AX15 shifts kindof rough

I just put in an AX15 to replace my BA/10, and shifting feels kind of rough. Actually, shfiting feels incredibly similiar to my old Peugeot.

What happens is when you're taking off in first, and shift into second, you can feel the gears mesh through the shifter. Almost like it's grinding, but there is no noise whatsoever. It's just the feel, it's not smooth like it should be. It doesn't hang up before it goes into the gate like when you try shifting without pushing on the clutch pedal, it shifts like butter but you can feel the gears mash when it does go in.

It's extremely annoying and ruins the fun of shifting for me; now the thing is, it did the exact same thing with the old peugeot. The Puegeot only had 70,000 KMs whereas the AX15 might have 350,000. (It was at a junkyard, and I don't know the history). I looked through the shifter tunnel and I saw a brass syncro ring (I think) and it looked fairly thick. There was no gold shavings that came out either, and it's currently using Redline MTL.

Sometimes it'll shift without the bad feeling, and it feels great. I've bled the clutch line a couple times with no effect, although the last time I bled it, it did raise the clutch engagement up some on the pedal.

Could it just be worn syncro rings, or do I have a clutch disengagement problem?

A lot still depends on the prior owner. Transmissions using bronze synchro rings don't like GL-5 (or GL-4) gear lube, as it does attack the metal. The outside will probably still look decent, but the inside of the synchro ring usually goes first anyhow - from what I've seen.

If it were a clutch issue, you'd note trouble when you're pushing the clutch pedal in and out - this doesn't seem to be the case, from what you're describing. Sounds like your 1-2 synchroniser is starting to go out on you. Without seeing the box or knowing its provenance, I'd have a hard time telling you why - but thinking that high-sulphur gear oil was used in the past wouldn't be too far off, I'm sure.

5-90 said:

A lot still depends on the prior owner. Transmissions using bronze synchro rings don't like GL-5 (or GL-4) gear lube, as it does attack the metal. The outside will probably still look decent, but the inside of the synchro ring usually goes first anyhow - from what I've seen.

If it were a clutch issue, you'd note trouble when you're pushing the clutch pedal in and out - this doesn't seem to be the case, from what you're describing. Sounds like your 1-2 synchroniser is starting to go out on you. Without seeing the box or knowing its provenance, I'd have a hard time telling you why - but thinking that high-sulphur gear oil was used in the past wouldn't be too far off, I'm sure.

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It actually does this with every gear change, first, second, third, fourth, and fifth. Though it's mostly noticable in second.

The junkyard does drain the fluid so maybe they wiped off the magnet too, but it didn't have any flakes on it. Hm..

Mine also has redline in it and is a remanned unit with less than 11k.It does the same thing if I shift too quick.Try modifying your shifting habits...I.E wait just a second or two more after you have pushed in the clutch before shifting.See if that makes any difference,it did on mine....After all we are talking about a jeep with a light truck tranny in it,Its not a fast shifting ricer.

It's all about technique.....

True, waiting a second or two for the syncros to spin up does help quite a bit, but it also lets the revs drop too much and I have to hit the gas again to rev match.

I should also note that when I feel it mesh into gear, it's not a horrid feel. It's just noticable. You can just feel it notch as it goes into gear, it's hard to explain.

mattbred said:

It actually does this with every gear change, first, second, third, fourth, and fifth. Though it's mostly noticable in second.

The junkyard does drain the fluid so maybe they wiped off the magnet too, but it didn't have any flakes on it. Hm..

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Well, the brass won't stick to the magnet anyway...non-magnetic. The "good" shifts are probably when you accidentally "match shift". You get the engine and tranny revs just right and it slide right in (like most over the road semi drivers rarely clutch while moving).

My AX-15 acted like yours, and I ended up replacing it. Stinks that you'd have to do it again, but you may have got a bad one.

