hard brake pedal

hey
working on the brakes on the 91 and cant really figure them out
so i have a really hard brake pedal, and not alot of stopping power, if i stand on the pedal it will still stop though. anyways it has all new brakes in the back, and new rotors and pads in front the calipers look old. also the front brakes are still dragging im pretty sure. and the check anti lock and brake light are on, is this due to the dragging calipers?



how do i know the calipers are bad and not something else in the system that is holding pressure?

jeeptorino68 said:

how do i know the calipers are bad and not something else in the system that is holding pressure?

Click to expand...

jack up a front wheel, check that it's dragging. Reach in and crack open the bleeder to allow a little fluid to come out, leave the bleeder open and see if the dragging is gone. If it is, then the system is holding pressure. If it still drags, it is something in the caliper/pad/rotor system causing the problem. Could be stuck piston, pads not installed correctly, warped rotor, wear on knuckle.

The "brake" light being on indicates the proportioning valve has traveled too far in the bore. Have you checked carefully for any leaks in wheel cylinders, pistons, and lines?

It sounds like maybe your front brakes aren't doing anything for you at the moment. The hard pedal and light lead me to think that you're doing all your stopping with your rear drums right now.

Don't start throwing parts at it. Diagnose twice, fix once. Much cheaper and more effective.

Good luck and report back on what fixes it.

ok i will do that to check for drag, also how easily should the tire spin, if i give it a good pull it will spin maybe 1 or 1 1/4 turn i know there should be some slight drag from the pads but not sure how much.

also there is no wear on the knuckles i had the calipers off yesterday checking them over, and the pads are on correctly. while the calipers were off, i put a piece of wood smaller them the rotor in between the pads and pushed the pedal, and the pads closed, then i moved them back slowly with a c clamp, so i think the piston is free and fine... thoughts?

there are no leaks in the system that i have seen, though if the fronts arent working that would cause an imbalance too and trigger the light. right?

Check your booster operation.
Pump brakes with engine off--bleeds all vacuum out of booster. Hold the brake pedal down, and start the engine. If your pedal drops a couple of inches, this indicates a good booster.

dont have a vacum booster on a 91, it is some kind of pump system

Didn't the '91's have that funky setup where they used the ABS system for the power brake boost? And the red brake warning light and ABS light would come on when there was a fault in that? I seem to remember there being a common problem with those, or a recall or something. Just my .02.

jeeptorino68 said:

dont have a vacum booster on a 91, it is some kind of pump system

Click to expand...

So then you need to test the pump system?

Are you getting any codes?

I think Joe's right. You need to pull codes. Betcha it's in that ABS system.

did the key on and off test and only got codes 12 and 55 nothing else, and 12 is battery disconnected within last 50 starts 55 is end of test. so no codes... i also put the VIN into the thing on the jeep website and it came back with no recalls. should i call the dealer and ask them?

also checked online and called the jeep service dept. those recalls, were usually only good to about 105k, and were only good for about 7-10 years, so if mine needed to be serviced then it isnt covered any more anyways. good info though on the ABS pump controlling the booster, i think that is the case on the 91, as i definitely dont have a vacum booster and the firm pedal leads me to think there is no boost to it, but the poor braking performance was a stuck caliper i think, that glazed the pads, i am going to replace those soon, jsut got the parts. so if i pull the ABS fuse will the light go off?

It might. Try it and see what happens.


Here's a link to some recalls I found:

http://www.automallusa.net/1991/jeep/cherokee/recalls.html



In particular, read up on this one:


Auto Recall Date: DEC 27, 1996


Vehicle Component: SERVICE BRAKES, HYDRAULIC:ANTILOCK
Estimated Vehicles Affected: 52000
Model Affected
1991 JEEP CHEROKEE


1991 Jeep Cherokee Defect Summary:
VEHICLE DESCRIPTION: VEHICLES EQUIPPED WITH ANTILOCK BRAKE SYSTEM (ABS). THE ANTILOCK BRAKE SYSTEM (ABS) HYDRAULIC CONTROL UNIT CAN EXPERIENCE EXCESSIVE BRAKE ACTUATOR PISTON SEAL WEAR WHICH COULD CAUSE PUMP-MOTOR DETERIORATION.


