I have a 1979 itasca sundancer class c. its on a chevy p30 chassis. after about a 2 to 3 miles of driving, my front brakes start to apply pressure until the motorhome wont move anymore. all this by itself. a hanndy little feature that keeps me from driving :( it has hydro boost braking system. has anyone heard of or experienced this problem. are there any solutions out there short of spending every last penny that i have to overhaul the entire brake system? any help is much appreciated.

Gary B

Senior Member

Hi JALOPY, if you have a class c I think you have a G-30 chassis, and it sounds to what you need is a rebuilt hydro boost unit, you won't need to overhaul the complete brake system, the hydro boost assy is located under the hood easy to get at. :)

I've seen this problem at my shop. It may be a misadjusted brake light switch or pedal stop that is applying the pedal just enough to cause a port in the master cylinder to be blocked preventing fluid from returning to the master cylinder reservoir. This causes the brakes to apply as the fluid expands from heat.
Look at the brake light switch and pull back on the brake pedal. If it is a self-adjusting switch it will have threads but no visible locknut (pulling back on the brake pedal causes the threads to slip and adjusts it correctly). If this doesn't fix it, don't replace anything until you have it checked out by a good shop. It may not require replacement of any parts.

I've got a 1983 p-30 chassis motor home. Master cylinder was leaking and replaced it. I'm now having the very same problem.

The actuating rod connected to the brake pedal must have clearance between it and the master cylinder. If there is no clearance the port in the master cylinder will not open and allow the return of fluid. Pirate and Jalopy seem to have the same problem. The rod is on a cam or threaded rod to allow adjustment.

Found out the problem. The brake light sensor which contacts the pedal arm was set too far foward and not allowing the pedal to fully return. This in turn just kept pressurizing the system without letting it release, locking up the brakes. Boy do I feel stupid! It was staring me in the face the whole time. Hope this helps you guys out!