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Manual Trans not going into gear after warming up

W

walkngdude

NAXJA Forum User
Location
Santa Cruz California
Hi all,


I have a 1992 XJ with 254K on it and a 5-speed manual transmission (I'm assuming an

ax-15). Me and my kid did the last clutch job about 9 months ago with a kit from

O'Reily's that included the pressure plate, cover, pilot bearing and slave cylinder. I

did some reading before hand and replaced the transmission gear oil with Red Line MT-

90.

My trans has always had to slightly grind into reverse ever sense I bought it used in

2000 and one time when we went to the snow in December the clutch completely froze up

for a night but was fine the next day. After using the MT-90 it was very smooth for a

long while even going into reverse.

A few month back it started getting very difficult to get it into gear. This includes

every gear and to the point now that sometimes I have to turn off the engine at a red

light to get it into 1st. It almost seems to have something to do with cooler weather

(though where I live in California it doesn't get much below 40°F). And it seems OK in

the morning (cold or not) then when I can drive to various places through the day it

gets worse as the day wears on.

I have bled the lines a few times but the clutch feels very strong and it doesn't help.

There is a good shop here that I have taken it to often in the past and the guy said

that the pressure plate might be sticking and recommended that sense Reilly's gave me a

"lifetime" warranty I should take it apart and re-replace everything again. I took it

to another small shop that was recommended to me and the guy asked me "if it easily

goes into gear with the engine off (when it is acting up)" and if so I need to replace

the transmission. It does but I'm hoping that I don't need a new trans because it will

be impossible to find and very costly.

My neighbor is a smart guy who has given me much good mechanical advice and he says

that it sounds like the gear oil is failing when it gets warm and I should try

replacing it with whatever Mopar recommends.

That sounds like a good place to start so I plan to go to Chrysler and buy whatever

they recommend. What, GL-4 or 5 maybe GL-3 Mopar brand?

Somehow it doesn't seem that that will solve it and with my kids away at school I'll be

changing it myself (or I could have a shop do it) if I want to replace the clutch parts

again. But I'm willing to do it. Should be easier the 2nd time. haha. And I made a nice

adapter for my floor jack for it.

I have always come here when I'm at a loss so I thought that I'd run it by you guys.

When I was installing the (internal) slave cylinder it really seemed like a flimsy

setup. In fact that's what failed last time. That weird accordion thing was all wrapped

into the shaft.

Anyways any advice for me?

Thanks
Marc
1992 4.0 BTW
 
I seriously doubt it's the oil. As I'm sure you're read, GL4/5 rated oil usually has sulfurs which damage the synchros over time. The MT-90 works well, as does penzoil synchromesh, or even just synthetic 10W-30. The dealers are supposedly putting in 10W-30 now.

It really does sound like the clutch is dragging, or what happened to me was the pilot bearing seized up.
 
Like Lawsoncl said. sounds like clutch is dragging. (not fully disengaging)

If getting into reverse always required grinding... sounds like engagement was an issue before clutch job. (get into reverse without grinding if you wait a few seconds with clutch in)

Check clutch master and slave system.

unfortunately.. hydraulic clutch cant be adjusted.

Check fluid level and dirtiness
Check for leaks
Bleed and replace fluid (if possible).
*Dig in and research more. (utube may help. read the comments before paying attention.. with no dislikes.. you have no idea whats a good idea or not.. )


If master/slave are good.. guess someone is doing another clutch job.


good luck !
 
Grinding going into reverse is pretty much normal for an AX-15. If you tap it into first gear you can usually get it to go into reverse without grinding. Otherwise, expect it to grind.

One factor that has not been brought up is the surfacing of the flywheel and the maintaining of the distance from the crank flange to the surface of the flywheel. If the flywheel has been machined (distance reduced) there are shims to install to restore that distance. Because of the fact that the hydraulic clutch does not allow for adjustment this may be an important factor in your situation.
 
Anak said:
Grinding going into reverse is pretty much normal for an AX-15. If you tap it into first gear you can usually get it to go into reverse without grinding. Otherwise, expect it to grind.
Click to expand...

Yes, because there is no synchro on reverse. Touching 1st first stops the intermediate shaft from freewheeling.
 
