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Replacing & Availability - '92 Manual 5-speed


NAXJA Forum User
Hi, my old 1992 XJ (4.0, 4-wheel drive) is still my daily driver at 260k. The manual 5-speed has been stubborn to get into reverse since I can remember and has deteriorated to the point that getting into 1st or reverse from a stop is most times a jam & grind deal depending on it's mood.

I assume it's the synchros from my 24-years of grinding into reverse. Aside from buying a used car/SUV for $30k I'm looking to replace the transmission. I did my last clutch replacement myself (with a little help) and might try the trans myself also or have a shop do it.

I did a quick search and I saw a rebuilt on Ebay for $1200 delivered (as I remember but could be wrong).

I live in central California (on the coast) & have a utility trailer so I can go pick one up if I can find it or get it delivered. But is this even a good idea? LOL.

Is there a specific model that I need to look for? Should I just get one that was pulled or look for a rebuilt or get mine rebuilt?

There is no synchro ring on the reverse gear on the AX5/AX15. Briefly shifting into a forward gear before shifting into reverse really helps avoid the grinding as it stops the intermediate shaft from spinning.

Using the right oil makes a big difference too. I recommend Redline MT-90 or plain old Mobil-1 10W30. The dealer is filling them with 10W30 nowadays. Not GL rated gear oil, as the EP additives are sulfur based which will eat the brass synchros over time. The additives also make the oil too slippery for the synchros to work right - they need some friction to work.
My AX-15 was rebuilt before it came to me, I run Redline MT-90, and it is still a pain to get into reverse at times.

As lawsoncl said, a shift into a forward gear helps with the grinding. I shift into 1st after coming to a stop.

When it wants to be a PITA, I will also briefly tap 4th gear. That seems to help convince it to go into reverse.
It's worth changing the oil with 10W30 just to see if that helps. If the oil coming out is glittery, then you probably need to do a rebuild and replace the synchros.

It's been a really long time since I rebuilt my AX-15. The hardest part I recall was having to modify my gear puller to get a few gears off, as I didn't have a press at the time. It you decide to rebuilt it, pay attention to what's included in the kits. Some of them don't include the big main input bearing.
The problem isn't just reverse any more, if I try to get into any gear at a stop it grinds. It's been like this for a long time, progressively getting worse.

To get into first from a stop is pretty stressful if I'm in traffic. It's not all the time. It seems to shift fine for a little bit in the morning then shortly gets worse. When it's acting up to get to fist I'll bump into 3rd, 4th or second and that seems to get something spinning then I can jam it into first.

At a stop it wont go into any gear without grinding. When I say "bump into 2nd" I mean a grinding bump. So from a stop I'll grind 2nd, then 3rd then drop into 1st with a forced clump.

The last time I did my clutch I put in MT-90 and it really cleared things up for a while then it went back to grinding again.

It's funny it seem like it's better in the morning then decides it's going to grind after noon. IDK I think that it's possessed by a very angry Native American warrior's spirit.

Please help me finally bring some peace to this poor tortured spirit.

How difficult is it to do a transmission rebuild. I can probably rent the gear pullers from O'Reilly's auto parts.

That sounds more like a clutch issue!
Did you surface the flywheel?

Rumor has it you are not supposed to surface the flywheel, or if you do then you need to shim it. I have not been down that road yet, but it might be worth looking into. It would be a bummer to rebuild the tranny only to find you hadn't resolved the problem.
I've resurfaced 1000's of flywheels and the only caveat is you have to remove equal amounts from the clutch surface AND the pressure plate surface.

Meanwhile, if you come to stop the transmission output shaft stops turning and when you push in the clutch the input shaft is supposed to stop turning. If the gears are grinding it means to input shaft is still turning which means the clutch isn't dis-engaging!
Meanwhile, if you come to stop the transmission output shaft stops turning and when you push in the clutch the input shaft is supposed to stop turning. If the gears are grinding it means to input shaft is still turning which means the clutch isn't dis-engaging!

This makes sense. Maybe I messed up my last clutch replacement.

Anyways, I've been reading and watching clutch theory videos all morning and I went through a thread that I started in March 2022 on this issue and Cruiser54 replied that I should get on a hill @ 20mph and burn the clutch in 4th until I can smell it. And that seemed to work.

I think that I'll try that again tomorrow when I'm out.



Thanks again.

