Brakes locking up or dragging — stuck/sticky brake calipers

[Deesh]

My brakes started locking up recently, kind of goes like this.... I get in my van and start it up, i start to go down my driveway applying light pressure to my brake pedal and they act normally, but then once i get out of my drive way and stop at the first stop light my car slows normally and then right before its at a complete stop the brakes lock up and it skids a tiny bit. it feels like the front right of the car gets clenched up and pulls down. If i press down on the gas there is some resistance from the brakes at first (feels like the front brakes) then it lets up and drives normally.

at first it would only do this once the first time i really stopped, then would be fine for the rest of the commute. Now it is doing it much more often so I've stopped driving it and am not sure what to do....

My van has had a slow leak under the dash (probably brake master cylinder) and I've topped it off twice in the past year to get it back to the max line (it goes down very slowly). Any ideas? I'm planning on taking it to a shop but I'd like to try to fix it myself. Would a new master cylinder fix this?

thanks

[timsrv]

Would a new master cylinder fix this?

thanks

Perhaps, but it's more likely time for new calipers. These aren't the best calipers and the slide pins tend to seize up over time. Since you have a leaky master cylinder too, I'd replace that as well (then you're sure to get the problem). www.Rockauto.com has some good prices on these parts. I've been using their cheap rebuilt master cylinders & calipers for years without an issue. Tim

[Deesh]

Okay, yeah the problem seems to only be getting worse, was going to take it to a brake shop but now that I'm scared to drive it across town I think I'll go for fixing it myself.

I've read and plan to follow the post on changing out a master brake cylinder, is changing calipers a hard task (I've only changed brake pads before). I guess the main thing I'm a little scarred of is bleeding the brake lines... any tips on what order I should tackle this brake job? I'll order from RockAuto, do you recommend any of the brands over any of the others?

Thanks for the help, this forum is a life (and wallet) saver! Plus it feels pretty good to have a more intimate relation ship with van problems and repairs haha.

[Deesh]

Also, should i go ahead and replace the rotors too? seems like it might be worth it if I'm going to be doing everything else... If I were to do the rotors is there anything else that should be replaced, cleaned, greased, etc?

[timsrv]

I usually replace calipers & rotors every 10 years regardless, but that's just me. If you're not having any vibrations while braking and if you've never allowed metal to metal contact, then the rotors are probably still okay. They are cheap though so I just replace them. My experience with inexpensive brake parts from www.rockauto.com have been positive (knock on wood). I do prefer Toyota pads though, so I still pay Toyota prices for those.

When you shop on rockauto, scroll down & check all calipers and compare prices with bare units & fully loaded. Also important is core charge fees. Often times these fees will make fully loaded calipers cheaper than the bare units. When I end up with the fully loaded ones I just toss the pads & replace with Toyota ones. Tim

PS: The other thing to check is shipping charges. Rockauto will often charge absorbent prices for shipping. I will sometimes experiment by adding then removing different products to my cart. Sometimes they will charge a lot more shipping on the cheaper parts............enough so that it can often be cheaper to purchase the more expensive parts.

[Deesh]

Thanks for the advice Tim!

I changed the front calipers yesterday and it seems to have solved most of my problems, no more locking up as of yet. I ended up getting Centric brand calipers from amazon with free shipping at a good price, from what I can tell they appear to be well put together and sealed.



It feels like the back brakes might be sticking a little bit but I haven't driven it enough post new calipers to be sure.

I bought new rotors to put on as well but the ones that are on there seem to be okay, and I got a little nervous about unpacking the wheel bearings and all that to replace the rotors. Is that something to be nervous about or is it pretty straight forward? Any insight or tips on that process would be great, I plan on doing it sometime in the next couple weeks.

How often do you service the rear brakes on your vans, could they cause minors sticking issues (after braking if I release the brake pedal the van doesn't pull forward sometimes, feels like the the brakes are slowly releasing then will idle forward normally... not sure if its my imagination though)

[timsrv]

Rotors are bolted to the hubs. You can swap rotors without repacking wheel bearings, but if you don't know when they were repacked last, then now would be a great time to do the job. All you need is some wheel bearing grease and some inner grease seals. To find out if they need repacking, just pull one of your outer bearings & inspect. While it's off, shake it. If you can hear the bearings rattling in the cage, then it's time to repack. If there's still grease in the cage the bearings won't rattle (and you can probably skip it for now).

