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brake caliper removal 95 Cherokee
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Guest
Anonymous Poster
Dec 30, 2008, 5:11 PM
Post #26 of 40
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Re: brake caliper removal 95 Cherokee
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Went through the process again - twice to be thorough. Got plenty of bubbles cleared out both times through. Tested the pedal and solid as a rock and the brake light was out too. Then.... started the vehicle. The pedal went "soft" immediately. Thoughts?
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Loren Champlain Sr
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Dec 30, 2008, 5:16 PM
Post #27 of 40
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Re: brake caliper removal 95 Cherokee
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Spend more time at each wheel. Open RR bleeder, go have a beer. Open LR bleeder, go have another. Open RF bleeder, have another. Open LF bleeder, well, you've probably had enough. Just takes patience. And perserverance.
Loren
SW Washington
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ZmanWA
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Dec 30, 2008, 5:18 PM
Post #28 of 40
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Re: brake caliper removal 95 Cherokee
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Did it all again - two times. Cleared a lot more air out. Pedal felt very solid when all done. Then started the vehicle and the pedal went soft immediately. Thought on this?
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ZmanWA
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Dec 30, 2008, 5:21 PM
Post #29 of 40
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Re: brake caliper removal 95 Cherokee
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Sorry I wrote twice. Didn't see Page 2. Time I've got, so no problem. I was concerned because it felt like it was done and then changed as soon as I started the vehicle. I'll likely report back tomorrow.
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Loren Champlain Sr
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Dec 30, 2008, 5:24 PM
Post #30 of 40
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Re: brake caliper removal 95 Cherokee
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With power brakes, your pedal will feel high and 'hard' after a pump or two with the engine off, but will go down further once the engine starts and vacuum is applied to the power booster.
Loren
SW Washington
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Tom Greenleaf
Ultimate Carjunky
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Dec 30, 2008, 8:28 PM
Post #31 of 40
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Re: brake caliper removal 95 Cherokee
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WOW! Did this thread take off! Now we have the bleeder bottle and lots of tricks out so I'll just make a quick note on the brake feel and the brake light being on as has been touched upon already - a bit.
New brakes will be softer feeling till "broken" in as Loren said.
Maybe - can't be sure - but in all this pumping (no jokes please) the master has given up OR that light is also there to tell/warn of a "front/rear" imbalance of pressure. It's not high on the likely list at this point but a good maybe that the trigger switch for this is off center. Arggh - I think Jeep may have used a GM style "combination" valve and sometimes when off center as would happen if one end had a failure would make the light, light. If that's the only case then with pressure applied and being held by a helper you slowly bleed a front or rear (even a line right at the master cyl) and watch for light to go out. DON'T allow fluid to stop flowing - just a leak down which can recenter that (proportioning/metering valve) such that light will go out. Unsure if front or back is the culprit if it is this at all so may need to try both ways. Some may still use a rubber like button that might recenter the sucker without doing anything but pushing it too. Man - that's old stuff but Jeep of all critters has been historical at using older items than the model years might suggest.
It's just on the "maybe" list. May have been mentioned already - adjustment (if drum rear brakes) and an inspection of rear brakes would be a great idea making sure parking brake isn't sticking too or was not fully retracting and just now showing up.
Note: Rear drum brakes are a great part of pedal feel and if not close really add to pedal travel........
T
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DanD
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Dec 31, 2008, 4:30 AM
Post #32 of 40
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Re: brake caliper removal 95 Cherokee
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Loren
You caught me; it is Tequila in the bottle. When I'm done bleeding brakes, I fill the bottle with Tequila; attach a needle to the hose and use it as an intravenous. The only problem is the dam worm keeps blocking the hose. LOL
Zman
One way of determining whether the low pedal is a hydraulic issue or mechanical at the wheels; is to LIGHTLY pinch off the flex hoses with vise grips.
If when all the flex lines (front & rear) are pinched off and the pedal is rock hard, with every little travel; you know that the problem is at the wheels. If so; by releasing one line at a time you can narrow it down further, as to which wheel(s).
