2nd Gen Non-Engine/Transmission Right Rear Brakes HOT!!!

[GCULP]

2001 HO, 6 speed, disc brake rearend.



I get home the other night and smell something burning, walk around the truck and the right rear wheel smells and feels hot, get out the temp gun and sure enough the right rear rotor is 470 degrees, left rear rotor is 98 degrees.



Background, wheel seals failed last summer, replaced seals, rotors, pads, and parking brake shoes. No issues till this week.



Here is what I have done to troubleshoot so far.



1. Immediately jacked up the truck without moving it, pulled the wheels, axles spin freely, no excessivie drag.



2. Thought it might be the parking brake so did not use the parking brake for two days, 1st day was fine, second evening when I got home, rotor hot again. Rotor was hotter at the outside edge than the inside edge which would indicate something other than the parking brake pads, if it were the parking brake the center should be hotter.



3. Today, had to set the parking brake twice before coming to work, no affect on the temp of the rotor so it leads me to believe it is not the parking brake.



A friend suggested a possible proportioning valve malfunction thinking it may not be letting fluid pass both directions through it, but they usually limit fluid going to the caliper in the event of a leak, I've never heard of one failing either.



Right now I am leaning toward a piston hanging in the caliper or ?

 

[B.G. Smith]

I agree with you, if it were the proportioning valve it should affect both rears. Be sure and check for movement in the hub on that side, loose bearings would let the rotor walk around. bg

 

[DCreed]

caliper is binding/dragging in the slides. remove and clean/reinstall with caliper(special high heat) grease.

 

[GAmes]

If it isn't the caliper it is the flex brake line going into it. They fail internally and do not let the fluid pressure release when you take your foot off the brake pedal.

 

[B.G. Smith]

If it isn't the caliper it is the flex brake line going into it. They fail internally and do not let the fluid pressure release when you take your foot off the brake pedal.

I believe there is just one hose that supplies both rear wheel brakes, if it is collapsed how could it just affect one wheel? bg

 

[DCreed]

I believe there is just one hose that supplies both rear wheel brakes, if it is collapsed how could it just affect one wheel? bg

even if there is a flex line it would affect the INNER pad the most.

 

[GAmes]

I believe there is just one hose that supplies both rear wheel brakes, if it is collapsed how could it just affect one wheel? bg

Yup, rear brakes don't have a flex hose do they?

 

[JacobsD]

There should be a shortie one just long enough to allow you to remove the caliper without bending a metal line. I think it sounds like it could be a caliper hanging up either on the slides or the piston, or maybe even a pad thats wedged in the stirrup and stuck against the rotor.

 

[RHestand]

I have an old Porsche (57 Speedster) that has been converted to four wheel disc brakes, and had exactly the same problems as GCULP.

After driving me crazy, (I R&R everything possible in there) it turned out to be the flex hose. (Ext. it looked almost new. )

Intermittent problems are definately the hardest to diagnose, but if you do have a flex hose there, I would definately try replacing it.

Good luck, Ray

 

[GCULP]

hey fellas, sorry I haven't replied. Thanks for the responses.



As for the caliper pins, they were removed, cleaned and lubed last summer when I had to replace the brakes and seals and they felt good when I removed them the other night. I am leaning toward the piston hanging up, I am going to remove the caliper, open the bleeder and gently squeeze the piston into the caliper and see if I can feel any resistance or ridges etc. If it is the piston, I will replace both rear calipers and the flex hoses as well since they are probably cheap insurance.

 

[dieselsam59]

i am having the exact same problem, let me know if you get yours fixed. mine only does it when i have the rear loaded, towing trailer or hauling. it changes wheels sometimes, either or both back wheels. it started when i replaced the pads 20,000 miles ago. it has since warped the rotors, which i just replaced and it did not solve my poblem. the slides are not the problem im thinking maybe the proportioning valve?

 

[DCreed]

i am having the exact same problem, let me know if you get yours fixed. mine only does it when i have the rear loaded, towing trailer or hauling. it changes wheels sometimes, either or both back wheels. it started when i replaced the pads 20,000 miles ago. it has since warped the rotors, which i just replaced and it did not solve my poblem. the slides are not the problem im thinking maybe the proportioning valve?

rear prop. valve or frame to axle flex hose.

 

[GCULP]

quick question, I'm only asking because I work from a simple form of logic. If it is the frame to axle flex hose, why is it only one wheel effected, is there one for each side? or are we talking about the flex hose from the axle to the caliper? And how does a hose of any kind fail such that it won't allow fluid both ways, I was always under the impression that if a hose failed it means there is a leak. Just FYI, it hasn't done it for a couple weeks now, I'm wondering if it could be a contaminate in the fluid that is effecting either the proportioning valve or the caliper.

 

[RHestand]

quick question, I'm only asking because I work from a simple form of logic. If it is the frame to axle flex hose, why is it only one wheel effected, is there one for each side? or are we talking about the flex hose from the axle to the caliper? And how does a hose of any kind fail such that it won't allow fluid both ways, I was always under the impression that if a hose failed it means there is a leak. Just FYI, it hasn't done it for a couple weeks now, I'm wondering if it could be a contaminate in the fluid that is effecting either the proportioning valve or the caliper.

IMO the reason the fluid won't go both ways is, when brakes are applied, the pressure is much higher going to the caliper, and able to push through a clogged flex line. When it is released, the pressure to return the piston to the non-braking position, and send the fluid back toward the master-cylinder, is much lower.

The power to return the piston is only created by the "roll-over?" of the rubber O-ring on the caliper piston. (Also, the older and stiffer the O-ring is, the less capable it is of doing this. )

Thats the best way I can explain it.

Ray

 

[DCreed]

post 12 was for dieselsam59. As for an internally collapsed hose, hoses are made of layers and if pressurized fluid can penetrate the internal rubber sleeve it will cause a bubble(just like it would on the outside) over time this bubble gets bigger or tears to a flap, either way it can act as a reed valve and the lack of pressure of the returning fluid cant push past it quickly or at all, and causes the caliper to drag. sometimes the heat created can ruin other parts(wheel bearings/rotors/pads/calipers)and as such can cause a misdiagnosis of the problem only to have it happen again. always change the fluid when a major brake service is done.

 

[GCULP]

ahh, ok, making better sense to me now. Thanks for the explanation.

 

[snug]

Same deal

My dually is doing the same thing on the right rear. It has done this twice, but only after I wash the truck. I'm not sure if something is freezing up, or what the deal is.

 

[GCULP]

I ended up replacing both calipers, good luck with yours.

 

[gradylaw]

I ended up replacing both calipers, good luck with yours.

Has it worked?

I have the identical problem... . intermittently. Took the caliper off, lubed it up, no prob for months then felt like it was dragging a little. Got hot and now has a jiggle in the rear that developed into a shake so bad I thought the truck was coming apart. Stopped, looked for something broken and nothing. Limped home and had another look. Nothing obvious. Right rear was hot but not smoking like before. Next day no prob til it did it again a few days later. Been a few more days without prob on 55 mi commute. RR wheel isn't hot.

WTF?