1 ton discs on YJ?

JugHead1 · Feb 1, 2007

i just recently did 1 ton axles on my YJ and and converted my 14 bolt to disc brakes. i have tried several different master cylinders but i can not get enough preasure to stop my rig like it should. if anybody has put 1 ton disc brakes on a YJ and used the factory brake booster and figured out what master cylinder to use or how to get it to work let me know. right now it has a E-350 master cylinder on it and i have tried the factory YJ one and an oold cj one as well, so if anybody can help me out let me know

thanx jUgHeAd

Totalled · Feb 1, 2007

What are you using for a prop valve? (or are you?)

Long&Low · Feb 1, 2007

The E350 MC should push enough fluid, but you'll need to get an adjustable proportioning valve to meter from front to rear.

I've heard of some folks not running porportioning valves at all. I've heard of some having luck with the stock YJ MC and valve.

Did you use 1 ton calipers? or 1/2 ton calipers?
Single piston, or multi-piston?

Eric · Feb 1, 2007

Is the problem that it requires too much pedel pressure to stop or too much travel?

If you have more then enough travel but you are having to push too hard on the pedel to get results use a better vaccum booster.

I might be wrong on this, but the theory works out in my head

JugHead1 · Feb 1, 2007

ya i am using a prop valve for the rear i just went and bought it from oly4x4 so i dont know what kind it is

JugHead1 · Feb 1, 2007

3/4 ton calipers and single piston

jeeptech 1 · Feb 1, 2007

JugHead said:
ya i am using a prop valve for the rear i just went and bought it from oly4x4 so i dont know what kind it is

If still no stoppy take the valve ouy of the prop. valve it worked for the YJ of treeclimber.We tryed the same thing you are right now. It worked on his.

CrustyJeep · Feb 1, 2007

The easy answer is to rip out the stock prop valve and throw it in the sticker bushes, then put an adjustable in the rear circuit.

motoman432 · Feb 2, 2007

i am running a 60 and a 14 both both discs and don't have any problem stopping with all stock components. But my buddy has a corvette master cylinder in his cj5 with 60's front and rear and discs and his stops great too. maybe that will work for ya

wheelinjp · Feb 2, 2007

Do you still have the stock d60 front calipers? If so then you will likely need the vette master cylinder. I run 3/4ton chev calipers f/r on my yj stock m/c through the stock prop. valve and can lock them up. The pedal just feels spongy. I attribute that to long rubber front brakelines though. Try the vette m/c with an adjustable prop valve for the rear line. It needs to do less of the braking than the front.

CrustyJeep · Feb 2, 2007

wheelinjp said:
The pedal just feels spongy. I attribute that to long rubber front brakelines though. Try the vette m/c with an adjustable prop valve for the rear line. It needs to do less of the braking than the front.

I doubt the rubber lines are the problem The vette M/C isn't all that large for four 3/4 ton calipers.

I think the vette M/C is 1-1/8" bore. You can go all the way to 1-5/16" in a bolt-on unit.

Oh, and that point about needing more braking up front really only applies in 2WD on the street. You can get a nice improvement on the trail by turning the rears all the way up.

benw1 · Feb 2, 2007

I run a '78 Mercury Grand Marquis MC in my YJ with Chevy 1-ton front brakes and 3/4 ton rear brakes. I didn't change anything else, my braking is very good.