I put the clutch in about 9 months ago. I don't think I resurfaced the flywheel then.


I was driving it today around town (about 2 miles back and forth) it was iffy all along but after the 3rd stop it refused to go into gear at stop lights so I has to stop the engine each time. I then drove about 10 miles and stayed for 3 hours and it was better.


It's funny, it seems to have very strong pedal. If I'm parked and put on the emergency brake, in 1st with the clutch all the way down there is absolutely no drag on the motor. Then when I slowly lift my foot it will start to drag the motor at about 2-1/2 inches from the floor (considering that I have 4-1/2 inches total pedal travel).


But if I put it in neutral and try to put it in any gear it either absolutely wont go or (if it in a good mood) I can search for a gear that it likes then I can move it to 1st.

If the friction plate or the pressure plate was slow to react or binding to the flywheel wouldn't the parking brake test show more drag earlier or something?


Also if the motor is off it goes into any gear easily.


One shop told me to check that the shifter is bolted on tight, which I have yet to complete. Though I have taken the boot off and put strong pressure down on it and don't feel ant movement or change in shifting when it's acting up.


So assuming if it's not blown syncro's. When I'm stopped and in neutral. With he clutch out the pressure is tight against the flywheel. 1st gear is spinning at engine speed somewhere inside the transmission. I step on the clutch that disengages the flywheel from the axle and shift into that (spinning) 1st gear and somehow the syncro's instantly bring the flywheel to up to speed (synced) with the 1st gear without grinding (supposedly).

So where is a dragging pressure plate or friction plate fit into this.

I don't mean to be lazy. I am planning on replacing all the clutch parts again this weekend (I think) but after that I may have to look for a rebuilt transmission. That sounds rather difficult...


Thanks
Again
Marc
 
I can't edit my post here right? So, I'll talk to myself for a bit. I guess if at a stop that the pressure plate sticks to the flywheel for some reason, or maybe it can't slide along the spindle or something then the flywheel wouldn't sync and that would do it.
All right, it's been a long day I need to stop now.


Thanks again...
 
alright, time to get through this.
Many times the clutch discs are a teeny bit too thick.
I've seen this a lot.
Get going about 35 MPH on a straight stretch of road. With the trans in 4th gear, depress the clutch pedal, rev the engine up and slip the clutch. Repeat this a few times until you can smell the clutch getting hot. Take the Jeep home and park it for a few hours. Then see how it works.
 
Thanks Cruiser54, Anaka, Lawsoncl & Clean96XJ.
I can go out and try burning the clutch a bit today. I plan on picking up some:

"penzoil synchromesh GL-4 or 3 Without Sulfars that damage brass syncros or even just synthetic 10W-30"


and another clutch kit from O'Reilly's. They should give me a full refund because of their "Lifetime warranty".


I'll try changing the gear oil then checking that the shifter is bolted down then start dropping the transmission. Good thing I saved my super-duper transmission floor jack adapter cradle.





I'll take next week off so I can take my time. By myself this time.



I check with O'Reilly's and I did the clutch on September 2020, so a year and a half ago. It was working great up until a few month ago and has been a very slow degrading (As I remember).


Thanks
Marc
 
Just an update, I bought all the parts, gear & transfer oil and some tools and was set to tear it down but first I took it out and did what Cruiser54 suggested (kind of). There's a steep hill down the street so on the way up I let the clutch out enough to get it spinning and revved the RMP for a bit and I think it worked.


I'm suspicious though because the weather warmed up and it's always worse in the cold. But damn, it sure has been shifting smooth for the last 2 days.


I'm really tempted to change it anyways because I might not be in a good place for it when winter comes again and I bet we don't get any more cold until November. But it's hard to start that whole process when it's working so well.


I did watch a few good videos on how a 5-speed transmission works and that convinced me that it isn't the syncros. So it has to be that the pressure plate is sticking or something.


I'm thinking that maybe I should have bought a better kit instead of O'Reilly's and should have replace the flywheel instead of scuffing it up.


Anyways, you guys are the very best for helping me think through this and I am soooo grateful.


Yours
Marc
 
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