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Front Caliper "stuck" "Tight".

S

scot4free

NAXJA Forum User
Location
Sacramento
OK, been battling this one for a while.
92 XJ, left front caliper won't release....new caliper, new rubber brake hose, pads new, rotor new.

I get vibration under acceleration on the rotor and it's pretty easy to feel it's the brakes, not a u-joint, as i replaced them last night,didn't help.

By hand, can barely turn when on jack stands and wheel off.

With this being 2nd caliper, I feel assured it should be good. What would make only one side keep it's pressure and clamp down on the rotor??

I doubt the metal brake line? But whos knows.
If the prop valve or master, why only one side???
 
If it is the second caliper, you must already know...but I have to ask. When the caliper is off, does the axle spin freely? Also on install, is there extra space in the span of the caliper for an easy install, or does it have to be hammered into place? Is everything hunky sorry until you hot the brakes and it adjusts onto the rotor?
 
Axel smooth, not bent. New hubs, u-joints.
It's like the pressure is not being relieved. I've never changed a master, so not sure if they can cause this only on one side. or perhaps it's more noticeable since the shorter metal brake line??
I used a caliper spreader to let it go smoothly. but once the pedal is pumped up, pretty tight to rotate, except the passenger side, which has normal drag.
Is it possible the prop valve is clogged, since this is the only seperation of left and right?

It's more noticeable when a few miles have been on it.
 
I used "Precision" 513084 hubs.
The rotors are the "high carbon" units from pepboys. They are both same thickness, height. Seem perfect fit. Calipers remanufactured from Autozone. Pads are Autozone Cmax.
Pedal nice and firm, brakes great, just not releasing drivers side.
 
process of elimination...... swap the rotors left to right and see what happens. you really werent clear if this was a problem before you replaced these parts so it's hard to troubleshoot from here.
also what about the bleeder screw?
 
lay the new rotor and old rotor flat on the floor next to each other. measure inside the hub from the floor to the top edge

Are they the same?
 
I had this same issue on my 87 Waggy. IIRC There are two different rotor " hat" sizes for a XJ wagoneer and regular XJ. Maybe not your issue but its worth a check. Took me a while to figure this out because the difference is so small.
 
They are the same....
Is it possible for the prop valve to be mis-behaving for only one side, since the master cylinder is only front and rear?
 
the prop valve has nothing to do with left to right, only front to back bias. sorry I can't help more than that.
 
Check all of the above. While you have the caliper off, check the part of the knuckle where the pads slide. A common occurrence is a small divot is worn into the slide and the pad will hang up there. The fix for this is either a better knuckle or weld it and file it smooth. Checking the bleeder screw would help eliminate the caliper I would think.
 
I've read somewhere about welding the knuckle, but never knew why or what it was about. I'll have to wait a few days to check that... after eliminating almost everything else, sounds hopeful... grrr.
Thanks everyone!
 
You must measure and inspect the hubs, calipers, and rotors to make sure all the parts play well together. Previous owners may have swapped around parts or the parts store may have given you the right box, but the wrong parts. Measure the rotors carefully, the size differences are not very big.

Read this -> http://www.naxja.org/forum/showpost.php?p=245269210&postcount=22
 
Brake hose collasped on inside not letting fluid return to m/c ?
 
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