Lengthening a '30 Ball and Trunnion propellor shaft

[Gunsmoke]

By way of introduction, I am fitting a '30 DC8 transmission, propellor shaft and rear differential in a '31 Chrysler CD8 chassis, boltted up to a CD8 Engine. Everything mates up well. However,the wheelbase on CD8's is 124" and is 116" on DC8's. So the ball and trunion style propellor shaft/driveshaft is about 4"-5" short and needs to be lengthened accordingly.

 

I am trying to determine proper length to get it made. As you may know, these shafts have ball and trunnion sliding joints each end, and a spring each end to keep the shaft from sliding easily back and forth and to also allow for some flexing of chassis. So my question is how do I establish the correct length to have the shaft made. I have installed one end on the transmission and bolted that end tight, and with the spring in place, there is about 1/2" of movement when shaft is pulled or pushed to limit. My logic suggests to me that the normal resting length would allow for 1/4" of movement in either direction (in or out) at each end. In other words if the shaft was pushed in tight at one end (that spring fully compressed), there would be 1/2" play at other end, and vice-versa. Any one have experience in fitting one of these?    

[moose50]

My experience is in shortening these shafts.  Are you planning on doing it yourself, or taking it to a shop?  I've done both ways.  Shortening is not as hard to do or as critical as adding material.  I would suggest you take this to a shop to be lengthened.  Then all you would need to do is tell them an exact length between the flange on the transmission and the one on the rear axle.  They will know what to do.

[Taylormade]

This is the setup on my 32 Dodge DL.  The splined shaft on the end of the driveshaft slides inside the ball and trunnion assembly that attaches to the transmission.

 

The drive shaft with the splined end to the left and the differential ball and trunnion to the right.

 

 

The splined end.  The round object at the right end of the spline is the shaft seal that screws onto the transmission end ball and trunnion.  As far as I can see, this sliding shaft takes up the movement and distance as the car is moving.

 

 

This is the transmission end which bolts directly to the fitting on the trans output shaft.  You can just see the threads at the top where the seal screws on.

 

 

 

I assume your driveshaft has a similar setup.  If so I will measure the distance between the trans and the differential from flange to flange and compare it to the length of the driveshaft.  The only problem is that I don't have the engine in the frame yet and it may be a few weeks before it's ready to drop in.  One thing my Owners Book makes very clear is that these shafts were balanced at the factory and that they must be put back in the position they were originally installed.  My shaft has markings for this purpose.  I'm not sure what steps you will need to take to get the shaft back in balance after the new section is welded in.

 

Another option is to have new, modern u-joints adapted and a new axle made.  I know it's not original, but parts for these old ball and trunnion joints are hard to find and I have no idea what kind of shape of yours are in.

[Silverdome]

Set the ball & trunion end in middle of its travel then put the splined end in the transmission and attach the seal. Slide it in and out to measure the distance of travel on that end. Set that end to the middle of its travel. Measure from the flange on the ball & trunion and the flange on the rear end. That distance will be the what you need to lengthen it. The tube between the splined end and ball & trunion will have to be replaced by a longer tube that is specifically made for drive lines, DO NOT just add in a section of tube. It shoudn't have to be balanced if attention is paid to lining up the splined end and the flange end plus when you put in the new drive line tube you indicate everything in so that is running true. At work we do this on an old lathe that has been converted for this.

[Gunsmoke]

The driveshaft I have has ball and trunnion on both ends, identical set up each end, can be put in end for end wither way, 4-bolt plate both ends. So it has the springloaded B&T joint each end, no splines, just a pair of original laced leather boots. I had a machinist who has done work for me before on old car stuff come by this evening and he has lengthened such shafts before, took the necessary measurements and so we will see.

[Taylormade]

I'm surprised a setup like that has enough movement to work properly. But I'm surprised by a lot of things these days. As always, let us know how it all works out. You certainly have your share of interesting problems with your hybrid roadster.

[ply33]

The driveshaft I have has ball and trunnion on both ends, identical set up each end, can be put in end for end wither way, 4-bolt plate both ends. So it has the springloaded B&T joint each end, no splines, just a pair of original laced leather boots. . . .

Sounds like the standard Dodge/Plymouth product driveshaft used from at least '33 through the 50s. Not positive, but I think the '61 Valiant we had back in '61 to '63 still had very much the same driveshaft as my '33 Plymouth. The main shaft is spring loaded to be in the center and there are no splines, etc., just a ball & trunnion joint at either end with the housings for the joints such that they allow the shaft to move fore and aft. The biggest change in those years was switching from leather boots to rubber boots.

 

 

I'm surprised a setup like that has enough movement to work properly.

 

 

I was expecting your driveshaft to be much the same as was surprised at the photos, yours is quite a different beast than mine even though the cars are only a couple years apart.

 

Seems like they used a more conventional cross type universal joint with a splined drive shaft on some of the Chryslers and DeSotos as well as some of the trucks. But the plain jane Plymouths kept that ball & trunnion with floating shaft for a lot of years.

[nzcarnerd]

I believe that ball and trunnion set up was used in the Australian Chrysler Valiant until the VC model of 1966-7.  I know of local people here in NZ who have used these drive shafts to update their early Plymouths.

[Silverdome]

The driveshaft I have has ball and trunnion on both ends, identical set up each end, can be put in end for end wither way, 4-bolt plate both ends. So it has the springloaded B&T joint each end, no splines, just a pair of original laced leather boots. I had a machinist who has done work for me before on old car stuff come by this evening and he has lengthened such shafts before, took the necessary measurements and so we will see.

I'm sorry i guess I didn't read your original post close enough and mistook Taylormades pictures to be what you had. To get the correct length you will have to have the transmission and rear end mounted in the frame in the correct position then measure the distance between the two flanges and that's how long your drive shaft should be. Everything else I wrote applies like using the correct drive line tubing and aligning the bolt holes on the flanges plus indicating everything in.

[Taylormade]

I was expecting your driveshaft to be much the same as was surprised at the photos, yours is quite a different beast than mine even though the cars are only a couple years apart.

 

Seems like they used a more conventional cross type universal joint with a splined drive shaft on some of the Chryslers and DeSotos as well as some of the trucks. But the plain jane Plymouths kept that ball & trunnion with floating shaft for a lot of years.

 

 

 

Only one year apart.  Interesting that they went with two different setups.  My 29 Model U had fiber disks for driveshaft joints.  As I remember my 48 Plymouth P15 had a setup like yours.