nchsa1120

I have a 1998 jeep cherokee 4.0l ax15 np231 tc. When i first start up and its cold it shifts pretty decent for a offroad vehicle, nothing like my civic but it doesnt really catch going into any gears when its cold. Once i drive for say 20 mins and esspecially idling it gets really hard to shift into 1-3 mainly and reverse gives me problems as well. Rev matching helps sometimes but if im stopped in neutral and try to put it into 1st its almost impossible at times. Also this year when uwharrie opened i went the first day and i rode in 4 low most of the time and it wouldnt shift at all while i was in 4 low. I would have to cut it off, shift into gear then cut it back on to continue on. Its become a real pain now that im trying to make it more of a dd and really wanting some advice to fix this problem. My jeep has 270k+ miles so problems are expected but its a awesome jeep that i plan on keeping and putting money into. I havent changed the transmission oil in it and have only owned it for about 15k miles. Any advice would be greatly appreciated. Thanks Jake.

Cummins93

Check your clutch master resevour.
Does double clutching while shifting help?
From a stop neutral try pumping the clutch 3 times briskly and put it into 1st, does it go right in?

I would change out the oil due to its unknown mileage. Synthetic 10w 30 motor oil is a good idea, I prefer mobile 1 high milage. That is the one with the blue label.

BwanaBob

Cummins93 has good advice. ^^^^

I have a 98 Cherokee and it is on its 3rd clutch master cylinder.
When those failed, it became hard to shift, much as you are describing.
Nowadays you can get a master/slave/line set with the line pre-filled
and purged.

Yes, you should drain and refill the transmission since you don't know the
service history. It takes about 3.5 quarts. Jeep originally recommended GL3
gear oil but that is no longer available so now 10w-30 is their recommendation.
Do not use GL5 gear oil unless it is synthetic and says on the label it is safe
for yellow metals (the synchros). Some guys like Redline GL4 and say it
shifts smooth.

shooptube

Absolutely nailed it. Had the same issue as you once the jeep heated up, replaced the master/slave assembly and solved the issue completely.

nchsa1120

When it first started happening i replaced the whole clutch master cylinder and slave cylinder assembly which is all one piece prebled and it did help it but its right back to how it was before and ive hardly drove it since i replaced it. The clutch is hard to push in and releases just a bit back from the floor. The clutch had been replaced right before i bought it so its got less than 20k miles on the clutch. The receipt says they resurfaved the flywheel too, idk if that is a no no or if it matters but thats what i know has been done recently. Ive been meaning to change the transmission fluid but havent got around to it. It seems like its gonna suck but i will do that next. Im thinking about buying a pump so itll make getting the new fluid in there easier. Ive heard that gl5 is not what needs to be in there so i wont use that but i am sceptical on the regular motor oil. Is pensoil syncromesh good?

nchsa1120

Btw the reason im not sure about the motor oil is that i put non synthetic motor oil in my dirtbikes tranny one time and it caused some problems. I just seen where yall recommended synthetic so as long as its synthetic itll be fine right?

Cummins93

With the clutch master disconnected does your pedal move freely?

Just because something is "new" and "installed by a shop" means nothing.

QuickNDirty

Changing the fluid on the AX15 is a breeze. Drain it, pump 5 quarts of 10w30 back in, done.

$7 harbor freight pump works fine. It took me about 10 minutes.

nchsa1120

Yeah the pedal moves free with it disconnected. I installed it and im pretty sure i done it right. Like i said it worked great but not for long.

investinwaffles

Check this thread for fluid advice;

https://www.cherokeeforum.com/f2/red...0-ax15-225576/

BwanaBob

Pennzoil Synchromesh meets Chrysler manual transmission fluid specification
MS-9224, which is what the AX15 requires. It is not expensive, either.

I think I would change the oil in the transmission before doing anything else. If there
is a way to bleed the clutch line you have now, try that, too. It is possible that the
new master/slave set you installed is defective and hopefully would be under warranty.

Resurfacing the flywheel is is discouraged by the FSM because "excessive stock
removal can result in flywheel cracking or warpage after installation; it can also
weaken the flywheel and interfere with proper clutch release."

nchsa1120

Ok ill change the fluid first and i dont believe i can bleed it. It was pretty cheap from rock auto compared to the other ones i think they were trying to get rid of them because they werent carrying them anymore.