WJ booster and MC

Daddy Longlegs · #1 03-13-2003, 12:22 AM

Here is the setup:

1999 TJ
1987 Waggy Dana 44 (The rotors are 12", larger than TJ or ZJ. Think BIG!)
1998 Ford 8.8 with discs.
2000 WJ vacuum booster
2000 WJ master cylinder
1997 ZJ prop valve

Well after two evenings of messing with this I went back and got a second WJ master and was still disappointed. Chris B was helping me out with the bleeding and we came to the conclusion that maybe I should pickup a vacuum pump and try suction bleeding instead of the old fashioned pump the pedal and then open the bleeder method.

The book that came with the $25 pump from Autozone was worth the $25 alone. It told me how to use the pump to bench bleed the master. After carefully removing all the air from the master I then installed it into the vehicle, pulled the plugs and quickly screwed the fittings into the prop valve. I then learned how to use the vacuum pump to do a one person bleed without pumping the pedal. After a bit of trial and error I figured out how to use the thing and started pulling fluid at each wheel. Eventually I had pumped a decent amount and felt that I should go for a drive.

I'm happy to say that it felt good. I will have to stop by Stu's and maybe drive his and then mine and he can drive mine and we'll compare notes. I think I may need to bleed a bit more air out but for the most part in normal driving it doesn't take much pedal effort to stop the vehicle. I no longer have to stand on the pedal like with the TJ master. For instance when I come to a red light I just apply a very light steady amount of pedal and it stops in a very reasonable distance. I do notice slight variations in performance depending on RPM which I attribute to the lower vacuum boost at lower RPMs but for the most part this isn't really too noticeable. Considering that I used to have a 5 speed in the TJ and did mostly engine braking, and now have a 4 speed auto and use the brakes to do all my stopping, I'm pretty happy with the performance.

If you do this mod be warned that you won't be able to do it without one of these handy vacuum pumps that have a fluid reservoir. Bench bleeding the master and then suction bleeding was the only method that worked. If any of you would like help with this if you are thinking about doing a master swap let me know and I'll bring over the vacuum pump (As long as you live in Arizona).

I'll let the rest of you know what Stu and I think after I let him drive it Thursday night if he's around. It may turn out that I was so damned happy to just be driving the Jeep again that I wasn't too fussy. We'll see tomorrow....

Oh yeah, we took one apart and it did have a 1" bore.

Later,

Scott K