Hey fellas,

The booster on my '87 Wagoneer XJ just failed so I'm finally going to commit to doing the WJ dual diaphragm booster/master cylinder upgrade. With that in mind, I have purchased a used 2002 WJ booster/master on eBay ($41/shipped free!!) and am now just trying to collect some information for the brake line conversion. I've looked and looked and damnit, I can't find the information anywhere, but I'm trying to determine the brake fitting size that goes into (male side) of the WJ master cylinder - I know it's bubble flared.

Also, I can't find the size of the (male side) fitting that goes into the original master cylinder. I think it's 5/16'' maybe? I saw a reference to it one place and now I can't find it again. What is the pitch of that? Anyone happen to know?

Reason I'm asking is because rather than cutting the lines and reflaring them to bubble flares, I'm considering sourcing adapters. That way if I want to go back to an OEM look master cylinder (if I can find an all metal one rather than the ratty looking plastic one) then I can.

Thanks gents!

-Matt

 

Actually, I might have just found part of my answer.

2002 WJ Master Cylinder on RockAuto:

https://www.rockauto.com/en/moreinfo...386783&jsn=410

2 ports; 1 is M12x1.0 and 1 is M10x1.0 so there is half my answer...

1987 XJ Master Cylinder on RockAuto:

https://www.rockauto.com/en/moreinfo...184587&jsn=501

2 ports; only primary size listed, but they look like they are the same - 7/16''x24

Does this sound right gents?

 

Here's my take: With stuff as important as brakes, I try to make every effort to avoid needless connections/potential failure points such as adapters. An easy way to get it done is to use the lines from a WJ booster to the proportioning valve, bend them to fit into the XJ proportioning valve, and flare them on the prop. valve end to your home-n-garden 3/16" line double flare. I found it pretty easy to bend the lines to fit into the XJ prop. valve, just need to be careful.

This way you avoid having to bubble flare and avoid sourcing imperial to metric adapters.

 

Thanks Evsta,

I think you're right. The whole reason I'm doing this in the first place is to *improve* the safety and braking effectiveness.

So since I can't get the lines from a WJ (bought the parts on eBay), I think I'll just grab the appropriate length new line from Advance (that Poly-Armour stuff is good and not too expensive) with some of the right fittings. on the bubble flared side and "rent" a double flaring tool from them.

As you say, the fewer connections the better!

Thanks,

-Matt

PS, for future searchers:

 

EvstaG is correct. That's exactly how I modified mine on my xj. Great upgrade, by the way.

 

This is exactly why I advocate getting the brake lines that are attached to the WJ master cylinder while at the junkyard......

 

Yeah, I definitely would have had I pulled it myself, but the pick-n-pulls around here were wanting darn near as much as buying reman'ed ones would have cost.

I ended up buying poly-armour lines with bubble flares at each end and also picked up some correct line nut fittings. I also rented the double flaring tool from Advance Auto and got a tubing bender from Harbor Freight.