Brakes - Dual Diaphragm Booster Upgrade Write-up

94 XJ, non-ABS, cruise

Finally got around to getting the dual diaphragm booster upgrade done this weekend. I had been looking into it for awhile now (there was some good info here on the forum, the madxj write-up, and cagedxj gave me some info, too), but it took awhile to get the courage up to tie into my brakes like that.

Started on Thurs, pulled the old booster and master cylinder (MC):


In this pic, note the adapter in the proportioning valve (PV) on the right, turns out I didn't need to buy one of the adapters because it was already there. More on the adapters later.


I was told that a TJ booster and MC would work for the XJ so I bought one off of e-bay awhile back. I put it in, but the booster rod was too long. I made up for this by putting some washers on the booster mounting bolts to space it out some from the fire wall and I adjusted the brake light/cruise switch out quite a bit, this in turn caused my brake pedal to be quite a bit higher, which I wasn't to thrilled about. I had meant to get the 8 mm spacer from later model XJs and ZJs? but hadn't been able to, I don't think I would have been able to use it anyway, because the booster bolts weren't very long.

Here is a pic of the light/cruise switch, I had pulled it back in it's hole and bent the mounting plate back to make it work: (dis-regard that booster rod, it's not from the TJ booster)


Here is the TJ booster installed, with the custom bent brake lines.


I drove around with that booster on Friday and part of Saturday and was happy with the increased braking power, but the booster had a small vacuum leak (damnit!) and I didn't like having my pedal so high. I had bought a remanufactured '95 booster and new MC in case the TJ booster didn't work, so I figured I would put that in instead. I had trial fit the booster on Thurs before putting in the TJ booster and it seemed to fit pretty good. The rod was also a bit longer than original (shorter than the TJ, though), and I figured I would try to find the spacer. The reman booster had longer mounting bolts, too. Finding the spacer was a PITA and took all of my Saturday morning, but I finally found one and got it off of an 01 XJ. I recommend getting this spacer for this swap.


Saturday afternoon I pulled the TJ booster and put in the reman booster and new MC.


Drinky treat to keep me relaxed


This booster fit better so I was able to adjust the light/cruise switch back down some and the pedal was not so high anymore, either. The brake light/cruise switch picture above shows the reman booster rod, you can see the space difference between where the switch was for the TJ booster and where it was going to be for the reman booster. This switch set-up is much easier to work with than the older style that I have seen in some of the write-ups. Anyone know what year it changed?

Here's the reman XJ booster and new MC installed. Aint that purdy?


This parts list posted earlier helped me find what I needed:

trekfuel80 said:

(2) Steel Lines (Part # BL-312) – “BRAKE LINE 3/16 x 12”
(1) Brake Adapter (Part # 327819.1) – “BRASS 3/16FTUBE 5/16TUB”
(1) Brake Adapter (Part # 327818.1) – “BRASS 3/16F TUBE ¼ TU”
(1) Brake Adapter (Part # 327857.1) – “BRASS 3/16IF TO M12-1.0”
(1) Brake Adapter (Part # 327850.1) – “BRASS 3/16IF TO M10-1.0”
(1) Brake Adapter (Part # 327841.1) – “BRASS 7/16-24 TO ¼ TU”

Click to expand...

You can find these at Advance Auto Parts (drop the .1 when looking the part up). I also sourced the Edelmann adapters from Car Quest, but they were quite a bit more $ there. I didn't use 327819, perhaps that was the adapter I already had in the PV? Also, I'm not sure what 327841 is for, I didn't buy that one. This pic shows the adapters and the custom bent lines:


Conclusions: The braking power is much improved! I'm definitely glad I finally got this done. Make sure you get the 8 mm spacer, you may not need it but it's nice to have if you do. I would recommend not using a TJ booster, the rod is too long and the MC seemed to be at a greater angle.

One more pic of the completed job:


Questions? Comments?

After the vacuum leak, you replaced only the booster?

Why does the MC have a yellow cap in the pics with the TJ booster, and a black cap in the pics with the reman booster?

Eagle said:

After the vacuum leak, you replaced only the booster?

Why does the MC have a yellow cap in the pics with the TJ booster, and a black cap in the pics with the reman booster?

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Sorry, must not have been very clear. I had bought both a remanufactured booster and a new MC to use in case the TJ booster/MC didn't work. That's the new MC from NAPA with the black cap.

Doesn't the MC have to seal tight against the dual diaphragm style boosters to hold in the vacuum? I know the single diaphragm are internally sealed but I think the duals are different. I've heard of a leak between the MC and booster on a few swaps....could be the source of your first vacuum leak.

Bender said:

Doesn't the MC have to seal tight against the dual diaphragm style boosters to hold in the vacuum? I know the single diaphragm are internally sealed but I think the duals are different. I've heard of a leak between the MC and booster on a few swaps....could be the source of your first vacuum leak.

