Sticky brakes??

[mobileortho]

Last couple of times I drove my truck it just didn't "feel right". The engine seemed to be running hotter than usual and just seemed to struggle. Pulling into the garage I noticed an odd smell that appeared to be coming from the brakes. When I jacked it up the I could turn it by hand but it would not spin freely. Took the wheel off & looks like the rotor shows signs of excessive heat so my guess is the caliper pistons aren't fully releasing. ( kinda hard to tell from his pic) Besides replacing them, any other possible solutions? From what I've been able to determine, these are s10 calipers.

[Jemezcrusher]

Robert, has your actuator rod to the master cylinder got any free play? I would check tht first as sounds like the system is under slight pressure all the time

[Nordic]

Make sure bushings and pins lubricated or caliper will not slide properly.

[joedoh]

drive the truck a short distance, crack the bleeder (better yet crack the line to the fronts at the master to get them both at the same time), if the brakes release its the master cylinder/pushrod. if the brakes dont release, its the calipers.

[jweb]

Originally Posted by joedoh

drive the truck a short distance, crack the bleeder (better yet crack the line to the fronts at the master to get them both at the same time), if the brakes release its the master cylinder/pushrod. if the brakes dont release, its the calipers.

This should tell you if the calipers are bad. Did you try it?

[mobileortho]

Originally Posted by jweb

This should tell you if the calipers are bad. Did you try it?

Yup.

[dsraven]

did you figure it out? was there pressure in the lines after a road test?

[mr48chev]

Make sure that the calipers aren't hanging up on the brackets too. They should be reasonably snug but you shouldn't have to force them to move

I'd still go with Post number 2 on making sure you have some free play in the pedal/pushrod before it puts pressure on the piston in the master cylinder. That piston doesn't have to move very far before it covers up the fill/bleed back hole from the reservoir and doesn't allow fluid to flow back. The wrong pressure residual valve could also do that.

[nail pounder]

I just went through the free play issue as well. Brakes work fine when cold but a after a few miles fluid gets warm, pressure builds and brakes drag.

[nail pounder]

Edit: I checked my slide pins first, didn't help, then did a search and learned about free play, took about 10min under the truck to adjust, then about 45 min of test driving

[Texas50]

Might also check the rubber hoses. Have had them collapse internally and act almost as an internal check valve causing the calipers to stick.

[mobileortho]

Ok, I'm checking the pins & under the dash to see if that helps.

[1project2many]

I'd still go with Post number 2 on making sure you have some free play in the pedal/pushrod before it puts pressure on the piston in the master cylinder.

Just had an issue with this at work. Aftermarket reman hydroboost was boxed wrong, applied pressure to master at all times.

[mr48chev]

One thing not mentioned was return spring on the brake pedal. I've run across a couple of rigs that either didn't get put together with a return spring (owner built hot rod) One that had the return spring removed because it got in the way of something (AD truck with V8 swap plus a couple of rigs with broken return springs.

On swing pedal a poorly adjusted brake light switch might hold the pedal down too much but it would have to be way out of adjustment..

[dubie]

if your pedal isn't adjusted properly, it'll depress the residual valve causing the brakes to stick when they get hot. I had the EXACT problem with my 56 after upgrading to power disc brakes. There is an screw adjustment on the rod that goes into your master cylinder. Try turning it out one full turn and take it for a spin till it gets warm. It could take a couple adjustments

[mobileortho]

Quick update; I tried all of the afore mentioned suggestions and nothing works. I'm thinking it may be the calipers. This is the same booster/mc I had on the previous setup & had no problems.

[dsraven]

-is your master cyl firewall mounted or frame mounted?
-has the unit sat for a bit (after having driven fine for miles before sitting) and then after driving it again you are having trouble?
-do you have free play at the pedal?
-do you have free play at the master cyl pushrod where it mounts to the booster? you have to unbolt the master and check pushrod length and then check that against the depth of the hole in the master cyl piston. gotta have some play there.
-what style of calipers do you have? some caliper mounts have a rubber bushing that fits into the bore on the caliper. rust or corrosion forms behind the rubber in the bore, effectively making the bore hole size smaller and thus making the pin become tight in the rubber bushing. then the pin will move but it is tight. in this case the rubber needs to come out, then the rust would need to be ground off the inside of the bore, then silicone brake lube the bores, clean or replace the rubber bushings and the steel pins, install the rubber bushings and then lube their bores with silicone brake lube and install the pins again. ensure the pins slide easily through the rubber bushings. this is a very common maintenance item here in Canada, especially if the vehicle has been sitting for a bit, like over the winter. the calipers will move on their slides but are tight. after the repair they slide easily like they are supposed to.
-take a look at the brake pads and see if one pad is noticeably thinner than the other (you maybe have not driven long enough with the condition to make a difference, but worth a look) or if the pad next to the pistons (with a dual piston caliper) is worn in a tapered configuration (this would indicate one of the pistons is sticking or siezed). if it is the pad next to the piston then the pistons are hanging up. if it is the pad opposite the piston then the caliper mounts are hanging up. it doesn't take much for the pistons to become sticky. there areno return springs on the pistons, they are sealed with a square cut "o" ring so when the piston moves outwards the square "o" ring rolls in it's groove and when the brakes are released the "o" ring naturally rolls back to retain it's original shape. it brings the piston back into the caliper at the same time.
-post up some pics of the caliper set up you have. S10's have 2 different styles of calipers and one style is more prone to corrosion than the other, so more prone to give "sticky brakes" issues. my son had the same problem with his S10 brakes and it was just the caliper mounts giving him issues. once cleaned they are good for awhile again.
-like joedoh says, drive it till you have the issue, crack a bleeder and see if you have pressure in the system. that will tell you if the calipers are sticking due to mounting issues or if it could be a master cyl or linkage problem.

