Proportioning valve options

[Knucklehead97]

Howdy guys! Been looking at options for proportioning valves for the brake system. My rear lift has ended with about 3" of lift and I'm happy with that. But since I plan to use the jeep to carry loads of whatever and pull a trailer, I want to make sure my stopping power is there. I've already installed a WJ booster/MC, just gotta work out the kinks with it. Have new 94+ XJ brakes up front, and have replaced the rear brakes. Soon enough I will have an 29 spline 8.25 with new drum brakes. The truck will be driven empty a lot, but also be driven loaded down a good bit (wood, gravel, bricks, ect). I've already decided I am ditching the rear load sensing valve due to not wanting to mess with the bleeding procedure and not wanting to risk it exploding under heavy brakes, i just don't like the idea of it. The option Ive really been interested in is a YJ proportioning valve. Or just using a hand adjusting valve and t-fitting the front brake lines. My problem with the adjustable valve, though, is setting it for an emptyload, and then having to reset for a heavy load. But I just don't know much about the YJ proportioning valve. How big are the canals for the YJ one? .050 like the MJ? Or bigger? Is there a setting for the adjustable one that could work for loaded and unloaded driving? I just want to make sure I have the best stopping power possible.

 

And on a side note... could someone tell me what size Speed Bleeders I need for 94 XJ front brakes and a dana 35 in the rear? They seem like they may come in handy for me.

 

Thanks!!!

 

 

[Eagle]

There is no possible setting for an adjustable that works well for both unloaded driving and heavily loaded driving. That's why the factory used the height sensing valve rather than the same proportioning valve they used in the XJ. If you run with no proportioning, you get full braking to the rear at all times. That's what I do in the red '88 MJ (the one that had the height sensing valve explode in a panic stop). Most of the time, I'm happy with the braking even when running light. But ... I learned early after eliminating the valve to be careful to avoid panic situations. A few miles from my house, there's a 4-way stop sign. Leaving home, the approach is down a fairly steep incline. I approached it one day in the rain, touched the brakes -- and found myself sitting sideways in the road. With no load in the bed, the incline took even more weight off the rear wheels and left basically no contact between the tires and the pavement.

 

By contrast, I've found from over a half million miles in XJs that the rear brakes never wear out. I go through two or three sets of front pads before needing to replace the rear shoes. That's because the proportioning valve pretty much "proportions" the brakes so the front does all the work. I suspect the YJ proportioning valve is the same. That would work fine in an MJ when unloaded, but it won't give you good braking when heavily loaded.

 

The best solution if you eliminate the factory height sensing valve is an adjustable proportioning valve, and locating it where you have easy access to adjust it when putting a load in the bed.

[Knucklehead97]

I just found out that the YJ valve reduces the rear brakes pressure by 20%. That doesnt sound like much to me.

[kryptronic]

The YJ valve works well.  I think this is because it's desigbed to be all-purpose.  The same valve is fitted on models which vary in rear weight substantially. 

 

YJs see unloaded soft top configurations (similar to the MJ with an empty bed) as well as hard top configurations with gear, passengers, heavy bumpers, etc. (similar to a loaded MJ).  

 

I run a YJ prop valve on my MJ and have no issues.  I typically run unloaded, but have had up to 500 lbs in the bed and noticed no issues with rear braking power.  I cannot speak to what it would be like at max weight, I have no need to load the MJ to capacity.

 

I think it's a really good replacement option.  Check my tutorial on the swap for specific questions.

 

 

[Knucklehead97]

25 minutes ago, kryptronic said:

The YJ valve works well.  I think this is because it's desigbed to be all-purpose.  The same valve is fitted on models which vary in rear weight substantially. 

 

YJs see unloaded soft top configurations (similar to the MJ with an empty bed) as well as hard top configurations with gear, passengers, heavy bumpers, etc. (similar to a loaded MJ).  

 

I run a YJ prop valve on my MJ and have no issues.  I typically run unloaded, but have had up to 500 lbs in the bed and noticed no issues with rear braking power.  I cannot speak to what it would be like at max weight, I have no need to load the MJ to capacity.

 

I think it's a really good replacement option.  Check my tutorial on the swap for specific questions.

 

 

Your tutorial is actually what got me looking into it! I ended up ordering a YJ one off of Ebay. It was shipped for 30$ so i figured I would give it a try. The max I'll probably have in the best is about 1000. And that would be rare. But the main purpose of my MJ is to pull a 12' long trailer.

[kryptronic]

6 minutes ago, Knucklehead97 said:

Your tutorial is actually what got me looking into it! I ended up ordering a YJ one off of Ebay. It was shipped for 30$ so i figured I would give it a try. The max I'll probably have in the best is about 1000. And that would be rare. But the main purpose of my MJ is to pull a 12' long trailer.

