Hyd Brake Issue STUMPED!

sickrunvanyardsale · 10-02-2015, 04:17 PM

Hey Eerbody,

I'm experiencing an ongoing issue with my driver's side front brake dragging. Basic backstory is as follows:

96 Int 3800 DT466 with 5 speed manual spicer trans, Hydraulic Brake system.
This spring I started experiencing "sticky calipers" in the front of the vehicle.
Drivers side front seemed to be the worst of the two.
Changed out both front calipers with remans from NAPA.
Changed out both front hydraulic brake lines with new.
Pressure flushed and bled entire system.

Upon application of brake pedal both while the vehicle is running and while the vehicle is off, results in an overly sticky drivers side front brake caliper/pad/rotor interface.

I made short video of what's going on for audio/visual learners.

https://www.youtube.com/watch?v=MBCntWLzF6U

At :30 into the video you can hear how the pads are still grabbing on the rotor.

Any ideas? I'd really like to get this thing squared away for the winter before snow starts really sticking!

sdwarf36 · 10-02-2015, 05:21 PM

With no pic of the caliper style, its hard to pinpoint-but the next thing to look for is the caliper sliding ok? If its the style that was on my old 85 GMC cube van, the caliper and pads rests on an area on the front hub. It would wear it out. Parts stores sell a cover that goes over the slide area to save having to buy a new hub/spindle. Hearing those pad slap back and forth makes wonder how much clearance is there.

Dragonpop · 10-02-2015, 05:24 PM

If the hoses have not been replaced then they should be replaced. They sometimes
develop a blister on the inside that will retain pressure in the caliper. If you open
the bleeder do the pads release, if so then its a hydraulic problem if they are still
stuck with the pressure released its a mechanical problem.

sickrunvanyardsale · 10-02-2015, 06:45 PM

Caliper style is floating (sliding) dual piston (73mm).

The area where the pads and calipers make contact with hub are clean with minimal wear (in my opinion). This vehicle has approx 57,000 miles on it.

The rotors are good to go, plenty of of metal left, even wear as far as I can tell.

The hoses were replaced with new ones as I considered a bad brake hose being the culprit.

bluebird90 · 10-02-2015, 10:01 PM

Two other things can cause caliper drag. the caliper binding in the mount and the pads binding. Remove the caliper, see how freely the inboard pad moves . there should be only some resistance. Next, reinstall the caliper without the pads, install the lock key, you should be able to move the caliper back and forth with a medium bop with your hand.
If the pads are binding, grind a little off the tabs. If the caliper is binding, take a file to the mounting surfaces to clean them up. If the key is the problem , the parts stores can get different thickness keys.

Jolly Roger · 10-03-2015, 01:53 PM

I had the same issue? Mine was I started to do the brake job as it was starting to rain so I got into a hurry and my front and back pads were different and I didn't pay attention?
With the caliper compressed fully they fit fine but with pressure we didn't move? The pads were not marked inner,outer or anything? My deciding factor was the retaining tab was slightly different.
I guess my only saving Grace was that I have done enough shade tree mechanic work that if I am working on more than one specific spot then I start/drive/move whatever it is the second I finish that piece? In this case I still had the driver side to do and was able to use it as a reference for the side that I screwed up. Matched the new pads 1for 1 and found my screw up. Pay attention when you take it apart and match the new part bolt hole, curve, retainers before you start and as you go. It could save some heartache later and you will know where or what then not when it don't work.

sickrunvanyardsale · 10-05-2015, 03:40 PM

Quote:

Originally Posted by bluebird90

Two other things can cause caliper drag. the caliper binding in the mount and the pads binding. Remove the caliper, see how freely the inboard pad moves . there should be only some resistance. Next, reinstall the caliper without the pads, install the lock key, you should be able to move the caliper back and forth with a medium bop with your hand.
If the pads are binding, grind a little off the tabs. If the caliper is binding, take a file to the mounting surfaces to clean them up. If the key is the problem , the parts stores can get different thickness keys.

Double checked the pads and they aren't binding in the slots. Slots were polished and all brake parts lubed with the Permatex Ceramic Extreme.

