AX5 Transmission Rebuild

[Lowell]

I'm pushing 300,000 miles on my lil 1986 Jeep Cherokee and on my trip from Southern California to Northern California the transmission started to whine and I could smell over heating oil.  I stopped and put in 2 quarts of oil.  I guess it's time to replace the shaft seals.  This was 3 months ago.  In that time the whine has been getting louder so a couple weeks ago I put the Jeep up on blocks and removed the tranny.  What a job as all that other stuff has to come off first.  From a very good Youtube video from JeepsandStuff I removed both the cases and have the intermediate mounted in the big bench vise.  I found Allstate Gear by doing a google search and the assisted me in getting all the right gear sets and accessory kits to complete the job.  The input shaft gear and drive end gear of the cluster shaft has several broken teeth and you could see where other teeth were worn and cracking.

Today the rebuild parts arrived and tomorrow I'll start the tear down.  I'll post pictures as I do the rebuild.

In the picture the input shaft has already been taken off.  It had the most gear damage.

[Moses Ludel]

Nice!  Similar to the AX15 in many ways, the AX5 is the 4-cylinder transmission of choice for Jeep YJ and XJ vehicles from the '80s to the TJ Wrangler era.  You're confident and happy with the process, Lowell...Thanks for sharing the photos, our members and guests will appreciate your work and enthusiasm!

Moses

[Lowell]

With parts from Allstate Gears, my project is complete and ready to go back in the Jeep.  Word of advise, yes, from experience .... ha ha ha ... get a plastic mortar pan from Home Depot and bolt it and your vise to the middle of the bench.  The rebuild works best holding the intermediate plate in the vise.  BUT ... when  you take out the shifting rods there's a lot of little lock balls and pins that are going to drop out.  Even though I used a magnet to with draw them I still miss the two tiny pins that ride inside the rods.  They both dropped into my saw dust shop floor.  My friend spent over an hour with a magnet but found them.  The 5th gear thrust washer also has a lock ball, yes, that fell into the saw dust.  That I got from McMaster Carr.  They carry all grades of balls.  This one was 6.5mm, so now I have 49 extra.  Anyone need one ... or two????  Oh, by the way, you're going to need a hydraulic press and a bearing splitter to do the job properly.

All in all it was a great project and I learned a lot.  Now, when I'm driving and shifting I can imagine what's going on beneath the shifter knob.  Would I do it again???  In a  heart beat.

[Moses Ludel]

Very informative and helpful to others with the AX5, Lowell, thanks...The mortar pan is brilliant, something to remember.  So you drilled holes in the bottom of the pan and placed the vise in the center, bolted down through the pan?

I get "bearing grade" chrome steel ball bearings in loose assortments from MSC Direct, same as your McMaster-Carr.  Be sure to use bearing Grade 25 as a minimum tolerance.  (Other grades are available, choose according to manufacturers' recommendations.)  Watch the tolerances and hardness when selecting products.  Here are examples, they are available in metric and U.S. sizes:

https://www.mscdirect.com/browse/tn/Raw-Materials/Steel-Balls?searchterm=chrome+balls&navid=4287922280

Here is a chart that should be useful for understanding tolerances:  http://bearingballstore.com/index.php?main_page=page&id=5

Moses

[alheim]

Lowell, was this your first time rebuilding a manual transmission?  I am curious how long it took you.

Looks like a fun job, thanks for sharing.

[Lowell]

Alheim ... The whole process took 4 week, but much of that time was waiting for parts.  I removed the tranny, ordered parts and waited 5 day, broke 5th gear with the wrong puller, waited 5 days.  Actual work time: removal 1 day, tear down 1 day, re-build 2 days, re-install 2 days.

Several months ago I had picked up a Harbor Freight motorcycle lift.  It was great especially for lifting and lining up the tranny when going back in.  The last time I had the tranny out replacing a broken clutch fork I muscled it in and out on my chest.  Yikes, no thank you.  If the input shaft spline and guide pin are not perfectly centered it is not going in.  When it is lined up it slides in like a hot buttered knife.

Now, only one problem, and it's the only gear I don't remember bench checking.  I don't have 5th gear.  When hand turning on the bench the new syncros were very "grabby" and it took some effort to break them loose and spin the input shaft by hand.  I was hoping that was the problem with 5th gear, but I don't think so.  Monday I'll take off the shifter plate and see what I can see with a light.  I'm wondering if I have the slider in backward.  I've tried putting it in 5th gear and starting, from stopped with the clutch in .... no dice.  She grinds.  It feels like it goes in when the clutch is depressed but then pops out and grinds.  ...  Not looking forward to taking it out again.  Been thinking about maybe just taking off the rear housing with the tranny in place.  What do you think, Moses?

I also made a modification to the external clutch slave piston.  The original has seal with a hole through the center.  This seal fails every few years.  I've been pouring in fluid ever couple months.  I cut the plunger in half removing the section where the seal sits.  I filed and polished the ends.  Then got a standard 3/4" (I think) brake cup (no hole) and put the spring end of the plunger in the cup of the brake cup and carefully slide it into the cylinder.  Then re-assembled the other half of the plunger and retainer clip.  I had also cut the tubing in half on the horizontal section on the other side of the tranny.  Sure makes it easier to get in and out.  Using the bleed screw and hand pushing the plunger you can suck fluid into the cylinder, pre-charging it before installation.

 

[alheim]

Ah, you must be frustrated with your 5th gear problem, but such is the life of a mechanic.  On the upside, removal & re-installation gets easier every time.  Good luck.