question: chevy TH400 yoke question

[plan9]

i was reading Rod & Customs "UP FRONT" by RIZ, (fun read by the way), and it was said that the TH400 he was running in the RPU was from a truck.. these trannys apparently use a fixed yoke drivesahft, not a slip-yoke type.

my question(s) is, how do yo go about identifying a truck 400 over an automobile 400? what kind of trucks used this type of yoke and do TH350's have this attribute as well?

when you think youve got a clue, something else comes along to kick your ass right back into cluelessness http://www.jalopyjournal.com/ubbthreads/images/graemlins/wink.gif

thanks!

[Verbal Kint]

plan9,

My '70 chev truck came with the fixed yoke TH400. Although I'm not sure it was stock for the truck. The truck was pretty hacked up when I got it. The yoke/tail piece was changed out for the slip when I had it rebuilt. The yokes also come in 2 different diameters, I learned that the hard way and did a nice job of undercoating the truck with tranny fluid on the way home.

swdobbs

[FKNPOZER]

ok here we go.

the "basic" differances are:

the truck th400 has the center of the output shaft threaded in order to accept the bolt for the yoke.
you can use a "slip" yoke (no hole for bolt) on a threaded shaft but not the other way round.make sense?
then there is the mounting of the u-joint.are they c-clips on the inside of the yoke? or out side of yoke.
the th350 yokes are a smaller diameter than the th400 on the shaft.
then buick,cad and olds decided to use thier th400 with a different shaft diameter also.(go figure)
Ive run into about 8 configurations on yoke and u-joint combos for gm .
hope this helps http://www.jalopyjournal.com/ubbthreads/images/graemlins/smirk.gif

[38Chevy454]

I'm not sure about this truck vs car shit, but I do know there are different yokes for the early vs later turbo 400. The early ones have the same spline on the output shaft as the later, but the wall thickness is thinner. Most turbo 400 use the later thicker wall yoke. I think it is only the mid 60's that use the thin wall yoke. BTW, there is a different seal obviously used depending on the yoke.

[DRD57]

As someone already said, you can tell the difference by the threaded hole in the end of the tailshaft.

You can use a slip yoke on a truck transmission. However, it will not slide in as far as it does on a passenger car transmission so, you may have to cut the end of the yoke off or have the driveshaft shortened.

[plan9]

excellant info guys, thanks ...ive got a 400 with a bolt at the end of the shaft... this answers the question as to why it was there in the first place.

terry - i need to give you a call about billetproof, ill be in touch soonish (like tommorow http://www.jalopyjournal.com/ubbthreads/images/graemlins/wink.gif)

[Scott]

Just answered my question as have many old posts on the Hamb.