Clutch Problems

[DGamelin]

Just finished rebuilding my NV5600, rear main seal was leaking so I replaced it, clutch looked like it had at least half of it's life left, wasn't slipping prior. I run a garage so we deal with this stuff, this one just doesn't make sense. Is there anything unusual with this hydraulic clutch system that you guys have ran into? Clutch slips with little effort.



Trans shift like a dream.





93 250 2wd xc 354 auto 263k

04. 5 3500 4wd cc dully 373 6-speed 85k

 

[lmills]

Must just be the luck of the draw. There is nothing special about the hydros that would lead up to this.

 

[SRadke]

Nothing special in the hydraulics. Something messed up in the release fork possibly, holding pressure on the throwout bearing all the time?

 

[DGamelin]

There is nothing wrong with hydraulics or anything, every thing looks real good. I had a nother guy in the shop look it over, he couldnt find anything ether. It like the pressor plat just gave up. I am going to order a new one tomorrow. Thanks anyways guys.

 

[jelag]

I don't know where your at... we have the ability in our shop to test plate load... You should consider this before you replace the pressure plate... They just don't give up, there is a mechanical reason why it slips... and usually its from the bearing touching the pressure plate... when installed the release bearing shouldn't touch the pressure plate. . or you might take it apart and see the problem. .

 

[GCroyle]

Jelag, Jim



Sorry, I need to correct your statement about the bearing and release system. Your Class 8 stuff has an air gap, but not our Dodge's.



Our Dodge release systems put the bearing in constant contact with the spring tips. This is applied through the spring in the slave cylinder that pushes on the SC piston, pushes on the fork, pushes on the bearing and applies enough force to cause the bearing to turn continuously. In order to have freeplay, our system would need a fork return spring. We do not have it.



Just some wild ideas about the slippage.



Oil leak on trans, I hope it did not contaminate any part of the clutch and cause the new slippage problem.



Any chance someone did some creative release system modifications and now the system has burped out a bubble and is back to full stroke? Look for un-authorized non standard mods to the release system.



One simple test that you can do to your hydraulics is a push back test. Remove the slave cylinder from the bell housing, leave the hydraulic line attached. Now push back on the pushrod and bottom it out in the SC. It should go all the way in and mechanically bottom out internally. If it doesn't then it can hold the clutch partially released.



Any mods to the fork ball stud on the passenger side of the trans? Extra washers?



Tell us about how and what you used to lube the input shaft to disc spline?



Jim, I just took a G56 hydraulic system apart this weekend at home, saw the preload spring and some other interesting stuff in it that I might have more info on later.

 

[DGamelin]

I am familiar with how the slave cly works and it is working as it should. with the slave out you can pull the throw out bearing off the fingers so there is no binding. The only thing we can come up with is the grease used on the throw out bearing was that hight temp synthetic grease for dic brakes and some got on the clutch, it has graphite in it, I know not good. But if it was there you would see some sings of grease splatter, there is little of none. I know it's not the ideal stuff to use, it was late saturday and we wanted the job done and we were out of anything to use.

 

[GCroyle]

I recommend to techs in my clutch classes to reach for high temp grease, the product might not be the issue. The issue COULD be how much was used. I suggest just a light film on the input shaft, then (clean hands) slide the disc onto the input shaft, remove disc, index and repeat several times to distribute the grease. Wipe off any excess grease. The grease is to help prevent corrosion that forms after many years of service. The corrosion inhibits the discs ability to slide freely resulting in hard gear selection from a standing stop.



The grease must hit the friction surfaces to really be a problem. I look at the ID edges of discs, pressure plate castings and flywheels for contact. I also look at rivet pockets for facing dust that has formed "muck" in the pockets from contamination binding it together.



The big NO NO is using any type of anti seize on input shafts, that stuff does not stay put when the shaft spins.



Good luck.