I would also check the throw-out bearing to pressure plate gap along with inspecting/greasing the pivot arm/pivot. I don't know if the pivot can be adjusted or shimmed.
Take time to inspect the pivot arm itself. I have heard of clutch forks cracking on GM F-bodies. I expect it could happen to just about any make. Any extra flex in the system could cause your problem.
I don't know why I didn't think of this before (CRS?), but check the clutch pedal itself. XJs have a weakness in the pedal design. The pivot is attached to a bracket on the pedal and that bracket can come loose because it is not particularly well supported.

This thread illustrates the issue: https://www.naxja.org/forum/showthread.php?t=1144027
Another thing to consider is whether the pilot bearing may be gummed up or defective. A defective or damaged pilot bearing can give symptoms nearly identical to a dragging clutch and one of the two sounds like a 100% match to your symptoms.

If it is not that here is a rough list of what you will need for a full rebuild.
rebuild kit (this spring I was told they are around $380 but that may have changed up or down since then)
fluid (GL3 or yellow metal safe GL5, or full syn 10w30)
red RTV
regular tools
shop press (you can kind of get away without this if you're clever and have a stack of stuff to use as long drivers, and also don't mind putting transmission parts in your freezer and kitchen oven)
autozone steering wheel and gear puller set with the pile of bolts and the kind of chickenfoot shaped forging (great for pulling 5th gear synchro hub)
a certain size of torx bit for a few of the detent ball cover setscrews, can't recall what size
10mm allen bit
whatever huge size hex fits the two shifter return spring assemblies
10mm, 12mm(?), 14mm 6 point sockets
lockring pliers
I use a 5 gallon pail full of gasoline for dissolving the really nasty heavy grease and gunk buildup and then a few harbor freight wire brushes to scrub stuff off.
quart of acetone and a chemical sprayer bottle from home depot to post-wash cleaned parts so that the gasoline won't screw up any RTV you try and use on it
deadblow mallet
some axle grease to stick bearings in place while assembling things that hold them in
blue loctite
razor scraper and a few new blades
seal puller/ripper

it has been a few years now but I think that's all the really specific stuff. Most of the rest is just general tools. It is certainly much easier if you have a shop press but I did without. The only thing I remotely needed a press for IIRC was the input bearing which I solved by placing the bearing in the kitchen oven at 170F preheat while the input shaft sat in the freezer, once they were both at a stable temperature I simply slid them together. Getting the old bearing off was actually harder, I can't recall exactly how I did it.

There are a few parts that need to be put on carefully.
- make sure you note where each lock ring came off. They are ground to thickness for a select-fit and you can't break them or you'll need to buy new.
- the fourth gear (usually, but not always) synchro ring feels identical to the other two (3rd, 4th, 5th are dimensionally almost identical, two actually are identical) but if you look closely the dog teeth on it are tipped at a different angle from the other two synchros. This is to improve either upshifts or downshifts to/from that gear and I can't recall which. Inspect the matching synchro collar and the synchros as you take it apart and remember where it goes and which way the collar faces, the "different" synchro collar teeth need to face the "different" synchro ring.
- speaking of this, the 5th gear synchro collar is only machined with dog teeth on one side because it only engages one synchro, so make sure you put it on facing the synchro because it will NOT shift well if you put it on facing the wrong way, which is totally possible.
- there is a ball bearing and a conical spacer between the countershaft midplate bearing and the 5th gear synchro hub that keeps them far enough apart but without interfering with the midplate bearing (thus why it's conical.) Make sure you catch the ball bearing when you take it apart and reinstall it on the way back together, make sure the conical spacer faces the same way it did when you took it apart too.
- it's easy to mung up the threaded holes in the shift rails trying to get the little bolts back in that hold the forks and stuff on. Make sure you get the bolts going perfectly straight before screwing them in. Use blue loctite on these, too.
- the 10mm allen plug in the tailhousing that covers the shifter slide rod end is easily removed... the shifter slide rod less so. Use needlenose pliers with duct tape or rubber hose over the tips so you don't mar the shaft, it gets slid out the back of the tailhousing through the hole after removing the 10mm allen.
- when you remove the shift rail detent spring+ball retention setscrews the springs WILL want to go SPROING into the dust under your bench so just be ready for em. They're not super enthusiastic about it or anything just don't be caught by surprise. There's a ball bearing under each and you need those too.

As long as you have a backup vehicle to go get things you forgot (I'm sure this list isn't complete) you will be fine, it's a very simple transmission really. If you weren't 1000 miles away I'd say toss it in the trunk and swing on by, they're a great intro to manual transmission rebuilding but it definitely wouldn't hurt to have an experienced person nearby to help if you get yourself in a bind.
My ax5 would do this when the clutch hydraulics were failing. Check the inside of the firewall at the master cylinder for brake fluid running down the wall. (And possibly into your fuse box if it is old enough...lol)