Question about 1988 Jeep Comanche

1 Answer

Rear brakes lock when press brake pedal.

Does there is a way to by pass the proportioning valve and discard it?

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  • Jeep Master
  • 20,706 Answers

Get is serviced.

its stuck in , low bed (loaded) mode. the lever is or parts in side

stuck in full load mode.

and guess what, if you bypass the valve, what will happen

the rear brake will lock, going fast and if on wet or worse roads. 10x worse. its there for a reason. to lower the brake pressure with no pickup bed load. or not heavy trailer tongue weight.



ever consider the rear brakes are bad. first. and not the valve.



service the rear shoes and slaves.

then check the bypass.



Does the truck still have the height sensing brake line bracket and line connected into the prop valve?



http://www.jeepforum.com/forum/f53/bad-proportioning-valve-any-ideas-1127468/#post10505224







here is the valve.

sold at , JEEP.



http://www.factorychryslerparts.com/products/JEEP/1988/COMANCHE/VALVE--Proportioning--VALVE--Proportioning--ECE-198789--1989--Except-France--Italy--1990--KDX--KDX-After-3-1-93--KDX-Up-to-3-1-93/4520728/52009114.html



Chysler p/n

52009114 ; 52003118



google that and find them for $75

Posted on May 08, 2014

  • gadgetguy11 May 08, 2014

    after the car is parked for an hour or so are the rear brakes still locked or only when the peddle is applied. if the rear brakes are not locked after it sets for awhile you might have asmshed steel brake line. check the brake linefrom the valve to the rear and check for kinks . the proportioning valve is a very inportant part of the braking system and should never be bypassed for any reason!!!!~. and heres why , if for sone reason there is a brake fluid leak in the system the valve moves to shut off the loss of fluid so you can safely stop the car. i would recomend you take it to a shop .

  • _-__-___-_
    _-__-___-_ May 08, 2014

    he talking about the Pickup bed, level, proportioning valve not the front located DIFF valve. His valve has lever that adjusts rear braking bias , based on bed load.

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Posted on Jan 02, 2017

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SOURCE: Brake line hose has hole in it

The only real solution to your problem is to replace the damaged line, bleed the brakes, and check for leaks after you are done. The line should go up to the frame, and go into a small metal bracket that is welded to the frame. The hose is usually held in place by a small metal clip, and a steel brake line will thread into the end of the hose assy. where it terminates in the frame mounted brakcet.

Posted on Nov 10, 2008

davespcr
  • 115 Answers

SOURCE: I have a Jeep Wrangler

The proportioning valve most definately can be the problem. Did you change it or is it the original? (A disc/drum system uses a 70%front/30%rear braking ratio, whereas an all-disc system is alot more even). I would first bleed the master cylinder. Then I would 'gravity bleed' the rest of the system by opening the bleeders on all 4 wheels. Do not at any point let the m/cylinder go dry. Also, do not touch the brake pedal.
Continuously check all 4 bleeders, when clean brake fluid with no bubbles at all is running from a bleeder, close it. When all 4 wheels are done, recheck the fluid level and you should be OK.
Pump the pedal to 'self-adjust' the rear calipers, then re-check the fluid level.
Any problem after that means you either have a loose connection (it's possible for a tiny leak to let air in, but not let fluid leak), a leak, or you need a new (disc/disc type) proportioning valve. I would try Summit Racing myself. Good Luck!

Posted on Dec 26, 2008

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SOURCE: when lights are on and

i take it the brake lights work ok when the lights are not on??? check the ground going to the lights

Posted on Jan 04, 2009

  • 18 Answers

SOURCE: brakes lock up slow speeds

it has to be the brake booster there is a valve in it that mut be sticking

Posted on Jan 26, 2009

reisdos
  • 1297 Answers

SOURCE: sounds like air is leaking behind the brake pedal

fairly normal...some are louder than others
but if the brakes work you will be OK

the air escaping is what allows the booster to function because it needs atmospheric pressure to boost the pedal application

I've replaced many of these for a customer only to find the replacement makes a worse noise!

Posted on Apr 06, 2010

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Related Questions:

1 Answer

What does the proportioning valve do?


Assuming you're talking about the brake system...
The proportioning valve is on the rear brakes only when the vehicle has rear Drum Brakes.
What it does is limits the brake line pressure to the rear brakes during normal stopping. This way the rear brakes don't lock up and cause the vehicle to fish tail or spin.
When you press the brakes harder than normal, the proportioning valve opens more to allow more line pressure so you're able to stop faster.

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Fleetwood problem


Pretty normal to not be able to lock the brakes without the assistance of the booster, it'll take a lot of pedal pressure without it. It's also normal for the pedal to feel harder without the booster, this goes for any car/truck with power brakes. Try it with any other car you have and you'll see.

I've worked on several old Cadis but don't recall what year they started using front disc. If it's been changed from drum to disc you'll likely need a different proportioning valve and possibly a different master to get them to work right. Talk to the seller and ask if the brake feel changed when they replaced the master and if they changed any other parts.

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1988 jeep comanche brake proportioning valve


there only 2 ways (USA answers)
they have a guage test (expensive gauge)
or replace it ,if in fact you know for sure the rear brakes are good.

i think raybestos sells this.valve rebuilt.

the valve is height measuring disconnect the link and see if its
free? is it jammed? i had a 88 from new.
i purged brake fluid every year and it lasted for 250k miles. and sold it.
so there is a bench mark on life.(best case)
did you read the fsm? yet
id does cover these tests.

try alldata.com (usa ) it may cover Commanche.

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