Brake fluid on your rear brake shoes can cause grabbing and/or lock-ups. To inspect, pull the rear drums & look for leaks coming from the wheel cylinders. They usually leak around the rubber end caps. If you don't see any, use a screwdriver to pry the rubber cap away from the cylinder. If brake fluid oozes out, then it's time to replace that cylinder. If your shoes are worn close to the metal, or if you find brake fluid on your them, then it's time to replace shoes. FYI, cleaning contaminated shoes isn't a good idea and usually doesn't work. Tim

[Deesh]

Okay, thanks Tim. I'll take a look at these next time I get a chance and see if any of the mentioned problems are apparent.

[bigeo]

This summer I replaced my front brake calipers. I had ingnored the signs too long and the passenger caliper was frozen, the pad down to metal and the rotor shot. I had replaced the calipers/rotors 6 years before (maybe 30k miles) and was surprised that this had happened so soon, but I'm not sure how long they usually last. I replaced with rebuilt "loaded" calipers from RockAuto. Brakes work a lot better now but the passenger side drags and even though it has gotten better (about 500 miles since the work was done) there still is significant resistance. I've never been clear on what makes brakes "release" when you take your foot off the pedal, but it doesn't seem to be happening as it should and since this is on the same wheel where I had the previous problem, I'm wondering if I should be looking at something other than the caliper.

[Burntboot]

Brakes function on hydraulic action.
When you push on a fluid (that does not contain air) it acts more like a solid, in that it won't compress or expand.
So when you depress the brake pedal, the pistons are forced out, when you release the pedal, the pistons are drawn back in.

First you should bleed the brakes to verify there is no air in the system.
Next you'll need to inspect the callipers to verify that everything is free to move, not just the pistons but also the sliders and the hardware the pads mount in.
It is possible that you have a defective rebuild.

As the problem is the same wheel as before, you will also want to verify that you are not having a problem with the rubber flex lines.
A visual inspection will sometimes yield insight, if the external rubber casing is cracked,kinked or otherwise showing damage, they should be replaced.
They can swell internally, effectively becoming a one-way valve, in that you can force fluid through the obstruction but there isn't sufficient pull back to overcome said obstruction.
It isn't as common as seized hardware issues, but I have run into this condition several times over my wrenching life and becomes more common with increasing age.
The easiest way to verify a problem with the flex lines would be to pump the pedal several times and (with the pedal released) crack the bleeder open, normally it should just dribble out, if it comes out under force, you've found a problem.

As far as how long brakes should last it is totally variable depending on useage and driving habits.
It is a very good rule of thumb to do a full brake service at least once/year and/or every 12K mls (20K Km).
Like everything, brakes like to be used, vehicles that don't see a lot of use should be serviced MORE often.
Rotors will rust and sliders will seize when not exercised regularly.

Location will also have a lot of influence on how long they last.
Dusty regions, wet regions, humid regions all have a detrimental effect.
Another big issue I have run into is excess lubricant on the sliding surfaces, inexperience combined with a "more is good" mentality.
Excess lube will attract dirt leading to binding, which will impact the ability of pads/pistons to move.

BB

PS, might also be prudent to spin the rotor with the caliber removed, just to verify that the "drag" is brake related as opposed to issues with the bearings

[bigeo]

Thanks Burntboot for the detailed reply. So, is it vacume that pulls the piston back when you release the pedal? I checked the caliper out a few days ago when I realized it was still dragging ( the hot brake smell had gone away so it wasn't as obvious). I had to crack the bleeder to get the brakes to release so I could pivot the caliper. The fluid did more or less just dribble out, but I hadn't pumped the brakes up immediately before. I think I will replace the hoses since they are cheap and I don't think they have ever been replaced. Next would be different pads. Another symptom I have noticed is that the brake pedal is a little "sticky" by which I mean, it moves smoothly initially, then catches, then releases. It's subtle but noticeable. Makes me think that something is hanging up mechanically. If it's the piston in the caliper, anything to do but buy another one?

