Don't need 'em

 

Jeep937,
Maybe you don't feel the need for brakes, but I want brakes that will hold me hanging off a rock or for an "Oh Shit" stop on the road! The feeling of just slowing down does not give me a sense of ease and comfort.

All 4 brakes had been working most of the time until the most recent failure. Now only the fronts are stopping the vehicle.

 

ideas anyone??

 

ditch the prop valve! Mine didn't work for shit either so I bypassed the valve and they lock up quick now. what size tires and gears are you running? also blow out your brake lines bleed from the pass rear to driver rear then pass front to driver front. use a clear hose have a buddy pump the brakes and hold in the down position crack the bleeder valve watch for air in the clear hose. close bleeder and repeat till no air is seen in the hose make sure to keep the master cylinder full. if you drain it start back at square one. not saying your lacking any skills but just in case. good luck

 

Thanks for your response Flatback,
I've got 35" MTR's with 4:56 gears.

Yes, we have bled the lines several times and blown out the long brake line from Prop valve to rear brakes.

The most recent prop valve is this one; http://www.summitracing.com/parts/SUM-G3910/

In theory with the adjustment knob turned all the way clockwise the rears should be locking up. Nope, the rears don't appear to be working at all!

 

Something is wrong with your system if you can't get rear brakes.

Something is also wrong with your system if you are having repeated brake failure.

I'd start over and trace each line from the MC to the brake and make sure they are not messed up, something in line, etc. Put it back together with NO prop. vale of any kind.

Bench bleed the MC. Bleed the system. Step on the brakes, etc...

Once you have it working with no prop. valve. add in the adjustable one and get it dialed in.

 

By-passing your proportioning won't do shit if there is something wrong with the system. If you try bleeding your rear brakes, can you get fluid to come out then?

 

Thanks for your responses. Yes, the rear brakes both bleed just fine.

 

What kind of proportion valve do you have, drum/drum, disc/drum, disc/disc? Either you don't have enough pressure or maybe it's your calipers.

 

Thanks for the responses so far.

Update on the brakes.
Found the R rear Caliper was leaking at the piston. Replaced L & R rear calipers, new pads, turned the rotors and reinstalled.
A dual diaphram Brake booster off a 95 YJ and a small bore stock TJ '02 MC.
Bled MC, each brake, etc.

Now all 4 brakes are working, but overall braking is so-so, an improvement, but really have to jam on the pedal to get a hard stop. Even a hard stop is so-so IMO. Pedal travels much further than before.
The fronts will slightly lock up at the end of the stop which is fine.

The Summit Prop. valve has adjustable rear. The valve is wide open so theoretically we should be getting rear lock up and adjust from there- not so. The rears feel and look like they are slow to engage.

The question is now how do we adjust for better rear end response?
thanks

 

P.S. at last check pressure was 900# on the rears.

 

Brake resolution

OK problem(S) resolved.
Put on a Ram 2500 disc disc MC (#3081 I think,) bled everything, etc.
Brakes still not good. What the F#$%$ was left? The front Calipers! They were not working properly. Swapped them with some used ones nearby and brakes were much improved.


A long journey with many problems not just one thing. So what was wrong- in short- EVERYTHING!!

Thanks for the input received here. Hope this thread will be helpful to someone else down the road.