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Dual diaphragm Booster questions


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Ive read most of the threads through the years about dual diaphragm boosters, but I can't remember if it was ever covered about the brake lines hooking up to the new master cylinder. I'm wanting to do this with all new parts if I can. Looking through rockauto, it looks like its going to be much cheaper going with a 96 XJ style setup rather than the WJ style setup. I think i remember something about with the WJ ones that the threads on the existing lines in the truck are different than what the MC is threaded. Is this also true for the XJ one? Are the trucks existing lines even able to be moved enough to screw into the MC if the threads are the same? My booster is starting to go bad, so I'm hoping to do this fairly soon, though I do have a bit of time if I need to. Any help with these questions is greatly appreciated. Thanks

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You'll have to run new lines from the MC to the distribution block....  You can buy new compression fittings or if you're careful when you remove the old ones, you can reuse them.  I've done the XJ booster mod on my XJ and the WJ booster on my MJ.  Both required me to have longer lines coming from the MC.  I took a bunch of brake line from a ZJ with ABS.  I actually took the lines off the ABS control box thingy and just bent them how I needed them to run, reflared the ends and voila.

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Master cylinder has metric threads. Either one.

 

WJ requires a bit of firewall massaging and it doesn't require moving the washer bottle.

 

WJ has FLEXIBLE brake lines to deal with. They're great!!

 

WJ booster has slightly smaller mounting studs also. Makes it way easier to fit through the XJ firewall. 

 

You need to bend them a bit and put SAE fittings on where they go into the prop valve, just like a 95 to 96 would require.

 

Keep in mind if you get a new 95 to 96 assembly, it likely won't come with the aluminum 1/4" spacer.

 

I've done both types in a swap. I'll Take wJ hands-down over 95 to 96 any day.

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I picked up "bubble flared" lines at NAPA that were about 12" long. I cut one end off, cut my stock line in half and removed the fitting, put the fitting off my old brake line on the new line and then did a double flare to the end. I then bent them to fit on the distro block. It has been working great for 5 years now.

 

Pics can be seen in the Onyx build somewhere.

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I picked up "bubble flared" lines at NAPA that were about 12" long. I cut one end off, cut my stock line in half and removed the fitting, put the fitting off my old brake line on the new line and then did a double flare to the end. I then bent them to fit on the distro block. It has been working great for 5 years now.

 

Pics can be seen in the Onyx build somewhere.

Yes. This^^ for 95 to 96.

 

WJ: use the nuts from your old line at the prop valve end. 

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I think I have a flare tool set, was just wondering before if the newer XJ MC had the same fittings. Maybe I should reconsider a used WJ unit with the flex lines. Ill need to do a rear prop valve elimination at the same time just because. Should I get a different real prop  valve or just run it full power to the rear? I know the XJ units were problematic,

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I think I have a flare tool set, was just wondering before if the newer XJ MC had the same fittings. Maybe I should reconsider a used WJ unit with the flex lines. Ill need to do a rear prop valve elimination at the same time just because. Should I get a different real prop  valve or just run it full power to the rear? I know the XJ units were problematic,

95 to 96 XJ have the same master cylinder fittings as WJ. 

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If you don't have any brake lines right now, you need to pick up 2 of them.

 

Bubble flare metric ones that go into the master cylinder. You'll be using those after routing and cutting to length, and using a flaring tool to put SAE ends at the prop valve.

 

Are you asking if I have new lines or existing lines on the truck? I have the existing lines on the truck but I do not have any brand new lines bought

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If you don't have any brake lines right now, you need to pick up 2 of them.

 

Bubble flare metric ones that go into the master cylinder. You'll be using those after routing and cutting to length, and using a flaring tool to put SAE ends at the prop valve.

Are you asking if I have new lines or existing lines on the truck? I have the existing lines on the truck but I do not have any brand new lines bought

 

The fittings at the master are metric bubble flare. You will need to get some bulk lines that fit the master and then cut those brand new lines and put your old SAE fittings on the ends at the brake valve. They will need to be DOUBLE flared at that end. 

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You can pick up universal 3/16" bubble flared brake line in varying lengths at any chain parts house, pic below. I got a 30" length (Autozone IIRC). Cut it in half, slide your old master cylinder flare nuts on for the master end. Then bend the lines properly to the distribution block (not a prop valve on the MJ), slide your old flare nuts on, then double flare for the distro block end. My existing flare nuts were in good original shape. Use a regulation flare nut wrench when removing the old lines so the nuts can be reused. Easy - peasy.

 

 

91031800_L.jpg

 

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