Brakes

[biscuitboy]

I have a 1986 Winnebago Elandan 34' built on a Chevy chassis and I installed all new brakes, from hubs,disc's, pads, calipers, and master cylinder. I have a great pedal when the motor is off. Start the motor and I loose the pedal. Anyone have this problem???

[mfire1339]

Does the pedal pump up with engine running?

[Dave78Chief]

Troubleshooting Hydroboost brake systems: http://www.bepco.biz/Catalogs/VacHyd...LESHOOTING.pdf

Dave

[biscuitboy]

No, pedal goes to the floor.

[spritz]

kinda, We just replaced the break booster on my 64 Cad convert yesterday and while doing so we bled the brakes after installing. Have you checked the fluid.
Now you just touch the pedal and you are stopping.
Good luck and let us know what you find out.
Tim

[Daveinet]

The hydroboost offers more force than you can push with your foot, which is why the peddle goes down when the engine is running. I used to have that problem with my hydroboost. Its not the fault of the hydroboost, it is working correctly, as it is helping you push on the peddle. The most likely problem is the quality of the fluid. It is very likely turned to gel inside the reservoir. Time to complete flush the system and get the gel out of the bottom of the reservoir.

[TeJay]

If you replaced all that you said you probably already replaced a lot of the brake fluid. If you didn't flush the fluid in the lines as suggested that would be a good idea.

Do you have discs in the back. You didn't mention drums or shoes so maybe you only replaced the front brake stuff.

I don't care if you have hydro boost (which is hydraulic assisted power brakes) or just the standard vacuum assist power brakes they both provide about 10 X's the pressure that your foot applies to the brake pedal. If the pedal goes to the floor you probably still have air in the lines. Even old dirty brake fluid won't compress until the water absorbed into the old dirty fluid heats up and begins to boil. When it boils it will turn into steam and then it will compress. If you just finished the brake job and started the engine and still have a low pedal you still have air in the system. If you replaced the rear drums/shoes maybe the shoes are not adjusted out to the drum surface. The shoes have to be almost touching the rotating drums to be correctly adjusted.

My educated guess is you have air in the lines.

I just re-read your post and you said that you replaced the hubs. Did you mean the rear drums or the front axle bearing hubs. If you replaced the rotors that usually includes the center hub which includes the inner and outer wheel bearings and seal.

TeJay