Seizing front wheels after drive
10-01-2022, 05:37 PM
#16
CF Veteran
Thread Starter
10-01-2022, 06:58 PM
#17
Senior Member
Lacking all the Kool tools these days I use a straight edge and dial calipers across the booster to measure how far the rod sticks out and a depth mike and bearing ball to measure the mc depth and do the math.
For the actual adjustment grab the splines with something and the hex behind the ball and turn.
Or, I suppose as the issue is the brakes locking up don't measure anything,shorten the rod about a mm and see what happens..... but don't do that
For the actual adjustment grab the splines with something and the hex behind the ball and turn.
Or, I suppose as the issue is the brakes locking up don't measure anything,shorten the rod about a mm and see what happens..... but don't do that
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cruiser54 (10-01-2022)
10-01-2022, 09:26 PM
#18
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Thread Starter
10-01-2022, 09:31 PM
#19
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
when you get it apart, you'll see how it can be measured.
10-01-2022, 10:57 PM
#20
CF Veteran
Thread Starter
Also noticed the brake fluid in the reservoir has some black contamination through it, which makes be think seals are deteriorating.
10-02-2022, 11:16 AM
#21
CF Veteran
Just a thought but if the axle U joints are freezing up you'll see that too but mostly when you try to turn
10-02-2022, 09:27 PM
#22
Junior Member
You didn't by chance mix silicone and standard brake fluid did you? That will cause all kinds of havoc. The black particles could also be from your brake hoses, but I remember you saying you installed new ones.
10-03-2022, 01:19 AM
#23
CF Veteran
Thread Starter
No, not mixed with anything but DOT3 breakfluid . Whats in there is from the last time I bled all my lines when I tried that other MC. Used 3x370ml (!) bottles and 2-person method , thinking I must still have air in the system because of the mushy brake pedal. After that I thought it can't be air anymore.
Correct, new brakehoses front under a year old. Haven't even got 30 km on them I think.
Last edited by Roler; 10-03-2022 at 01:25 AM.
10-03-2022, 07:25 AM
#24
CF Veteran
I went around a half dozen times trying to solve a brake drag on a back disc. It was so bad it would slow the vehicle down and heat up the wheel, almost hot enough to burn, but only after driving for a while. Which would leave me quite perplexed and far from home.
Could not for the life of me believe the caliper was the cause. Greased the bolt boots, slides, pads, ground and welded the ruts out of the spindles, greased everything. But broke down and bought one. $50. Solved. Upon very close exam, it seems the piston boot gets old and dirty, and rust forms in the folds behind where you cant see. Makes it harder to fold back in when the brake is released. I cannot tell you how much better the zj rolled after that.
I now an highly suspicious of any old caliper and prefer to just change them out. But your best tool is a digital thermometer to check disc temps after a ride.
Could not for the life of me believe the caliper was the cause. Greased the bolt boots, slides, pads, ground and welded the ruts out of the spindles, greased everything. But broke down and bought one. $50. Solved. Upon very close exam, it seems the piston boot gets old and dirty, and rust forms in the folds behind where you cant see. Makes it harder to fold back in when the brake is released. I cannot tell you how much better the zj rolled after that.
I now an highly suspicious of any old caliper and prefer to just change them out. But your best tool is a digital thermometer to check disc temps after a ride.
10-03-2022, 04:20 PM
#25
CF Veteran
Thread Starter
Already rebuilt the piston on left side. Which seized up together with the other side this time. Still can do the right side since I have a new piston and kit for that side anyway.
If I could buy new caliper here for $50, I would have done so long ago!!
If I could buy new caliper here for $50, I would have done so long ago!!
10-04-2022, 06:36 AM
#26
CF Veteran
Oh Austrailia, right! Yeah, I did try to take the piston out and clean it, but as I say that boot, right in the rear you know where I mean. That was it and really no fixing that unless you can sandblast it all first. The rust distorts the seat the boot mounts into, pinching the boot against the piston. which only gets worse as you brake and it heats up making it stick more
Last edited by 97grand4.0; 10-04-2022 at 06:57 AM.
10-05-2022, 09:34 AM
#27
CF Veteran
Excerpt from FSM
If brake drag occurs at all wheels, the problem may be related to a blocked master cylinder compensator port or faulty power booster (binds-does not release).The condition will worsen as brake temperature increases.
Based on that, I would try the easiest two things
1) Dismantle the compensator valve
2) Try and ease the master cylinder free of the booster, which may be possible without undoing all hydraulic lines, but if you are doing the prop valve, a bleed will be needed anyway,
check for obvious corrosion around the plunger and MC/booster junction, which is not uncommon, as fluid leaks often take place here on older systems
If I saw corrossion, I may be tempted to spray Inox or similar into the area to hopefully free up any sticking parts
Ultimately, in my experience, a braking system does require a "parts cannon" approach, I have an over 50 year old brake system on one of my other cars, and its had a virtually complete overhaul by me, including rebuilt booster, re-sleeved master & calipers, new pistons, seals and rotors, new hoses and some steel lines, park brake overhaul, brake switches
If you get stuck on the road, I found loosening the appropriate master cyl union allowed me to get a few more miles down the road, then do it again etc etc, got me home, was a bad hose
If brake drag occurs at all wheels, the problem may be related to a blocked master cylinder compensator port or faulty power booster (binds-does not release).The condition will worsen as brake temperature increases.
Based on that, I would try the easiest two things
1) Dismantle the compensator valve
2) Try and ease the master cylinder free of the booster, which may be possible without undoing all hydraulic lines, but if you are doing the prop valve, a bleed will be needed anyway,
check for obvious corrosion around the plunger and MC/booster junction, which is not uncommon, as fluid leaks often take place here on older systems
If I saw corrossion, I may be tempted to spray Inox or similar into the area to hopefully free up any sticking parts
Ultimately, in my experience, a braking system does require a "parts cannon" approach, I have an over 50 year old brake system on one of my other cars, and its had a virtually complete overhaul by me, including rebuilt booster, re-sleeved master & calipers, new pistons, seals and rotors, new hoses and some steel lines, park brake overhaul, brake switches
If you get stuck on the road, I found loosening the appropriate master cyl union allowed me to get a few more miles down the road, then do it again etc etc, got me home, was a bad hose
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