AX-15 Swap External Slave/Clutch Problem Please Help!

Hi All, I'm stumped and need help to get my MJ back on the road!

Ok, here is what I installed in my 88 MJ 4.0L:

-'95 XJ External Slave Bellhousing mated to a '90 AX-15 (same size input shaft and pilot bearing as the Ba-10), using a mopar '95 XJ one piece pre-bled plastic master/slave assembly.

-New Pilot bearing, New Clutch, New Throwout Bearing

I finally got everything buttoned up, but now she won't go into gear when running? The clutch pedal has good resistance (better than pre-swap). It grinds when I try to go to Reverse and it won't go into any forward gear.

With the truck off, I can shift through all the gears no problem.

I checked the slave pushrod and it is seated in the fork cup. I tried to turn the adjustment? nut on the opposite side of the bellhousing, but it just turned with the bolt...

Did you change the front bearing retainer as well? I don't see that mentioned anywhere...

Why is this important? Because the later front bearing retainer (for the external slave) has a sleeve upon which the T/O bearing rides. If you don't have that sleeve in place, the T/O bearing won't reliably disengage the clutch.

I understand what you did with the early transmission converted to the later bell setup (I'm planning on doing the same thing, for the same reason, to my 88. Unless I manage to score an NV3550 or NV4500 - and do the extra work to fit the 4500 if I get one.)

The catch is, the "internal" slave is a bellows arrangement, and is retained to the front bearing retainer by a speed nut shoved onto a roll pin in the FBR. The "external" slave works on a fork, which engages ears on the T/O bearing, which drag it away from the front of the transmission case.

If you don't have the proper front bearing retainer (I haven't verified this for a fact, but I'm highly inclined to think they'll swap...) the T/O bearing will not only end up pushing away from the front of the transmission case, but it will also slide sidewise away from the clutch slave cylinder - which will not only end up with it missing half of the diaphragm spring fingers, but will also reduce travel into the clutch diaphragm spring in the first place. Both will mean the clutch won't disengage when you step on the pedal.

Hi 5-90, Thank you for the reply! (and thanks again for the top notch Cables and Customer Support!)

I did not swap a throwout bearing retainer.... I did not see one when I pulled the external slave bellhousing at the junkyard. The input shaft was larger on the '95, but I didn't see anything except the fork and throwout bearing?

Your explanation seems to hit the nail on the head though!

Would you know the part number of this bearing retainer or where I can obtain this? Thank you!

1988MJ said:

Hi 5-90, Thank you for the reply! (and thanks again for the top notch Cables and Customer Support!)

I did not swap a throwout bearing retainer.... I did not see one when I pulled the external slave bellhousing at the junkyard. The input shaft was larger on the '95, but I didn't see anything except the fork and throwout bearing?

Your explanation seems to hit the nail on the head though!

Would you know the part number of this bearing retainer or where I can obtain this? Thank you!

Click to expand...

Yeesh - best place to get one would have been the donor transmission - just unscrew the one you have, and replace it with the "snout" one.

I was looking for conversion parts to make the AX-15i into an AX-15e (before I managed to just score an AX-15e...) and I think the front bearing retainer was something like $150-180 from an aftermarket outfit - I didn't even check OEM!

If you try to get it from a salvage yard, be ready to tapdance around why you want a single part from a transmission, or just take yours in to replace it when they're not looking. Junkyards don't like to break up assemblies...

The "snouted" front bearing retainer, to the relatively unitiated, can look like you've just got a huge input shaft. I take it the "input shaft" you saw was somewhere around 1-1/2" to 1-3/4" in diameter? That would have been the sleeve on the FBR where the T/O bearing rides.

Oh - and I've never lubricated the sleeve using grease. I've had good luck with heating the part to about 200*F in the oven for 10-15 minutes, and then spraying on a "dry film lube" like CLP - then putting it back in the oven for about five minutes. There are some "baked-on dry-film PTFE/MoS2" coatings hitting the gun market that I'd like to try on parts like this, but haven't had the opportunity to do so as yet. Why no grease? Clutch dust. CLP has been around for years - and before that, I'd heat it up and rub dry graphite into the surface of the sleeve (more or less the same net result.)

Thanks again for the great info :thumbup:

No yards around me have any Jeeps with AX-15s, just empty holes where they should be... :tears:

Best I could find OEM was $220 shipped for the FBR... More than I paid for the trans and t-case. Can you recall those aftermarket sources?

I've never torn one of these transmissions down. Should I replace the FBR seal behind it? Any tips or tricks to removing/replacing it? It looked like the FBR had RTV around the edges on mine.. Thanks again 5-90 :gee:

Change the seal? You're already there.

From what I've seen, there may be a paper gasket behind it as well - a thin layer of RTV on the mating surfaces (and probably on the screw threads) shouldn't go amiss.

