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Modified braking question

R

RANSOM

NAXJA Forum User
Location
south jersey
Scenario: I'm going to be putting D60's under my 2000 xj. I just finished narrowing, and loading the gears and lockers. I'm running 5.13's and 35 SSR's (for now). The front is a out of an f-350 and has dual piston calipers. The rear is a 35 spline semi-floater out of an E-250 van an it has dual piston calipers as well.

My question(s):

1: What master cylinder size should I use. My thoughts were to use the same size an F-350 would use. But I can't seem to find what size it is. And I thought it might be TOO much braking because of the 4000+ lbs LESS that the brakes will be carrying. Any thoughts?

2: Does anyone know what size a factory xj set-up runs (no abs). I can probably calculate what I need if I have this number.
 
Okay. What kind of mods are we looking at using the dual dia. booster, and dodge 3500?

Brake pedal, fire wall (bolt pattern).

And is the dual booster out of the Dodge 3500 or are you talking about the xj dual dia. booster?

How much does a hydraboost run? Coins not an issue but I like to keep things a "factory" as possible in case something blows unexpectedly. Junk yards are more forgiving on Sunday.
 
Nevermind on the dual diaphram booster. I skipped over the year of your rig, you have one because its a 2000.

In not exactly sure on the mods needed to run the Dodge 3500 MC, but try to PM SeanR and see what he did. Ive heard they work great, and thats my next mod.

Hydraboost, you can get them from Chevy or GMC trucks, also Astro vans.

Not sure whats all invlolved again, but some plumbing through the power steering and such would be needed. Im sure there are some threads out there somewhere either here or on Pirate about hydraboost.
 
No need for hydro on your setup unless you like flying through the windscreen. Fitting the same master as the brakes come from is the best idea. You wont have too much brake at all and in fact keeping the smaller stock XJ one will give you 'more' brake than a larger one but also a lot of pedal travel. The bigger the master the more effort needed but less pedal travel. E350 mc I have seen used quite a bit with these sized brakes so might be your best bet.
 
You will need to use a master with a large bore, pressure won't be the problem it will be volume due to the huge piston size on the front calipers. I would also plumb in a adjustable proportioning valve so you can dial in the issues you will have with pre-mature lock-up in the rear. You best bet would be a master from an older f-350.
 
Thanks. I figured I'd have more line pressure but more pedal travel. Which is what I wanted to stay away from. I also don't want to have to raise the hood from using a bigger mc. Maybe I can get creative with it and machine a adapter plate to mate the ford mc the the xj booster and drop the booster down on the fire wall a little bit for clearance. I'll post my results. Should be a few weeks before I can get to it, though.
 
I have the same front calipers as you, but with a chevy 1/2ton front caliper on my rear 14bolt. I run the WJ master/booster and no prop valve. Stops like a stock XJ . no real mods needed and very direct swap. look it up in here. Search WJ brake conversion
 
well I threw that out there, because in my opinion it would be benifital in many ways, to ditch the current rotors and calipers (cores for the new stuff) for a set of ruffstuff caliper brackets (45$) and convert over to the typical 1/2 chevy stuff. you would not have to fab and hope and wonder if it will even function, just get a WJ master/booster, and swap rear stuff to the 1/2t stuff.

What size is the hard lines that run from the master to the prop to the rear brakes on that E250??? bet its larger then the XJ has, so if you want the extra volume and petal pressure and travel to be the same and use the same master and booster from that same van/truck the axles/brakes are from, then you better swap out all the hard lines to the larger size, and lengths also. And what about the lever working ratio? the petal hinge to push rod distance will be different then the van/truck, so you might want to fab that to be the same too. All that is very relivent if you want the "same" full brake system as that truck/van the axles are out of.
 
Any body have a bore and stroke size of an xj mc?

And does anyone know what size an f-350 mc is?


-I cant seem to find the actual sizes anywhere. If have these it will be easy to calculate what the perfect size will be for my app. I'd like to calculate/figure and get it close to dead-nuts rather than trial and error. Time is a premium for me.
 
I belive the bore in a superduty is 1 1/8 and you can also use the 1 1/4 inch which was a TSB for people who felt there was to much pedal travel. FORD PART NUMBER 5C3Z-2140-LA
 
Last edited:
well your still guessing here. Like I tried to help by mentioning. The brake lines are smaller ID on the XJ then the superduty's and I would bet the booster on the XJ is smaller then the SD? SO by taking a SD master and bolting it up to your rig and thinking thats all your going to need, its not "dead-nuts rather than trial and error". its trial and error your going to be doing.

Why not do what 90% of those with that type setup do. Dual front piston stock calipers, and 1/2t chevy rear? thats tried and proven with the WJ booster and master adn some even say a stock dual diapham and xj master is very nice even.

Just seems like your not listening to proven experience, but rather this should work or try this..
 
I do know a guy that used front and rear Dana'a from a 05 superduty, it was on a WJ, his stock master did not have the volume, Ford master worked pretty well but there was a issue with the rod length and getting it correct, once it was figured out it worked very well. I just don't know why you would want that big of brakes unless you were running 40's
 
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