xj super duty axle swap brake questions

[mtdilbeck]

so i have spent time reading online and i cant seem to get the answer i need. i have a 91 xj i am doing super duty axles on. i need to know what the best options for brakes. is it ok to run the stock hard lines that are in the jeep or do i need to larger. gut or take out prop. valve. what master and i know i am going to update the booster to the newer xj dual diaphragm unit.. i and going to use all stainless lines where the old rubber lines used to be (at the calipers). i just want this thing to stop good. i know there are lots of people doing this swap and i know someone has figured out how to have lock up brakes.

 

[justind1407]

Following....

I am in the process of acquiring parts for basically the same thing. 2006 LJ with 05+ SD axels.

 

[arse_sidewards]

Hard lines and whatnot are fine to keep.

You're gonna have to calculate your pedal ratio and compare to the superduty in order to figure out what size master cylinder to use.

 

[Jkxj]

I bought a MC for a 2500 Ram van. Works great and simple bolt in. I did just the prop valve. I'm using all Super Duty brakes and hose to the jeep hard lines. The brakes are better than when the XJ was brand new.

 

[badKarma]

For what its worth, when I swapped in super duty axles in my TJ, I retained the factory hard lines with the exception of a couple of sections of -3AN lines to connect to the calipers.

I did switch out the MC for a ram 2500 because the OEM MC couldnt drive enough fluid to stop the jeep in one pedal press.

 

[mtdilbeck]

Thank you everyone for the input. so i what i ended up doing was changing the booster to the newer xj dual diaphragm booster and i went the master out of a 99 dodge 2500 van. it is the same size 10mm and 12mm line fittings and it has a bore size of 1 5/8 it a large bore same as the 2500 ram truck master but the difference is the length of the bore. it is almost an inch and a half shorter so the short throw of the xj peddle rod works great. i even left the stock proportioning valve in there. i ran new stainless lines from the front corners to the calipers and the single line from the unibody to the rear axle an used the stock hard lines that are in the xj.. i have good brakes they dont lock up my 37s on the highway but dang close. i dont worry about stopping at all and they hold great even in 4low. so anyone doing this i would say do the 99 dodge ram VAN not the truck master cylinder. also it being shorter i didnt have to modify my stock air box. with the longer ram truck master i would have had to modify the air box to make it work..