NB: the AX-15 was also used in RWD Toyota (RWD Van, Pickup) and is also found in the Dodge Dakota behind the V6. The bellhousings will be different, but the FBR will likely be the same. I'd measure the ID of the T/O bearing, note it, and take a caliper with you. Measure the OD of the FBR - figure you'll need a good .010-.015" for operating clearance between the T/O ID and the FBR OD, and work with that. You can even take your AX-15i FBR with you to compare the screw patterns.

Yeah - AX-15i means "internal slave," and AX-15e means "external slave." I got tired of typing them out every damned time six months ago...

Most AX-15e variants are 1994 and up, so you can probably find them in the Toyota truck section or Dodge light truck section of your local salvage yard.

Ok, found an aftermarket supplier for these at manualtransmission.net (aka Man-Trans LLC). They had good used ones for $35 and new ones for $55. I had them next day air me a new one including new seal and rtv for $82. Should get here tomorrow.

Sure beats pulling a tranny at the jyard in this 90 degree heat!

I will post with the results. Thank you again for the great info 5-90. :wave1:

Problem solved! And the part fits the early model (1990) AX-15 no problem:





http://i632.photobucket.com/albums/uu47/m2kapp/IMG00132-20100527-1734.jpg

There are two issues here. First, those slaves are a PITA to bleed. You really need to take the thing off and point it down and bleed it. Second, from my experience some master cylinders will not push enough fluid to disengage the clutch completely. I have gotten two from NAPA on different rigs that didn't. I ended up lengthening the push rod on the Master cylinder about 1/2" and then it did the trick.

4.3LXJ said:

There are two issues here. First, those slaves are a PITA to bleed. You really need to take the thing off and point it down and bleed it. Second, from my experience some master cylinders will not push enough fluid to disengage the clutch completely. I have gotten two from NAPA on different rigs that didn't. I ended up lengthening the push rod on the Master cylinder about 1/2" and then it did the trick.

Click to expand...

Would this also cause a very stiff/tight pedal??? i have a new slave and the prior owner put a new master on my rig. and once i drive around for about 20mins it feels like im driving a stage 3 performance clutch. it's killing my knee to the point where I may have to sell it!!!! so any help would be great. and sorry to hyjack the thread.

I would say that is a problem with the clutch itself.

RE "stiff pedal" (appears original thread is complete, so I'll comment, RE: "hyjack" question!) If your clutch releases at a point significantly above the floorboards, I'd say the prior owner replaced the MC with one with a larger volume (bigger bore).
My experience is the XJ clutch release is basically on the floor (my '88, anyway).
A larger MC volume would raise the release point, and increase the pedal pressure.

xjbubba said:

RE "stiff pedal" (appears original thread is complete, so I'll comment, RE: "hyjack" question!) If your clutch releases at a point significantly above the floorboards, I'd say the prior owner replaced the MC with one with a larger volume (bigger bore).
My experience is the XJ clutch release is basically on the floor (my '88, anyway).
A larger MC volume would raise the release point, and increase the pedal pressure.

Click to expand...

Sorry about the hyjack, i just thought that it was a close/similar situation. yes mine doesn't engage till the top of the pedal, but it doesn't slip, which in the past has told me the clutch is gone, done, garbage. lol I did look at the perfection brand master cylinder that we sell at advance auto and its longer than the one on the truck now. also the one on the truck is made of plastic, perfection brand was metal. so maybe i need a clutch and a different master??

I replaced the master cylinder on the eliminator a couple weeks ago and the new one definitely has a shorter pushrod(about 1-2" below brake pedal level, whereas the old one was parallel). I've bled it real good and it just barely engages w/o grinding from a stop. I might have to add some linkage to it like you did 4.3LXJ. I will be swapping the ba10 out for the ax15i on my brother's 90 MJ when we put his stroker in(or should I bless myself with a pukegoat experience?). Good info on the front bearing retainer.

You need to know the bore and stroke of your MC, as compared to an OEM bore and stroke. Bore and stroke = volume. Less volume than the slave (normal OEM arrangement) results in longer pedal travel and less foot effort to disengage clutch. Push-rod length will determine where the pedal sets. Shorter push rod than OEM results in a pedal setting lower than OEM, resulting in shorter piston movement when pedal is on the floor. This would result in clutch not disengaging properly. The MC and slave cylinder need to be sized to accommodate pedal stroke, as designed by the manufacturer, and to insure full travel of the slave cylinder.
Buying OEM MC and slave insures that designed pedal pressure will be experienced with adequate slave cylinder extension to properly release the clutch.

When I had trouble with my NAPA parts, I did compare them and found them to be the same. There is just some design fluke there somewhere.