Brakes Problem need help!

[Guest wpoll]

This may not be the correct forum for this question, but unfortunately it's a last resort.....Iv'e got a 1986 Maserati Spyder (convertible version of the 6 cylinder Bi-Turbo)...these are not complex as one might think....But I'm having a strange brake issue that no one can seem to help me on...when the car is started (without even getting in) the brakes lock up. That's right, the brakes lock up after approximately 2-3 minutes, all without touching the brake pedal. Once the car is shut down, after approximately 30 minutes, the brakes release....strangest damned thing I've ever encoutered...The system is a typical GM American style system utilizing a vaccum power booster, and master cylinder. has anyone out there ever encountered this in any vehicle at all???

Thanks,

Wayne<!-- google_ad_section_end -->

[Larry Schramm]

First thought is your have a dragging brake pad on one of the calipers. Do you smell any break burning smell or hotness?

[Bhigdog]

I'm guessing small vacuum leak in the booster system. Somehow applying pressure on the master cylinder. Kind of like a short circuit allowing vacuum to go where it doesn't belong. Very small leak taking a couple of minutes after starting to do it's work, them 30 minutes or so for the vacuum to bleed off after shut down.................Bob

[tom_in_nh]

I agree that Bob is on to something, check the vacuum circuit.

[Guest stude8]

Has there been any recent work removing and replacing the master cylinder on the vacuum booster? If so it could be the adjustment of the master cylinder push rod is incorrect with out adequate end play so it is being activated prematurely by the vacuum booster. A service manual for the car will explain how much gap is required and how to adjust it.