SBC no longer disengages

[Vaughn MacKenzie]

I've had my ol' beasty 1996 2500 4x4 since July 2004. In 2005, at 360,000 miles, I rebuilt the transmission and installed a South Bend clutch, ConOFE as I recall, upgrading to the larger flywheel. I installed SBC's roller pilot bearing.

The clutch has worked perfectly since then, until lately at 494,900 miles it suddenly stopped disengaging properly. Dang, 500k was looming not too far on the horizon. It only disengages slightly, you cannot get it in gear at a stop and shifting is heavy once rolling. I had just gotten back from a fairly long camping trip with the truck, thank goodness it didn't happen in the woods 300 miles from home.

We tried bleeding the slave cylinder, then replaced it, but I am fearing the pilot bearing suddenly failed. The truck had been out of order and parked for 3 years, but I have driven it 12,000 miles since it's been back on the road. Hoping I'm not looking at a trans R&R to replace the pilot bearing, but give me your thoughts. I have only driven it briefly a couple times, I know a bad pilot can mess up the nose of the input shaft and create a much more expensive problem.

 

[GAmes]

Pilot bearing was the first thing I thought of. Of the clutch linkage I've had fail it was possible to "pump them up" to shift. I've never tried to replace the slave, always the whole assy.

 

[jdross440]

Mine did the same thing with only 22000 miles on the second SBC that was upgraded to the 13". When the transmission was pulled, the clutch plate had worn into the flywheel and was worn out. It wouldn't release completely either as it was partly sticking to the flywheel. My first SBC only lasted 32000 miles and it wasn't being used to tow more than 6K pounds. Mostly just a daily driver. After 2 failures that close together I said I would never use a SBC clutch again.

 

[KATOOM]

If its been working perfect for over 100k miles and then all of a sudden problems, I would lean towards the hydraulics. Especially if its been sitting for a long period of time. Yes a pilot bearing will cause engagement problems but an easy diagnosis is to park on a level flat surface. Start the engine in gear and continue holding the clutch in. If the truck wants to roll then its not the pilot bearing because the small pilot is can not offer enough resistance to move the truck. Only a dragging clutch plate can...

Do you have the OEM hydraulics or the SB hydraulics?