I was having brake issues - the pedal was spongey, ended up posting here- got some great suggestions and fixed the problem by pulling the MC out a bit and spinning that nut shown in this thread.
https://www.f150forum.com/f6/brake-issues-192007/.

It was fine for a while. I rarely drive the truck and today when I went to drive it I drove about 2 miles and then it seemed all the calipers locked up- I could still move the truck under its own power but could definately tell the calipers were engaged- I brought it back and jacked up the front, tried to spin the front wheels by hand- no good. Then jacked up the rear, tried to spin the rears, no go. I have all new calipers and a new master Cylinder. I dont want to just keep throwing parts at it but all I am left with is the power booster-. I dont think that nut that I spun before is the issue because initially the brakes weren't locked up until after I drove it for a while.
Any suggestions, any chance the booster is not releasing pressure after the pedal is pushed several times?


1999 F-150XLT 4x4, 4.6 ext cab

 

How far did you turn it? Maybe you turned it too much? I really have no clue, just throwing a guess out there.

I have the same issue - spongey brake pedal. Unfortunately my hood won't pop open, so I have to get that fixed first.

 

No- its not turned too far because I release the brake pressure by loosening the 2 brake lines coming off the master cylinder, the brakes released, then drove the truck, came back and the brakes were like they were applied.

 

You probably do have it turned to far. You need to adjust it back. What's happening is your building up brake pressure when your pressing the pedal. and it can't release it because it won't let the piston in the master cylinder return far enough. I.e. thats why your brakes keep locking up. For a spongy brake pedal- check for leaks, bleed all of them starting with the wheel farthest from the master cylinder. Make sure none of your brake pads are seized to the anchors, the should be able to move freely.

 

What initially got me to turn the bolt was not so much a "spongy" pedal but rather a pedal that would go a bit more than halk to the floor. I will try to turn it back though and see what happens

 

Does your brake pedal settle? This is almost certainly your problem if you have ABS:

https://www.f150forum.com/f6/brake-p...-150-a-157374/

 

No- it is weird, from what the above thread is describing is the brake pedal "engages" at a normal point then "fades" away towards the floor- that is not what mine is doing- it just doesn't engage until 3/4 of the way to the floor but then works fine. I turned that bolt and it brought the engagement point further up but now the brakes lock up so I think it may be turned too far

 

I'm telling you your pads are seized or slides are seized. That will cause your concern

 

A low pedal sounds like the rear brakes are out of adjustment, undo your previous adjustment and adjust the rear brakes. They may also need to be bled since you opened the lines up.

 

I've bled them several times and they are rear disc so I don't believe there are any adjustments

I see your screen name- what type of Harley do you have. a '13 as the name says? I have a '12 Ultra Limited- are you on any of the HD forums?