Drive Shaft: Driveshaft Length Question: '64 Hardtop w/ 4 spd

[t1003nl]

I'm restoring a '64 Daytona hardtop and have replaced the original 3 spd auto trans and Dana 27 rear axle with a T10 4 spd and a Dana 44 axle. I have a donor driveshaft from a 4 spd Hawk that is set up for Spicer u-joints. It needs to be cut down in length to fit my car. The Chassis Parts Catalog lists driveshaft 1561901 which has a length of 51 29/32" for a '64 hardtop w/ 4 spd and Dana 44 axle.

When I insert the yoke in the trans I line it up to a mark left where the rear trans seal contacted. When I measure from the centerline of the yoke u-joint to the centerline of the axle u-joint I get 50 5/8". If I push the yoke in until it bottoms, I can almost get the Chassis Catalog dimension of 51 29/32". I'm worried if I get the driveshaft cut down to 51 29/32" it will be too long and will bottom out the yoke in the trans. I'm taking measurements with the chassis supported by jack stands on the frame and the axle is hanging unsupported. This looks like it should provide the longest distance between the two u-joints (see pic below).

I'm leaning toward cutting the shaft to 50 5/8" and rebalance but I wanted to run this by the Forum for thoughts in case I'm making a mistake. Thoughts?

Thanks!

Neil

[BobPalma]

Neil: Can you physically take the car to the shop where you are going to have the driveshaft length changed? That's really the thing to do, even if it means trailering a dead car you cannot drive.

The shop will know what they are doing. Let them put the car in the air supported by the wheels, as it should be for such things, and they can measure and fit the driveshaft just right no matter what the final length needs to be.

That is the thing to do, instead of trying to second-guess a length and wind up its being wrong. BP

[JDP]

The chassis parts book lists drive shaft lengths.

[studegary]

It sounds like you are trying to use the length for a 4 speed with a 27 axle (if they offered such a weird thing) instead of a 4 speed with a 44 axle.
Do not fit the driveshaft at the longest possible dimension.
As Bob P. stated, have the shaft fitted to the car by driveshaft professionals.

[tbirdtbird]

The correct way to measure for a new driveshaft is to have the car OFF a frame lift or jackstands, with as much on the car as is supposed to be there, meaning all sheet metal, gas tank, etc, all the usual weight on the car. Tank need not be full and you don't need passengers. Now slide the slip joint all the way into the back of the tranny until it bottoms out. Now slide it out (back) 3/4 of an inch. Drive shaft shops usually want the weld-to-weld distance, meaning where the ends of the shaft are welded into the tube. With the shaft slipped back 3/4 inch you can determine your weld-to-weld distance. You can confirm this method with your shop, it is what I have used for years, or take the car there as stated

[sweetolbob]

I'm restoring a '64 Daytona hardtop and have replaced the original 3 spd auto trans and Dana 27 rear axle with a T10 4 spd and a Dana 44 axle. I have a donor driveshaft from a 4 spd Hawk that is set up for Spicer u-joints. It needs to be cut down in length to fit my car. The Chassis Parts Catalog lists driveshaft 1561901 which has a length of 51 29/32" for a '64 hardtop w/ 4 spd and Dana 44 axle.

When I insert the yoke in the trans I line it up to a mark left where the rear trans seal contacted. When I measure from the centerline of the yoke u-joint to the centerline of the axle u-joint I get 50 5/8". If I push the yoke in until it bottoms, I can almost get the Chassis Catalog dimension of 51 29/32". I'm worried if I get the driveshaft cut down to 51 29/32" it will be too long and will bottom out the yoke in the trans. I'm taking measurements with the chassis supported by jack stands on the frame and the axle is hanging unsupported. This looks like it should provide the longest distance between the two u-joints (see pic below).

I'm leaning toward cutting the shaft to 50 5/8" and rebalance but I wanted to run this by the Forum for thoughts in case I'm making a mistake. Thoughts?

Thanks!

Neil



[ATTACH=CONFIG]12153[/ATTACH]

Neil

If you can't take the car to the shop, stop by there and have them describe how they want you to measure the length of the shaft and clearance for the yoke. That way when you get it back it will fit correctly.

That way you are speaking the same language and no assumptions.

Hope it's on the road quickly.

Bob

[Studebakercenteroforegon]

Years ago, I changed a '63 Daytona station wagon from a straight 3 speed to a 4 speed T-10. The shorter 4 speed required a longer drive shaft, so I gave the drive shaft maker the length dimensions as stated in the Chassis Parts Catalog - and it fit perfectly.

[t1003nl]

This is good input. I will hold off getting this cut until the body is back on the frame. Then I will trailer the car to the shop and let them do the measuring. I want to do it right so I'll let the experts at the shop make the call.

Thanks everyone!

Neil

[Studebakercenteroforegon]

Good idea not to be in any rush on this. But do note all the arch in the unloaded springs in your picture. Yes, it does move the yoke down some, but also a lot farther forward that it will be with the nomal weight on them. I bet when all is complete, you will find that the specified 51-29/32" length will be correct. As an alternative to having a new drive shaft made, I see that Hawks (C-K, '60 - '62) with automatic transmissions also use a drive shaft that is 51-29/32" long. Part numbers are different since the shaft tube diameters are smaller than the 4 speed version, but I don't see that as a big issue for what I assume will be a street driven car. In the world of used Studebaker parts, a Hawk drive shaft from an automatic should be easy to locate. It looks like your existing drive shaft has Spicer u-joints so you would need to be sure you got the same type, since you will have to retain your 4 speed slip yoke.