Clutch issue/external slave cylinder conversion? -
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post #1 of 2 Old 10-10-2019, 02:27 PM Thread Starter
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Clutch issue/external slave cylinder conversion?

So I’ve had my 91 comanche eliminator with a ax-15 for a few months now, but have never been in freezing temperatures with it until now. 2 days ago I went to drive it after it dropped below zero and my clutch just went to the floor with no feeling, couldn’t put it into gear while running, but went through the gears fine with it off. Yesterday I checked the clutch fluid and discovered it looked like mud, so I drained the fluid and cleaned it out as best I could. Filled it back up and bleed it and it was fine, actually felt better than it did before. This morning it was about 14 degrees and it was fine, I drive over to school which is less than a mile. Came back out a few hours later and it went to the floor again. Should I try cleaning it out again or could it be the internal slave cylinder sticking? It’s never leaked clutch fluid before. If it is the internal slave cylinder I’ve heard of an external slave cylinder conversion but can’t find anything about it. Any help would be appreciated, thanks.

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post #2 of 2 Old 10-10-2019, 09:26 PM
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1987 MJ Comanche 
Join Date: Dec 2012
Location: New Market, MD
Posts: 511
If the master cylinder is still full and clean, I would suspect the master cylinder is going bad. If the MC is empty and no fluid is leaking from the bell housing, look inside the cab. Is the inside of the MC where the push rod goes into the MC wet? Feel the top of the fuse box. Is it wet? The MC is bad. (The fuse box needs to be cleaned or changed. Brake fluid and plastic do not go together well.)

If everything appears dry (bell housing and interior) the seals inside the MC may be bad. Fluid is getting past the push rod and not pushing the clutch. You can either rebuild the MC or swap it for a new one. (Try to avoid Chinese Replacement Auto Parts - C.R.A.P.)

As for converting to external slave cylinders, you will need a bell housing from a later model 4.0 XJ or YJ that had a manual trans - 94+. These have the proper bell housings. Also, be sure to get the BH internals: release bearing fork, fork retaining bolt (proper name?), the retaining spring for the bolt, and the trans front bearing cover. (It may be easier to find an AX15 from an appropriate year XJ (not YJ) and get the whole trans and BH internals.) [See note below.]

Additionally, when you swap to the external, you will need to change the pressure plate for the clutch system. (Ask me how I know.) The PP changed from the internal to external slaves.

Note: Depending on the year of the AX15, the input shaft tip changed diameter. The earlier ones (which you must have with the internal slave) is 1/2". Later model AX15s had/have an input shaft tip of 3/4". So, with the later model AX15, you will have to change the pilot bearing/bushing.

I swapped out a BA-10 on mine to a later model (98) AX15. No regrets!

Good luck with your trans.


87 Comanche, 4.0, AX15 (formerly BA10/5), D44
84 CJ7, 4.0 (93 XJ) AX15 (Formerly T5)
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