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This TH400 in the '73 is about to come out and the pre-70s M20 to take it's place. Instructions say a Driveshaft and Slip Yoke are needed. Why?
I'm assuming different numbers of splines between the two make the M20 Slip Yoke necessary.
But is a different shaft necessary due to different lengths? Is the TH400 Driveshaft and an M20 S.Y. incompatible?
Thanks for any insight on this folks.
Steve
P.S.: Was St. Louis really that sloppy in the application of Firewall coating?
[QUOTE=Cavu2u;1603967600]Got a question on Driveshaft differences.
This TH400 in the '73 is about to come out and the pre-70s M20 to take it's place. Instructions say a Driveshaft and Slip Yoke are needed. Why?
I'm assuming different numbers of splines between the two make the M20 Slip Yoke necessary.
But is a different shaft necessary due to different lengths? Is the TH400 Driveshaft and an M20 S.Y. incompatible?
Thanks for any insight on this
This is really interesting. I reasoned just like you when I’ve did this swap so I reused the driveshaft that came with the th400. Bought a yoke that fitted my munche and put it together..
I got some small vibrations all over the rpm register but the thing is i got em even when in neutral and revving.
That makes me believe that my clutch not is 100% centered and that my driveshaft/yoke setup actually works.
This is really interesting. I reasoned just like you when I’ve did this swap so I reused the driveshaft that came with the th400. Bought a yoke that fitted my munche and put it together..
I got some small vibrations all over the rpm register but the thing is i got em even when in neutral and revving.
That makes me believe that my clutch not is 100% centered and that my driveshaft/yoke setup actually works.
Thanks Fredric!
The factory service manual has the same driveshaft part number for both manual and automatic transmissions, so I questioned the need for another one for the conversion.
Thanks much.
Best idea is to do the swap and then check the driveshaft length. I don't remember what yoke fits which tranny anymore, but again you could easily check yours. My one recommendation would be - even if the DS works I would take it in & let a DS shop replace the U-joints with quality USA made parts and have them re-balance the whole unit.
Best idea is to do the swap and then check the driveshaft length. I don't remember what yoke fits which tranny anymore, but again you could easily check yours. My one recommendation would be - even if the DS works I would take it in & let a DS shop replace the U-joints with quality USA made parts and have them re-balance the whole unit.
That's a great Idea!
I replaced the rear half-shafts a few years ago (whew!) with Spicer products, but did nothing with the "Propeller" shaft. Will take the shaft in and have 'em balance it.
Thanks.
In my swap of 71 th400 to Muncie, I actually had access to an original driveshaft of a OEM manual car and upon comparing the manual driveshaft to the auto, they were exactly the same length. The Autogear Muncie that I installed had a 32 spline output shaft which uses the same yoke as the th400. So I just reused my auto driveshaft that already had new u joints install recently. No issues so far
When I installed my Richmond 6-speed it uses a Turbo 400 output yoke and I mated it to the M-21 driveshaft yoke using the following conversion u-joint (I think you're doing the same thing by the opposite way??.... anyway, in case that's what it is). I installed a Richmond ROD with a TH400 32 spline slip yoke GM part number 3930827...and I mated it to my former M-21 driveshaft with the following conversion U-joint:
Spicer 5-134x or TRW 20056
Part numbers are from my records and 20+ years old but looks like they're good.....
Auto to 4-Speed Conversion Driveshaft?
