Brake Booster Upgrade questions

[acfortier]

After reading over some guides and threads about the '95/'96 brake booster upgrade, decided to go ahead and do it for myself as I plan on re-doing all of my brake lines. Went to the junk yard, picked up the booster, master cylinder and combo valve for $50 from a '96. Referring to the MADXJ guide, it says I will need conversion brake fittings, but if I want to use the 96' valve, does this still hold true? Unluckily, one line going from the M/C to the valve was disconnected, but one is still there. Basically, will I need to still grab those Edelmann fittings as per the guide or will I be able to get away with something else?

[HOrnbrod]

You should use the 96 proportioning valve only if you plan on eliminating rear the load leveling valve on your MJ, otherwise you'll have two prop valves. I kept my MJ load leveling valve and reused the MJ combo valve flare nuts up front and fabbed new lines from the combo valve to the master cylinder.

[airspeed]

When I did my upgrade I left the original proportioning valve and the load leveling valve on the truck. I'm happy with the way the brakes work, from 75 mph that truck will stop fast and straight! I don't understand the different thread sizes but AutoZone had what I needed, two brake lines and one adapter. I formed the lines around a 1-1/2" socket, cut and flared the lines. Note: remember to install the threaded fitting before you flare the line, I made that mistake once.

[HOrnbrod]

When I did my upgrade I left the original proportioning valve and the load leveling valve on the truck.

 

The original MJ combination valve under the master is not a proportioning valve, it's simply a fluid junction block. The proportioning (brake biasing to the rear wheels) is done by the load leveling valve on the rear axle. You did your install as I did. Nice job on the brake lines too. :cheers:

[acfortier]

It'd be easier for me to eliminate the rear load-sensing valve anyways. Instead of two lines, only have to run one to the back. As per this thread, I planned on eliminating the rear and just using the XJ. But I wasn't sure about the different thread sizes (if the even did differ) or what actual sizes the XJ proportioning valve uses.

[RDAN1]

It'd be easier for me to eliminate the rear load-sensing valve anyways. Instead of two lines, only have to run one to the back. As per this thread, I planned on eliminating the rear and just using the XJ. But I wasn't sure about the different thread sizes (if the even did differ) or what actual sizes the XJ proportioning valve uses.

 

Question/Clarification: Where is the XJ "proportioning valve" located? is it connected to the XJ Booster/Master Cylinder ? Or? A friend has a 96 XJ he's parting out and I'd like to get all the necessary parts/items from him to do this upgrade and also eliminate my rear MJ Proportioning valve as it no longer appears to work.

[acfortier]

It'd be easier for me to eliminate the rear load-sensing valve anyways. Instead of two lines, only have to run one to the back. As per this thread, I planned on eliminating the rear and just using the XJ. But I wasn't sure about the different thread sizes (if the even did differ) or what actual sizes the XJ proportioning valve uses.

 

Question/Clarification: Where is the XJ "proportioning valve" located? is it connected to the XJ Booster/Master Cylinder ? Or? A friend has a 96 XJ he's parting out and I'd like to get all the necessary parts/items from him to do this upgrade and also eliminate my rear MJ Proportioning valve as it no longer appears to work.

 

Yes, the proportioning valve for a XJ is connected the to master cylinder/ booster. You can keep the MJ valve in the front and just plug the extra line that goes back to the height-sensoring valve , but you are more prone to locking up the wheels.