If the pedal is still crap, with the lines pinched; then it’s a hydraulic issue. As in; air in the system, the master cylinder or possibly an issue with the ABS unit?
With the red light on; I’m leaning towards a hydraulic issue?
Why I say master cylinder or ABS unit is that when you first began on this journey and pushed the caliper pistons back; possibly some form of dirt was pushed back into one of these and is causing an internal leak?
If there is an internal leak; it will be hard to determine where or who is at fault. Is it the master cylinder that is by-passing pressure because of damaged/dirty seals or is it the ABS unit absorbing the pressure in its accumulator(s); again because of a damaged/dirty dump valve?
It’s the small things that can cause you the problems. What I always make my techs do when compressing a caliper piston into its bore; is to open the bleeder screw and allow the fluid to escape there, rather then be forced back into the system.
It’s kind of like the old saying; let sleeping dogs lie, if you don’t want to be bitten.
But that’s water under the bridge now; let us know what you find and we’ll go from there?
If this does turn out to be hydraulic; it maybe time to take the truck in and have the system flushed/bled; by someone that has a pressure bleeder?
Dan.
PS: You have to remember that all of the suggestions here are just that; plus this is starting to sound like a hand’s on type of problem and I’d hate for you to be sent in the wrong direction because of our speculations.
Canadian "EH"
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ZmanWA
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Dec 31, 2008, 10:42 AM
Post #33 of 40
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Re: brake caliper removal 95 Cherokee
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The only thing I can try now given my level of knowledge is to go through the basic process a few times with some patience and see if it gets resolved. If not, then I'll have to take it in. I'll let you know how it turns out. 
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Tom Greenleaf
Ultimate Carjunky
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Dec 31, 2008, 11:19 AM
Post #34 of 40
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Re: brake caliper removal 95 Cherokee
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Zman: I'm back and unless power goes out with a storm here in Massa-two-shoots will get you thru whatever crops up best I can. I hope the guys have something better to do tonight than more car stuff
If you are continuing right thru (New Years Day) with this get any supplies now - take back what you don't need later. Stock up on brake fluid and perhaps get a "hardware" kit for rear brakes and maybe the "star" adjusters - that only if they are drum brakes! While there if you do that get "brake spring pliers" (not much $) and a "return spring" tool - you can fake that with good pliers too if you don't want but hard for return springs without the right tool - pretty universal for drum brakes.
If need be as this thread go long fast, make a summary of where you are at and post a new thread. It can get hard to follow what's already been done or discovered when this long.
Good luck. It can work if you have the patience and a box of band aids!
T
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ZmanWA
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Dec 31, 2008, 12:36 PM
Post #35 of 40
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Re: brake caliper removal 95 Cherokee
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Per your request, here is where I've been and where I'm at. '95 Jeep Cherokee 4.0 L 6-cyl.
Replaced front rotors, brake pads and with help both calipers. Went fine.
Sought help in how to bleed brake lines because initially wasn't doing it correctly.
Have implemented use of suggested bottle to see bubbles (that has worked great)
Went around to all wheels in order RR, LR, RF, LF, bled each until no bubbles. Brake pedal was solid until vehicle started.
Test drove. Brakes worked well but pedal needed to be depressed a long ways + brake light was on.
Told to continue the process.
Did so twice around the system, removing air bubbles each time. Brake light went off OK
That is where it stood this AM, with a need to continue the process.
Spent the last couple hours removing air from the system. Put in about a 1/2 gallon of fluid to steadily replace that being released during the process (there are no apparent leaks anywhere). The bubbles do not seem to be slowing up let alone going away. Test drove again. Brakes work great but pedal still must be pushed nearly to the floor & brake light is staying on again.
Do not want to touch the rear brakes. Just not comfortable opening that can of worms. Is there simply an amazing amount of air in this system and thus continue what I've been doing? Is air somehow entering the system? Thoughts?
Thanks!
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Loren Champlain Sr
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Dec 31, 2008, 2:51 PM
Post #36 of 40
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Re: brake caliper removal 95 Cherokee
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Zman; It sounds as though, even though you don't want to, you're gonna have to take a look at the rear brakes.