 

Once you have some miles on it after the change, I'd appreciate it if you could post back on my thread with feedback, positive or negative.  We're lacking information on performance when loaded heavy and also towing.  Thank you.

[omega_rugal]

so no one has though of installing a lever insde the cab to change the braking bias??

 

ex. keep the MJ proportioning and load sensing valves, unhook the lever  from the diff, use your brain to hook a cable from there to the cab, that way you can control the braking power on the fly...

[Eagle]

4 hours ago, omega_rugal said:

so no one has though of installing a lever insde the cab to change the braking bias??

 

ex. keep the MJ proportioning and load sensing valves, unhook the lever  from the diff, use your brain to hook a cable from there to the cab, that way you can control the braking power on the fly...

 

What if (like the OP) you don't trust the factory valve or (like me) the factory valve exploded and is no longer functional?

[omega_rugal]

1 hour ago, Eagle said:

 

What if (like the OP) you don't trust the factory valve or (like me) the factory valve exploded and is no longer functional?

 

then you have to settle with a fixed bias...

[Eagle]

2 hours ago, omega_rugal said:

 

then you have to settle with a fixed bias...

 

Or an adjustable, and that brings us right back to the question of where to mount it.

[Knucklehead97]

If the YJ valve doesn't satisfy me then I will be going with an adjustable one next. And I'll definitely add my opinion of it in the DIY topic once I get an opinion of it. It'll be a couple months, though. Gotta finish mylift and some other things before I order 31's and get her back on the road. One step at a time

 

as far as mounting the valve, for adjustment on the go. If you were 2wd like me then you could always fab a mount and put it where the T-case lever would usually be. There's plenty of good places for it. The hardest part would be the mount and then re routing the lines.

[Eagle]

I suppose if the YJ valve doesn't work you could try an XJ valve, and then a ZJ valve. Where did you find the reduction rating for the YJ unit? Does that source also give the corresponding numbers for the XJ and ZJ units?

 

My concern is that any reduction is ... a reduction. I think I've commented before that I have probably half a million miles under my tires in various XJs. I typically go through at least three sets of front pads for every set of rear shoes. That means under normal driving (which is what I mostly do these days), the rear brakes just aren't doing much work. On my '88 I had the hard line to the rear blow out, and I drove it for weeks like that. Other than the peddle being a bit lower, I didn't notice any difference in performance. It's difficult to lock up the rear brakes on an XJ -- on my '88, it's impossible, even on sand or gravel.

[coolwind57]

17 hours ago, omega_rugal said:

so no one has though of installing a lever insde the cab to change the braking bias??

 

ex. keep the MJ proportioning and load sensing valves, unhook the lever  from the diff, use your brain to hook a cable from there to the cab, that way you can control the braking power on the fly...

 

My original plan was to install an adjustable proportioning valve (APV) inside my cab, but I changed my mind and instead installed under the hood near the master cylinder. 

 

I had completely removed my MJ factory proportioning valve and replaced with a full-open brass "T" (inverted-flare) for the front brakes.  I deleted all of the old system for the rear drums and ran a new single line through an APV back to the rear drums.  

 

My Speedway APV was set full open throttle and I have no issues with quick braking with an empty nor heavy payload, so far.  I've had no need to make any adjustments, with varying loads since I installed this custom brake system about 6-Months ago.  Having no idea if whether or not I needed one at the time of install, I put in an APV just in case.  I'm using stock front and rear brakes, with stock master cylinder. 

 

Just thought I'd share my experience on this topic.  Couldn't be happier with my brake system mod and I thank Cruiser54 for the idea.

 

[Knucklehead97]

10 hours ago, coolwind57 said:

 

My original plan was to install an adjustable proportioning valve (APV) inside my cab, but I changed my mind and instead installed under the hood near the master cylinder. 

 

I had completely removed my MJ factory proportioning valve and replaced with a full-open brass "T" (inverted-flare) for the front brakes.  I deleted all of the old system for the rear drums and ran a new single line through an APV back to the rear drums.  

 

My Speedway APV was set full open throttle and I have no issues with quick braking with an empty nor heavy payload, so far.  I've had no need to make any adjustments, with varying loads since I installed this custom brake system about 6-Months ago.  Having no idea if whether or not I needed one at the time of install, I put in an APV just in case.  I'm using stock front and rear brakes, with stock master cylinder. 

 

Just thought I'd share my experience on this topic.  Couldn't be happier with my brake system mod and I thank Cruiser54 for the idea.

 

I actually REALLY like that small of a valve. I probably am going to cancel the YJ valve and order one of those. The main thing about that that i like is the rings and numbers on it to help with adjustment, and the set screw. Seems pretty fool-proof.

