Brake Problems
09-01-2013, 07:02 PM
#1
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Brake Problems
Okay so a little over a year ago, my jeep had a broken brake line. We replaced the line and bleed all 4 wheels, but it still had minimal brakes. We have since bleed all 4 wheels 4 or 5 times and still have poor brakes. What do we need to do?
It's a 1994 Sport
It's a 1994 Sport
09-01-2013, 07:12 PM
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Year: 1985
Model: Cherokee
Engine: 2.5L
Does the pedal go to the floor with little resistance and little braking, or does it build pressure at half pedal then bleed down or does the pedal just feel squishy?
Can be several problems.
When was the last time the rear wheel cylinders or front calipers were changed or rebuilt?
Can be several problems.
When was the last time the rear wheel cylinders or front calipers were changed or rebuilt?
09-01-2013, 07:18 PM
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Does the pedal go to the floor with little resistance and little braking, or does it build pressure at half pedal then bleed down or does the pedal just feel squishy?
Can be several problems.
When was the last time the rear wheel cylinders or front calipers were changed or rebuilt?
Can be several problems.
When was the last time the rear wheel cylinders or front calipers were changed or rebuilt?
Second half there is some resistance.
Rear shoes were replaced within 6 months.
Also the drivers side, one of the wheels locks up.
And it has ABS.
09-01-2013, 07:43 PM
#4
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How old are those Flexible Brake Lines? There are three (3), two in the front and one in the rear. I had similar odd behaviors until I replaced all the flexible hoses at ~175K miles.
A simple test of the front lines is to raise the front wheel and spin it. Have a helper pump up brake pressure then release. Can you spin the front wheel again within the first few seconds? If yes then no problem. If no, and there's drag, then the brake hose to that wheel may be decaying internally and preventing return upon brake release. The converse is also true, internal failures in flexible lines can prevent flow of hydraulic fluid pressure to the brake(s) in question. If the rear brakes drag (no pressure return) or do not seem to pressure up (slow or no pressure flow to the wheel cylinders) then the rear brake hose may be decayed internally. Either way, if one hose is bad then the others will soon be same, so just do all three at one time. It's worth it to protect your life after-all, isn't it?
Tips/Comments:
What's the ID of those rear drums? Maximum ID is supposed to be 9.06".
Mechanical self-adjusters working right? They may need a manual tweak with a brake spoon at first and then you can do the occasional hard reverse pedal taps several times to force self-adjusters to tweak.
Are front pads and calipers all good? Check the pad slides for divots that can "hang" the pad on the slider (part of the knuckle) because this condition can cause lock-ups and odd pad-wear - and hot spots/warpage of the rotor. These notches in the pad slides can be repaired and there's more than one way. I went to a good welder/machinist who added weld beads where the notches were and then milled flat the welded spots (and then we shared a case of beer). The repaired section is now harder then the original.
A simple test of the front lines is to raise the front wheel and spin it. Have a helper pump up brake pressure then release. Can you spin the front wheel again within the first few seconds? If yes then no problem. If no, and there's drag, then the brake hose to that wheel may be decaying internally and preventing return upon brake release. The converse is also true, internal failures in flexible lines can prevent flow of hydraulic fluid pressure to the brake(s) in question. If the rear brakes drag (no pressure return) or do not seem to pressure up (slow or no pressure flow to the wheel cylinders) then the rear brake hose may be decayed internally. Either way, if one hose is bad then the others will soon be same, so just do all three at one time. It's worth it to protect your life after-all, isn't it?
Tips/Comments:
What's the ID of those rear drums? Maximum ID is supposed to be 9.06".
Mechanical self-adjusters working right? They may need a manual tweak with a brake spoon at first and then you can do the occasional hard reverse pedal taps several times to force self-adjusters to tweak.
Are front pads and calipers all good? Check the pad slides for divots that can "hang" the pad on the slider (part of the knuckle) because this condition can cause lock-ups and odd pad-wear - and hot spots/warpage of the rotor. These notches in the pad slides can be repaired and there's more than one way. I went to a good welder/machinist who added weld beads where the notches were and then milled flat the welded spots (and then we shared a case of beer). The repaired section is now harder then the original.
Last edited by Cherryokee; 09-01-2013 at 07:51 PM.
09-01-2013, 07:50 PM
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How old are those Flexible Brake Lines? There are three (2), two in the front - one in the rear. I had similar odd behaviors until I replaced all the flexible hoses at ~175K miles.
A simple test of the front lines is to raise the front wheel and spin it. Have a helper pump up brake pressure then release. Can you spin the front wheel within the first few seconds? If yes then no problem. If no then the brake hose to that wheel may be decaying internally. If the rear brakes drag then the rear brake hose may be decayed internally. Either way, if one is bad then the others will soon be same, so just do all three at one time. It's worth it to protect your life after-all, isn't it?
Tips/Comments:
What's the ID of those rear drums? Maximum ID is supposed to be 9.06".
