Measurement details from my driveline on my 60 Coupe

[Ed Mobley]

All,

To continue my driveline saga:

Here are the measurements from my driveline on my 1960 Caddy Coupe.  They raised more questions than provided answers:

Tranny - 6.75 degrees up
Front shaft - 2.25 degrees up
Rear shaft - 3.5 degrees up
Pinion - 1 degrees down

So, the working angles of the front and rear u-joints are 4.5 degrees so they cancel each other out.  But the working angle of the middle joint is 1.25 degrees.

The result of these angles is contrary to what I read in the the following post regarding two piece drive shafts:

http://www.vibratesoftware.com/html_help/html/diagnosis/Propshaft/Propshaft_Angles.htm

Can be the middle u-joint be the odd joint?  Or does the odd joint have to be the one by the transmission?  Even if the middle joint can be the odd joint, 1.25 degrees is excessive according to what I read. But Ive also heard they can be as much as 1.5 degrees.

Another thing I noticed is the yokes on the rear shaft are out of phase by 7.5 degrees.  Ive read that some two-piece shafts are designed to have some out of phase yokes but I dont know if they mean 90 degrees out of phase or just a few degrees out of phase.  As such, I dont know if this is factory or not.  Im thinking the shaft may have twisted since the piece on the end has a friction fit with the rubber damper and all.  According to the following post, yokes should not be out of phase by more than 2 degrees:

https://www.fleet.ford.com/truckbbas/non-html/Q14.pdf

This piece from Ford leads me to believe that the middle joint can be the "odd" joint as shown by some of their illustrations.  In other words, the front piece of the driveline does not have to be an extension of the transmission shaft as per the first post.

I tried moving the rear of my transmission up, but there is not enough room to make the front part of the shaft come out straight.  Shimming the middle support would only increase the working angles of the front and middle u-joint.

My preliminary evaluation leads me to believe the angles are not the issue.  Im starting the think the fact that the rear yokes are out of phase is causing the problem.

Can anybody take a look at their drive shaft and tell me if their yokes are slightly out of phase?

Ed

[Mike #19861]

 Typically, driveline angles should not exceed 15 degrees. It seems that all is within this specification on your car. I would not suspect that as a cause.

 Also, at times I have heard that some manufacturers specify out of phase drive lines to nullify vibrations caused by  excessive angles. I have not heard thus far that this is part of the specification on any of the GM standard cars from 1957-1964 with 2-piece drive lines.

 I do also assume that you have checked and eliminted other possibilities such as out of balance shafts, worn hanger bearings, worn or tight u joints etc.

 Maybe, if you can, assemble the driveline in phase and see how you make out. If you cannot do this, perhaps the drive line has had previous work that has left it out of phase. Check and see other like cars and see what the drivelines are like. Perhaps you have nailed the out of phase driveline as the culprit. If so, that is good mechanics and diagnostic procedures!

  Mike

[Ed Mobley]

Mike,

The splines on these shafts are keyed so it is not possible to assemble the shaft out of phase.  In my case, the rear section of the drive line itself is twisted.  Its hard to explain, but you can see how the part of the shaft near the pinion is slightly larger and has rubber inside.  Im wondering whether the smaller diameter part of the shaft can twist inside the rubber part over time.

Ed

[JIM CLC # 15000]

01-08-05
Ed, are you ready for a sad tail?
I purchased a 75 Chevy Monza in Dellas, TX and the salesman said not to go over 55MPH for the first 500 miles.
So, when the odometer turned 500 miles, it was pedel to the metal time.
To make a long story as short as I can, after:
1. new drive shaft
2. new set of tires
3. several wheel/tire balance jobs (Both on and off the car)
the service manager made an appointment for me with the regional rep.
(each attempt to fix car was with a difference dealer, car an/or tire)
so, I was restricted to 55MPH for about a month.
On the appointed day, just for fun, I headed for the Interstate.
**^&&percentpercent$$ thing didnt viberate at 90MPH.
Have never figured that one out.
Good Luck, Jim

[Mike #19861]

 It is quite possible that the front and rear portion of the shaft has twisted on themselves. With the rubber now 45 years old, I would quite expect some deterioration to exist.

 This has been a problem on much newer cars that use this same sort of rubber insulator in the drive shaft where due to deterioration, the length of the shaft can actually decrease.

 A shaft out of phase is the most likely cause of your vibration. I would at least adress this. In looking for the cause of a problem, if you find something that may contribute to it, fix it. Even if it does not fix the problem, you have eliminated it as a possible cause.

  Mike

[Ed Mobley]

Mike,

After speaking to Bruce Reynolds last night, he told me that section is called the torsional damper.  I read elsewhere that as these degrade over time they can contribute to vibrations as well.  So even if mine were in phase, it would probably be a good move to replace it.  However, no driveline shop that Im aware of can reproduce these torsional dampers due to the equipment required.  As such, Im going to have a simple straight shaft made up.  Hopefully it will not cost me that much money.


Regards,

Ed

[Ed Mobley]

Jim,

I remember reading that in an earlier post.  Maybe there was a piece of undercoating on the drive shaft and it flew off?

Ed

[Ed Mobley]

All,

Bruce Reynolds took a look at his shaft on his 60 Coupe and it is slightly out of phase like mine.  And they are both out of phase in a counter-clockwise direction (facing the back of the car) so it is not a product of slipping (if it slipped it would be in a clockwise direction.  That only leaves me with the rear ball joint as the potential cause.  Ill change that out and see if it makes a difference.

If only I could find the alignment tool that Kent-Moore made for Cadillac then I would know if I had any issues with driveshaft geometry.  Based on my measurements so far, this driveshaft uses some aggresive angles and is manufactured out of phase so Im not able to apply conventional rules so to speak.  Maybe it was just a bad design subject to vibration?

The saga continues....

Ed

[Michael Stamps 19507]

Ed,
  Id take a look at mine for you but right now I dont have a way of doing so.  These 60s sit a lot lower to the ground than the 70s Im used to.  Remind me this coming weekend and maybe I can redneck engineer a way of seeing for you.

Stampie

[Roger A. Zimmermann]

Hi!

My 57 Brougham has also some vibrations at about 60 mph. I removed the drive shaft last year, replaced the central bearing and the front joint. I noticed also, by doing the assembly, that the joints of the rear shaft are not in line. I had the same idea, that with age the rubber let the shaft turn a little bit. As the shaft is specific for the Brougham and probably real hard to find in good condition, I decided to assemble as is. Maybe the other parts I replaced will improve the vibrations; I will notice that point at the first drive in April or May. (the car is not used during wintertime)

Roger, Switzerland

[Ed Mobley]

Roger,

As per my subsequent post, it looks like these shafts were slightly out of phase from the factory.  Bruce Reynolds confirmed by looking at his - and now youve confirmed by looking at yours.  

Regards,

Ed