Driveline Phasing

[n9ads@domain.elided (Howard R Pletcher)]

I'm not sure if we reached a consensus on U-joing phasing in the previous
discussions, but I just saw the following in the Propeller Shaft Section,
CTS-2730 of the CTS-2313 78-80 Scout Manual:

Universal Joint Phasing  (See Fig. 37)

When u-joints or yokes are assembled to their shafts in the same plane,
they are in phase.  When they are assembled to the shaft in different
planes, they are out of phase.  To obtain vibation free operation, check
the following.

1. Yokes or flanges between the main and auxiliary transmission must be
"In Phase". 

2. In the case of a two-piece driveshaft assembly between the
transmission and fhe forward rear axle, the joints on this shaft should
be assembled "In Phase" unless otherwise specified by the manufacturer.

Fig. 37 further shows what they mean by "In Phase" by showing that the
flat part of the ends of the yokes would lie on a flat surface on both
ends of the shafts, or alternatively, bars placed through the eyes on
each end would be parallel to each other.  This section is a general
section with heavy truck drivelines in mind rather than light trucks, but
it emphasizes the "In Phase" several other places.

Other points made are:

If the flanges on the transmission and axle are parallel to each other
(but offset), the flanges must be held parallel within 1 degree  to
minimize vibration.  However, it this results in a U-joint angle greater
than 12 degrees, then the axle should be tilted upward so that the
centerline of the transmission intersects the centerline of the pinion
1/2 way between the two, which still results in equal angles at each end.
 This may be of concern to those doing spring overs.  

I'm sure that we can get away with excessive angles and other bad designs
on our Scouts that would be "fatal" in a big truck with 600 hp grossing
100,000#, so these rules can probably be bent to some extent.

Howard Pletcher
Howteron Products Scout Parts

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