Defect Consequence:
IF THIS OCCURS, THE ABS FUNCTION WOULD BE LOSE AND REDUCED POWER ASSIST WOULD BE EXPERIENCED DURING VEHICLE BRAKING. THE INSTRUMENT PANEL WARNING LIGHTS WILL SIGNAL SYSTEM IMPAIRMENT AND THE BASE MANUAL BRAKES WILL REMAIN FUNCTIONAL.


Remedy:
DEALERS WILL TEST THE VEHICLE'S ABS AND REPAIR AS NECESSARY. THE WARRANTY ON ALL ABS COMPONENTS WILL BE EXTENDED TO 10 YEARS OR 100,000 MILES (EXCEPT FOR THE BRAKE ACTUATOR PISTON ASSEMBLY AND THE PUMP-MOTOR ASSEMBLY WHICH WILL HAVE A LIFETIME COVERAGE). OWNERS WILL BE REIMBURSED FOR PREVIOUS ABS COMPONENT REPAIR COSTS.


Estimated Vehicles Affected:
52000


Notes:
CHRYSLER CORPORATION 702





An idea might be to take it in to the dealer and pay the $100 for them to diagnose it. You never know, you might get lucky and they'd be able to fix something under that recall for ya. I know you called 'em, but, long shot, you never know. I did see that word "lifetime" up there on a couple ABS components. You never know. I guess it depends on how bad you want it fixed. I know having no power brakes kinda sucks.

Just my .02.

God, just realized I said " you never know ", three times in that last post. Sorry 'bout that. LOL

haha no problem, well i will try calling again, where did you get that information, i just want it to be an official technical service bulletin not something that they wont believe.

I just did a google search on "91 jeep cherokee brake recall". I don't know if this is true for Daimler Chrysler/Jeep, but I work at a GM dealer as a warranty admin, and if a customer calls up wanting me to pull a recall, I can just print it out and give it to him. You could just stop by there and ask them to do the same. They've gotta have a similar setup. 'Course, the more info you have, the better able they'll be to help you, too.

so they told me that first of fit is about 300-400 to diagnose the system, and then on top of that they usually find other parts need to be replaced, accumulator etc. so it would be 300-400 plus other parts that they would have to replace, so that is already 3-4 times the cost of this jeep lol so i think i will go for the WJ swap, i already have new calipers and pads that i will put on first then when my refund check arrives i will go for the WJ parts, which will be like 100$ at the boneyard.

THREE TO FOUR HUNDRED DOLLARS!?!?! Just to diagnose it? Christ! Man, no wonder dealerships get such a bad rap. Here, I'd charge you $100, and it STAYS a hundred til I find out what's wrong with it, even if it takes me weeks. Yikes.

Well, good luck to ya, man.

Take your rig to AutoZone for a free code read in case the key method is wrong. I have the 90 ABS fault code manual, might give us some clues.

Heck, for that much money I'd rip out the ABS and stick in a later master and booster. Do a search and you should find some writeups for swapping on the double diaphram booster from the 96+ years.

yea i know no way i was paying that, i found a member on JF who is going to sell me his booster and MC from a 99 grand cherokee, for 75 and shipping, so that should work out great i hear its a good swap, though i loose the ABS but whatever. i have read alot about it, and other then the brake line fittings i should be able to do it

I have the same issue on my 94 no ABS replaced the MC & booster with later dual diaphragm design - same issue: hard pedal but with enough force will eventually lock my 235s @ highway speeds.

I thought it might be a clogged line or a bad piston it always had been like that since 1997.

its a real pain in stop & go traffic