Check the cylinders for leakage, of course. If everything is kosher, adjust the rear brakes as needed. It's best to do this while the tires are off, removing the drum for each adjustment. You will want to adjust them to the point that you can still get the drum back on. If the emergency brake pedal goes down quite a ways before it's tight, that's a good indicator that the rear brakes are out of adjustment. Yes, the e-brake cable is adjustable, but shouldn't need to be dealt with if the rear brakes are properly adjusted.
Loren
SW Washington
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ZmanWA
User
Dec 31, 2008, 2:59 PM
Post #37 of 40
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Re: brake caliper removal 95 Cherokee
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Loren,
I have never worked on rear brakes ever and honestly don't know anything about doing that - how to adjust, etc. The drums haven't come off at this point. Would they not simply be functioning the same as they had before I worked on the front?
What can you tell me (if anything) about the volume of air I'm finding in the lines? Does this amount seem possible without some additional issue?
I'm asking remedial questions I'm sure, but simply don't know a lot. Thanks!
Zman
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Loren Champlain Sr
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Dec 31, 2008, 3:10 PM
Post #38 of 40
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Re: brake caliper removal 95 Cherokee
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>>The only problem is the dam worm keeps blocking the hose<< That's hillarious!!!
Loren
SW Washington
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Loren Champlain Sr
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Dec 31, 2008, 3:32 PM
Post #39 of 40
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Re: brake caliper removal 95 Cherokee
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You are right. The rear brakes should be functioning as before. And, unless the master cylinder went empty, there shouldn't be any air in the rear brakes. That's what's puzzling. There are two bolts holding the master cylinder to the power booster unit. You can remove the nuts and pull the master forward just enough to feel or see if it is leaking any fluid out of the rear. You should be able to do this without disconnecting the brake lines. It's not unusual to find a master leaking fluid externally, into the booster unit, but it is rare for one to suck in air. If there is any fluid present at the rear of the master where it goes into the booster, then it needs to be replaced. Assuming you have no other leaks, that's the only place that I can think of that air could be getting into the system. Back to the bleeding procedure; With the brake pedal depressed (I prefer gravity bleeding, but is slow), you open the bleeder, allow fluid to come out, then close the bleeder before the pedal is allowed back. Just wanted to make sure!
Loren
SW Washington
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Tom Greenleaf
Ultimate Carjunky
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Dec 31, 2008, 4:11 PM
Post #40 of 40
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Re: brake caliper removal 95 Cherokee
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Ok - I see this is going along fast as a shot once again.
Zman - I agree that back brakes really need to be at least inspected AND how the parking brake works is a clue of their condition and or if out of adjustment. The original "star" adjusters common to drum brakes work pretty good for the first round or several years and then kinda give up and can need manual adjustment vs the automatic that virtually all are and will self adjust when brakes are applied while backing up - they quit that in most or at least in my experience.
Drum brakes were once the 99.9% of all brakes by style and now seem old fashioned and confusing when you first look at them and all their springs and things. It's real "Erector Set" stuff - primal mechanics really.
They were probably far off proper adjustment (has a lot to do with pedal travel) in the first place but wasn't noticed because "frozen" calipers or even snug in the front covered up how loose the backs really were. Now that fronts are free to retract with new calipers (you don't really see them retract but they do) that accounts for more pedal travel which would be normal. Brakes need some freeplay before engagement or they would be dragging which is what happened already. That freeplay is the room for them to retract and first inch or so of travel is waste to get linings to touch their respective rotor or drums - then you feel the resistance in the pedal.
I'm getting more confident that air is now bled out of this and not the cause of "spongy" pedal/low pedal. Now it's either back brakes or the master cylinder has gone out - perhaps unseen as Loren mentioned. If back bleeders can really shoot out brake fluid with a bleed by pump and hold with helper the master cylinder is less suspect IMO for now but always a possibility in the cards.
BTW - Replacing the master in many isn't all that difficult or expensive - not sure on exact price of this one and don't if not needed clearly yet.
Again - hang in there. This is our test too, to convey what we know to you and the busted knuckes it took to get to know it!
T
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