AX-15/ Clutch Problems continued...

XJNick · #1 (**permalink**) 10-18-2003, 08:03 PM

Hi,

For those who didn't read my previous posts about this... This is an issue on my '97 TJ w/ AX-15 Transmission. I have good reason to believe there is still something wrong with the clutch.

I've been having occasional grinding when upshifting to 2nd, and it takes an unusual amount of force to enter 1st or Reverse gears (as if pushing against something). What I believe is happening is for some reason the Clutch isn't fully disengaging and is slightly dragging.

For example: I've just started the Jeep, with the clutch pedal in, the brakes are on and the Jeep hasn't moved an inch. However, when trying to enter say reverse, I hear (and feel) it grinding that slows until it stops, as if the transmission is spinning internally. If I then go back into neutral, (with the clutch pedal still pressed and the Jeep still stopped), and then try reverse again, exact same thing happens. The same holds true for 1st gear, except there is no audible grinding, it's just Very hard to get into.

I Finally got the correct new Master/Slave cylinder kit for the Jeep. That didn't solve the problem. Also, the clutch pedal in this Jeep has always felt mushy, even with the new cylinders installed.

I don't believe this is simply the transmission taking a while to spin down internally, so what else could be causing this? My 2nd gear syncro is already pretty dead, but I feel I'm damaging the other syncros if I don't solve this problem.

Thanks for any suggestions

-Nick

Snitty · #2 (**permalink**) 10-18-2003, 09:15 PM

ok.. here is whats up.... your synchros are going bad, likely because of their brass composition... if you have not yet... get some REAL approved fluid in there...

the reason you are getting a grind in reverse is because of the mechanics of the reverse gear... and is the same reason you cannot get it into reverse if moving forward. in all forward gears, the actual gears are always engaged at all times. but the transmission engages the shafts to a driver selected gearset... but for reverse, there is an actual gear to be engaged... all forward gears are helical cut gears to reduce friction and noise... the reverse gear is not helical, but straight cut to allow that engagement... that is also why, when in reverse, you hear the whining noise...

don't worry about it being tough to get in first, or the grinding in reverse... if you want to prevent the reverse grinding... come to a stop, toss it in second gear (with the clutch still pressed) to bring all transmission shafts to a stop, then put it into reverse... as for first gear.. there really are no tricks to fix that... sometimes you can try another gear first to stop all shafts, but sometimes a very very slow roll can help get into gear... and like said before... if you haven't gone to a better fluid.. do it now... redline mt90 or pennzoil synchromesh

XJNick · #3 (**permalink**) 10-18-2003, 09:36 PM

Snitty, Thanks for your help so far!

I put Pennzoil syncromesh in there after you guys said to in my first post. That was almost a month ago. I am aware the syncros aren't in great shape, as the 2nd gear one is almost gone. The new fluid has helped!

As far as reverse, I'm not complaining at all about the whining. I am wondering why I feel things moving inside the transmission when the clutch pedal is completely pressed to the floor, and the Jeep isn't rolling at all. I can actually feel and hear something moving in there when trying to engage reverse. It stops as soon as I engage the gear completely.

I guess my main concerns here are:
1. The clutch pedal still feels mushy, it has little resistance although I just replaced the Master/Slave cylinders. It also is engaging almost right off the floor. (could this be normal?)
2. Should anything be spinning in the transmission if the clutch is fully disengaged and the Jeep is not rolling? (Once again, is this normal?)
3. I've begun to notice a sort of rattle/clunk sound that is rythmatic to engine RPMs and seems to be from the bellhousing. It sounds as if it happens only when the clutch pedal is pressed. If I pull out on the clutch, it goes away. I forgot to mention this in the above post. (Could it be the clutch disc hitting/scraping something?)

The above just doesn't sound/feel right to me. Maybe I'm just being paranoid though. I'll drive it tommorrow doing 2nd before reverse and see if it helps any.

Thanks!

-Nick

Snitty · #4 (**permalink**) 10-19-2003, 12:17 PM

1.have you bled the system completely? if you have... you can also find at some parts stores a bleeding tool that actually bleeds through the bleeder by suction, rather than bleeding with the pedal... this ensures the best bleed possible, when you bleed the system fully, your contact point should be at the top... if the clutch is warn too far, the springs will move inward, moving the contact point further away.. this can also give you a spongy pedal

2.when the vehicle is completely stopped.. there is still a possibility of the input and layshaft of the vehicle to be spinning from previous momentum, and are in constant connection with the clutch disc... only the output shaft is in constant connection with the driveline... when you put it into any forward gear, it usually is much easier than reverse because they are synchronized, which helps match the speed of the shafts before the collars engage... but for reverse, there is no synchronizer to sync the speed of the layshaft and the output shaft, and it is not a collar that engages, it is actually the teeth of 2 gears engaging... and since there is no synchro... the layshaft is still spinning from previous momentum, and when you grind, that is acting as the synchro... if you put it in a gear prior to engaging reverse, you will stop the layshaft so it can mesh with the already stopped output shaft... but... you do have limited time, because the air friction in the clutch can act as a viscous coupling and move the input shaft slowly, but will hurt nothing at all, maybe cause 1 or 2 clicks upon engaging... i hope this made some sort of sense

