I'm losing my mind. About a month ago the clutch in my 97 TJ started to slip from time to time and chattered a bit after a session of getting unstuck in the sand at the beach 2 years ago. I was told the clutch was replaced right before I bought it, but with no documentation. That was about 30,000 miles ago. Anyway, I'm lucky enough to work in a shop that has all the tools necessary and really nice lifts making jobs like this somewhat easy. I hardly use my own garage or tools anymore. During clutch replacement I found the clutch to be ok, so the previous owner did not lie. No big deal, now I have a new one. I had to replace the fork pivot stud and retainer spring (broken, obviously not replaced prior). At this point I quickly realized the culprit was the master/slave cylinder. It was stuck "out". I could not re-install it if I wanted to. I replaced it with a sealed system. ALERT: having never done this, I took the plastic nub off the end, thinking it only helped keep the thing together during shipping. This part stays on until after install and than you push the clutch the first time and it breaks the little tabs off. Anyway, after about 10 days, it started acting up. On hot days, after the engine and transmission warmed up. it got harder to get into 1st and second gear. Than if it sat running, say in a drive-thru, the clutch would seem to engage even with the pedal all the way down. I could start to lift the brake and it would chatter. I could literally let up the brake, with clutch pedal in and it would ease around the drive thru!!!! I assumed the brand new clutch/slave was bad out of the box. i returned it and got a new one (sorry NAPA if this is my fault). Thats when I realized the plastic nub needed to stay on. I removed the tabs, but put them back in when I realized how to do it right. I also replaced the AX15 fluid with Pennzoil Syncromesh. Man did everything go well. That Jeep ran and shifted like brand new............for a week. The weather was cool. Today it was hot again. The exact same problem has returned. HELP!!!
Clutch / Transmission / Slave Cylinder Driving me Crazy!
- Thread starter Michael Condo
- Start date
I'm no expert on the matter, but it sounds like maybe your slave cylinder is going out again? I wonder if it's possible that you got another bad one?
It sounds like the sc is bleeding off. Not sure why it only happens when hot. Is it possible the fluid is heating up to the point where is boils and develops air bubbles??? I would definitely try another sc but use a oem or equivalent.
While that retainer should stay on a new slave cylinder shaft when replacing it, I reinstalled the original slave several times on my previous TJ without it on there without problem. When you replaced the master-slave hydraulic system, did you use the OEM Mopar or an aftermarket replacement? Store-brand replacements seldom work as well as the Mopar part does.
Also, I would not have used Pennzoil (or GM's version) Synchromesh in your AX-15. While it 'technically' meets the specifications for the AX-15, its reputation is spotty with lots of reports of giving poor shifting quality after filling the transmission with it. Not to mention it is not a synthetic so it won't shift well when it gets really cold there in Maryland. A better choice would have been Redline MT-90 which is a full synthetic. Those who ran MT-90, which included me years ago, universally give it high praise.
Also, I would not have used Pennzoil (or GM's version) Synchromesh in your AX-15. While it 'technically' meets the specifications for the AX-15, its reputation is spotty with lots of reports of giving poor shifting quality after filling the transmission with it. Not to mention it is not a synthetic so it won't shift well when it gets really cold there in Maryland. A better choice would have been Redline MT-90 which is a full synthetic. Those who ran MT-90, which included me years ago, universally give it high praise.
This post struck a note as I am (leisurely) doing my clutch job. I am, realistically, the second owner of my 2002 SE that had 143,000 miles on it. According to the paperwork, a clutch job was done at 92,000 miles, so I was surprised that despite feeling excellent when initially purchased, the clutch began slipping progressively worse after about 1,500 miles or so. I rarely drive the Jeep, but my wife and I love it when we do.
I have replaced many a clutch over the years in rear and front wheel drive vehicles, but never a Jeep. It has been a learning experience...and I appreciate the advice I have received here for my "newbie" questions, the solutions to which, eventually became more obvious to me as I dove into the job.
I had expected to find a fluid leak either from the rear main or transmission input shaft that would account for a relatively new clutch to begin slipping so early. Nope. Bone dry. And the clutch, flywheel and pressure plate looked decent as well. (I purchased an entire Luk kit, including flywheel that has been installed). In my own post about replacing the clutch, I noted that the slave cylinder was not bolted up tight to the bell housing, leaving about a one-inch gap between the bell housing and the mounting flange, leading me to believe that the prior owner was trying to coax some extra life out of a worn clutch disk by slacking off of the linkage engagement point, and since there is no mechanical means to do so, they loosened the slave cylinder mounting.