[dsraven]

PLEASE put some jack stands under that truck if you plan on working on it. jacks fail, vehicles can move causing them to fall off the jack. lots of things can happen, that's why they are called accidents. even if you think you are outside the "fall" zone just working on the brakes, it only takes a second for something to happen and the fender cracks you on the back of the head as the truck falls, or worse. as a firefighter I have seen all sorts of auto repair incidents/accidents. most don't turn out well. as a mechanic I have seen jacks fail or vehicles roll causing them to fall off the jack. please be careful. a moment saved isn't worth it if you get hurt, or worse.
ok, end of rant.

you may have used this set up on other vehicles but the adjustments, although possibly the same, still have to be done or be checked.

if frame mounted master cyl, do you have residual valves inline?

check all the linkage pivot points for wear as well, especially if you have the frame mounted booster. that frame mounted pedal assembly can be heavy and has potential to become sticky or stretch the pedal return spring allowing the pedal to "fall" down towards the floor causing the master cyl to hold a slight pressure in the system. as the system gets hot the fluid expands and tightens the brakes up.

[mobileortho]

Originally Posted by dsraven

PLEASE put some jack stands under that truck if you plan on working on it. jacks fail, vehicles can move causing them to fall off the jack. lots of things can happen, that's why they are called accidents. even if you think you are outside the "fall" zone just working on the brakes, it only takes a second for something to happen and the fender cracks you on the back of the head as the truck falls, or worse. as a firefighter I have seen all sorts of auto repair incidents/accidents. most don't turn out well. as a mechanic I have seen jacks fail or vehicles roll causing them to fall off the jack. please be careful. a moment saved isn't worth it if you get hurt, or worse.
ok, end of rant.

you may have used this set up on other vehicles but the adjustments, although possibly the same, still have to be done or be checked.

if frame mounted master cyl, do you have residual valves inline?

check all the linkage pivot points for wear as well, especially if you have the frame mounted booster. that frame mounted pedal assembly can be heavy and has potential to become sticky or stretch the pedal return spring allowing the pedal to "fall" down towards the floor causing the master cyl to hold a slight pressure in the system. as the system gets hot the fluid expands and tightens the brakes up.

The shadow in the left of the photo is the jack stand, it just not in the pic. It's a firewall mounted booster.

[mobileortho]

Yep, I've tried all the suggestions but the results are still the same.

[nail pounder]

Really? You tried everything above and still have no answer? Is your master cylinder full? If so remove most of the fluid, leave 3/8". Drive it and see if it still gets sticky when it's hot. The fluid expands when hot and needs to go somewhere. I've had brakes work perfect with very little fluid, then get "sticky" after I top of the reservoir. This is just a symptom, my problem was the adjustment on the rod, I think I added a return spring as well.

[mobileortho]

Originally Posted by nail pounder

Really? You tried everything above and still have no answer? Is your master cylinder full? If so remove most of the fluid, leave 3/8". Drive it and see if it still gets sticky when it's hot. The fluid expands when hot and needs to go somewhere. I've had brakes work perfect with very little fluid, then get "sticky" after I top of the reservoir. This is just a symptom, my problem was the adjustment on the rod, I think I added a return spring as well.

I'll give it a go this weekend &see what happens.

Originally Posted by mr48chev

I think that this is something that is so simple that you are overlooking it.

You're probably right! Going back through everything to see if I can figure it out.

[mr48chev]

On Floor mounted pedals I have had them hang up where they went though the floor.

I think that this is something that is so simple that you are overlooking it.

[mobileortho]

So I took it out today and sure enough, it was something simple. As I was driving I just happen to reach down and pull up on the brake pedal & voila! Instant relief! Looks like I need a stronger return spring!

[dsraven]

yup, figured you would find something small that got overlooked by thinking too much into it. that is why I mentioned to check all the linkage and return springs etc. glad you got it figured out. it's always good to start with the basics and, when you know they are all good, then look deeper. usually something basic.
good on you for figuring it out.