[dkenitz]

Coolwind, did you just split that single rear brake line to each drum?

[Knucklehead97]

12 hours ago, dkenitz said:

Coolwind, did you just split that single rear brake line to each drum?

He probably ran that one to the soft line that drops from the frame to a T end on the axle which then go's to each drum. The soft line is what you have to worry about stretching during a lift.

[coolwind57]

On 5/19/2018 at 9:47 AM, dkenitz said:

Coolwind, did you just split that single rear brake line to each drum?

 

I ran a single new brake line to a new (OEM) rubber line, mounted just below the bottom of the bed.  That soft flex line then splits at the axle to go to each of my drums.  

[dkenitz]

On 5/19/2018 at 10:36 PM, Knucklehead97 said:

He probably ran that one to the soft line that drops from the frame to a T end on the axle which then go's to each drum. The soft line is what you have to worry about stretching during a lift.

 

13 minutes ago, coolwind57 said:

 

I ran a single new brake line to a new (OEM) rubber line, mounted just below the bottom of the bed.  That soft flex line then splits at the axle to go to each of my drums.  

 

Thanks much, I'm considering copying your setup when I upgrade the MC/booster in the near future.

[Eagle]

On 5/18/2018 at 11:07 AM, coolwind57 said:

 

My original plan was to install an adjustable proportioning valve (APV) inside my cab, but I changed my mind and instead installed under the hood near the master cylinder. 

 

I had completely removed my MJ factory proportioning valve and replaced with a full-open brass "T" (inverted-flare) for the front brakes.  I deleted all of the old system for the rear drums and ran a new single line through an APV back to the rear drums.  

 

 

So you eliminated the brake failure warning light completely? How is that legal? Your state doesn't have safety inspections?

[HOrnbrod]

59 minutes ago, Eagle said:

 

So you eliminated the brake failure warning light completely? How is that legal? Your state doesn't have safety inspections?

 

Yep. I'd want a low brake pressure switch plumbed in for sure. Would only require the addition of another inverted-flare "T" fitting or replace the existing "T" with a cross fitting.

[coolwind57]

1 hour ago, Eagle said:

 

So you eliminated the brake failure warning light completely? How is that legal? Your state doesn't have safety inspections?

 

No, no State safety inspections here in Southern Indiana.  

 

I assume the wires running to the old MJ proportioning valve ran a brake warning light.  So if that's the case, then yes I no longer have an indicator light.

 

So, my front brakes are completely independent of my rears and vice versa.  

 

Since I did this mod, which Cruiser54 had done similarly to several vehicles, I had experienced one issue that provided me a trial opportunity.  I happen to blow a front caliper piston seal once early on while out and about.  Yes, my pedal lowered closer to the floor, but I was still able to drive home (with caution of course) just fine with 3 brakes only.    I placed a small c-clamp on the effected front brake hose, got home and put both new calipers up front.   

 

My Speedway APV for my rear brakes so far has been set only to "fully open" on its dial.  I've had no need to adjust it.  It's a valve, which will by it's nature adds a bit of a restriction but essentially, I'm running with bare minimal restriction to the rears.  And certainly to the front brakes without the orifice restrictions of the stock MJ proportioning valve.

 

I'm stock master cylinder and mechanical brakes (front and rear), by the way.  

 

[Eagle]

The front brakes are independent of the rear brakes even with the factory distribution block.

 

I'm not certain, but I'm pretty sure it's a violation of federal law (and likely state law, as well) to remove or disable that brake warning light. I know the system will work the way you did it -- it's just like leaving the factory unit in place -- but it's not legal. However, I realize that I'm probably in a minority by worrying about little things like laws.

[Eagle]

The brake warning light is required by Federal Motor Vehicle Safety Standard 135 (49 CFR 571.135). See section 5,5:

 

https://www.law.cornell.edu/cfr/text/49/571.135

 

Disable it at your own risk. Regardless of how well your brakes work (or don't work), it's illegal to disable the warning light.

[Knucklehead97]

Now my question is, if you were to go the route of adding an aftermarket warning light switch and using a T on the front lines (completely deleting the distribution block) , would you have to use 2 warning light switches? One for the front lines and one for the back?

[coolwind57]

Its also illegal to remove the catalatic converter.  And EGR deletes.  I suppose I'd be in big trouble if my State cared about a 1989 Jeep Comanche sitting in a driveway in rural Georgetown, Indiana.  I don't know if you're in a minority as you question Eagle, but I think there's plenty of people out there doing mods to these 30-year old vehicles that don't match laws that many States care enough to hunt down and enforce.

 

Perhaps those reading Cruiser54 and my posts on this procedure, will also read your "Do at your own risk" legal concern also, just as they should prior to performing the other illegal mods than some do.