Anyone whos done the WJ master cyl and booster swap...

[Backroads]

SO today I accomplished a lot! Scored a wj master cylinder and booster from the yard yesterday, so I figured what better day than today to put it all in!

 

When I got the truck it had 0 brakes....found a bad rear line and that only began the work ahead.

 

So now its got, new drums shoes, and cylinders out back. New brake line coming from the nose of the prop valve all the way to the axle. Bottom port (front) of the prop valve plugged up. And the WJ MC and BB.

 

Bench bled the wj bb/mc, flared the lines, bled the brakes and I've got brakes...but not the lock em up awesome brakes I was expecting....

 

Without the truck running, the pedal is rock hard like it should be, once its running its got pressure but its got a long throw to it as well. Feels spongy.

 

I used a couple washers to space out the booster and achieve pretty much the same pedal position as with the stock mc/BB setup.

 

So what gives? Should I have nixed the MJ prop valve and used an XJ one? Does that even matter? Only thing I really have left to go over again would be the vacuum line from the intake to the BB and make sure its not leaking or anything...and to check the adjustment of the rear shoes. After that I'm gonna start throwing tools!

[A-man930]

I would start by plugging up everything coming out of the "proportioning valve" and see what things feel like. This will eliminate the calipers and wheel cylinders from the eqasion. Is this a new master cylinder?

[Backroads]

it is not new. It was a junkyard find.

 

I'm not ready to tear everything apart just yet. It was enough of a headache to break those old lines free from the prop valve in the first place!