HELP TH400 tailshaft question?..pics included

[darthvegagt]

I have a TH400 like the one pictured that has a fixed yoke rather than a slip yoke. I got this transmission with a 454 as a package deal for my 69 camaro. I know that I need to change the tailshaft and output shaft in the trans but does that involve tearing down the whole trans? Or can this be coverted to a slip yoke with minor work? The trans has a lot of work done to it and I would definately like to adapt it with the least work. Can this be done easily or will it be more hassel and money then what its worth? Should I start looking for another trans.? Any ideas or help would be great. Thanks Jordan

[Josh]

Are you talking about a yoke that has the bolt through the center? If so then you have little work to do. Buy a yoke out of a passenger car and slip it on. I had a bolt-on style one that came out of a truck and that is all I had to do.

[darthvegagt]

yes it has a bolt through it. I was told that it must be counterbored to fit the threaded output shaft.Below is what I was told. Sounds to me like they know what there talking about. I just need to find one somewhere to buy now. anybody know of a website that has one, anyone have a link??

"The Th400 output shafts used in trucks with a bolt on yoke have an o-ring and a raised portion just ahead of the splined portion, this will cause a regular passenge car yoke to bottom out on the raised ring portion.
The "conversion" yoke is counterbored to fit over this raised portion, and still have enough spline engagement and travel."

[Texas Hotrod]

I agree with Josh.
My tranny came from a 3/4 ton Chevy truck and it had the bolt-on yoke. I just installed a slip-in yoke and didn't think anything of it, it worked fine. I have seen some TH400 yokes that are longer w/a counterbore. A friend of mine tried to use one and it placed the u-joint too far rearward (but it wasn't a bolt on type). I chucked it in the lathe, cut off the counterbore portion and it worked fine.
In some applications, the counterbore seals w/the o-ring, which lessens the chances of having a fluid leak.
Most slip-in yokes have a "master spline", which I understand gives fluid trapped between the end of the output shaft and the inside of the yoke a path to excape from, during suspension travel. Otherwise the output shaft would be crammed inward (hydraulicing), resulting in tranny trashing.
So, if you're shopping for a slip yoke, look for one that has a missing spline.

[Texas Hotrod]

I agree with Josh.
My tranny came from a 3/4 ton Chevy truck and it had the bolt-on yoke. I just installed a slip-in yoke and didn't think anything of it, it worked fine. I have seen some TH400 yokes that are longer w/a counterbore. A friend of mine tried to use one and it placed the u-joint too far rearward (but it wasn't a bolt on type). I chucked it in the lathe, cut off the counterbore portion and it worked fine.
In some applications, the counterbore seals w/the o-ring, which lessens the chances of having a fluid leak.
Most slip-in yokes have a "master spline", which I understand gives fluid trapped between the end of the output shaft and the inside of the yoke a path to excape from, during suspension travel. Otherwise the output shaft would be crammed inward (hydraulicing), resulting in tranny trashing.
So, if you're shopping for a slip yoke, look for one that has a missing spline.

[Madspeed]

They are both right bud
the person you think knows his Crap does not know crap at all
get the yoke without the counter bore for an oring amke shure it has one spline missing as stated by Tex
Makle shure it is sealed at the end and your all set
I too had the same truck trans in a 69 BBc camaro as well as one connected to a 205 TCase in my 72 blazer also BBC powered