After repeated braking, the drivers side front calliper will lock up. I have to stop truck and wait for 10 or 15 minutes before it will release. Anyone have a idea of what is causing this? Callipers and lines have been replaced but it is still doing it.

 

Just one caliper will lock up?

Do you have ABS?

Somehow you are trapping pressure in the one caliper. Next time it happens try loosening the fitting at the caliper and see if the fluid squirts out and releases the caliper. If this is the case, then you just have to trace it back and figure out where the fluid is getting trapped.

If its just the one wheel then it shouldn't be the master cylinder that is trapping pressure. If it was the master cylinder then both front brakes would be locked up.

 

No abs, and just one calliper locks up. What is a proportioning valve? Heard that mentioned today.

 

A proportioning valve prevents fluid pressure from going to the rear brakes till you apply a certain amount of pressure to the pedal. Without one, the rear brakes would lock up before the fronts.

You should have rear ABS.

 

Didn't know drum brakes had ABS.

 

Proportioning Valve - it doesn't really "prevent" fluid from going to the rears, it reduces the pressure. I guess you could say prevent, but I wouldn't use that word.

Prop valves only are used on the rears, so even if you have them it shouldn't have anything to do with the front brake locking up. Chances are, if you have one, it is on the rear axle and it is a load sensing prop valve... it lets more pressure through when the bed is loaded down.

Drum vs Disk brakes have nothing to do with ABS.

Whether he has Rear ABS depends on the model year and options... I have not kept up with what model years had what. If you have rear ABS then you probably do not have a prop valve.

I don't think they had front ABS back in 97... did they?

 

I believe RABS was standard in 97, with 4 wheel optional.