Problems with WG brake system...

Hello,

i do have a 90 model. wanted to get rid of the old brake system. Put WG dual diaphram system, new rotors all new pads but it is like shit. the pedal is very very soft and the rear brakes hits first so its like an e- brake.

What could be wrong??

You have air in your lines. Need to bleed them better.

no thats been done allready by pros do u think its because of a proportioning valve?
maybe i dont have one?

No, I think there is still air in the line somewhere - or less likely, your master cylinder is tweaked (sometimes happens when you first pump it after having no fluid in it).

Trust me. I know what I am talking about. I've done that swap about 15 times in the last year, and have 2 more WJ master/boosters sitting in my garage now waiting on people who I owe favors to come get them installed.

I did this swap and I like the air in the lines diagnosis by cal, it took a few tries for me. And since you dont have an adjustable proportioning valve and upped your line pressure, the rears will lock up first because there is less weight in the rear of the jeep during hard stops. Can you come to a stop slowly and not lock the rears up?

Maybe check to see if your WG booster has a disconnected vacuum source?

By the way do you have stainless lines run or are you still using the originals, i have heard that upgrading to all hard line/stainless helps because the originals are rubberish and expand a little, causing very small pressure loss.

hope something i said helps

The rear should not lock up. it gets a lot less pressure, and has drums.

There is air in the lines.

Echo air in the lines. "professional" mechanics not bleeding the brakes thoroughly enough or perhaps leaving something loose enough to let air into the lines isn't exactly unheard of. Most of them see our beat up old Jeeps and the first thought through their heads is "it doesn't have to last long"

Professional mechanics replaced my YJ's ENTIRE hard lines and put in new MC's twice before I went in their and redid it all myself. Replacing the visibly cracking rubber rear line that they left(!) in place instantly solved my problem

(That was the point in my life when I stopped paying other people to work on my Vehicles. Mostly because I couldn't afford bulls**t like that.)

I then had about 250 dollars worth of the most twisted narley kinked up horribly routed hand bent mild steel hard lines that WEREN'T EVEN ATTACHED to the frame with the stock hold downs (they cut the old lines out on either side of most of the hold downs and just left them there!). Instead they used zip ties!

After replacing all that mess with pre-bent stainless (great kit from Quadratec) and bleeding three or four times the YJ was braking like the day it came off the assembly line.

Seriously get a buddy and re-bleed, or buy some one way bleeders from Quadratec some clear hose and do it by yourself. But first put a flare end wrench on everything they touched. look for fluid and crushed or cracked metal lines where they may have been over bent or overtightened.

Also I bet they didn't reset or bleed your proportioning valve, if they got air in that far and they only bled your lines a little then the proportioning valve still has some air or may even be locked in the rear position which means you only get fluid pressure to the rear, (this is a safety feature to keep fluid in the rear lines when their's a leak in the front)