Author Topic: Driveshaft lateral alignment  (Read 4051 times)

Ed Mobley

  • Guest
Driveshaft lateral alignment
« on: January 03, 2005, 08:35:25 AM »
Hi,

Is anybody familiar with the tools and procedures required to laterally align a two piece drive shaft?  I ask since the June 1960 Cadillac Serviceman makes reference to such a procedure to address low speed propshaft shudder.  They also mention a Kent-Moore tool J-8905 to do the job.  

Im wondering if somebody would have more information on the procedure and/or the tool?

Regards,

Ed

Ed Mobley

  • Guest
Problem Solved
« Reply #1 on: January 03, 2005, 02:01:36 PM »
All,

I called up the place that balanced my driveshaft and they gave me some general advice:

Vibration at high speed = balance issues

Vibration at low speed = driveshaft geometry (angle) issues

They told me how to check the angles in the vertical plane using an inclinometer.  Heres a web site with the same info:

http://www.vibratesoftware.com/html_help/html/diagnosis/Propshaft/Propshaft_Angles.htm#Tools20Required

They said the most "violent" vibration on a two piece shaft results from driveshaft geometery issues with the front part of the shaft that is attached to the transmission.  Im thinking the the transmission mount may have compressed/settled over the years to the point that the driveshaft working angle is out of spec.  

The rear part of the two piece shaft can also cause problems if the pinion angle has changed due to worn suspension parts - can we say worn rear ball joint?

To check angles in the horizontal plane, one would use the frame rails as a point of reference to determine if the shaft is centered in the horizontal plane.  However, this method is complicated by the X frame of the Cadillac or in situations where the frame is not straight.


Regards,

Ed

Ed Mobley

  • Guest
Kent-Moore faxed me the procedure from their archives
« Reply #2 on: January 04, 2005, 11:45:06 AM »
All,

Kent-Moore faxed me the instructions for the drive shaft alignment procedure mentioned in the June 1960 issue of the Cadillac Serviceman.  It also shows all the tools that are needed - its quite a complex setup.  I have a copy in .pdf format and can email it to anybody that is interested.

Regards,

Ed

Ed Mobley

  • Guest
Now I know why owners of 59/60 Cads may have driveshaft problems
« Reply #3 on: January 04, 2005, 08:45:02 PM »
Reading through the Kent-Moore alignment manual, they make reference to adding or removing shims from the driveshaft center support. This leads me to infer that the factory may have inserted shims. Ill bet that most of those shims were never put back when u-joints were replaced because it is very difficult to see if there was a shim under the center support in the first place.  Ill be that if I search around in the boxed part of the frame that houses the center support, I might find an old shim.

Bottom line: Ill bet a good number of low speed driveshaft problems may be the result of shims getting lost during servicing resulting in driveshaft geometry problems.  Until I did some research into driveshaft geometry, I had no idea how critical small changes in U-joint angles are.

Ed

Lynn 10923

  • Guest
Re: Now I know why owners of 59/60 Cads may have driveshaft problems
« Reply #4 on: January 04, 2005, 09:03:12 PM »
Nothing like a one man thread, huh?

Actually I would like to know if CV joints should to be lined front to back like U joints do, since the second U joint in the CV joint will tend to cancel out any vibration setting tendencies of the first U joint. That is, the CV joint cancels itself out as far as any vibration goes, and theres nothing developed in the front CV joint for the rear CV joint to have to cancel out. In most CV joint cars I have seen, like my 68s, the angles arent even close. It looks like the factory didnt even try to get the angles similar. I dont feel any vibration out of them, but the rear joint is at such an extreme angle that it doesnt seem to last very long before it needs rebuilt.

Lynn

Porter

  • Guest
Ed Mobley, The 60 CAD detective
« Reply #5 on: January 04, 2005, 09:14:53 PM »
Ed,

Those cars are brutal to maintain factory correct, still the coolest ride you could have. (well, maybe a Stampie flat top is almost as cool)

I can now see how far advanced my 66 CDV is, GM had made much progress in the early 60s with drivetrain technology.

Now that you have everything almost sorted out you will be good to go for a long time.

At least you have real dual exhaust, some members have stated the "X" frame 64 Eldorado has superior ride and handing to the 65 Eldorado perimeter frame.

Keep up the good work,

Porter



Porter

  • Guest
Lynn, you are cruel
« Reply #6 on: January 04, 2005, 09:33:59 PM »
I talk to myself all the time, Ive read the psycologists say it is perfectly normal.

Ive replied to a few of my own posts first already, it is okay, as long as someone else eventually "chimes" in, then you know you are pefectly sane and fit for society.

LOL

Porter

Ed Mobley

  • Guest
Re: Now I know why owners of 59/60 Cads may have driveshaft problems
« Reply #7 on: January 04, 2005, 11:34:36 PM »
In my research they said CV joints (being double cardan joints) are not that sensitive to geometry.

The most important thing with u-joints is not the working angle of any particular u-joint but the fact that the angles cancel each other out within 1/2 - 1 degree.  

And yes, I talk to myself a lot.


Ed

 

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