Brakes locking up!!!

Hi all
I have 08 crew I recently put new pads all the way around after doing a 10 minute test drive the brakes started locking up I could pump the pedal and it would eventually free up. I did some research and everything lex to the rubber hoses or bad fluid so I replaced the hoses and flushed the system with new fluid still the same problem. I then put new calipers on the front hoping that would fix but still same problem. So the brakes are free when I first start up but after a few miles they start dragging like I'm pulling a 20k trailer any ideas? Thank in advance

 

I'd immediately assume collapsed rubber lines, however there is something else going on here. If you replaced them they are not the issue.

Only other thing that jumps out at me is the pads themselves. Did you make sure they are free in the calipers (floating almost) if they aren't they will not return back where they should be and after getting hot might get stuck? I had to clean my calipers and the powdercoat from my stoptech pads so they would actually float in the caliper.

Good news is the problem didn't exist until you changed the parts (pads). So most likely its linked to your pads.

Also what did you use for replacements? I wonder if the pad material is too thick in the caliper, when it heats up it acts as if the brakes are on.

I'd almost install the removed pads and see if it still happens if possible.

Only other thing i can think of.
Start at each corner, remove caliper, check operation of pistons in caliper, check bleed nipple see if you can push the caliper back out with the bleed nipple in. Lift rear of truck (safetly with stands) spin wheel and use brakes, release and see what the caliper is doing per each side.

Good luck.

Keep up posted.

 

Thanks for the response actually the issue did start before the pads but didn't realize it. Every once in awhile the steering wheel would wobble like a wheel was bent I would jam the brakes a couple times and it would go away. After inspection the back side of the front brakes were virtually gone. That's why I replaced the pads. I had to open bleeder to get the pistons back in the calipers. So I believe the problem was there for awhile but there was very little pad left to cause a problem. I bought the pads from Napa not sure the brand name. The pads seem to have ample space and I even took out the squeal brackets to see if more room would make a difference but nothing did. Even with the calipers there was no change. What about master cylinder I've read tha t could be bad?

 

My take on the M/C. (if you pump up your brakes with truck off and pedal gets firm and holds you m/c is fine). I could be missing something here. (my brake job last fall determined that my inside rotors where bad).

If you couldn't push the caliper pistons back without cracking the bleeder you have a blockage in one of your lines.

If you crack the bleed nipple and push the brake and get flow at all four corners you ruled out blockages there.
You have 4 lines in the back (I'm assuming you already know this) two from the frame down to the rear axle and then one at each rear caliper. Then one at each caliper in the front.

Next step in troubleshooting. You can remove the center rubber lines and cap the lines 100%. This will take the rear brakes out of the troubleshooting. if your problem goes away you know that is the rears and can test each side.

Other option is lift the truck off the ground all four wheels and have someone push the brakes while you spin the wheels (most likely requires the wheel installed so you can physically turn the rotors. See what one is seizing up and try to figure out why. If its just front or rear again I'd assume your M/C is fine because it operates all 4 wheels.

Again, be safe and take this one step at a time. The shaking at the wheel would be the rotors being warped.

How much fluid is in your M/C? If you aren't leaving space at the top of the reservoir when it gets hot and can't expand it could be putting the brakes one?

Sorry, wish I nearby so I could troubleshoot with you.

Just remember if you changed something and a problem started that wasn't existing before your change most likely caused it.

The front pads are a straight forward swap so I'm guessing you installed correctly? Start over at each wheel double checking each part and ensure everything is together tightly.

I've been there many times and what seems like a simple thing can cause major problems.

I'm making some assumptions here.
You cleaned all surfaces between new rotor and the rear axle, your loosened your parking brakes out so they are not binding, all components are clean, rotors and wheels all sit 100% flush where they contact each other, caliper brackets and such all sit flush.

(When my buddies Ram caliper pistons won't go back without cracking the bleed nipple it was the rubber lines collapsed internally and ended up ruining the caliper due to heat).

 

Thanks for the reply Triharder. You mentioned cracking the bleeder to get the pistons back in. We did have to crack them and I agree with the blockage or collapsed hose so we replaced the hoses and flushed the rest of the lines with a quart or more of fresh brake fluid. I read that some people said the master cylinder plunger could be allowing fluid to the brakes but won't let it return.

 

A brake pedal pushrod that is adjusted too long will cause this, as the master cylinder will not allow the fluid to return when the pistons are partially depressed.

A plugged return port in the master cylinder can also do this, and contrary to a post above, a master cylinder issue can affect only one axle. All master cylinders since at least the 1970’s are dual circuit, and each circuit operates independantly of the other.

So, now I have a question. Which calipers required you to open the bleeders to be able to push the pistons back in?

All 4? Front two? Rear two?

 

@triharder the test you mention where you pump the pedal with the engine off is part of a booster test (the other part is starting the engine after pumping the pedal, then holding an application to ensure the pedal depresses more), but isn’t a great indicator of a good or bad master cylinder.

 

Landphil all 4 we cracked the bleeder but the front were the 1st ones we did this on because we couldn't get them to push in with the c-clamp. The back ones we just opened the bleeders because of the fronts giving us headaches so can't say if they would have pushed in otherwise or not. Definitely both fronts the pistons were stuck. As far as the brakes sticking both fronts are sticking and possibly the backs they feel hot after a test drive. One thing is for certain that I may not have mentioned before they have to be building pressure because the brakes won't be dragging for the 1st few minutes and I can set the cruise at 60 then a couple miles later they start dragging like I'm pulling a 20k trailer. So I'm not braking before they build pressure to stick. This is the most confusing part.

 

Check that pedal pushrod adjustment next.

If that’s good, you can also try driving until the brakes drag, then loosen the brake line fittings into the master cylinder to see if there is any release of pressure.

 

Thanks for all the responses it ended up being the pushrod was out of adjustment. Previous owner must have replaced tge master cylinder and never measured for pushrod alignment. Anyway thanks again especially landphil.

 

Glad you found and fixed the problem. Sorry it cost so much money and grief.

 

Great news! Just what I needed to hear after this week at work. It wasn’t for lack of trying, but I can honestly say that I accomplished nothing all week. This news makes my day.

 

one of 'em, and you probably got it right the first time.