Topic: AX5 Issues

[VA_YJ]

Lost 5th gear in the AX5.  Pulled everything apart to fix leaking oil pan gasket and rear main seal (done) while I had the TC and tranny off.  When I opened the front half of the tranny case to reseal, I found some gear chunks in the case.  Three teeth on the main drive gear (the one made onto input shaft) are damaged.  It was working OK, but I figured that I'd fix while it's all torn down before something else bad happens.

I need a new input shaft 83506020 and bearing 83502681.  I can get a new Mopar OEM shaft/bearing for $362 (ebay) or a Crown set (Morris) for $200.  Omix-ada makes the parts  also.  I am taking a risk with the Crown parts?  I usually buy Mopar seals as I've had a few issues with the aftermarket stuff.  Or maybe someone a good input shaft in their junk drawer...

[VA_YJ]

Correction: The Mopar parts are $462.

[neale_rs]

Fairly recently bought a TJ AX5 in good working condition (just to have as a spare) for $150. 

Might want to just buy one and save some money.

[VA_YJ]

Good idea, I've been looking on local Craiglist as well.  The broken teeth are not next to each other, although two are separated by only one good tooth.  I could just run it till it breaks and then put in a used one later.

[Jeffy]

Yup, buy a used/salvaged AX-5.  They go for pennies on the dollar.  They used to go for less the $350.

[VA_YJ]

I think I'm going to put it back in and run it 'til it blows up.  Meanwhile I can look for a used replacement (they're hard to find around here).  I guess the torque from my 2.5 is too much for the AX5   

[Jeffy]

Well, 5th usually breaks because of improper shifting technique.    The clip could have fallen into the other gears and ate them up.

I know Crown and Omnx-Ada both bought up a lot of Jeeps parts stock when they were dumping them.  I don't think there's any difference in parts from either source.

[dwtaylorpdx]

You can also lose 5th when the main bearing fails from bad lubrication when the wrong lube is used...
Towing in 5th is also bad mojo with the AX5.

They are in a lot of Dakota 4 cyl & cherokee, does not have to be from a YJ.. THe Toyotas also came equipped with a Japanese sourced version that shares 90% of the parts, but with bigger bearings..

Cheers
Dave

[VA_YJ]

Dave, thanks for defending my shifting with your comments, but I think Jeffy is on to something (like he knows anything about Jeeps...).  The gears are cut at an angle, and when you have a mismatch between the engine (flywheel) speed and the clutch speed, it forces the input shaft forward and the output shaft backward.  This is causes the fifth gear to slam into the snap ring on the output shaft and the teeth on the input shaft gear to slam into the bearing at the front of the case.  Which explains what I saw during the AX5 autopsy. Mix in a little wear on the bearings and you get enough slop to get excessive motion. I confess that I have peformed a hard downshift or two that likely contributed to the problem.  Reminder to self - Jeeps are not sports cars.

I am running MT-90 and do not tow any trailers or let fat girls ride in the back seat.  The clip (snap ring) fell into the back half of the case, so I am pretty confident that the frags played no role in the damage on the input shaft.  Thanks!

[dwtaylorpdx]

For me its been broken synchros and bearing failure,, last rebuild I finally found a guy who really knows the jeep transmissions, one of the major changes he made in the rebuild was to remove all the bearing shrouds, I run 20W50 motor oil in it now,, and knock on wood it has 100K on it since the rebuild,,, The prior 3 times it lasted 30K... Yes there may be some less than kind shifting involved... But the first time around the main bore of the tranny was out of line by .1 inches.. That one wasn't me.... LOL Next time I was running a standard gear oil and it turns out the Syncros don't like that heavy stuff nor do the needle bearings in the cluster gears. (Re-builder showed me the galling on the bearing and surfaces had to replace the input shaft... ) He also switched from a caged needle in each cluster to packed needles..

Cheers..

Dave