Automatic C6 question

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Dec 22, 2017 | 03:36 PM

ClintonA

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Automatic C6 question

76 hiboy with 390 automatic C6

I had been getting weird drive train vibration above 30mph. I went under the truck and found my output shaft has a lot of play and leaking. Never been inside this transmission before. I get a new bushing and seal pop open the tailstock and find the bushing doesn't even touch. The output shaft still has the same play. I read some places the output shaft is like the last thing you take out on a rebuild.

What can I do? If it's a transmission rebuild it's a transmission rebuild in my future.

Thanks for reading.

Dec 22, 2017 | 05:31 PM

77F250Diesel

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Sorry but it's a complete tear down to get to the output shaft.

Dec 22, 2017 | 06:45 PM

ClintonA

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Alright, before I decide to drop it and rebuild it, is the up and down play normal? I will put it all back together with a new bushing and seal and see if it is better.

Dec 22, 2017 | 09:04 PM

somethingclever

Cargo Master

Joined: Dec 2008

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From: SW PA

Can't hurt to throw a bushing and seal at it....although I believe that is just a dust seal.

If fluid is coming out then I believe you have another seal issue of possibly way over full?

Been a while since I had a c6 apart.....

Dec 22, 2017 | 10:24 PM

1976 f-250

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From: Mokelumne Hill

The seal rides on the slip yoke. So if that has been removed then yeah the bushing will not touch the output shaft itself. Try that new bushing on the slip yoke.

Dec 24, 2017 | 08:29 AM

F-250 WARHORSE

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From: starship enterprise

"IS UP AND DOWN PLAY NORMAL?" WHAT? what kind of question is that; no it isn't. if there is oil in there, it needs to not move very much or the oil won't be in there anymore. just like every oil reservoir. I would suggest it is on borrowed time, seeing as how the splines have wear now from running loose, but that is my survey of the damages.

Dec 24, 2017 | 11:04 AM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

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From: SE Florida

The up and down play is normal if the slip yoke is not installed. The bushing in the extension housing rides on the slip yoke, not the shaft, so if the slip yoke isn't there you have a lot of open space that lets the output shaft move.