3/4 Ton Brakes on a YJ

[Brett Polwell]

I put an 86 E350 Master Cylinder on my YJ the other day, but I don't have any brakes until the 3rd pump. I am running axles front and rear out of a 1975 J20. The Brakes are stock drums in rear and discs in the front off of the truck. I have bled them several times and put new calipers and pads on the front. I tried adjusting the rod in the booster but by the time I get brakes the front wheels don't want to turn.

Could the stock YJ Brake lines be too small, or is there a check valve somewhere that is supposed to hold pressure? This thing is deadly with a 401 and no brakes, but it sure is fun.

[jeepsr4ever]

Its most likely your proportioning valve that is making the sponge in the system.

[Brett Polwell]

So what kind of proportioning valve do I need and where should I get one?

[BREK]

if you don't mind spending a little money i'd say go to summit or jegs and get an adjustable one

[bor]

Ditto---- Adjustable proportioning valve. Easy to install-- and use. Question, what sequence are you bleeding the brakes/ Are you starting with the wheel that is farthest away??? Have you gone through the sequence more than once???? I had to go throught my system 3 times before they were completely free of any air bubbles.

[Brett Polwell]

I finally got brakes. I have bled the brakes at least 6 times when I got to looking at the front calipers. The breather is on the bottom. I took them off and used a C-clamp to keep the piston in place while I held it upside down and bled the brakes one last time. This cured everything. I finally have better brakes than I ever had.

Thanks for all of the help.

[tufcj]

The front calipers might just be swapped side/side. They usually have R and L cast into the caliper somewhere.

The rear discs on my CJ are difficult to bleed because the pinion is rotated up about 12 degrees. The calipers are rotated just enough that the bleeders aren't exactly at the top. I have to pull the mounting bolts and rotate them around a bit to bleed, otherwise they hold a little air and the pedal is soft.

Sometimes it's easy to overlook the obvious. Glad you got them working.

Bob
tufcj