WJ brakes on MJ

[zomeizter]

So my 'manche is in need of an MC replacement but I want to upgrade to the WJ MC and booster. I want to procure all new parts and avoid the JY items but I have no idea what year WJ parts to order, if someone can share this info it would be greatly appreciated. Also, I'd like to retain the rear height compensating system if possible, or must I eliminate it with the upgrade? Thanks.

[cruiser54]

99 to 2004.

[Green Mesa XJ]

For the booster upgrade you'll need the master cylinder and booster from any WJ 99-04, getting them pulled together gets gets you the bolts and spacers if they are there. If they pull it for you ask to get all the bolts, understandably the guy pulling the parts don't care about saving bolts .

IMO the harder parts are making the new brake lines but that's partly because I suck at it.

 

 

Here's a video in converting a 1989 XJ

 

Here is somebody that did the 95/96 XJ booster upgrade (which might be slightly easier,)

 

http://comancheclub.com/topic/39437-1996-xj-dual-diaphragm-brake-booster-conversion/

 

 

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[cruiser54]

For the booster upgrade you'll need the master cylinder and booster from any WJ 99-04, getting them pulled together gets gets you the bolts and spacers if they are there. If they pull it for you ask to get all the bolts, understandably the guy pulling the parts don't care about saving bolts .

IMO the harder parts are making the new brake lines but that's partly because I suck at it.

 

 

Here's a video in converting a 1989 XJ

 

Here is somebody that did the 95/96 XJ booster upgrade (which might be slightly easier,)

 

http://comancheclub.com/topic/39437-1996-xj-dual-diaphragm-brake-booster-conversion/

 

 

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I've done both. WJ is easier.

 

Get the lines coming off the master also. 

[Green Mesa XJ]

Yes, ask them to disconnect not cut the lines.

I've got a WJ booster and lines to convert one of my jeeps (whichever needs it first) , the WJ has a flexible line, but I think it needs the flare fitting swapped. Last time I made brake lines it sucked so I haven't been in a rush to tackle this job.

 

Cruiser54 did you have to bend the lip on the firewall? Some say they didn't have to and some say they did, I know bending that lip out would bug me .

 

 

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[cruiser54]

I cut the firewall. Easy.

 

It's okay if they cut the lines close to the proportioning valve because you're gonna be changing the ends anyway.

 

[Eagle]

 Also, I'd like to retain the rear height compensating system if possible, or must I eliminate it with the upgrade? Thanks.

 

The only way to retain the height sensing valve is to retain the original MJ front distribution block. The front distribution block has to have two outlets, one for the primary rear brake circuit and one for the bypass circuit. The XJ/ZJ/WJ proportioning valves don't have a secondary outlet.

 

You could eliminate the bypass circuit, and just run the one line to the height sensing valve. That will work fine as long as you don't have a problem with the front brakes. If you lose the front circuit, though, instead of getting full power to the rear brakes you'll only get as much (or as little) as the height sensing valve is allowing. If the bed isn't loaded, that's probably not very much.

[HOrnbrod]

Yes, ask them to disconnect not cut the lines.

I've got a WJ booster and lines to convert one of my jeeps (whichever needs it first) , the WJ has a flexible line, but I think it needs the flare fitting swapped. Last time I made brake lines it sucked so I haven't been in a rush to tackle this job.

 

Cruiser54 did you have to bend the lip on the firewall? Some say they didn't have to and some say they did, I know bending that lip out would bug me .

 

 

Me too. Makes it look like a kludge.

[cruiser54]

 

Yes, ask them to disconnect not cut the lines.

I've got a WJ booster and lines to convert one of my jeeps (whichever needs it first) , the WJ has a flexible line, but I think it needs the flare fitting swapped. Last time I made brake lines it sucked so I haven't been in a rush to tackle this job.

 

Cruiser54 did you have to bend the lip on the firewall? Some say they didn't have to and some say they did, I know bending that lip out would bug me .

 

 

Me too. Makes it look like a kludge.

 

Whatever.

 

My Comanches stop way better than you can imagine. 

[Minuit]

I don't doubt that the WJ is the better option if you're willing to modify the firewall, but I'd never be able to live with myself if I did that on my truck.

 

I've had a 96 XJ booster sitting in my garage for almost 3 years now. Shows you how fast I move  :dunce:

[HOrnbrod]

Take the time to fab a spacer and do it right.

 

[cruiser54]

I don't doubt that the WJ is the better option if you're willing to modify the firewall, but I'd never be able to live with myself if I did that on my truck.

 

I've had a 96 XJ booster sitting in my garage for almost 3 years now. Shows you how fast I move  :dunce:

The ones I did it on were not beauty queens. I did the 95 to 96 set up on my white one.

 

I

[cruiser54]

Take the time to fab a spacer and do it right.

 

 

Yeah. Pedal will be a bit lower is all.

[HOrnbrod]

So what? As long as it's not detrimental to braking performance, and it isn't, no problemo. Better than hacking up a firewall.  :thumbsup:

[zomeizter]

Thank you all for the great info, I forgot to mention I'm swapping in an Explorer 8.8 with discs, I reckon I shall grab a WJ proportioning valve as well? What do y'all think?

[Rockfrog]

I tried to make my WJ booster fit (2000), in the end I wound up using the 98 ZJ booster and master instead. Fit better. The WJ booster I had would have also required some bending of the lip below (sides) upper firewall lip.

