Braking for 1/2 ton axles....

I've done the searching on Pirate, here, and other message boards, but to no avail...I'm still uncertain.
I'm throwing a HP44 and a 9" under the rig. The HP44 is going to run chev knucks, chev calipers, and f150 rotors. The rear is going to have the caddy calipers and CJ rotors. I'll be running 37's.
I've seen the e350 MC swap, but I'm kind of skeptical that it's going to work. I see the MC swap working with the d30/d35 or d30/8.25 combo, but I don't see it working with larger calipers, rotors, etc...
Wouldn't it better to get rid of the stock lines and go with larger lines? Like taking the full e350 brake system and using that?? Also, the XJ diaphgram, is it going to provide enough force to move the larger calipers without having to pump the pedal or push the pedal to the floor?
My knowledge of hydraulics is limited to 2 lessons in my college physics 105 course. All I remember is P=F/A and F1/A1 = F2/A2, and that's because that's all the MCAT requires. If I were a engineering major I would have already figured out what to do, as it is, I'm a Neuroscience major. The only hydraulics we use is....um....well....maybe...That's why I'm not an engineering major. So, I'm asking those of you who are to please give me guidance. Then when you have a question about neuronal function, etc.. I'll come to your rescue.

I just did the E350 MC swap. Haven't had the Jeep on the road and won't for a couple more weeks so I have no feedback for it's effectiveness.

I'm curious why you figure that the MC from the E350 won't be effective for 1/2 ton axles?
The E350 is a 6000lb vehicle with an 8000+lb GVW and and a Dana 70 rear axle.
I think that more than qualifies it for a 1/2 ton axle application; seeing as it's a 1 ton platform to begin with.

C-ROK said:

I'm curious why you figure that the MC from the E350 won't be effective for 1/2 ton axles?
The E350 is a 6000lb vehicle with an 8000+lb GVW and and a Dana 70 rear axle.
I think that more than qualifies it for a 1/2 ton axle application; seeing as it's a 1 ton platform to begin with.

Click to expand...

Sorry, misunderstanding, I'll try to clarify.
I don't mean that I feel the e350 MC wouldn't be effective for pushing 1/2 ton axles in the proper brake system setting. I meant that I don't see how using the e350 MC with the stock XJ booster and stock XJ brake lines would be effective with 1/2 ton axles. I can see using the ENTIRE e350 braking system (MC, brake lines, booster) would be very effective on 1/2 ton axles. After all the system is used on a 1 ton vehicle.

So, my question is, will swapping the e350 MC into the stock XJ braking system work well with 1/2 ton axles?

Also, I can't just give it a try. I'm waiting for the tires. If I had the tires, I'd be able to throw the axles on and see. Since I don't have them, I thought I'd ask.

I think the lines have little to do with it.
Line size has a small effect on how 'fast' fluid can get to the calipers or wheel cylinders but that's about it.

The vacuum booster will dtermine how much 'power' assist you get and that's it.

My desire to go to the E350 was to get the larger bore piston that displaces more fluid and is better matched with the displacement volume of my calipers.

I can lock up all 4 35" tires, on dry pavement, with a system identical to the one you are planning. I use the OEM booster and the Ford master cylinder, with the OEM proportioning valve (minus the rear residual washer).

CRASH

I also pulled the o-ring out of my propotioning valve on the advice of several people. Is this the same thing?

Yes. U.R. Fawked Racing will soon offer a kit to help people with this worthwhile modification.

CRASH

I have the same front end setup except ford explorer rear discs. I'm using the stock '97 MC, booster and portioning valve. There is a little more travel in the pedal, but the braking force with 33s is a lot better than stock. I've locked the 12.5" wide 33" street tires a few times and you have to brace yourself. You might want to try the system with the stock parts before replacing. Year of your XJ does matter. I hear that some of the pre-97 models don't have as good a booster.
BTW stock brake lines from a '76 blazer fit quite nicely especially if you relocate the hard lines down to the bottom of the "frame"
HTH
Mattk

I'm putting a Waggy D44 under my MJ right now, and it has larger brakes than the D30. I definitely think the new MC is in store for me, but I think it is pointless to run larger lines, have you looked at the size of the hole in the banjo going to the caliper? It is about 1/16", so even with bigger lines, the "weakest" link is still in another place.