When driving down the road, if I let go of the steering wheel, my truck pulls hard to the right...

So, I jacked up my truck, and my front wheels hardly spin... (They spin a little but you really have to work at it...) Both the left and right side tires hardly spin... So, I took the wheels off and saw the both of the calipers were holding the rotor, so I took the brake calipers off, and bam... Both of the rotors spin nice and smoothly...

Which means, my calipers aren't releasing... Which is weird, due to the fact that my right caliper was just replaced in July...

What could be the reason for both of my calipers to lock my wheels?

 

First, you should always replace calipers in pairs. Never just one because you can develop a pull to one side.

Second, it's either your calipers or the brake lines. On a truck this old, the rubber lines are in bad shape in they're original. They break down internally and block the lines, making it hard for the calipers to retract far enough.

 

Generally, the caliper has a plastic plunger inside. That is whats causing you locking problem. Personally,I'd return it for a metal plunger one.

 

I'm not entirely sure how the F150 calipers of this era are, but on the 86 F250 I just got I had the same issue on the passenger side...

I found that the spring-clip thing that keeps tension on the caliper was WAY bent up and held excessive upward pressure on the caliper... so it didn't want to freely move.

I took it out and took some of the bow out of it and it freed up... no problems since.

I applied a bit of high temp caliper grease to the sliding surfaces of the caliper/bracket and pads to caliper.


Take a close look at your brake pads too, chances are they have overheated... mine had some cracks in the friction material and need replaced(on my to-do list for this coming weekend).