Now having inspected the other clutch parts and finding them to be certainly serviceable, I am having doubts about this slave cylinder and wondering if it was the problem all along. There is absolutely no way that it will go back on the mounting studs...it is rock solid more than a quarter-inch away from the start of the studs. Seeing that Jerry has re-installed his slave cylinder multiple times without problem...I wonder if the valving in the master/slave system was not allowing fluid to return from the slave to the master until the point that the slave would no longer retract against the pressure plate springs enough to engage the clutch disc?
This would explain why the prior owner had loosened the slave cylinder and, perhaps why an otherwise good looking clutch disc and pressure plate began slipping. (the fork and throwout bearings were fine).
I have a new master/slave to install (no, I scoped out the retention straps on the slave and saw how they work...so I won't remove them!), so hopefully that will be the end of this journey.
I am just curious at this point whether my theory holds and whether anyone else had ever experienced this?
kim
I have replaced many a clutch over the years in rear and front wheel drive vehicles, but never a Jeep. It has been a learning experience...and I appreciate the advice I have received here for my "newbie" questions, the solutions to which, eventually became more obvious to me as I dove into the job.
I had expected to find a fluid leak either from the rear main or transmission input shaft that would account for a relatively new clutch to begin slipping so early. Nope. Bone dry. And the clutch, flywheel and pressure plate looked decent as well. (I purchased an entire Luk kit, including flywheel that has been installed). In my own post about replacing the clutch, I noted that the slave cylinder was not bolted up tight to the bell housing, leaving about a one-inch gap between the bell housing and the mounting flange, leading me to believe that the prior owner was trying to coax some extra life out of a worn clutch disk by slacking off of the linkage engagement point, and since there is no mechanical means to do so, they loosened the slave cylinder mounting.
Now having inspected the other clutch parts and finding them to be certainly serviceable, I am having doubts about this slave cylinder and wondering if it was the problem all along. There is absolutely no way that it will go back on the mounting studs...it is rock solid more than a quarter-inch away from the start of the studs. Seeing that Jerry has re-installed his slave cylinder multiple times without problem...I wonder if the valving in the master/slave system was not allowing fluid to return from the slave to the master until the point that the slave would no longer retract against the pressure plate springs enough to engage the clutch disc?
This would explain why the prior owner had loosened the slave cylinder and, perhaps why an otherwise good looking clutch disc and pressure plate began slipping. (the fork and throwout bearings were fine).
I have a new master/slave to install (no, I scoped out the retention straps on the slave and saw how they work...so I won't remove them!), so hopefully that will be the end of this journey.
I am just curious at this point whether my theory holds and whether anyone else had ever experienced this?
kim
A hydraulic clutch is a wonderful thing, until it isn't. And just like electronic devices they tend to be 'all or nothing'. While the system is extremely simple, about as simple as a hydraulic system can be, when they are designed as a throw away system I find it becomes common to need to throw it away. If the fluid level is good and you can push the slave plunger back in without binding then you have pretty much done all the maintenance you can. They are made cheaply. And if you get a 'Monday' built one then it may not hold up as long as you would hope.
In your case, I think you answered your own question. If your slave is not retracting correctly then your clutch may not have been fully disengaged. I mean your clutch was probably still slightly connected with your foot off of the pedal. If you got in there and the clutch was fine, that sounds like your theory was correct, but weirdly I bought a whole clutch slave all in one kit from mopar for like $150, not sure why someone would rig it with the chance of blowing a more expensive clutch than just fix the issue. Anyway it sounds like you have it under control.
Thanks. I think that had to be the most likely cause. At least I will have all new parts going in...I didn't bother with the rear main or input shaft seals...they were dry and appeared in good condition. The fact that the master/slave might have not been retracting didn't occur to me...even when I saw that the slave cylinder was mounted an inch away from the bell housing! My only other vehicle that had a hydraulic clutch was a '63 Triumph TR4...and I made the assumption that the failure mode of such a system involved either a fluid leak, piston not sealing and not pressurizing the slave or air in the system...it never occurred to me that internal valving might cause a problem causing the slave not to retract. Live and learn!
kim
kim
I can't picture any valving that could be in such a simple hydraulic system !!!??? Just a master and slave piston ? A spring or two and a little tank. And U in business.