SteveT said:

Well, the brass won't stick to the magnet anyway...non-magnetic. The "good" shifts are probably when you accidentally "match shift". You get the engine and tranny revs just right and it slide right in (like most over the road semi drivers rarely clutch while moving).

My AX-15 acted like yours, and I ended up replacing it. Stinks that you'd have to do it again, but you may have got a bad one.

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Ah, you're probably right. If I can't get another one at the same bone yard (they are redicuously cheap there) then I'll just keep it as is.

mattbred said:

True, waiting a second or two for the syncros to spin up does help quite a bit, but it also lets the revs drop too much and I have to hit the gas again to rev match.

I should also note that when I feel it mesh into gear, it's not a horrid feel. It's just noticable. You can just feel it notch as it goes into gear, it's hard to explain.

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The notch feeling you are describing are the gear "dogs" catching on each other because the syncro's haven't slowed the two gears down to the same speed enough to allow them to mesh better while you shift.Either due to technique(not implying that you can't drive) or to worn syncro's.....

outlander said:

The notch feeling you are describing are the gear "dogs" catching on each other because the syncro's haven't slowed the two gears down to the same speed enough to allow them to mesh better while you shift.Either due to technique(not implying that you can't drive) or to worn syncro's.....

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That's what I figured. I'd definitely say they are worn then, but not too much because it's not difficult to shift, and it only does it 50% of the time. The jeep I took it out from had 350,000 KM's so it wouldn't surprise me that it's just normal wear and tear. Plus it might of had the wrong oil at times etc.

I've tried a few different ways of shifting, fast and hard, slow, normal, etc. They all give about the same results. I'll look at the junkyard for another one with fewer miles, but if there isn't one, then I'll drive it till it breaks.

Another problem I've been having is every time I take my foot off the gas pedal, or step on the gas pedal, the jeep will shake forwards and backwards and really jolt you around until it settles down. You can even hear the exhaust note change on every jolt, and if you pay attention, you can hear and feel some clunking under neath the floorpan. Now I have to say that this isn't me being a bad shifter, as I rev match every shift including down shifts. There's no real jerking when I shift, it's whenever I get on and off the gas.

It did it with both trannies, and I installed a new mount with the AX15 (it's only a couple weeks old) so it's obviously not the problem. Could it be motor mounts? Or is it normal for a manual cherokee? It makes it very uncomfortable, and if you're in first gear and hit the gas it almost gets out of control. Keep in mind, my foot is not changing the throttle at all, it's like something is trying to catch up with the wheels and engine.

It's just a guess since it's a second hand diagnosis, but you could have a bad clutch disk or pressure plate that's grabbing when it shouldn't. How many miles on the clutch?

Another option for your AX-15 is buying a set of new synchro gears. I recently saw a set on ebay for $155. Even after paying to have them installed it might be cheaper than a junked AX-15 tranny in who knows what shape.

otto said:

It's just a guess since it's a second hand diagnosis, but you could have a bad clutch disk or pressure plate that's grabbing when it shouldn't. How many miles on the clutch?

Another option for your AX-15 is buying a set of new synchro gears. I recently saw a set on ebay for $155. Even after paying to have them installed it might be cheaper than a junked AX-15 tranny in who knows what shape.

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Clutch and pressure plate have I believe 70,000 KM's on them. If the clutch was still grabbing, wouldn't it make it just plain harder to shift? If I'm at a stop and put it into any gear it doesn't grind or lurch or anything.

Weird thing is that I got the exact same feel with the old tranny, perhaps a cooincidence.

Weird thing is that I got the exact same feel with the old tranny

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That should tell you something, that is, the culprit isn't the tranny but the clutch. Clutch disk, cover, pilot bearing, and new slave cylinder will run you around $150. New flywheel is around $70 after core return. If you went to the trouble and expense to upgrade your old Peugot wth the AX-15, it might be worth doing. Guess it depends on how bad the problem is and how much you can stand.