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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Pontiac Technician
Category: Pontiac
Satisfied Customers: 2373
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2000 PONTIAC SUNFIRE: MY BACK BRAKES ARE LOCKING..WHEELS

Customer Question

I HAVE A 2000 PONTIAC SUNFIRE ,MY BACK BRAKES ARE LOCKING UP. MY BRAKES AT
THE WHEELS ARE FINE.I'M THINKING PORPORTIONING VALVE,IS THERE ANY RESET BUTTON?
IF I HAVE TO BLEED BRAKES TO CENTER VALVE,WITCH ONES?
Submitted: 7 years ago.
Category: Pontiac
Expert:  Jim replied 7 years ago.

I do not think you have a problem with the valve. Here is what you need to check:

 

From donig this for 38 years I find most of the time the problem is with the rear shoes,

I find very small hair line cracks in the shoes. This is the most likely. There can be no cranks what so ever, the drums need to be turned and have no marks on them except for the groves the brake lathe leaves. The wheel cylinders must have free movement and no leaks. The front brakes also need to be checked. If they are not working properly the rear will lock up. Proportion valves are very uncommon but can not be ruled out. But first all other items need to be checked. Please let me know if you need me to help or clarify my information. Best to you .. Jim

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Customer: replied 7 years ago.
REAR BRAKES ARE NEW, BOTH WHEELS LOCKING WHEEL CYLINDERS SEEM FINE.FRONT WHEELS STOP WHEN BRAKE IS APPLIED(WHEN I JACKED IT UP),REAR PARKING BRAKE IS DISCONECTED ,JUST NOT SURE WHAT IS CAUSING IT.
Expert:  Matt J replied 7 years ago.

Hello my name is XXXXX XXXXX I will be more than happy to assist you.

 

I need to know for sure do both of the rear brakes lock up or is it just one of them?

Customer: replied 7 years ago.

MATT

BOTH WHEELS LOCK UP(REAR)

Expert:  Matt J replied 7 years ago.
Did this problem start before or after the rear brakes were changed?
Customer: replied 7 years ago.
AFTER, BUT IT WAS THREE OR FOUR MONTHS AFTER
Expert:  Matt J replied 7 years ago.
Since this problem started did you remove the rear wheels and inspect the brake pads?