This weekend I installed a new flywheel/clutch/pressure plate, throwout bearing, pilot bearing, shift fork and pivot ball in my 1999 4x4, 5.2, NV3500 5-spd. Everything came out and went back in without and major issues. However, the new clutch will not disengage. Pedal feels fine, not super firm, but not very light either. Feels about the same as it did before the surgery.

I'm looking for anything that you guys might think is the culprit for this. The clutch kit is a Sachs K70144-02, with a Sachs NFW7225 flywheel. The clutch kit itself is a 12in, same as would be installed on a 99 Ram 1500 4x4 with a 5.2 and NV3500. I read that a 12in clutch is a replacement for the stock 11in clutch. The new clutch fork is a ATP ZA140, and the pivot ball in a new OEM Mopar.

A couple thing to note that I saw. The clip that hold the clutch fork to the pivot ball had one of its wings broken off. Since I didn't have a new clip on hand, I used for wire to tie it back it to the pivot. I also couldn't find a clear answer as to which way the new fork is to install. I went with the slots for the throwout bearing being towards the slave. I check the movement of the fork on the input shaft and it all seemed fine. Went through its oemotions fine and the throwout bearing looked happy.

Now, the concerning thing was the slave cylinder. I didn't have a new one, so I reused on the old one. The plunger on the old was was floppy so to say. Only when it was pushed into the cylinder for about an 1" did it stop becoming floppy. By floppy I mean that I was able to move it in a circular motion without much resistance. Seems odd to me, but not signed of hydraulic fluid leak. I don't see signs of external leaks, could it be an internal bypass leak somewhere in the master/slave system?

Before the new clutch, I had trouble with the clutch disengaging when driving a loaded truck uphill, off-road. Toward the top of a long drive up a mountain on a dirt road, the clutch would like half disengage. Once it cooled down, everything was fine. It was never an issue during normal driving. Was that a sign of a master/slave issue? Not sure.

Old clutch was defiantly worn, but not catastrophic. Flywheel/pressure plate were glazed, but smooth. Throwout bearing was toast, but pilot bearing was okay.

Would love to hear what you guys think. Is there a manual way of actuating the clutch fork through the slave hole to confirm mechanics are right? Hammer and a punch? A portapower and a punch?

 

A new data point to add. Went to move the truck from the garage this morning. I was prepared to move the truck using the starter motor. Foot down on the clutch, stick it in reverse and turned the engine over. To my surprise, I had the engine running, trans in gear, foot on the clutch and the truck was stationary. So it's disengaging! Lifted my foot, truck started to move as per usual. Backed it up, stopped, and tried to put into 1st. Wouldn't go. Shut it off, put it in 1st, start it up, lift the clutch and off we go.

So it disengages, but not enough to select gears. I think I'll start with a new master/slave and see what happens. Pedal feels normal, but it might be an internal bypass leak?

 

Not sure if you would even notice a bit of air in the system, but, they are darn near impossible to bleed..... Forcing air DOWN a tube, just doesn't work well.

 

I don't think it's air introduction into the system, rather a failure of the internal seals in the MC. Between the reservoir and high pressure sides. Just a theory. But the pedal feel good so......

The other thing causing this lack of disengagement could be the pilot bearing. But I put in a new one and it all lined up fine with the alignment tool. Getting the transmission on was very smooth too, so I don't have reason to think that something went wrong there. I didn't try the new pilot bearing on the input shaft before pressing it in. Now I regret that.

I've got a new master/slave pre-assembled kit on the way. Fingers crossed that'll solve my issue.

 

Pilot bearing will have zero effect on clutch function. All it does is support the end of the input shaft of the trans.

If the hydraulics are working properly, I.E. the salve cylinder has proper stroke length when the pedal is pressed, it's probably a geometry problem with the fork, and throwout bearing.....

 

I think it does. The transmission input shaft has two places it interacts with the crankshaft. One of these is obviously through the clutch. Additionally the pilot on the input shaft sits in the pilot bearing, which is on the crankshaft. If that’s seized, or tight, or ruined, it will also cause the input shaft of the transmission to spin with the crank. This will happen even if the clutch is actually disengaged.

I do think my problem is not getting enough travel out of the slave cylinder plunger. I hope for my sake at least. New parts arrives on Thursday and I hope to install on Friday. Will update on the result of a new master/slave.

 

I most definitely suspect its a hydraulic issue. When replacing these I've found it best practice to remove the master cylinder, disconnect it from the pedal, or tie the pedal up to the steering wheel or something to support the pedal. The basic weight of the pedal will gradually push the master/slave over time sitting and leak fluid out the slave with there no longer a fork holding it in. This can result in an air pocket. In time they can work out, make sure the master is full and just keep pumping it. Working it from the slave end can sometimes work. I've removed the entire hydraulic system. Put the slave in a vice and ties the master on a ladder above the vise as high and as straight as the lines will allow and pumped it back and forth. It will come in time.

I am fairly certain the fork can only fit one way. The clips for the ball socket inside the bellhousing stay in the fork, so if you put the clip side on the ball socket in the transmission you're good.

Yes in a very freak happening of incidents the crank could directly drive the input shaft through the pilot bearing. Very unlikely as the snout on a new input shaft is very loose fitting, not to mention one with xxxxx miles on it. Could there be some rotation drag there gently rotating the input shaft yes, but soon as the teeth on a gear line up it'll slide right in

 

Well, the new master/slave didn't fix my issue. Maybe it's a hair better, but not significantly. I can drive it around if I stick it into 2nd and then jam it into 1st. Truck drives fine otherwise, but it's clear that the clutch still doesn't fully disengage.

I'm somewhat stumped as to what is causing this. Now I'm somewhat regretting going with the 12in clutch from the Ram 1500, rather than a stock 11in. Maybe it's something with that? Maybe I didn't completely clean the surface that the release bearing slides on? I check the movement before installing and all seemed good. Looks like the transmission has to get dropped again. I don't know if I've got that in me again. Might pay someone to do it this time, or just sell the truck honestly.

 

I wonder if the 12 inch clutch is thicker than the 11 inch. I've seen some posts mentioning bent shift forks but those were on the diesel variety. Is it possible the pressure plate isn't seated correctly and is pushing at an angle?

 

I think you hydrolic system is the problem. My '99 quit shifting and I had to buy and install a new system. You cannot buy just the slsve or master cylinders, but must get the entire set up hoses and all. That is the fastest way to fix you issue.