Combination Valve

NicKnack

NicKnack

TJ Enthusiast
Joined
Apr 15, 2017
Messages
132
Location
Millerstown, PA, United States
I've looked around online haven't found anything about rebuilding a combination valve... any insight?

I haven't noticed any leaking brake components but I'm planning to pull everything apart and give it a once over.

Just thought I'd ask now in case this is the issue because I'd rather rebuild than replace if possible.
 
If you mean the proportioning valve, just a few shots of brake cleaner back & forth in it is all that would be needed.

If you want more info than that, Google "cleaning proportioning valve" and you'll find more info on the simple procedure.
 
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Jerry Bransford said:
If you mean the proportioning valve, just a few shots of brake cleaner back & forth in it is all that would be needed.
Click to expand...

I do mean the proportioning valve, but it's part of the combination valve that's installed in 98 TJs. A proportioning valve alone would only be a tube-like inline valve towards the rear of the vehicle, but instead this is a aluminum block directly beneath the master cylinder with a proportioning valve and pressure differential valve.

I've heard of them being serviced with new o-rings but wasn't sure if that was possible with this model.
 
I took apart my combination valve once to see if there was any gunk in there causing my Jeep to brake to one side. I also replaced my calipers, checked my pads and rotors, flushed all of my brake fluid, and took out my brake fluid reservoir and cleaned it as much as I could; finally after no luck, I just replaced my front brake hoses and that fixed the problem.


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Nashorn101 said:
I took apart my combination valve once to see if there was any gunk in there causing my Jeep to brake to one side. I also replaced my calipers, checked my pads and rotors, flushed all of my brake fluid, and took out my brake fluid reservoir and cleaned it as much as I could; finally after no luck, I just replaced my front brake hoses and that fixed the problem.


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Click to expand...
My current issue is nose diving during braking. I'm hoping that a flush and bleed will do the trick, but to be honest... I haven't even taken the wheels off this Jeep yet, so I have no clue what's waiting for me.
 
Nick K said:
My current issue is nose diving during braking. I'm hoping that a flush and bleed will do the trick, but to be honest... I haven't even taken the wheels off this Jeep yet, so I have no clue what's waiting for me.
Click to expand...

What exactly is the issue? Because, when I imagine a vehicle nose diving when braking, I just imagine what a vehicle normally does when the brakes are applied.


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It feels like only the front brakes are engaging. I really need to get the wheels off and give it a flush n' bleed. Just replaced the booster and master, but I have a hard pedal so I didn't bother bleeding the whole system yet. Rarely drive it since I'm a full-time dad. Hopefully I'll get to it this weekend and figure it all out. (Shouldn't be difficult, I used to wear one of those nifty silver ASE Technician badges for work lol)
 
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Nick K said:
It feels like only the front brakes are engaging. I really need to get the wheels off and give it a flush n' bleed. Just replaced the booster and master, but I have a hard pedal so I didn't bother bleeding the whole system yet. Rarely drive it since I'm a full-time dad. Hopefully I'll get to it this weekend and figure it all out. (Shouldn't be difficult, I used to wear one of those nifty silver ASE Technician badges for work lol)
Click to expand...
Man if you are an ASE technician, you certainly know more than me!

Why not check out your drum brakes and see if they need to be adjusted?
 
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Nashorn101 said:
Man if you are an ASE technician, you certainly know more than me!

Why not check out your drum brakes and see if they need to be adjusted?
Click to expand...
Once the weather breaks (rainy here) and I get some free time (stay-at-home-daddy) the wheels will be off and the whole system fully diagnosed. Until then, it's all contemplation lol. :laufband:
 
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Ok, so I just finished replacing the rear shoes, springs, drums & cylinders, checked out the front brakes & bled/flushed the entire system...
No more nose diving or pulling but that blasted brake light is still on... the only thing left to replace on the system is the proportioning/combination valve... $125 gaaaahhhhhhh!!!!!!!:BangHead::BangHead::BangHead:

Somebody please tell me another possible issue, because my brain is racked right now.
 
I had an issue with my brake light being on. I called up Blaine and of course, he had my problem fixed in 5 minutes. I didn't read your whole thread to see if this has already been investigated, but Blaine had me remove the plastic brake light sensor from the combo valve. Then, he told me to stick a small screwdriver down in the hole and shift the shuttle inside the valve over.

What happened to me is my front passenger brake line busted so the shuttle shifted over to block the front brakes. So, I had to shift the shuttle backwards from the front of the Jeep just a tiny bit. The light has been perfect ever since.
 
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Brantley said:
I had an issue with my brake light being on. I called up Blaine and of course, he had my problem fixed in 5 minutes. I didn't read your whole thread to see if this has already been investigated, but Blaine had me remove the plastic brake light sensor from the combo valve. Then, he told me to stick a small screwdriver down in the hole and shift the shuttle inside the valve over.

What happened to me is my front passenger brake line busted so the shuttle shifted over to block the front brakes. So, I had to shift the shuttle backwards from the front of the Jeep just a tiny bit. The light has been perfect ever since.
Click to expand...
This is actually what I ended up doing on my own prior to reading this but I also shot it with some brake clean because it was all gunked up. THE LIGHT IS OUT!

Shame I didn't post earlier, you could've saved me a bunch of headache from bashing a brick wall lol.
 
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Hi all:
First post, sorry to resurrect an old thread.
Having the same nose diving problem that Nick started with, and I am a little confused on the fix for it. The brake light switch he spoke of, is the plastic, 2 pin connector on the proportioning block under the master cylinder, right? Just remove it, stick in a screwdriver, move toward the front, shoot it with brake clean, and reassemble? I unplugged this switch the other day and tried it, with the same problem.
The jeep has good brakes all around. The pedal engages and starts slowing when pushed, but when pushed down further, has a hard spot that, when moderate pressure is applied, locks the front wheels. If pressed slowly, it works fine. It does it on either wet or dry surfaces. I think the rear brakes are engaging to begin with, followed by the fronts. It only locks up during moderate braking.
Think the above fix will help, or are there other suggestions? Everything else on the system seems fine.
 
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