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Renix era Brake Combo proportioning valves

Ecomike

NAXJA# 2091
NAXJA Member
Location
MilkyWay Galaxy
I have tried getting the brake lines off the ancient combo valves on my 87 Waggy and 85 Cherokee, with no luck (I was afraid the fitting and line would get damaged and did not want to do a full line replacement...), so I never replaced or serviced these valves.

I was thinking of just swapping out the guts on mine with the guts from here:

http://www.ebay.com/itm/87-96-jeep-...-valve-disc-drum-new-/350517371264#vi-content

Last time I priced a new one they were well over $100 so these look like a great deal :clap: :-)

But not sure the guts would be the same. Also wondering if I can service the oem valve guts with a kit (but I need a source?).

I am thinking that mine are only letting my front brakes do all or most of the work.

I found a good thread 5-6 years ago on servicing the valve off the jeep....And I have a used one I bought years ago....
 
Calling all brake proportioning or combo valve experts?
 
I like to unscrew any lines I can, cut the rest with linemans pliers about 1.5" back, then place it in the vise, cut the lines as close as I can with a tubing cutter, and use a deep well 6 point socket to unscrew the fittings. IIRC all of them are regular double flares, just odd flare nut sizes, so you can simply form new lines from 3/16" brake line at that point and use the original factory flare nuts instead of the standard parts store ones. Remember to put the flare nut on the tube before reflaring it :banghead: and remember to put it on the tube FACING THE RIGHT WAY before reflaring it :banghead: :banghead:

I've also done this on-vehicle by using a large pair of vise grips on the proportioning valve body as a "handle" of sorts.

Not sure how you can service them - if anything, all that should be required is replacing the sealing o-rings. I'm not really sure how much good that will do. Are you sure both pots of your master cylinder are actually providing pressure/fluid?
 
Note from DJ
Proportioning Valve by Go Jeep
http://www.go.jeep-xj.info/HowtoPvalve.htm

And this you like technical stuff
Brake Proportioning Valve
By Bill (Billa Vista) Ansell
From http://www.pirate4x4.com/tech/billavista/Brakes/

Bottom looks real interesting, Had not seen that one before. The top one I had read about 4-5 years ago. It is why I was thinking of servicing the valve while still installed.

kastein:

I am trying very hard not to get tied up replacing the lines. It looks like a real pain, and I am under the impression that making the brake line double flares is a real PITA and nearly impossible to do right manually?
 
Is it possible for worn drums (or maybe rotors) to cause a soft peddle for the first 50% of travel, and act like air in the lines?

This caught my attention on the linked site:

You will have a lower pedal if the rear needs too much extra fluid and the pedal will be noticeably lower when in use if the rear calipers are bigger than what I used
.

The reason I ask, is I have fought a low soft peddle (87 wagoneer) that seems to be an unsolvable problem. That is why I am finally back to thinking of opening up the Prop valve. But I have never checked the rear drums to see if they are at or slightly beyond the wear spec limits. But, while the brakes have always been marginal, I did have a higher hard pedal before the last MC died, and few miles since then, and the low soft peddle has been since I replaced the MC. I am on my second brand new MC in just 2-3 years. Even though the peddle is soft (to me), I do get some braking almost right away in the first 1" of travel, and it is even (likely just the two front rotors working).

Oh, also, the new MC has a hard peddle with the engine off, only feels too soft on the first 50% of the stroke engine running, then it bottoms real hard. But it feels like rear brakes don't work until it bottoms to the hard area. When I bleed the brakes I get great fluid flow at all 4 wheels. I got an improvement when I bleed the combo valve for the first time recently (but have not done the wheels again yet)!!! I plan to do that again today, and then re-bleed all four wheels.
 
I'm honestly not sure, make sure the drums are adjusted properly and it SHOULD be fine.

As for double flares - they really are not that bad. If you have a good quality double flaring tool, you should be able to do them. Since you're in TX there is a chance they will simply unscrew, just make sure you are using a good quality flare wrench...

I buy pre-flared sections of line so that I only have to reflare at most one end of each line.
 
Hmm, flare wrench? I use either open end or solid HD US made vise grips. My problem has been holding the damn valve well enough to keep it still, or keep it from damaging the other lines. It is not bolted to anything, not like the MC for instance.
 
I solve that by putting my largest vise grips on the end of the prop valve further from the firewall and using it for leverage instead of the ground or the chassis.

Don't use vise grips on brake fittings... just not meant for that. Only reason I'd ever use vise grips is if the flare nut is rotted to the point that a wrench won't fit.
 
Which flare wrenches do you like? Would offset ones be better on this beast?
 
OK, so back the combo brake valve, still looking for ideas, input on my original question.

I picked up a small set of SAE flare nut wrenches, but with out removing the MC there it is a very tight area to work in.

Does any one have a repair kit source for the Renix 87-90 guts on this valve? I am thinking of replacing the guts, and cleaning the inside, with out removing it?
 
I doubt very seriously that there is a repair kit for a prop valve. There's not much in them. Why not just remove the 2/4" cap nut and carefully remove the guts. Careful, there's a spring in there.
 
I doubt very seriously that there is a repair kit for a prop valve. There's not much in them. Why not just remove the 2/4" cap nut and carefully remove the guts. Careful, there's a spring in there.


My guess is after 25 years the o'ring and cup seal need replacing.
 
I took the guts out of my 88 XJ prop valve and swapped in the 94-98 Grand cherokee guts. The 88 stuff was fine.

How many miles were on it, and was it the original prop valve?

What the ZJ guts do for it.
 
A late model (up to 98) ZJ with rear drums should probably have the same guts as an XJ. IIRC all XJ prop valves are pretty much equal too. Worst case swap the whole prop valve, it will bolt right in and they didn't change the XJ brake cylinders or calipers for basically the entire production run aside from changes to accomodate wear-part design changes and some minor stuff for the 10" rear drums used on police package vehicles. I'm reasonably certain any 87-01 (possibly 84-01, don't know the early years well) prop valve will work as long as it is from a non ABS vehicle.
 
Final update: I never did anything to the combo valve on my 87, except bleed it on mine. Finally discovered it was front rotors that were bad. One was tapered, too thin near the center, in spec at the outer area, and the brake pad was only making contact on about 20% of the pad surface at best, getting too hot.....fading, the other was just at to past the OEM spec wear limits. Turned out the new MC was OK, and the tapered rotor made it appear bad.

Got excellant brakes on this beast now. New rotors made a huge difference!
 
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