The calipers move with the "medium bop". Mounting surfaces were "gunked" up prior to the brake job so I polished them up real nice before mounting the new rotor.

I checked into the different size lock keys for this application and for the life of me can only find one for this caliper. Our one and only parts store says there is only one lock key for this application, no alternate thicknesses available.

On a side note, I'm not pleased with the calipers our local parts store is giving me for this application. I had to return the last drivers side caliper because the dust boot installation was all jacked by the factory, cockeyed and exposing the piston. This particular caliper also had a bad bleed screw hole. The flare face inside wasn't mating with the bleed screw face allowing fluid to escape around the threads. The replacement caliper they gave me is having the same issue, although this time the fluid is dripping out of the bleed hole.

Never had so many issues with calipers before until working on this application. Certainly not the end of the world but I don't jerry rig brake jobs, definitely not an area that you want to skimp on.

bluebird90 · 10-05-2015, 11:38 PM

Just so you know, there will always be a slight drag with disc brakes. usually as you drive the wheel turning will push the pads away slightly. when you drove it did it pull a bit to the dragging side on braking? Did the brakes get hot?
One thing I have found is the calipers with phenolic pistons tend to drag more. If this issue continues you may want to try calipers with steel pistons.

sickrunvanyardsale · 10-06-2015, 09:48 AM

Quote:

Originally Posted by bluebird90

Just so you know, there will always be a slight drag with disc brakes. usually as you drive the wheel turning will push the pads away slightly. when you drove it did it pull a bit to the dragging side on braking? Did the brakes get hot?
One thing I have found is the calipers with phenolic pistons tend to drag more. If this issue continues you may want to try calipers with steel pistons.

Roger that on the "slight drag"... The latest caliper sticking incident included a notable pull to the drivers side and that side did get hot... Like smoking hot.

Tango · 10-06-2015, 01:35 PM

Just a thought...but have you micked the pucks to make sure they are indeed the right thickness?

I only ask because of a reeeeeaaly scary 185mph motorcycle incident that involved a puck that turned out to be a hair too thick. Made three laps at Texas World Speedway before the heat swelled things up enough to lock the rear wheel going down the front straight. Good news being it was the REAR wheel. I doubt I would have survived the same issue if it had been on the front.

slidewayzm5 · 07-19-2016, 03:31 PM

sickrunvanyardsale - did you ever find out what the cause was? My right rear brake was dragging to the point that the rotor got red hot... but the bus had sat in a shed with a dirt floor for 7 years.

I plan on checking the rotors, doing all of the brake pads, full fluid flush and seeing if that gets me to a better spot.

Jolly Roger · 07-19-2016, 03:58 PM

Slidewayz that sounds more like a caliper is hung up? Could be rust on the slide/guide bolts or a collapsed break line not letting the caliper release.

sickrunvanyardsale · 07-20-2016, 12:28 AM

Quote:

Originally Posted by slidewayzm5

sickrunvanyardsale - did you ever find out what the cause was? My right rear brake was dragging to the point that the rotor got red hot... but the bus had sat in a shed with a dirt floor for 7 years.

I plan on checking the rotors, doing all of the brake pads, full fluid flush and seeing if that gets me to a better spot.

Yes, we got it figured out after trying out 4 different remanned calipers from NAPA. I broke down and bought a new caliper off Amazon. The hose ports on the remanned calipers were all slightly oval in shape, the flares inside the caliper were all slightly off center. All except one remanned caliper leaked brake fluid after the hoses were screwed in and seated properly.

The new caliper worked exactly like it should, flares and ports were spot on/perfect. I think the issue was that the ramanned calipers were so grossly out of spec that they were hanging up on the caliper slides causing them to lock up on the rotor. The new one didn't have any problems with it and functions flawlessly.

slidewayzm5 · 07-20-2016, 01:38 AM

Awesome thanks guys for the replies! I'll see when I tear into it and do a full mechanical check over.

Tango · 07-20-2016, 08:58 AM

Re-manned brake parts have the potential for disaster if the work is not properly performed.

Who supplied the parts that were so screwed up? They deserve some free advertising.

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