according to the service manual I was supposed to mark the shaft 6 years ago when I started the MAW. Its time to start reassembly and there are weights on both ends of the shaft but not sure if it makes a difference. Any help would be appreciated.

 

It should not make a difference, the drive shaft is independently balanced.

 

I believe the "slip joint" end (Right side in the pic) goes towards the rear. Look down the shaft and make sure the u-joints are "in-phase"(parallel). The two piece automatic shafts are known to twist out of phase. It will effect the balance.

Edit Clarification...when I said slip joint above I was referring to the two piece drive shaft interface. Automatic Olds of certain years had a two piece driveshaft where they inserted a smaller diameter tube into a larger tube with a rubber sleeve in between the two. That joint is biased towards the pinion yoke or the rear axle. The design was to reduce drive train noise, as Olds was noted to be a level above Chevy in this manor. With a hard shifting automatic, high performance upgrades and or age these two shafts can rotate in relation to each other. Thus becoming twisted "out-of-phase" in relation to the ujoint yokes. Always verify Ujoint yoke phasing with these two piece shafts. I know for a fact my automatic 68s all had the two piece shaft. It appears that practice went through at least 70. Not sure about 71-72 and beyond or before 68. The stick shifted cars received the one piece shaft tapered down on both ends. Olds and everyone else knew that the stick cars were harder on the drive train.

 

thanks guys I didnt think it made a difference

 

I always thought the driveshaft and pinion yoke were balanced together. True or not - two weeks ago I installed the drive shaft in our 1975 Firebird and ended up with a slight vibration (did not mark the shaft prior to removal). Flipped the shaft 180 degrees and now it is smooth as silk.

 

The pinion yoke does not get balanced...A trans slip yoke does for sure, think thats what ya meant. They should be balanced as a unit. Best practice is to mark everything before disassembly. Even Ujoint replacement can effect balance. Thats why Ive learned to just take shafts into the local shaft house have them install spicers and balance.

 

No, I meant pinion yoke. All components are balanced and I would guess as a complete assembly. I pulled this from the 1966 chassis manual, see below.
Note the part about marking the parts during disassembly of both pinion and slip yoke. Also note the alignment marks on prop shaft and pinion yoke in the picture.

To summarize - it looks like the factory balanced everything together and if possible you should keep all three components in their original alignment. If you lose it - no problem, just try it the other way(s). I have done it, heard it, read it and seen it work many times.

 

I have never had a problem in over 40 years of changing Ujoints with a vibration problem unless the driveshaft was damaged.

 

This is something I had wondered about too. When I restored my driveshaft and rear axle in 2012 there was no way there were going to be any identification marks left on the pumpkin or spider. Since I didn't change u-joints (still OEM Saginaw and perfect) I don't expect there would be any issues with balance.

Here's something you can discuss further. When the shaft was installed at the factory chassis assembly, do you think they had time to do anything but install the slip yoke and tighten up the spider? I think not and those cars rolled out with no vibrations.

 

Thats why Im somewhat confused and maybe misunderstanding Rocket. Sure its good practice to put the drive shaft back into the same place it was removed from particularly if nothing was replaced...just good mechanical practice. Will it effect balance...it can, as things get seated and like to be put back in the same spot. But when a drive shaft is pulled and new ujoints are installed, or other...common practice is to dynamically rebalance the shaft with the trans slip yoke attached and the rear ujoint installed. No pinion yoke. The balance machine receives the slip yoke and the two caps of the rear ujoint. No pinion yoke in that equation.

 

How many people had to replace their yoke for one reason or another? Did they rebalance the assy? I for one never have.

 

Sorry my answer was for 1970 cars
Alain

 

Slip yoke replacement can be done as a stand-alone separate from driveshaft replacement for many reasons. Replacement is required when the yoke is heavily grooved on the seal surface, its damaged in some manner or wben changing the series of u joint or series of transmission for custom applications. If it inspects ok no reason to not reuse it.