I installed the WJ with and without the spacer and felt it was not a good fit, much shorter than the ZJ unit though.

Fit the ZJ unit in without the spacer and pedal height was fine, lengths of booster rod matched up as well.

Oddly my ZJ booster looks similar to the WJ boosters pictured. My actual WJ booster does not though. Odd, pulled them both myself.

Either way I had to replace my stock booster, the diaphragm was leaking or something (huge audible vacuum leak until I pressed the pedal).

 

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[cruiser54]

I tried to make my WJ booster fit (2000), in the end I wound up using the 98 ZJ booster and master instead. Fit better. The WJ booster I had would have also required some bending of the lip below (sides) upper firewall lip.

I installed the WJ with and without the spacer and felt it was not a good fit, much shorter than the ZJ unit though.

Fit the ZJ unit in without the spacer and pedal height was fine, lengths of booster rod matched up as well.

Oddly my ZJ booster looks similar to the WJ boosters pictured. My actual WJ booster does not though. Odd, pulled them both myself.

Either way I had to replace my stock booster, the diaphragm was leaking or something (huge audible vacuum leak until I pressed the pedal).

 

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I understood ZJ boosters didn't work.

[Rockfrog]

That's what had me boggled as well.

 

 

But, there it is pedal height is the same as with the WJ booster. About 3/16" shy of the clutch.

[Green Mesa XJ]

Thank you all for the great info, I forgot to mention I'm swapping in an Explorer 8.8 with discs, I reckon I shall grab a WJ proportioning valve as well? What do y'all think?

I've done the 8.8 swap on my 85 XJ, I used the original proportioning valve, just removed a o-ring from it, since then people seem to say leave the o-ring alone and it works fine. Not sure what the wisdom on this is now, I did my swap in 2004.

 

If your trying to keep some of the original MJ features (load sensing, leveling?) I'd leave the original proportioning valve as it is. But I'm no expert on it.

 

 

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[Green Mesa XJ]

That's what had me boggled as well.

 

 

But, there it is pedal height is the same as with the WJ booster. About 3/16" shy of the clutch.

I zoomed into see the part number, looks like 52008648(6?)

 

52008647 is the omix-ada 84-96 XJ/MJ booster and master kit, which looks essentially like the 95-96 XJ booster.

 

Your booster looks almost exactly like the Omix booster.

 

52008646(?) comes back to 1995 ZJ and a 1996, I'm wondering is the 95-96 (maybe 97-98 too) ZJ are essentially like the xj booster.

The 93-94 ZJ booster definitely look like the wrong one for the xj.

 

If the ZJ 95-98 are a source it could be easier to find than the 95-96 XJ.

 

 

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[zomeizter]

 

Thank you all for the great info, I forgot to mention I'm swapping in an Explorer 8.8 with discs, I reckon I shall grab a WJ proportioning valve as well? What do y'all think?

I've done the 8.8 swap on my 85 XJ, I used the original proportioning valve, just removed a o-ring from it, since then people seem to say leave the o-ring alone and it works fine. Not sure what the wisdom on this is now, I did my swap in 2004.

 

If your trying to keep some of the original MJ features (load sensing, leveling?) I'd leave the original proportioning valve as it is. But I'm no expert on it.

 

 

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Yes, my goal is to maintain as much MJ features as possible...

[zomeizter]

 

 

Thank you all for the great info, I forgot to mention I'm swapping in an Explorer 8.8 with discs, I reckon I shall grab a WJ proportioning valve as well? What do y'all think?

I've done the 8.8 swap on my 85 XJ, I used the original proportioning valve, just removed a o-ring from it, since then people seem to say leave the o-ring alone and it works fine. Not sure what the wisdom on this is now, I did my swap in 2004.

 

If your trying to keep some of the original MJ features (load sensing, leveling?) I'd leave the original proportioning valve as it is. But I'm no expert on it.

 

 

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Yes, my goal is to maintain as much MJ features as possible...

 

What O-ring do you speak of?

[Green Mesa XJ]

Inside the portioning valve there's a o-ring I believe to restrict/control the brake fluid pressure to the rear drums. When I did this swap converting to rear discs the common knowledge advice was to remove the o-ring. When I read up on the swap recently that was no longer the advice,. People say leave it alone and some claim the part numbers are the same even for the ZJ with rear disc. Plenty of folks a running rear disc with no changer to the proportioning valve so I'd say leave it be unless you have a problem.

 

Here is a link talking about it, remember is old advice now, I'd probably leave it alone, more likely to break it than have it go right.

 

 

 

http://www.lunghd.com/Tech_Articles/Suspension_Steering_Axles_and_Brakes/Proportioning_Valve_Mod.htm

 

 

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[zomeizter]

Roger that.

[Green Mesa XJ]

Ok here is the answer to a question probably nobody was asking.

The 95-98 ZJ booster looks very close if not identical to the 95-96 XJ. Maybe the XJ brake actuation rod is slightly longer, didn't have time measure because a thunder storm came up.

Also don't know why the brake masters are a bit random. The 95 XJ and WJ look the same and the 97 looks likes another WJ brake master I have in the parts box.

 

Spent just under $60 for used 95 ZJ brake booster and 95 XJ booster and master.

 

 

These pictures are of the 97 XJ brake booster and 2002 WJ booster

 

This is the back of the boosters

Far right with no brake master is the 95 ZJ, next to it is the 95 XJ booster &master, next is the 97 XJ booster & brake master, at the end is the WJ booster & Master.

 

 

 

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