7260 to 1310 slip yoke

[66coronet500]

If you swap a 29 spline 7260 slip yoke on a 1966 small block a727 to a 29 spline 1310 slip yoke would the driveshaft length need to change? Also changing the end of the driveshaft to a 1310 so no conversion ujoint would be needed.

 

[67 coronet]

just measure your two slip yolks,or compaire them.as long as they are the same then no need to change shaft length.remember to check center of u joint cap to slip end for measurement.

 

[66coronet500]

That is part of the question. My 7260 slip is 9" from center of cap to end of tube, the 1310 is 8" from center of cap to end of tube. I will put both in the tranny and test fit. Just dont know yet what part of the slip yoke stops on when you slide it into the tranny. All the 7260 slip yokes being sold know are 8" center cap to end of tube. Not sure why mine is 9".

 

[66coronet500]

Put both yokes into the tranny over the weekend to measure. The 1310 sticks out 3/4 " more than the 7260 yoke. To me that would change the length of the driveshaft. Anyone know anything about the 9" long 7260 yoke? I know there is an inner seal on the output shaft but is the 9" tube length needed for that seal or would a shorter tube be ok?

 

[67 coronet]

if you are already changing the end,i would shorten the shaft the diff in length between the two.that would be the safe way to go to prevent any sort of potential binding and subsequent breakage.

 

[chignikred]

I see 4 implied questions going on.
1...Conversion U joint, yes they exist, large plus small to downsize to the 29 spline.
2.. If you are switching to a 29 spline trans output doesn't that imply you are changing to a 904 trans??? If so your output lenght will be shorter than a 727 and you need a longer drive shaft.
3...Yoke lenghts vary and really isnt the issue. Amount of spline slide inside trans is designed to allow springs to flex and body to rise and sink. You never make drive shaft lenght so that yoke is hard against end of mainshaft.
4...Comment about a 'seal' on mainshaft is likely mis-information, BUT is actually true on one year only -1965 slip yoke trans. That was done away with in 66, and as a note, 65 yokes have a tiny vent hole at end which is required with that seal on shaft.

Red

 

[66coronet500]

Was trying to stick with the 7260 setup on my orig driveshaft. Car is lowered so when the rear slip yoke seal let go I checked how much travel the slip yoke had. pushed it in till stopped then it cam out about 3/4 of an inch so I figured i would take off 1/4 of an inch, remove the inertia ring and high speed balance the shaft. found a wear mark on the slip yoke so the driveshaft place was going to put a new 1310 slip yoke and 1310 mating end on my driveshaft, so no conversion joint would be needed. so I took the 1310 slip yoke and pushed it into the tranny until it stopped and measured from tranny to end of slip yoke and it measured 3 3/4 vs my 7260 that measured 3. decided too many changes going on so had a new driveshaft made, new 7290 slip yoke, 3 inch driveshaft and a 7290/7260 on the other end as my 489 case has the 7260 yoke on it. gave needed dimensions to driveshaft place, 55 inches from tranny to rear pumkin yoke with car on the ground, output shaft stick out 1 1/4 past tranny housing. new driveshaft came and center to center on ujoints is 52 vs 52 1/4 on orig driveshaft. need to check how much travel the slip yoke (7290) has as the driveshaft seemed tough to get into rear yoke. I think the orig 7260 yoke which is 9" goes into the tranny further than these new yokes do. the tranny is an orig 727.