dogkatcher

90 XJ Laredo 4.0

so ... installed new front pads about 7k miles ago up front ... just did new cylinders,springs,drums, shoes in rear 2 weeks ago

heard a faint noise while doing 60 mph .. both front pads barely rub against rotors (consistently as turned),....... too much fluid ?? not sure, thought they "self adjusted" .. not helping my MPG very much im sure .. not to mention premature pad-wear

also, the rear passenger side "rear" facing shoe gets barely rubbed by drum ( from about the 8-11 oclock position) .. when spun by hand, its just once per rotation, not like the whole drum is rubbing it (9 inch brakeset)

a mechanic said return springs caused that, but those are now new. not sure why it would rub in one spot like that .. was hoping they would finally seat themselves, but the new show has an obvious wear mark from this .. gonna jack it up again it looks like

Abovetimberline

your front calipers are suppose to back off after you release the pedal,I did not read where you replaced calipers,I am not saying they need to be,but if your pads are installed right the calipers might not be relaxing enough,I have heard of situations where you can have to much fluid,if your master cylinder is overfilled,but I have never seen it.
Your rear shoes is not all that big of a deal,unless you are having driving issues,it sounds very slight from what you ar saying.

winston427

The rears may just need to be readjusted. If the front caliper is not releasing properly, then that is something that needs attention immediately. When I first got my 91 it had been sitting for 2 years but all the brakes had been replaced prior to it being parked. On the way home from getting the tags the right front caliper locked up after a panic stop. I was only a few miles from the house so I got it home. By the time I got there to rotor was so hot it was glowing and all the dirt and oil that was built up on the steering knuckle almost caught on fire. When it had cooled off the rotor had blued form the heat. I ended up replacing both calipers (they should always be done in sets), both rotors, pads, hoses, and the right front hub assembly. After getting everything installed I flushed the out the old brake fluid and refilled the master cylinder, then bled the system. As soon as I had everything put back together and tried to drive the right rear wheel cylinder blew out. Yep.. had to do all the rear brakes as well.

dogkatcher

so .. just checked them again. fluid was a bit high so took some out .. about 1/4" of space at top according to chilton manual (1 piece cast reservoir)

drove it a bit to see if it would relax them .. nope .. but both sides feel exactly the same .. w/ engine on & off

no hissing sounds, no change in idle when braking

could the pistons just need lubing ?? I dont remember them rubbing when I 1st installed pads ... weird they would both fail exactly the same like that (as far as pressure on pad)

also, have a squeal now & then .. probably the rear thats mis-adjusted ?

4.3L XJ

How much drag are you talking about. There are no springs in the calipers, so they only back off far enough for the pads to still be touching. There will be some drag as a result, but not a lot. Just the nature of the beast.

dogkatcher

with wheels on, can barely feel it, slightly hear it ... engine on/off ... doesnt really stop wheel from turning either

with wheel off, can feel it a bit more .. not locking up by any means

maybe they'll just wear down

or should I have the rotors machined? something I did not do when I did the pads .. was an emergency fix kinda .. pads were getting thin .. probably originals with 120k-ish miles

I was just concerned because I heard what sounded like a turbo motor sound driving in mtns the other day .. thought it was the rear brakes making trouble since new, but no.

I took a newer work truck on same route this week .. now Im thinkin that noise was the pavement / tires humming .. 2 sections of road sounded loud. highway 285 colorado if anyone cares (kenosha pass & top of crow hill .. roadwork area)

Abovetimberline

It is always a good idea to at minumum have your rotors checked for warpage,they are so cheap,you can replace them for what it cost to turn them sometimes. If it is not causing a safety issue,just keep an eye on them.

bigomudders

Best thing to do is raise front of jeep up and have a friend press the brake pedal and then release it as soon as he releases see if you can turn the wheel, if you cant then you have a brake hose colapised or possible cailper slides sticking easiest way to tell is if they dont release imed. the open the bleeder screw if it turns then its a hose if it dont its a caliper issue hope this helps.

dogkatcher

open bleeder w/ brakes applied ? if fluid comes spraying out & wheel turns, lines should be ok .. is what youre sayin ?

lines seem fine when I replaced pads .. pushed pistons in to remove caliper & had brake fluid spill out of reservoir .. wasnt watching, haha

bigomudders

No the brake pedal needs to be released that way theirs no pressure coming from the system. What happens when a brake hose collapes is the internal rubber seperates and will not let the pressure release. If its a caliper slide issue the pressure will still be there even when the bleeder has been opened. Any ?'s pm me and I'll give you my ph#

4.3L XJ

This is normal for disc brakes. No worries

dogkatcher

gotcha .. thanks!!