Brakes O plenty
Thread Starter
Instructor
Joined: Apr 2008
Posts: 240
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From: Peachtree City GA
Brakes O plenty
What is the most likely thing to cause My Front calipers to lock up driving down the road? Would it be Master cylinder or calipers: Just a note the car sat 9 years, I drove it, the right front caliper locked up, so I replace both front calipers and pad, Pumped the fluid utill it was clear thru the brake lines, They work fine for two Months Now they are lockin up again. The guy At the Parts store said It was the Booster, I just dont agree with that. Please help with any suggetions. 
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
brakes
The guy at the auto parts store is possibly right.
The booster has an adjustment bolt in the middle of it where the master cyl. bolts on. If it is out too far, it can possibly press on the master cylinder piston and allow fluid to flow to the brakes.
That said, you should be like Inspector Cleusseau, and get out your magnifying glass and go to work.
1. release the fluid pressure at the bleeders, make sure the front rotors are free, then start the car up, and watch the bleeder hose for pressure with the bleeder cracked.
If there's pressure, loosen the master cyl. bolts and see if the pressure goes away. If it does, the master is pressing on the adjustment bolt too tightly, and you have to back it off a little bit
OR see if the brake pedal under the dash needs to be adjusted, or something is keeping the pedal from returning all the way, causing this.
The booster has an adjustment bolt in the middle of it where the master cyl. bolts on. If it is out too far, it can possibly press on the master cylinder piston and allow fluid to flow to the brakes.
That said, you should be like Inspector Cleusseau, and get out your magnifying glass and go to work.
1. release the fluid pressure at the bleeders, make sure the front rotors are free, then start the car up, and watch the bleeder hose for pressure with the bleeder cracked.
If there's pressure, loosen the master cyl. bolts and see if the pressure goes away. If it does, the master is pressing on the adjustment bolt too tightly, and you have to back it off a little bit
OR see if the brake pedal under the dash needs to be adjusted, or something is keeping the pedal from returning all the way, causing this.
