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I have a 1979 F-100 2WD with manual brakes. The front brakes seem to drag when they get warm. What happens is, everything will be fine, then the truck starts to feel like slowing down, it also hops a bit. When it is doing this and I take off from a stop the rear tires try to spin, so I think it is the front brakes. Once the truck sits for a bit it is fine. Any Ideas?
Sounds like the calipers are sticking. When they get hot the metal expands and binds up. Try some brake caliper lube on them, if that doesn't work you may have further probs like needing new calipers altogether.
There is actual caliper lube, however I just used axel grease and it works fine.
Pull the calipers off of the rotors. Pump the brakes so that the pistons extend all the way. Rub some grease on them (be sure not to overdo it cause you don't want to get any on the pads or rotors). Use a C-clamp to push the pistons back in, this is easier with the brake fluid cap off. Reinstall.
If that doesn't work, then you're probably looking at new calipers.
Ok, so I took the calipers off, they appear to be in good condition. When I tried to collapse them to put them back on, they wouldn't collapse unless I opened the brake bleeders. The pistons moved freely at that point. So I am guess it isn't my calipers. That said, what is next?
the problem may be the rubber line to the calipers. the lining inside them restrict the flow of fluid back because it is not under pressure . to check this crack open the line above the rubber line and see if the caliper comes back .If it doesnot crack open the bolt where the line attaches to the caliper. This happen to all brands
Next time they stick, loosen the brake line fitting for the front at the master cyl. If fluid jets out and the front calipers free up, your MC (or pedal linkage) is the prob.
No, I changed the brake lines, didn't help. The front brakes locked up yesterday completely, had to open the bleeders to get them to release. Didn't have a wrench at the time to try it at the master, so don't know if it is calipers or master....any ideas?
Next time they stick, loosen the brake line fitting for the front at the master cyl. If fluid jets out and the front calipers free up, your MC (or pedal linkage) is the prob.
Where is the proportioning valve located. I traced the hard lines out of the master cylinder and down to the frame and didn't see a proportioning valve.