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View Full Version : Advice on JY Brake Booster for 89 Limited


stockli
July 9th, 2010, 19:52
I know there have been a lot of threads that cover this, but I have found no definitive answer on which Booster would be the best to snag from the JY.

If you guys had to grab a new booster what would you put in your 89 Limited with the stock rear drums?

Is there one that would be the best option then on down the line to stock?

Also Im not really blessed with a lot of cash, so cost effective would definitely help!

joe_peters
July 9th, 2010, 20:51
If you grab a 95-96 XJ you can also grab the pedal assembly and not have to modify the rod.

There are quite a few write ups on the dual-diaphragm booster swap, WJ or 95-96 XJ.

JP Magazine's take on the upgrade: http://www.jpmagazine.com/techarticles/drivetrain/154_0810_cheap_jeep_brake_system_upgrades/index.html

stockli
July 9th, 2010, 22:54
Thanks Joe

So these would be the easiest swap.

I figure if I have to replace it anyway might as well upgrade before I start lifting the jeep.

in4aride
July 9th, 2010, 22:58
Just grab the dual diaphragm booster and lines that go to prop. Valve. Grab the pedal while you're at it. We did a 98 booster into an 88 no prob without swapping pedal.

joe_peters
July 10th, 2010, 10:07
Just grab the dual diaphragm booster and lines that go to prop. Valve. Grab the pedal while you're at it. We did a 98 booster into an 88 no prob without swapping pedal.

Because you have done this you would be the best person to ask. I had heard that the 97+ boosters mounted at a different angle, and that if you used one of those boosters the rod working at an angle off-center would lead to premature failure of the MC piston/bore.

Have you monitored this? If so, any signs of odd wearing?

2stix
July 10th, 2010, 11:30
i used the booster/master, and pedal assembly from a 95 on my 89 limited and it was a complete bolt on deal. works awsome. my 89 had the bendix antilock system and needed replacing. as mentioned, get the master WITH the lines to the prop valve when pulling from the yard. they are tight bends and hard to duplicate. i also grabbed the prop valve from the 95 but didnt use it as i scored the sealing area on one of the ports, so i used the 89 prop valve. (identicle). got it all on half price day and have 29 bucks invested total.
oh and i am running the stock d35 with worn out shoes, just waiting to re-gear the d44. but the new booster and master stops the jeep great with 235/75-15s. do the swap and youll be happy, and safer.

stockli
July 10th, 2010, 23:11
Thanks guys!

Fixed the oil leak today, now just got to get a new booster and replace the real leaf for a DD.

After I put a few miles on her she will get a jy lift ZJ coils and bastard rear leafs pack.

She is running great and PULLLLS nice and strong!

in4aride
July 11th, 2010, 06:54
Because you have done this you would be the best person to ask. I had heard that the 97+ boosters mounted at a different angle, and that if you used one of those boosters the rod working at an angle off-center would lead to premature failure of the MC piston/bore.

Have you monitored this? If so, any signs of odd wearing?

only issue we had to work on was making the likeght switch work consistantly

also the booster rod sait only 1/4' too high to mount right up, so angle isnt too far off, but the pedal ahd to be pulled toward the seat a few times to make room for it to come back far enough..


its only been 1000-1500 miles or so, and as of yet no issuees, brakes work great, easily lockin up his 35" yellow labels :thumbup:

js_customs
July 11th, 2010, 12:12
I did the wj booster/MC swap. The only thing i had to modify was the rod that goes to the brake pedal (easy, just cut your old one off, tape it to the new one, and grind the wj rod so it's the same) and make a new line with a double flare on one end and a bubble flare on the other. 95+ booster swap may be easier, I just found a great condition booster/master cylinder in a wrecked WJ in the junkyard and got it cheap.

1990JEEPXJ
July 11th, 2010, 12:14
and a note on the WJ booster is that it is smaller and doesnt require renix guys to move the washer bottle

stockli
July 16th, 2010, 19:51
I got a good price $50 for a WJ master, booster and prop valve. So that is what im going with, they wanted the same amount for a 96-97 xj set up.

So my new question, if I keep the WJ prop valve then I will only have to worry about refitting the brake lines from the jeep to the prop valve, right?

I thought I read to keep the prop valve so you dont have to mess with bending up a bunch of crazy bends from the MC to the Prop valve.

Is this correct?