Drive shaft wanted !

[DartThis74]

Hello all, I'm in need of a drive shaft that will fit in a '74 Duster and hook up to the small block(360) 727 transmission and 8 3/4 rear end. Thanks for any help !!

Located in Central Texas (76579)

 

[physixx]

I have one that came with a 72 340 Duster that I just picked up. The car had an 8 3/4. Would you be able to get the U-joint center-center dimension? The one that I have is 45" with the small U-joint and a 727 trans yoke. May not from this car but it was in the trunk when I got it and looks to be the right one.

Ken
Edison, NJ
[email protected]

 

[crackedback]

That should be the correct driveshaft that Ken has on hand.

 

[72 slopar]

If not I got good one you could have cut down. Set up for 727, but a bit long.

 

['74 Sport]

Can someone please explain the "small U-joint" comment? Aaron's '69 B-body 8-3/4" rearend has a 489 carrier of unknown vintage. Also, what is the diameter and spline count of the correct yoke for a 727?

Jerry

 

[physixx]

The 2 common U-joints that are used are referred to as the small and the large U-joint. The small U-joint pinion yoke measures 3 5/16" at the U-joint saddle of the yoke while the large one measures 3 7/8" at the yoke saddle. The cup sizes are also different and are not interchangable.

The trans yokes differ between the 904 and 727 in the outside diameter and the spline count. The 904 is 1.560" OD with a spline count of 26 while the 727 has a 1.680" OD and spline count of 30. If you look inside a trans yoke you'll most likely only count 25 or 29 splines but there will be one spline not cut into the yoke from the factory.

I hope that this helps.

Ken

 

['74 Sport]

Thanks, Ken, exactly what I was needing to know.

The next thing I need to understand is where to take measurements for a driveshaft length, especially since we are missing one entirely. I figure its to the center of the U-joint saddle on the pinion yoke. I'm not sure where on the transmission end.

Jerry

 

[6pk2goDemon]

I believe driveshaft length is measured from center of u-joint to center of u-joint.......the yoke takes up the slack.

 

['74 Sport]

Cheryl, my problem is I don't have the 727's yoke to slip onto the transmission's shaft to take a measurement. Is there a "standard" point of reference, like the end of the shaft or the face of the seal, to get a measurement to the pinion U-joint, then add or subtract a specified amount for the slack factor?

 

[physixx]

I measured the distance from the center of the U-joint to the yoke seal face on a 727 and it measures 2 1/4 inches. If you slide the yoke out 1 inch to allow for movement, the U-joint center would then be 3 1/4 inches. If you measure the face of the rear pinion yoke where the U-joint straps attach to the trans seal face (end of output shaft housing) then take 3 1/4 inches off that measurement, you should have your dimension.

Ken