brakes seizing up on older motorhome.

[Islandtime]

We have replaced all calipers, flexible hoses, master cylinder, and power assist booster on our 1985 Class A P30 Chevy chassis motorhome. After traveling 2 to 3 miles, the travel on the brake pedal becomes less and less, until there is no travel left and the brakes are seized up.

I am at a lose for the cause of this, as everything is now new. Any suggestions as to what could be causing the brakes to seize??

[rgatijnet1]

If I read it right you get less and less brake pedal travel, which is the opposite of what would happen if your brake fluid boils. Dragging brakes usually causes the fluid to boil and the pedal go to the floor. I would guess that your problem is caused by too much pressure being developed in the master cylinder that prevents the pedal from being pushed down.

[wolfe10]

Also check brake pedal free-play. That should be adjusted/checked with installing a new master cylinder. Make sure there IS some free-play before the master cylinder piston is activated. A seized pivot point can also cause the master cylinder piston to stay activated.

[jplante4]

The brake pads have to move freely on the pins holding them in, and the caliper needs to retract slightly after the pressure is released. I'd start by pulling each pin, wire brush the rust off and lube with white lithium grease. Are the calipers new or rebuilt? If rebuilt, I've seen the reman guys just blow them out and reassemble with new seal without honing the cylinders out. When the new seal scrapes across the ridge it starts leaking and could bind.

[Rickieblue]

If the master cylinder is not releasing all the way back, the system will build pressure and apply the brakes..especially if the brake lines go anywhere near the exhaust. You need to make sure that the pedal is coming all the way back and you can feel looseness in the linkage. I have seen brake light switches keep the pedal from coming all the way back and then I have seen where the brake light switch has been adjusted too far into the pedal linkage so the pedal could not retract all the way.

[Mike_Hohnstein]

[Mike_Hohnstein]

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