Click to expand...

Yes, but I was hearing it inside the Jeep while braking. It could have been it, though, but the whole TJ set-up was less than ideal anyway.

I am in the middle of this project and have a question about the lines, fittings, and adapters. Can I just cut the stock lines that came with the booster and MC and take the fittings from them to make the new lines? I do not understand what all of these adapters are for.

How did you guys flare the lines? What kind of flare is it? Did you rent the bender and flaring tool from autozone or someplace else?

Thanks
katarn

katarn444 said:

I am in the middle of this project and have a question about the lines, fittings, and adapters. Can I just cut the stock lines that came with the booster and MC and take the fittings from them to make the new lines? I do not understand what all of these adapters are for.

How did you guys flare the lines? What kind of flare is it? Did you rent the bender and flaring tool from autozone or someplace else?

Thanks
katarn

Click to expand...

I didn't want to worry about flaring brakelines, that's why I used the adapters. With the adapters you just buy 2 12" standard brakelines (BL-312) bend them up and install them. I bent my lines by hand.

If you have the proper fittings and flaring tool you can do that, too.

I see. Thank you.

katarn

resurecting thread.


madxj seems to be no more, so if going from an 87 to a 95 booster and MC, IIRC the rod has to be swapped from the 87 booster to the 95. is this correct? how hard is it, whats all involved, is it easier to get a 95 pedal from the JY?

streetpirate said:

resurecting thread.


madxj seems to be no more, so if going from an 87 to a 95 booster and MC, IIRC the rod has to be swapped from the 87 booster to the 95. is this correct? how hard is it, whats all involved, is it easier to get a 95 pedal from the JY?

Click to expand...

I thought the idea was to use the 95-96 booster so it was a bolt in swap, as long as you got the booster with the correct part# pedal rod. Which all 95-96 seem to be?

Mines still sitting on the shelf waiting install, i can get you that pedal rod number if needed.

You mean this wright-up? http://madxj.com/MADXJ/technical/technicalfiles/ARbrakeBoosterUpgrade/BrakeBoosterUpgrade.htm

That's the whole point of using a 1995 brake booster- the pedal rod is the same length as the rod on the older single-diaphragm boosters, so no rod swap is needed. Later model brake boosters (1997 up XJ boosters) have a longer pedal rod and don't fit. I'm not sure on the 1996 boosters. There have also been reports that a WJ booster fits straight in, in place of the single daiphragm boosters.

John B said:

I thought the idea was to use the 95-96 booster so it was a bolt in swap, as long as you got the booster with the correct part# pedal rod. Which all 95-96 seem to be?

Mines still sitting on the shelf waiting install, i can get you that pedal rod number if needed.

Click to expand...

Yes, just get the 95/96, the pedal rod is the same for all. I think I may still have one of these (booster) if anyone is interested.

RockTracXJ, thanks for those adaptor part#'s. Picked them up last night, that will save me time.

Did you do any proportioning valve mods? I have no o-ring in my stock XJ PV now, and i plan to swap in ZJ 4wheel disc PV internals when i swap the booster/cyl. Wondering if i should run the o-ring with the ZJ internals.

John B said:

RockTracXJ, thanks for those adaptor part#'s. Picked them up last night, that will save me time.

Did you do any proportioning valve mods? I have no o-ring in my stock XJ PV now, and i plan to swap in ZJ 4wheel disc PV internals when i swap the booster/cyl. Wondering if i should run the o-ring with the ZJ internals.

Click to expand...

I'm planning to do the ZJ internals swap as well, but I haven't been able to find one yet. I just got back form the junk yard and ZJs get cleaned out pretty good, so no PV. And I don't want to have to buy one from the dealership. I would just swap the ZJ internals over excatly as they are.

Speaking of adaptors, I am after one that converts the large 7/16" rear line fitting down to a 3/8" fitting, both with a 5/16" line. Cant find one anywhere.
Anyone ever seen one? Can find a step up, but not down.

I went to a junkyard and spent about $5 for a set of lines from the MC to the prop valve. I used the stock fittings from the newer MC and the old fittings to the old PV. My bends aren't as pretty, but they work and the flares don't leak.

http://www.cardomain.com/ride/325707/15

I got my booster off Ebay for $5 and I think the shipping was pretty cheap as well.

I did the zj rear disc and zj MC/Booster swap to my 90 XJ. The brakes suck now. its probably 50% decreased. The lines were bleeded perfectly. My XJ doesnt have an abs but the zj which we took the MC and booster had an abs so do you guys think that the pressure is not enough because XJ doesnt have the abs pump zj has??

I think it has more to do with the proportioning valve. Did you swap in a ZJ prop valve or modify the stock drum valve?

standart prop valve stays there i guess but the brake gut put a shitty limitor at the back