3. the rythmic rattle clunk MAY be your pilot bearing, which helps hold the input shaft centered in the crankshaft.. and might only be making noise when the clutch is not acting as a supplemental support for the input shaft... that is only a guess... but...

guessing from the symptoms of the grinding/noises... i would start looking for a new tranny... and get it installed with a new clutch and a new pilot... i GUARANTEE every problem you have now, will be gone then... except for the reverse grinding.. that is just a property of a manual transmission

BostonJeep · #5 (**permalink**) 10-19-2003, 12:23 PM

when i pump the clutch a couple times, it grinds alot less when putting it in reverse.

Snitty · #6 (**permalink**) 10-19-2003, 12:44 PM

that is possibly because of the pressure building in the hydraulic system which will allow the plate to open up further, reducing the air friction on the disc...
just a guess really

Bounty__Hunter · #7 (**permalink**) 10-19-2003, 01:07 PM

Two problems, and in agreement with Snitty, you've got air in the clutch system and your synchros are getting worse.

If you replaced the clutch master cylinder you should have bench bled it before installation. This involves mounting it in a vice and working fluid through it until there is no more air.

Try Redline MT90, it's a synthetic that is specially formulated to be easy on the soft brass synchros. The Penzoil Synchromesh is not synthetic and will not improve your shifting (especially cold weather) as much as the Redline.

Bleed your clutch if it has a bleeder valve. If it doesn't, then remove the clutch master cylinder and bench bleed it. Reinstall and pump the heck out of the clutch. Sometimes it takes a few days to work the air out of the clutch lines through normal use.

I run into the air problem every time I remove and reinstall my tranny, the clutch engages just before hitting the floor and improves after some use.

XJNick · #8 (**permalink**) 10-20-2003, 07:25 PM

Thanks for the replies.

Quote:

have you bled the system completely?

No i have not bled the new hydraulic system. This system is supposed to be "sealed." When it came to me, it already had fluid in it and was bled. The factory service manual for the '97 wranger says DO NOT attempt to bleed the master or slave cylinder as they are a set and must be replaced as a set. However there is a plugged bleeder port (no valve), but this hydraulic system is working the same (no better) than the old one that I DID bleed several times.

Quote:

there is still a possibility of the input and layshaft of the vehicle to be spinning from previous momentum

Yes there is momentum, I understand that. However, the momentum surely can't last over 30 seconds! I feel the transmission moving even if the Jeep has stood still with clutch pedal pressed for that long.

Quote:

because the air friction in the clutch can act as a viscous coupling and move the input shaft slowly

This sounds like what I'm talking about, only it seems like the shaft is being spun more than normal. And I end up getting Way more than 1-2 clicks upon engaging reverse. Also, I've never heard ANY grinding/clunking upon engaging into reverse with my Cherokee's Peugeot transmission. Maybe this is an AX-15 thing?

Quote:

If you replaced the clutch master cylinder you should have bench bled it before installation

The master cylinder, slave cylinder, and fluid line are a complete unit. The only way to remove the fluid line is to remove a cotter pin and then pry the line off of either cylinder. However, the factory service manual says NOT to do this since the unit comes pre-filled with fluid and pre-bled.

Quote:

The Penzoil Synchromesh is not synthetic and will not improve your shifting

I've got the Pennzoil stuff in there. It has helped the shifting alot in general.

I'm still wondering if there could be something wrong inside the bellhousing. Could the shift fork be not aligning properly, or maybe the clutch or flywheel need to be replaced. I've not yet seen the insides of this bellhousing and am not exactly familiar with how the external slave and stuff works, since I'm only used to my cherokee which had the concentric throwout bearing/slave cylinder unit mounted inside the bellhousing.

Sorry for the long response. :P
Thanks again

-Nick

Snitty · #9 (**permalink**) 10-21-2003, 12:52 AM

before i put that new system in, i would have taken the plugged bleeder port out and put a new valve in there... but that step is long passed...

many many manual transmissions will give you trouble with engaging reverse... it is NOT a bad thing at all.. you just have to deal with putting it another gear first, even with a transmission that goes right in... i ALWAYS put it in second gear before reverse, just habit.. and it only takes a fraction of a second to do.. for some reason, maybe the cherokee's transmission just likes to go in..

and yes... your clutch plate/disc MAY be warn low... the external slaved clutch system inside the bellhousing will be VERY VERY similar to the old style mechanical clutches... it is just operated by a hydraulic cylinder rather than linkages.. if you decide to get a new transmission, which by the sounds, you should be... you should also look into putting in a new clutch