Right front brake caliper always dragging-- ive changed everything!

[The_Josh_Bear]

@The_Josh_Bear have you replaced the master cylinder? My dad's 82 f150 4x4 did this on the passenger front years ago. I have no idea how the master cylinder had any effect on just the one front side, but it fixed it after replacement.

Prior to the master we replaced all the front brakes (calipers, rotors, pads,flex lines) then thought that maybe the rear was doing something crazy and causing issues with the front so we went through them (turned the drums, new shoes, wheel cylinders, hardware kit, flex line). Then swapped the proportioning valve, adjusted the booster rod. Still no change.

We actually used the truck for about 6 months with a nail between the steel and flex line on that side to block the fluid to that side so it was drivable. Finally on the recommendation of a mechanic my dad knew we changed the master and it fixed it. If you have a spare laying around or want to spend the money on a gamble it could be worth a shot.

I still cannot wrap my mind around what in the master could possibly cause only 1 side to lock up when they work off of the same line.

James

No, I haven't changed the master. And I can't imagine how it could affect just one side either, as you said. Maybe your nail knocked something loose?? I'm thinking about pulling that hard line and blowing air through it, etc. Just to check things out. I would suspect the new flex line from just a year or two ago but it bleeds so easily and backs off easily...

I even bought a brake pressure tester and of course every adapter it has is metric and not even close to matching my pickup's brakes...ugh.

 

[Kdo58]

I have the same problem, I just found this video on YouTube.

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[The_Josh_Bear]

Holy cow. I never thought to crack the hardline to flex hose connection to see if the pressure was built up behind the flex line! That's the perfect next step. Thanks so much for the video!

 

[The_Josh_Bear]

I went out to check out where the pressure is in the line... and there isn't any. What the heck. That's with turning on the engine and standing up on the brake pedal a few times, which always pressurized the line before. Now I'm realizing that was from the booster rod being out of adjustment!

So I pull off the caliper and sure enough, the pistons are super hard to back off with the bleeder nut open. Time for ANOTHER caliper. But hopefully this time it'll be licked.

I think the whole thing happened thus:
1. Brake booster pushrod out of adjustment, always holding a little pressure.
2. Rear brakes far enough out of adjustment that I never had pulling/dragging issues.
3. Tightened up rear brakes. Over time, started pulling to the right.
4. Swap brake caliper, still pulls right and caliper holds some pressure.
5. Adjust booster rod, everything gets a bit better, maybe 30-50%, but still pulls to the right.
6. Find brake piston dust boots burned up from before the booster rod adjustment. Left that alone thinking it wouldn't matter for a couple weeks/month.
7. It mattered, as the caliper pistons are very rough in the bore, quite hard to compress.

Getting another brake caliper today, will see how she runs. I really want this thing to track straight again, she's a pleasure to drive!