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99 Clutch Master Cylinder into 87 MJ

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I'm converting my 87 MJ 2wd to 4wd. The trans, clutch,and MC assy came out of a 99 XJ. Here was my problem and how I solved it.


This is a pic of where the 87 MC mounted.



And this is a pic of the configuration of how the 99 MC would mount.



The problem is that the 87 mounts at the 12 and 6 O'clock position, and the 99 mounts at the 5 and 11 O'clock position.

Another problem is the bolt mounting centers are also different.

I thought about just drilling holes at the 5 and 11 as shown by the Xs, and I also trimmed the index on the mount thinking that if I rotated the mount I might be able to gain a more favorable mounting position.

I eventually left it in the stock location at the 5 and 11 position.

To gain more room, I rerouted the hood release cable threw the grommet to the upper right in this view.



Then I cut a 4"x4" piece of 3/16 steel. Cut a 1 1/2" hole in the center, welded 2-3/8" bolts to the backside, on the stock mounting centers.





Then I Cut the 99 mount into a round shape, welded it onto my new mounting plate.





Hows this for my first weld project with my new HF welder? Better than some guys can't do.... :yes:

Although it still looks like DOO-DOO.


The reason that I didn't just drill holes at the 5 and 11 positions is this, first there might have been clearance issues on the backside and second and most important part is that if I did this then structurally I would be putting the force/stress of using the clutch on the sheetmetal of the firewall alone. The force needs to be on this bracket.

If I was to do anything different I would have taken the time to remove this bracket/brace from the backside of the firewall,before I did any fabricating. There is only one bolt holding it on when the MC is removed.


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I would have removed this bracket for 2 reasons. One, the stud on the bottom has to be removed (I tried to remove it the hard way, cutting drilling it from the engine side) Do yourself a favor and take it off from the backside of the firewall, way easier! And second it can be used as a jig in setting up your mounting bracket to insure you have the correct bolt centers.





Well all that is left is to take finished pictures of the install, but first I have to get a plug for where the hood release cable originally ran. Then I can put a bead of sealant behind it and bolt it up!

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  • 3 weeks later...

I would have, but the JY that I bought the AX-15 from is halfway across the state and Montana is a big state. I bought the trans and accessories sight unseen (delivered by truck) from info I got from the Car-Part.com web site. The JY told me the parts were off of a 99 Cherokee (and according to the bill of lading), Then I never got around to installing these parts till lately. Also since, the MC had a different configuration, I assumed.... it was because of the different years. Last of all, I didnt have any idea that I had a TJ MC, as I had no reason to think or research for otherwise. Oh Well.....Done deal now.

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That wouldn't have been structurally correct, as the support for the MC comes from the mounting bracket behind the firewall.If I would have drilled where the X's were the support for the MC would have relied solely on the firewall sheet metal, not really a very good idea.

You can see in my pics what I am talking about.

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