ZF6 input shaft

[hntngkd]

Well finally got to drive the truck today, I did 2 good 6th gear pulls at 70 mph. The tires broke loose a little bit and I learned that I need a bigger boost gauge. Slowed down at a stop sign went to take off and it was like the clutch wasn't pushed in at all, it did not want to go into gear. But you can hear the clutch chatter when you push it in. Im thinking I twisted the input shaft so im looking for some ideas on where to get a billet one or somewhere that could make one. Ive heard cryo-treating helps but I don't know that it would help enough. It is an 8000lb truck after all. Any input is greatly appreciated.

[diesel-max]

The pilot bearing probably fell into the crank shaft. It's a south bend problem. Unless it's one of the newest style that I think they FINALLY updated to have a lip holding the bearing in. It only took me 3 years of arguing with them about that problem.

I've been through this a number of times. It would do something similar as well. All of mine since have been tig into place.

The inputs are tough, I've seen some hard abuse and they keep on going. I'm not foreseeing that being your issue at all. I'm betting clutch related for sure.

[zf>allison]

If you put it in gear while it's not running and start it with the clutch in what does it do? Disc could maybe be stuck to the flywheel as well.

[hntngkd]

Originally Posted by diesel-max

The pilot bearing probably fell into the crank shaft. It's a south bend problem. Unless it's one of the newest style that I think they FINALLY updated to have a lip holding the bearing in. It only took me 3 years of arguing with them about that problem.

I've been through this a number of times. It would do something similar as well. All of mine since have been tig into place.

The inputs are tough, I've seen some hard abuse and they keep on going. I'm not foreseeing that being your issue at all. I'm betting clutch related for sure.

Ill have to check that out when I pull the trans. Why would that make it hard to get into gear though?

[hntngkd]

Originally Posted by zf>allison

If you put it in gear while it's not running and start it with the clutch in what does it do? Disc could maybe be stuck to the flywheel as well.

It starts up fine doesn't lurch forward or anything that I noticed but it does make a whining sound as soon as I get it into gear. Sounds ridiculous like somebody just started a giant shop vac. I was sitting at a light trying to get into gear and its so lloud the guy next to me thought I was reving my truck at him.

[hntngkd]

Sent from my SM-N920P using Tapatalk

[zf>allison]

I would think an input shaft would vibrate in neutral with the clutch engaged because it would be spinning it. I put a clutch disc in backward and it made alot of strange racket but didn't hold power. Seems like when your synchro starts engaging and spinning the other shaft in the trans it makes the noise. I'm interested in knowing what happened.

[zf>allison]

Does it make that noise when you put in in every gear?

[hntngkd]

Yes it does

Sent from my SM-N920P using Tapatalk

[zf>allison]

It is strange because if you are on flat ground and hold the shifter against a low gear hard like that usually the truck will try to roll, I had a slave cylinder go out more than once in my old 6.2 turbo half ton and that's how I got it home. Held it against gear and it got rolling enough to pop into gear. Hell on the synchros though.
Try putting the t case into neutral and see if the trans will go into gear. These transmissions are tough but that's alot of power and weight you got. I hope it's something simple.

[CarolinaHD]

You ever get time to look into this?

[hntngkd]

Finally got the truck apart. Wasnt exactly what i thought it was which is good. South bend had accidentally put the wrong hubs on the discs so the input shaft wasnt fully engaged on the splines. I took it to UCC with me and gave it to the guys at the south bend booth. They fixed it and shipped it back to me free of charge.

Sent from my SM-N920P using Tapatalk

[zf>allison]

I had a dual disc do the same thing but it's because I put the front disc in backwards.

[hntngkd]

Originally Posted by zf>allison

I had a dual disc do the same thing but it's because I put the front disc in backwards.

that's almost what I thought I had done at first but I don't think I could have put it in backwards if I wanted to. The all pilot into each other.

[zf>allison]

Originally Posted by hntngkd

that's almost what I thought I had done at first but I don't think I could have put it in backwards if I wanted to. The all pilot into each other.

That's how mine was to but the front disc the hub stuck backwards off the disc. So when I turned it around it was sticking forward and the input couldn't reach it all the way and I had about the same damage as you. They hooked me up pretty good for it being my fault.