I've seen so many people ask about this, I decided to post my overhaul, rather than answer the same questions over and over. Overhaul vs. swap is a whole other thread.
Part of the reason I bought my Wrangler was it came really cheep cause of the broken gearbox. Not broken per-say, the Jeep was drivable, but 1st and 2nd gears wouldnít always work and 5th was gone altogether.
The story from the previous owner was he was driving down the highway around 70, in 5th and all of a sudden there was no power to the wheels. He quickly got on the emergency lane and stopped. Since nothing appeared to be wrong with the engine, he decided to try and drive home. 1st seemed to work, so did the other gears except 5th. And with even a salvage gearbox (+ installing) would be around 1000 euro (2000+for a new one) the man decided to sell the car.
So basically I had a running 95 YJ with only 2 good gears. I decided I would go the long way around and try to overhaul the AX5, rather then put in a salvage one that might also be faulty. That and the fact that AX5s, much like any other Wrangler parts are really hard to come by in Europe. Hereís how I did it..
Taking the transmission off the Jeep
Support the gearbox
Support the engine
In order to take the tranny off, you need good access both from above and below. My carpet and insulation are long gone so I had plenty of space above once I removed the shifter knobs and boot. The knobs just unscrew. Mind the nuts below the knobs. You may have to loosen these with a wrench before you can undo the knobs. The shifter boot is held down with a bunch of screws.
Removing the shift stick
is a bit tricky. You have to pull up the smaller rubber boot that seals the stick to the gearbox case. Then push down on the flange around the stick. It will go down about an inch. Now twist clockwise while still pushing down. Everything should spring out and you should be able to easily pull the stick out of the gearbox.
Now you need to get under the Jeep.
Disconnect all wiring and hoses
from the gearbox, including oxygen sensor, flywheel position sensor and clutch slave cylinder. Be sure to tag/mark all the wires so you know which goes where when itís time to reinstall.
Secure the engine
by supporting the oil pan. The engine is supported by 2 side mounts and the tranny itself at the back. When you take out the transmission, the engine will want to roll and drop oilpan first. You can see I used a hydraulic jack with wood as protection for the pan. It held for the full month that the car was in the garage. But Iíd recommend a jack stand, theyíre safer.
Secure the gearbox
. I used a wooden cross beam held up on either side of the Jeep at the height of the gearbox. Also, a strong strap around the gearbox, up through the hole in the floor and secured to the rollbar. Just for safety, but I highly recommend it.
Disconnect the drive shafts
. The front drive shaft comes off by unbolting the ujoint straps at both ends. The rear drive shaft is connected with ujoint straps at the rear (the axle end). Once freed up from the axle, you can just pull it out of the transfer case. It should slip out easy.
Remove the bell housing bolts
. With the gearbox secured, you can now remove the bellhousing bolts. Try to mark which bolt goes where as these are not all the same and you donít want them mixed up.
Removing the bellypan
. This is difficult as it implies taking all the weight of the gearbox and tcase off the chassis and resting them on your supports (cross beam and strap) . AT LEAST 2 PEOPLE SHOULD ATTEND THIS TASK. Once everything is secured, your gearbox and tcase should be held up by the cross beam and the clutch shaft in the flywheel. At least one man should support the tcase while you unbolt the bellypan from the chassis. This is only to correct any stray movement that may occur. Remember, one man alone cannot possibly support the weight of the transmission!
exhaust manifold to pipe bolt
Removing the exhaust
. With everything disconnected and the bellypan out of the way, you can start removing the exhaust. As it curls around the bell housing, you cannot remove the gearbox until you take the exhaust off. Itís likely to be rusted so WD40 should be plenty available. It took me a week to get the exhaust off. Every day Iíd use WD40 on the 2 bolts that connect the exhaust manifold to the exhaust pipe. One of the nuts finally came loose but for the other one I had to grind off with a dremel. The space is tight and you cannot get large tools nor a grinder in there. Once the exhaust was free, I had to drill inside the bolt to take it out of the manifold. NOTE: thew they appear to be, these 2 bolts arenít threaded in the manifold, but rather wedged in. So with plenty of lube and a good size hammer, you should be able to push them out (by hammering from below).
With the exhaust out of the way, you can remove the gearbox
. At least two people should support the bellhousing-gearbox-tcase assembly while gently pulling it back about 2 inches, so as to slide the gearbox shaft out of the flywheel.
Taking the AX5 apart
Remove the bellhousing. Itís held up by a bunch of screws on the inside. They shouldnít be a problem.
Detach the t-chase from the gearbox. Try to hold everything level, cause as you take the two apart, oil will spill.
Drain the gearbox. Thereís the drain plug, but you can just turn it upside down and flush the oil out the shift stick hole.
Open the gearbox. This is where it gets bad. You need a large, clean, work bench, plenty of newspapers and rags, and a good set of tools. Iím not going to take you through each bolt cause that forever. If youíre uncomfortable opening your own gearbox, you may want to take it to a shop. I myself worked together with a friend that happens to be a professional mechanic. Haynes isnít much help either. They just provide you with a diagram of all the parts inside. So does Transpartsí overhaul kit.
inside the gearbox
broken gearbox case
ax5 5th and fork
synchro rings (worn and regular)
Things that can go wrong with your AX5:
No 5th gear
. This is the most common. You put it in 5th and nothing happens. It acts as neutral. This is because the c-clip holding the gear on its shaft snaps and the gear slides back, thus unable to engage. If this is your chase, you need a new clip. I had mine made from hi-grade steel to exact measurements. I talked to someone that found a match from a tractor. There are ways. I was unable to find a supplier that carried the ring. Good luck with this.
Will not go in gear.
It starts with 1st and works itís way up. Often enough i had to drive off in 3rd. This is because of worn out synchro rings. Replace them. They came with my Transparts overhaul kit.
Obviously not a transmission failure, replace your clutch. I got a clutch kit from Rugged Ridge for 250$. If you go through the ordeal of taking your transmission out, you will understand why changing the clutch at this time is so recommended.
We got rid of all the clinks and clucks by replacing the bearings that came with the overhaul kit.
Worn o-rings and paper gaskets. They come with the kit, thew we went ďgasket makerĒ instead of paper gaskets. I also found a large crack in the housing. This had to be welded at a shop as the chase is aluminum alloy. Apparently some guy thought banging a hummer on the gearbox would loosen the fill plug.
Putting everything back together.
It took me two moths to take everithing apart, overhaul the AX5 and get everything together for the refit, which took only a long Saturday. The clutch goes together easily. The bellhousing and t-chase have to be joint to the gearbox before mounting. The whole assembly had to be lifted in place with 2 hydraulic jacks. Itís all really just the opposite of disassembly. This is where all the tagging, marking and photos come in handy.
well, it cost me ~500$ in total. Thatís a lot less then a remanufactured or new one. The AX5 has 5 working gears now. Iíll admit everything seems a bit loose in there because there are a whole bunch of clips, bearings and seals that didnít come with the overhaul kit. Iíve been driving it for almost a year now, it holds out ok. I still take great care shifting and 1st and 2nd recently started acting up thew definitely not as bad as before. Iíll also admit Iím at a loss as to what to do in the long run. Taxes and costs here forbid a 4L swap and I honestly donít feel ďat easeĒ driving this AX5. Hopefully, JK