Rear brake proportion thingy

[rejeep]

I was having an oil change done on the MJ this weekend and the mechanic called me and said the rear prop valve was rusted, missing, or something t that effect..

I wanted to replace the brake lines, wheel cyl, etc.. but I’m trying to locate this part and can't..

any help on what this is..

[Pete M]

doesn't exist and isn't fixable unfortunately. :( But the good news is that many of us have just deleted it from the system with no ill effects. :D just plumb a T-fitting in it's place. :thumbsup: another alternative is to get an aftermarket manually-adjustable on and put that in its place (removing the factory one will give full pressure to the rears and it's possible to lock them up before the fronts in some trucks).

[rejeep]

I figured it was NLA..

Wonder if one from an S10 or simmilar would work..

 

Or like you said.. Just forget it for now..

[Abyx]

I've always wondered - what's the downside to the rears locking before the fronts? Wouldn't you want it that way?

 

Personally I just plugged the preportioning valve and ran a single hardline back.

[MJRemi]

If the brakes lock up, then you are just sliding on the surface without any real control of the truck. My 4x4 had the valve removed by the PO and not properly adjusted regarding brake fluid distribution. I was driving on the highway in rush hour and had to brake a little harder than normal due to a sudden slow in traffic and my rear brakes just locked up. I slid toward the car in front of me but luckily was able to stop before colliding.

[89 shortbed]

If you remove the valve in the back and delete it by a tee or plug off at the combo valve and even if you replace the combo valve by the master with one from a xj or yj you will have 100% pressure to the rear and could lock up the brakes. The mj combo valve supplys fluid to the load valve in the back and to a bypass (the second line) and if you loose front brakes it then sends fluid down that line for 100% braking power. The bypass line only sees fluid in the the loss of front pressure. Do yourself a favor and get a xj or yj combo valve and run one line back. In my opionion it is the safest soultion.

[Abyx]

If the brakes lock up, then you are just sliding on the surface without any real control of the truck. My 4x4 had the valve removed by the PO and not properly adjusted regarding brake fluid distribution. I was driving on the highway in rush hour and had to brake a little harder than normal due to a sudden slow in traffic and my rear brakes just locked up. I slid toward the car in front of me but luckily was able to stop before colliding.

 

But if the rears lock up before the front, it's like riding a bike - you want all the rear braking power you can get before you want the power from the fronts. Am I the only one who pumps my brakes and 'lets go' if they lock up? I don't even run a preportioning valve in my cherokee, and I've NEVER had problems.

[Pete M]

if the rears lock up first, they can fishtail the truck around.

[Dirteatr717]

thats what the steering wheel is for pete :D

[HOrnbrod]

I figured it was NLA..

Wonder if one from an S10 or simmilar would work..

 

I have one from a 95 Toyota 4Runner standing by if and when my stock load sensing valve goes belly up. It's close in design and looks like it will bolt up pretty easily.