an issue with the pads and/or rotors. Such problems can be tough to find and fix, sometimes nothing but replacing parts that look fine will do. Some of the things that I have found helpful are:
1) sand the surface of the rotors in a rotary/random pattern. 3M makes an abrasive disc for just this purpose.
2) File a small bevel on the leading edge of the pads, so the corner does not touch the rotor first.
3) Add a thin soft aluminum insert between the pads & pistons. Don't have the number handy, but the inserts are sold in a cut-to-fit form in the "Help!" section at FLAPS.

If the hoses were not replaced along with the calipers, then I'd go with Andy's suggestion first and just replace them. They don't last forever. Might as well do the ones at the rear wheels at the same time.