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I would finally like to lay rest the mystery surrounding the P30 hydraulic brake malfunction. Based on my experiences and after reading about 25 previous forum threads, I can see that I am not alone in this, and very few threads really touched thoroughly on the specific issue. Please read on for the solution.
My story:
1993 Tiffin Allegro Bay 30 footer Chevy Control Chassis 454 FI engine gasoline. Hydrobooster braking system. 4-wheel disc. P30 Chassis. I have been fighting this brake locking issue for a while. One day I jacked up both front wheels. Applied the hydraulic brake and I could not spin the wheels, (after 2 minutes I could make the left front spin with great force, the right was perpetually locked) I sought out the solution. I cracked the bleeder screw on caliper and the wheel loosened up completely and the fluid shot out under pressure. I reapplied the brakes, I used a 9/16 and a 5/8 wrench to loosen the union where the rubber flexible line meets the steel tubing. No pressure came out (it just dribbled a bit) and the wheel remained locked. I reapplied the brakes and this time loosened the 7/16 fastener that holds the brake line to the caliper, and fluid shot out under pressure and the wheel loosened. Therefore i determined that the flexible brake line was restricted closed somewhere (at the metal clamp that fixes it to the upper A-arm, there was no rust present on this clamp.) Pressure would force the fluid past the restriction, but when the natural dynamic of the pressure trying to equalize and go to the area of non-pressure, the restriction prevented it from releasing. My best guess is that the excessive heat generated during normal driving inside the front brake lines and caliper damaged the rubber component and caused this restriction (heat swollen rubber) I then consulted a chevy dealer and they wanted $73 for each brake line. It was the steel line and rubber. I said I wanted only the rubber, they said, too bad. I then consulted O'Rielly's Auto Parts and they had the rubber hose for $18 each. I purchased them and within 30 minutes had them installed and bled. This problem has been finally solved. Many parts were replaced trying to satisfy my initial thoughts of diagnostic. Both Rotors (they were heat damaged badly) Pads, Master Cylinder. None of these fixed the problem at all.
The vehicle currently drives like a dream, no squealing from the front brakes, no oven like heat generated from the front wheels (when checked at a stop), The vehicle doesnt hesitate at takeoff because the front brakes are holding while the rear brakes have released. I will add these brake lines to the maintenance schedule for every 2 years. They are cheaper to replace at $40 than to burn up another set of pads and rotors.
I hope this helps all who own a P30 chassis under some type of motorhome who experience this problem and seek this forum for answers, but instead, someone asks a new question over your question, and overrides your question. I cant stand that. Ask your question in your own forum thread.
Enjoy
Happy Motorhoming!
John |
RV and bus conversion info since 1996.
email John Flemings
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