hjhughes
rhode island
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Joined: 02/28/2005
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Hello: I have a pursuit camper that seems to be having a problem with the brakes. I have changed the master cylnder, brake lines, brake booster,pads etc. For some reason when i am driving it, all of the brakes lock up. Does anyone have this problem and how do you fix it. Thank you and happy camping.
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sum1
So-Cal
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Joined: 11/07/2005
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What chassis?
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adondo
Pasco, Washington
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Joined: 07/28/2004
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Do they lock up as to prevent ever moving again? Maybe the self-adjusters are installed backwards, and are ratcheting themselves tight every time you step on the brakes?
If there’s air in the lines, the fluid can heat up and cause the cylinders to cram the pads out against the drums or disks. The pedal will feel ‘’spongy’’ if that’s the case.
FMCA# F355513. 1997 Safari Continental, 40 foot, 1 slide. Cat 3126B, Allison MD3060. 2000 Durango SLT 4x4 toad with a Blue Ox Aventa II and stopped with a Brake Buddy.
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Aiming a Direct TV dish
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hjhughes
rhode island
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sum1 wrote:What chassis?
chevy
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itsalleasy
USA
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Joined: 07/20/2007
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Are both axles locking up, all brakes? Disc front, drum or disc on the rear?
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j-d
Sunny Florida USA
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Joined: 09/04/2003
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Was this happening before you changed all those parts or did it occur after? What did you do with the front disc brake calipers? If a piston is sticking, or the arrangement the caliper slides on is sticking, a disc brake will stay applied. Is this so predictable that you can get it to a stop someplace and jack up a front wheel and see if it's still stuck?
People overlook the brake hoses for a problem like this but you have changed yours. Still, the odds of both hoses (thinking of front wheels) failing in the same way at the same time are incredibly slim.
A master cylinder has a tiny bleed hole to release all pressure once the pedal is released and the piston has moved all the way back. IF the bleed hole is clogged, the fluid will remain under pressure. This will cause the pads to drag and this heats the caliper. This expands the fluid and since the pressure cannot release, the brakes apply even harder. This has happened to me with a car. I got out and both front brakes were hot like BBQs. Since the blockage was in the master cylinder, both brakes were applied equally. A hose, caliper piston or slide would apply only one. Anyhow, took the master cylinder apart - twice - Did not notice a little dark spot that turned out to be the bleed sealed shut with rust. I cleared it with a small "number drill" and honed the inside to remove the burr. Worked fine ever after.
Another possibility: IF the pin that extends from the booster into the back of the master cylinder is adjusted too "long", the relief port will also not get exposed, and the pressure will remain in the same way it did when mine was plugged.
God Bless, jd
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hjhughes
rhode island
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itsalleasy wrote:Are both axles locking up, all brakes? Disc front, drum or disc on the rear?
all breaks lock up. drums in the back, disk in the front. Axels are fine.
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96Bounder30E
Birthplace of the Boysenberry, Orange County, CA
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I don't know that much about the Cheby chassis and I maybe way off base but........it sounds like the auto park parking brake to me........what do you P30 guru's think?
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j-d
Sunny Florida USA
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I think an 83 is too old to be autopark... If it's a vacuum booster system where pedal connects to vacuum booster and master cylinder bolts to vacuum booster, I think something is pressing on the brake "pedal" or keeping the master cylinder pistons from coming all the way back to the rest position. Could be how pedal links to booster or that rod from booster to master cylinder. You should not feel the master cylinder piston being pushed in as the cylinder mounting flange contacts the front of the booster.
New parts, like a booster, can be bad.
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itsalleasy
USA
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It's doesn't have autopark.
Kind of sounds like it should be something common to all brakes, the mc and booster were replaced, is the pedal linkage free? The linkage is pretty long and has moving parts that are exposed that could be rusted.
When you replaced the front pads did you replace the calipers? Did you check the pistons, are they are free, seals not so hard the pistons can't return? Clean and lube the mounts and the calipers, make sure they are sliding correctly, assembled correctly.
New hardware kit on the drums, shoes installed in the correct position, adjusters cleaned and lubed, everything free?
If you are sure all of the installation is correct when they lock up crack a bleeder to see if there is pressure in the system. This will tell you it is because of a mechanical/assembly/corrosion problem or the mc or proportioning valve is not releasing pressure.
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