Mechanical self-adjusters working right? They may need a manual tweak with a brake spoon at first and then you can do the occasional hard reverse pedal taps several times to force self-adjusters to tweak.
Are front pads and calipers all good? Check the pad slides for divots that can "hang" the pad on the slider (part of the knuckle) because this condition can cause lock-ups and odd pad-wear - and hot spots/warpage of the rotor.
A simple test of the front lines is to raise the front wheel and spin it. Have a helper pump up brake pressure then release. Can you spin the front wheel within the first few seconds? If yes then no problem. If no then the brake hose to that wheel may be decaying internally. If the rear brakes drag then the rear brake hose may be decayed internally. Either way, if one is bad then the others will soon be same, so just do all three at one time. It's worth it to protect your life after-all, isn't it?
Tips/Comments:
What's the ID of those rear drums? Maximum ID is supposed to be 9.06".
Mechanical self-adjusters working right? They may need a manual tweak with a brake spoon at first and then you can do the occasional hard reverse pedal taps several times to force self-adjusters to tweak.
Are front pads and calipers all good? Check the pad slides for divots that can "hang" the pad on the slider (part of the knuckle) because this condition can cause lock-ups and odd pad-wear - and hot spots/warpage of the rotor.
How do I measure the ID?
Self adjusters were rusted and came off.
Front has new pads.
Also before the broken line, the brakes were perfect.
09-01-2013, 08:06 PM
#6
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Rear drum ID is measured on the lathe during cutting or by use of a caliper or drum-gauge. You can take your drums to a brake shop (or the whole Jeep) and ask for a "polish-cut" of ~0.002" - this is advisable when you add new brake shoes - or at any time you want to know their status. Out of spec drums will negate all of your new rear brake hardware. New drums are ~$30 each.
Get new self-adjuster kits for the rears and install them. I hope you retained the removed self-adjuster hardware somewhere. If you did then you'll only need to replace the things that were scrap (cheap widgets, cheaper at the JY). What part(s) of the self-adjusters rusted and came off?
New pads are good. Check the pad-slides, or "saddles" as some peeps call them. Look for notches where the pad tabs rest/ride on the slide.
Get new self-adjuster kits for the rears and install them. I hope you retained the removed self-adjuster hardware somewhere. If you did then you'll only need to replace the things that were scrap (cheap widgets, cheaper at the JY). What part(s) of the self-adjusters rusted and came off?
New pads are good. Check the pad-slides, or "saddles" as some peeps call them. Look for notches where the pad tabs rest/ride on the slide.
09-01-2013, 08:15 PM
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Rear drum ID is measured on the lathe during cutting or by use of a caliper or drum-gauge. You can take your drums to a brake shop (or the whole Jeep) and ask for a "polish-cut" of ~0.002" - this is advisable when you add new brake shoes - or at any time you want to know their status. Out of spec drums will negate all of your new rear brake hardware. New drums are ~$30 each.
Get new self-adjuster kits for the rears and install them. I hope you retained the removed self-adjuster hardware somewhere. If you did then you'll only need to replace the things that were scrap (cheap widgets, cheaper at the JY). What part(s) of the self-adjusters rusted and came off?
New pads are good. Check the pad-slides, or "saddles" as some peeps call them. Look for notches where the pad tabs rest/ride on the slide.
Get new self-adjuster kits for the rears and install them. I hope you retained the removed self-adjuster hardware somewhere. If you did then you'll only need to replace the things that were scrap (cheap widgets, cheaper at the JY). What part(s) of the self-adjusters rusted and came off?
New pads are good. Check the pad-slides, or "saddles" as some peeps call them. Look for notches where the pad tabs rest/ride on the slide.
I will look into new adjusters.
What are the pad slides?
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09-01-2013, 08:22 PM
#8
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Did you replace the front pads yourself? If yes then the pad slides (or saddles) are the flat rails that the pads sit on and between - the hooks on the ends of the pads rest on the two slide rails - the pads move, or slide, in toward the rotor when you brake and slide away from the rotor when you release.
09-01-2013, 08:25 PM
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Did you replace the front pads yourself? If yes then the pad slides (or saddles) are the flat rails that the pads sit on and between - the hooks on the ends of the pads rest on the two slide rails - the pads move, or slide, in toward the rotor when you brake and slide away from the rotor when you release.
09-01-2013, 08:30 PM
#10
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Everything I said still is worthy of your attention if you want to get through your braking problem. At this point, I'll recommend that you get a repair manual to become more well informed on brake system operation and maintenance/repair procedures in-general. Having the knowledge can save you from a lot of pain and bucks spent.
09-01-2013, 08:30 PM
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If you don't have any adjusters in the rear I'm not surprised you have a lot of pedal travel. In fact I'm surprised the rear brakes even work. Replace those first and adjust the rear shoes, then see where you are.
09-01-2013, 08:35 PM
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09-01-2013, 08:36 PM
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