[Burntboot]

Vacuum isn't involved (on the return stroke at least) but there is a spring within the Master Cylinder that provides that function.

If the calliper released after cracking the bleeder, that is a pretty sure sign you're having issues with flex lines, so good call to replace them.

Not sure what your "catching"issue is.
The pedal swings on a pivot, the master is activated by a push-rod attached to the swinging brake pedal.
The pivot pin sees little stress and is likely fine.
It's the pushrod pin that takes all the load and wear, often just replacing the pin is sufficient.
When they get really bad, it can start to elongate the holes in the pedal &/or pushrod. (bigger/harder fix)
(There is supposed to be a bit of play within the linkage so that the master isn't pressured by the brake pedal, until called in to play)
Push rod length is set at the factory and doesn't normally require any changes, unless someone has been in there previously and messed it up.
The other possibility would be an issue within the master itself but I would eliminate all other possibilities first (master is expensive and a PITA to change)


While you're in there replacing the flex lines, service the fr brakes (both sides) just to verify that the pads are sliding within the brackets as this too can cause odd sensations with pedal movement.

[bigeo]

replaced the hoses, checked to be sure the piston was moving freely in the caliper (I could push it in with my fingers without much effort), tried different pads, made sure everything was sliding freely, bled the system and the brakes still drag a bit. The only thing that seemed to help a little was removing the shims. I think I'm done for now.

[Kyle]

I'm pretty sure I have too much front brake drag. Without the tire on I need two hands to turn the hub at all. After driving for 15 miles my rims are *hot* to the touch, not just warm (the rotors, of course, are searing). Pretty much happens on both sides, one side a bit worse. I just replaced the calipers with a reman set. I know it's not the bearings because the hubs spin free as a bird when the calipers are swung out and I just set them to spec when I put my warn hubs on. The calipers don't free up when I crack the bleed nipple open either. Fluid doesn't shoot out, just dribbles.

I know disc brakes should always make a little contact, and it's not like I'm grinding to a halt, but I feel like the brakes are dragging just a little too much to be acceptable. Problem is nothing seems obviously malfunctioning.
What is actually supposed to make the calipers open back up a smidge other that rotor irrregularity? A spring in the master cylinder to draw a little fluid back? Some square-something-o-ring?

I know there was a thread like this a little ways back, but seems like it ended unresolved.
Help, Anyone have any ideas?

[Burntboot]

Kyle - If the rotors spin free without the callipers installed, then your issue is with the callipers!

I know you said they were "rebuilt" but sadly, that doesn't guarantee that they are "good".

[Burntboot]

As far as the piston retraction goes, its a function of the hydraulics and the piston's seals, it has nothing to do with the trueness of the rotor.

You should be able to easily compress the pistons with a large pair of pliers, and all the pistons should move with equal force.

[originalkwyjibo]

This could also be caused by bad hoses. The hoses may look fine on the outside but could be collapsed internally. The high operating pressure of the brake system will force the fluid through but with no real return pressure the bad hose effectively holds the brakes on. There's a fairly simple way to test this. Try pumping the brakes a few times and then with no pressure on the pedal, open the one of the bleeders. If fluid comes out under pressure than this is likely the cause. If you just get some dribbles with no pressure than something is binding either in the mounting or the caliper internally.

[Burntboot]

OW - He's already cracked bleeders, without resolution.

Kyle - What kind of "rebuilt callipers" did you install? "fully loaded" (complete ass'y including saddles and pads) or just bare callipers?
If the later, did you service/replace the pads &/or hardware?
When you're checking the pistons you also want to verify that both pistons push back evenly and with the same force.

BB

[originalkwyjibo]

My bad. I somehow missed that sentence when I read the post.

[JDM VANMAN]

My 4WD van was having a brake drag and left pull for about 400 miles and I finally took it in about 2 weeks ago to have it fixed.

The left wheel wouldn't move freely so my mechanic ordered a new remanufactured left caliper (not sure which brand) and replaced the old cracking hoses, new brake pads, brake fluid, and safety inspection of brake operating system.

All was good except the left pull is still there and he said looks like the rack is going bad... I posted about the rack in another thread.

JDM