61 Drive 1pc shaft ?

[Surfdaddy]

I was working on the seals of my Hydromatic and had to pull the trans out. I never looked at the drive shaft until then, but I found that it’s a single piece drive shaft without a slip yoke on it. The output yoke on the trans did not have a bolt and washer on it and there is a tapped hole which looks like maybe a 5/16 or ½ 24 screw. It looks like has maybe 2 inches of movement on the yoke but I’m sure it would was not designed to move. On all my other trucks from this time (63 GMC ½ ton and 64 Carryall) I always had a 2 pc drive shaft with a carrier bearing. But this is the first I have seen a Hydromatic and don’t know if it’s wrong or not.

[jbgroby]

Surf,

What you have is correct. The Hydra-matics came from the factory with a 1 piece shaft.

Jake

[Surfdaddy]

How do they figure out the slip yoke. It dosen't look like ther is enough play to allow for the full movement of the suspension. Remember this truck had a 10ft camper on it for it's whole life and was near the stops. I would think that there would be a bolt to keep the yoke on the output spline of the trans. I don't have a Hydra-matic manual and the service manual does not specify what shaft goes to what truck combo.

[awbrown]

You can't bolt the trans yolk on a 1 pc shaft , it has to have movement ... if it were a 2 pc then the shaft could be bolted , but even then the center bearing will center trans yolk and the slip joint in the driveshaft will allow movement when the rearend goes through it's travel...so there are 2 pc shafts that are not bolted .. mostly on th400.. oh by the way , when I used to make drive shafts I looked for about 3/4 - 1 inch clearance between the yolk and the seal surface (push it all the way in and pull it out that amount before measuring for a drive shaft ... Hope this helps...

[Surfdaddy]

I agree there has some thing that allow the shaft to slip. I just thought there would be more than 1-2 inches of slide on the output shaft yoke. I know it's been working for 50 years but I didn't know if the P.O. had the shaft modified and it wouldn't work unloaded. I just never have seen a single drive shaft on these trucks before and it kind of freaked me out.

[awbrown]

I had a 72 C-10 that I grafted a 57 3/4 ton international rear half to to make a wrecker , this was in the mid 80's and I made a 1 pc shaft that was 78 inches long , it worked fine ..even thought the frames were different widths.... I later put a 67 nose on it and cut it behind the cab and grafted a short bed to it ..fun truck ...

[jbgroby]

I have some pictures here that may help, I can take a few of the set up right now if you need, but it is the same.

http://rides.webshots.com/album/570438270cjSEvE

[Surfdaddy]

Thanks. I was conserned about the rear seal leaking. It seems that I'm worring about nothing. I'll just put it all back together and see what happens. The orig owner really kept good records but I really don't trust some of the shops he went to back in the day. The trans had the seals replaced in the mid 70's. Mark C Bloom did the trans work and they went out of business in the late 70's early 80's and they were mostly a tire shop. So, I didn't know what they cluged together. Some of the seals were ok they looked like they were changed at some point but the reverse seal looked like it was made out of bakealite plastic it was so hard and brittle.