Perhaps my use of the term "valving" would not be correct..perhaps "port". At any rate...a quick search yielded this from a Jaguar forum that describes a chap with similar problem...new clutch but the slave cylinder not retracting fully resulting in a progressive clutch slip.
"Hello chaps, I’m in the UK and have been getting my old 1957 XK150 FHC on the road after many years of ownership. I have spent days on this problem with no conclusion. Just a little background, the car has a complete new clutch assembly and thrust bearing. What has been happening is that once out for a run the clutch progressively starts to slip. The reason is that the clutch has been left slightly in a compressed position. by the slave cylinder not fully retracting. I’ve spent days trying to fix this but am out of ideas. If I really pump the clutch pedal quickly the slave cylinder pops out.
I’ve spent hours trying to diagnose the problem. Now the master cylinder rod is adjusted correctly with just a little clearance between the rod and piston. The slave rod is initially adjusted with 1/16" clearance and there’s a good spring on the lever to retract he piston. Lever taper pin is intact.
What I have observed is that after several pumps the slave rod clearance disappears and no amount of spring pressure will retract it. Only when I crack open the bleed nipple does it retract by itself. I’ve had the slave apart numerous times and its clean and piston fully moves within the cylinder.
So the net effect is that the slave cylinder is pumping itself up and causing the clutch slip.
The only way it retracts fully is when the bleed nipple is cracked open(with tube into a bleed jar) and it
happily retracts back importantly by itself.
The hose has no kinks and doesn’t seem blocked as the clutch does work. Is old though
The only thing I can now think of is either a new hose or some master cylinder problem.
Any suggestions appreciated. It seems to have been a common problem but no conclusive resolutions.
Adam, London(Also V12E owner-both 39 &42 years)"
Not exactly, but pretty darn close to what I found when opening the Jeep up. Of course we have no means to bleed our system, but the fact that the slave cylinder's failure to fully retract leading to progressive clutch slippage mirrors my situation pretty well. I just had never heard of such and certainly did not expect it as a possibility with my clutch slippage.
After seeing, essentially, a good clutch and pressure plate...and noting that the slave cylinder was intentionally backed off about an inch from the bell housing...this scenario seems the likely issue all along...no matter how bizarre it seems...
Kim
"Hello chaps, I’m in the UK and have been getting my old 1957 XK150 FHC on the road after many years of ownership. I have spent days on this problem with no conclusion. Just a little background, the car has a complete new clutch assembly and thrust bearing. What has been happening is that once out for a run the clutch progressively starts to slip. The reason is that the clutch has been left slightly in a compressed position. by the slave cylinder not fully retracting. I’ve spent days trying to fix this but am out of ideas. If I really pump the clutch pedal quickly the slave cylinder pops out.
I’ve spent hours trying to diagnose the problem. Now the master cylinder rod is adjusted correctly with just a little clearance between the rod and piston. The slave rod is initially adjusted with 1/16" clearance and there’s a good spring on the lever to retract he piston. Lever taper pin is intact.
What I have observed is that after several pumps the slave rod clearance disappears and no amount of spring pressure will retract it. Only when I crack open the bleed nipple does it retract by itself. I’ve had the slave apart numerous times and its clean and piston fully moves within the cylinder.
So the net effect is that the slave cylinder is pumping itself up and causing the clutch slip.
The only way it retracts fully is when the bleed nipple is cracked open(with tube into a bleed jar) and it
happily retracts back importantly by itself.
The hose has no kinks and doesn’t seem blocked as the clutch does work. Is old though
The only thing I can now think of is either a new hose or some master cylinder problem.
Any suggestions appreciated. It seems to have been a common problem but no conclusive resolutions.
Adam, London(Also V12E owner-both 39 &42 years)"
Not exactly, but pretty darn close to what I found when opening the Jeep up. Of course we have no means to bleed our system, but the fact that the slave cylinder's failure to fully retract leading to progressive clutch slippage mirrors my situation pretty well. I just had never heard of such and certainly did not expect it as a possibility with my clutch slippage.
After seeing, essentially, a good clutch and pressure plate...and noting that the slave cylinder was intentionally backed off about an inch from the bell housing...this scenario seems the likely issue all along...no matter how bizarre it seems...
Kim