AX15 Manual Transmission Issues.

[Aspirated]

Anyone rebiuild a AX15 manual transmission from a 91 Wrangler before? Is it worth it or is there a better solution? replace with a better? Any info would be great.

The issue is a hard shift into 1st and 2nd, im assuming is the synchro's.  When truck is at a stop it is sometimes hard to shift into 1st, when this happens it is hard to shift into 2nd aswell.

[BlackYJ]

The issue is a hard shift into 1st and 2nd, im assuming is the synchro's.  When truck is at a stop it is sometimes hard to shift into 1st, when this happens it is hard to shift into 2nd aswell.

I used to have this issues and i changed the oil with a good synthetic (Redline) and it went away.  I would give it a try but I know it is just a band-aid solution

[JackstandJohnny]

hey Scott, would a good synthetic like that help with grinding going into 3rd gear?

[Woolf]

If it's grinding going into gear you're syncro's are likely done and you will need a rebuild but if the issue is simply that it doesn't want to go into gear that could aslo be the pressure plate not fully releasing which could be as simple as a bad clutch cylinder or the pressure plate itself!

cheers

[Aspirated]

I have a clutch assembly sitting here, complete with flex plate and release bearing. Although.. replacing the fluid will be a cheap first step....

Anyone know a good place to get a rebuild kit? Tried Gear Centre no kit through them.

[Elsifer]

Rebuild's on a weak tranny are so so.

If you're looking at replacing the tranny, find an NV3550 (03-06 4L TJ's), or go to the big donkey, NV4500. Both should actually be shorter than the AX15.

You might run into spline issues on the output to your tcase.

Or find a low-mileage AX15 out of another YJ or XJ from the same era.

Bnine could shed a lot of info in regards to stepping up to a bigger/better/badder tranny. Might be better off finding a used AX15, swap it in. And then rebuild the existing one on your own time so you are not down and without a rig.

[JackstandJohnny]

sorry didn't mean to semi hijack the thread, just my tranny's messing around too......

as for my syncros, ya they are bad;  when i shift fast/hard, it grinds bad. on the upshift if i let the rpms get low (round 15oo rpm) she goes in smooth. any higher it grinds.  downshifting is real bad; it grinds no matter what......  should i be looking of rebuilds/new trannies sooner than later? or can i wheel her till end of summer/fall?

[Aspirated]

recommend a good model/year for doner for the NV4500?

[Elsifer]

Not sure on years, Bnine could help with this.

So long as the NV4500 comes out of a 4x4 3/4 or 1 ton, you're golden. It'll bolt to a tcase without divorcing it.

Swapping the output shaft should be pretty easy. Bellhousings are available from Advanced Adaptors, prolly same with output shafts. The hydraulic clutch might need a different length of tube, but your master should be able to move the slave. You might need someone to tig the appropriate fitting on the tube end tho. I can do that for ya. Heck, Advanced might be able to help with that too.

From what I recall, an NV4500 is good for 400+ lbs of torque. There is one in the Nissan Monster Drunken Elephant, and its hooked up to a BBC454 to a divorced Profab 19" drop transfercase and 2.5t rockwells and 49's. Rev the motor, and dump the clutch, the 49's will chirp! So an NV4500 is *plenty* good in a jeep!

[mike s]

Hard into gear seems to be a pretty common problem with alot of the yj's, mine included. Thinking mines caused by clutch disc sticking to trans input shaft splines from rust. Clutch disc seems to be dragging with engine not allowing gears
to come to rest inside box. Gears/syncros can come to
rest with tips of gears lined up not staggered so the teeth won't
mesh, ESP cold box. Dip clutch in neautral to get fresh mesh of
gears. Higher gears mesh easier, waiting at light I'll try 4th first. Once it meshes I'll go to
2nd then 1st. Save your $$$$ and live with it.