sound like a stuck caliper?

[V8BoatBuilder]

I'm going to jump in here, it seems like this problem is really frustrating, though 410 has been giving some awesome advise.

Back to square one, before the problem started, the rear brakes were fine, it was just the fronts that were dragging. However, you could still (sort of) drive.

You then replaced the front calipers. And then the rubber lines, and then the MC. And the fronts are still dragging? What about the rears? If they are not dragging, I don't see how the RABS valve could be contributing to this problem of holding pressure to the front calipers. The valve is not a pump from what I gather, and could only cause the rears to lock (or not). It won't effect the fronts in yoru case.

Before you buy any more parts, do some diagnostics to try and locate your problem.

Step 1) Do the test mentioned where you open the bleeder screw on each front caliper and try to turn the rotor. If the rotor turns, then the rotor/caliper assembly should theoretically be ok. If ok, do step 2.

Step 2) Close the bleeder screw, and pump the M/C untill you have pressure on the caliper so its holding the wheel. (Assuming you filled/bled) the system. Now remove the hard lines from the M/C, one side at a time. You will get fluid from the M/C and the line, catch it as it eats paint and be careful. With pressure released, see if you can turn the rotor. If you can, then the problem is most likely in your M/C. If not, bingo. Its in your hard lines.

This problem is rather weird. Most of the time its a spongy pedal, rather than a non-release. Its very weird after a caliper replacement. Keep us posted - we'll get this problem fixed.

 

[jgilbs]

i am going to have to wait until tmo to properly bleed the system. i only bled one wheel and it still locked up. also, jacked the entire truck up and pulled the rear tires and drums. looks like the rear has been dragging as well(damn i got 14mpg with dragging brakes, what will i get when this is fixed?!)
im gonna focus on the slide calipers as a possible trouble spot. they were kinda hard to hammer in, and this was with a 5lb sledge. they WERE sufficeintly greased, but who knows.

thats good to hear the RABS valve doesnt play a role in the front. looks like ive replaced all the expensive stuff. i can deal with an extra few bucks for hard lines(if its that)

i have a feeling its just something super stupid on my part, like the pushrod length is long or something like that.

 

[V8BoatBuilder]

iim gonna focus on the slide calipers as a possible trouble spot. they were kinda hard to hammer in, and this was with a 5lb sledge. they WERE sufficeintly greased, but who knows.

Whoa. I've never worked on a TTB front end, but I have NEVER needed a hammer to re-assemble brake parts on any car I have worked on. Nor would I ever want to.

410 - can you comment on this?

 

[jgilbs]

well, you use a hammer to punch the slide pins out, and punch them in. the first gens dont use bolts for the calipers. theyre pins.

youve never used a sledge on brake parts? i take it youve never tried to take a brake drum off WITHOUT one?

 

[V8BoatBuilder]

well, you use a hammer to punch the slide pins out, and punch them in. the first gens dont use bolts for the calipers. theyre pins.

youve never used a sledge on brake parts? i take it youve never tried to take a brake drum off WITHOUT one?

I mean for reassembly. And for disassembly, I try to use a large crowbar whenever possible rather than banging away.

 

[jgilbs]

u cant use a crowbar on the drum. you would bend the backing plate and it still wouldnt budge the drum(beleive me i tried when i first did drum brakes) look for the post "how do you get the friggin drum off"

 

[jgilbs]

OK, so I cracked the bleeder screw and tried to turn the wheel. nada. I am looking back on the install and it was kinda hard to jam the caliper in there. I am starting to feel like a fool for buying all of these parts. As I was sittin in the garage, got an idea. Tmo, I think I'm gonna take my trust angle grinder to the mounting surfaces on the caliper and "persuade" it to fit properly. Anyone think this is a good/bad idea? I am just wondering why the caliper doesnt fit on the track properly - it is now blazingly obvious there is too much friction between the caliper and mounting bracket. This odd because I have new slide pins, copious amounts of grease and I have never been in any accidents to bend the kunckle(it looks fine as well) also, it is very peculiar it will move in one direction and NOT the other.

 

[special_k1979]

ok not to sound redundant but take the caliper off the rotor, crack open the bleeder screw and try to push the piston and see if it goes in easy, if it does then the caliper isn t the problem, didn t read the whole thread so some of my suggestions may have been already said, and u did already change to brake hoses, cuz i know on some GM s that have a mounting bracket half way on the hose build rust and cause resriction on the hose making it a one way vavle basically, but it s better to work from the calipers back, never heard of a master cylinder causing a problem like this, if the master was bad u would have no pedal, it would hit the floor, could be a combination valve but unlikely, lastly u could always try a brake system flush...

