What do the colored stripes on the drive shaft mean? Do the designate the rear gear, trans ect? I have a 72 convertible what would be the correct colors if it even came with them in 72?

 

The stripes designated which DS the assembly line worker needed to install in the car. Different trans...3 or 4spd, TH350 or 400...were different lengths + maybe different yokes. A 72 had them, I don't know the colors for 72, it's in the 1972 Olds Inspector's Manual.

 

The stripes helped the worker pick and install the right 'propeller shaft' as the industry calls it quickly. Same thing as different shapes on the front stabilizer bars. Yes, this information is in the 72 Inspectors Guide, it's also in the 72 Cutlass Assembly Manual. Here ya go

 

The interesting thing in that table is the fact that the 3 spd MT got the same rubber-damped driveshaft as the automatic cars. Only the four speeds got the solid driveshaft.

 

What trans code was a TH350?

 

Did they have balance alignment marks too?

 

m38

 

They were definitely balanced, and marked on the pinion yoke and drive shaft. So if you removed the shaft you could line it up again.

 

I have never seen any marks like that. Mine still has original Saginaw balancing but I have no idea whether it's exactly the same orientation as when I took it out. Part of the rear end restoration both the driveshaft and yokes were done. I did find the ghost outline of the stripes however and used them to put the yellow/black back on.

 

News to me. Driveshafts are "internally" balanced. How they go into the trans or rear axle is irrelevant.

 

What is internal balancing? Mine has circular weight tacked to the outside of the shaft. Reattach to the differential yoke I always was similar to putting a balanced wheel onto studs and tightening them down.

 

I put that in quotes because it isn't a term normally applied to a driveshaft, but an internally balanced engine means that the balance is self-contained (for lack of a better term). The driveshaft is balanced by itself, not with any other parts attached, so it can be installed in any orientation. It is not necessary to mark how it is aligned to the pinion flange, for example. And no, I did not intent to mean that the balance weights were internal.

 

Joe, I BELIEVE, and that's believe, not know, that there is a tolerance for balance and they will be slightly out of true balance, but within spec. The rotating assemblies on the diffs are also flagged that way, I BELIEVE to put the tolerance drift either way against each other to balance them out. I know we have them at our plants now, the marks are blue and you line them up.

 

News to me...I've never heard of "internally" balanced drive shafts! I'm pretty sure drive shafts were externally balanced, like Allan said...you can see the weight on them. Maybe they used both methods, one for rubber insulated jobs and one method for solid shafts. I only have Buick manuals here where I am right now. But there is a picture of the circular weight that I know is on my 442 shaft. There are also instructions to balance the shaft on the car.

 

Again, as I just said above, I obviously wasn't trying to say that the balance weights were "internal", I was trying to say that the driveshaft was balanced independently of any other components. Yes, there will always be a tolerance on the ability to balance a rotating assembly, and I do believe that today's cars probably do have an extra step to minimize NVH, but this was not done in the 1960s.

 

I don't know...I don't make this stuff up. They were marked at the rear like I said. I've even seen factory lit that said be sure to re-align the marks when assembling. I have no Olds lit here, it might be in the inspection manuals, it might be in the assembly manuals about the mark. Maybe the mark meant the pinion angle was checked...but I don't know why they would say to re-align it.

 

I have seen CSM troubleshooting wording regarding driveline balance issues where the #1 thing to try is remove aft end of shaft, turn 180, reinstall. If that does not make it better, attach hose clamps and vary the position until favorable. Then leave them in place I guess.

I believe the shaft is balanced unto itself, and also that it can matter which way 'round it goes in, such that its bit of imbalance either tends to cancel or magnify that of other parts in the driveline.

I have always read that it is good practice to mark assemblies before dismantling, in order to ensure reassembly as found... or, in the above case of checking for operation the other way around... not.

 

Here's the problem I have with that concept. First, exactly how much imbalance can one get in the pinion flange and pinion gear of the rear end? Precious little. Second, there's nothing to constrain how the front yoke goes onto the trans output shaft, so again, what imbalance are you accounting for? Given how poorly GM built cars in the 1960s, I'm willing to bet (no, I have no proof) that the driveshaft was balanced by itself, without yoke or u-joints and that was the only balancing that was done. The front yoke is small enough that you can't build up a big imbalance and the u-joints are similarly symmetric and of small diameter (low polar moment). Now, when I get a driveshaft made or rebalanced, the shop will balance it with the yoke and u-joints in place, but I doubt the factory did that. Yes, there are tolerances on how well the shaft was balanced and how well centered the u-joint mounting features were in the pinion flange and this is why flipping the shaft 180 on the flange might help, but don't expect a big change.

 

Interesting on the 180° flip. I'll have to see if that ever becomes an issue. Joe, I'm totally out on a limb here with no ladder, but I'd bet that Saginaw balanced the shafts at their plants. I think I've had worse vibration off a bad set of balanced tires than a driveshaft though.

 

Like I said a few posts ago, it's still done this way, so there is obviously something to it.