brakes locking up

[junktruck]

I have a 1981 chevy k10 and starting just recently the front brakes are locking up even at low speeds and with not a lot of pressure apllied, its extremely noticable and dangerous when the roads are wet. I have checked and adjusted the back brakes but that didnt help.I was told it could be the propotioning valve but not sure. Anyone with any other ideas would be appreciated.   thx

[77c15]

It sounds like the proportioning valve or a stuck caliper. Usually you don't have to replace the caliper, although they are extremely cheap for our trucks (at AutoZone anyway), you just replace the guide pins/caliper bolts so they slide easier. If the guide bolts and proportioning valve don't work, i'd start replacing calipers and make sure the lines are bled completely of air.

[VileZambonie]

Are you sure it's the fronts locking up? It's most lcommonly the rear. Make sure the primary shoe is on the front and secondary shoe on the rear. Make sure the shoes are fully seated on the anchor pin. If not back off on the parking brake cable or free up the sticking parking brake lever (the part the cable goes to). Make sure there is no axle lube or brake fluid leaking onto the shoes and they are equally adjusted.

For the front clean and lube the caliper slides. If your brakes are still locking up replace the combination valve.