 

[Runnin'OnEmpty]

they were kinda hard to hammer in, and this was with a 5lb sledge.

Jeff, I agree with V8Boat, you shouldn't have to use a hammer that big. Small taps should be enough to seat the pins.

I would focus on the caliper alignment with the rotor. Is it possible that the rotor itself isn't seated properly, and causing it to bind with the caliper? If not the rotor, then the caliper on the bracket? I think what's happening is that when you pump the brake, the pads are seating, but then they won't release because of something binding......???

 

[jgilbs]

it seems like the caliper is binding on the mounting bracket. rotor is seated properly. when i put the caliper in, it fits easily inot its mounting point, but as soon as i put the pins in, its like they are too big or something. thats why i was going to try to enlarge the hole they mount in.

EDIT - I alosso tried the bleeder screw thing, which is what leads me to believe it is stuck in the mounting bracket.

 

[410Fortune]

Sounds to me like you have the WRONG calipers.
Can you compare them to the ones that were replaced? They could be dana 28 or dana 44 calipers you are trying to install on a dana 35???

 

[jgilbs]

but they fit onto the mounting thing just fine. it seems like the hole for the slidepins is too small - but that is the only problem with them - otherwise they are fine. are there any problems with grinding them down? might i cut into the fluid cavity?

 

[V8BoatBuilder]

but they fit onto the mounting thing just fine. it seems like the hole for the slidepins is too small - but that is the only problem with them - otherwise they are fine. are there any problems with grinding them down? might i cut into the fluid cavity?

While this may be a temp fix, its not the right fix. You should not have to machine the calipers, and honestly I would not want to ride in your truck, or be on the same road as you if you took a grinder to your calipers.

Find the real problem.

 

[jgilbs]

its almost like the pins are too big for the hole.

EDIT - I put the caliper in the mounting hole, and with no pins, it moves easily. As soon as the pins are installed, it wont budge(it will engange, but not disengage)

I have some spare caliper pins lying around, im going to machine THOSE instead of the caliper and see if that helps any.

 

[jgilbs]

4x3?! wtf?!

ive got the truck jacked up on all fours. i got the pass side brake to release just fine(its the one i repacked for the second time) but now theres a funny thing happening with my driver's side axle. not only is the caliper STILL sticking - now the axle wont even turn when put into 4x4. wtf?! everything else works fine. its like this wheel hates me. the brakes wont let go and the axle wont turn. whats goin on here?! are these seperate issues or what?(the rotor turns fine by itself when the caliper is off. and when the brakes are applied and released, you can see the caliper piston apply and release - its just not releasing as much as it sould be.

 

[V8BoatBuilder]

ive got the truck jacked up on all fours. i got the pass side brake to release just fine(its the one i repacked for the second time) but now theres a funny thing happening with my driver's side axle. not only is the caliper STILL sticking - now the axle wont even turn when put into 4x4. wtf?! everything else works fine. its like this wheel hates me. the brakes wont let go and the axle wont turn. whats goin on here?! are these seperate issues or what?(the rotor turns fine by itself when the caliper is off. and when the brakes are applied and released, you can see the caliper piston apply and release - its just not releasing as much as it sould be.

Relax. The axle is not turning because of your open diff in the front. Since the caliper is holding the rotor, there is resistance on that side. Meanwhile, the other wheel is free, so all power is going to it. Thats normal.

Again I feel you shouldn't need to machine anything here, but trying different slide pins is a good way to progress.

 

[jgilbs]

yea, im tryin to stay away from machining - my logic is, if theyre not fitting properly, theres a reason for it. i thought that maybe the heat from my old calipers(that were actually bad) may have warped the mounting points. Looks like they didnt. I am in the process of repacking my bearings(theyre soaking in paint thinner right now so I can start over) so hopefully that will help, since it did help with my pass. side.

i just wasnt sure bout the front axle - i dont have a whole lot of experience with diffys.

 

[jgilbs]

ok, this is gettin weird. pass side caliper works great. driver side is STILL sticking. what is the likelyhood that i got a bad caliper? im gonna go and swap calipers from the pass side to the drivers side and see. this is just ridiculous!

 

[jgilbs]

Relax. The axle is not turning because of your open diff in the front. Since the caliper is holding the rotor, there is resistance on that side. Meanwhile, the other wheel is free, so all power is going to it. Thats normal.

but the problem was my hubs werent on. it was just the axle. it should have been freewheeling. pass side worked.

 

[jgilbs]

ok, new caliper - same problem. WTF?! did i install the calipers wrong?

EDIT - REWARD: $20 to anyone who can provide information resulting in the correction of this problem!