Larry, It is common to have cross and yoke universal joints slightly out of
plane by 1 or 2 degrees. That is supposed to minimize vibrations and ensure
that the needles circulate instead of remain in a stationary position, The
purpose is to extend the service life. The Ruzeppa type joint like our GMCs
use on the outboard end, have large diameter balls with mating housings that
will tolerate considerably more misalignment than the cross and yoke design.
The inboard joints on our GMCs are ball and trunion design with three needle
filled large diameter balls that run in a machined track and are located by
hardened trunion pins. The purpose of this type of joint is to allow the
shaft to extend and retract with suspension movement and also to transmit
power to the wheel. A tip that I learned about whether the joints are failed
or not is to point the wheels straight ahead, and moving the coach slowly
forward on a very smooth surface, lightly hold the steering wheel between
the thumb and forefinger, see if there is any oscillation felt through the
light touch of the wheel. If you feel three oscillations per revolution of
wheel travel, the inboard joints are at fault. If you feel a lot more
oscillations, then it is likely that the outboard joints are the problem.
Not scientific, just seat of the pants stuff, but it tells you where to
start looking if problems are suspected. The horiziontal plane of the entire
shaft when the coach is at correct ride height is slightly lower on the
outboard end. If your bushings are worn out in the lower control arms, then
it could be quite different. Some coaches with everything in the front
suspension quite worn drive fairly well on smooth roads when there is slight
winds. When driving conditions are poor and everything is worn, the same
coach can be a handful to control.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, Sep 3, 2011 at 8:50 PM, Larry and Cheryl Dilk wrote:
>
>
> > Roy,
> >
> > This is interesting. I got to thinking about how you could have level
> axles at a lower ride height and as far as I can figure the OD
> > of the tires is one reason (which you've noted) and the second is the
> condition of the lower bushings.
> >
> > If they are like the ones on the right in SteveF's picture:
> >
> >
http://www.gmcmhphotos.com/photos/showphoto.php?photo=17313
> >
> > That would cause some of it but not half an inch.
> >
> > Anybody else have any ideas?
> >
> > Regards,
> > Rob M.
>
>
>
> Does it say anywhere in the manuals that the axels should be level? When I
> set up the suspension and drive train of a hotrod I strive for 2 to 3
> degrees of offset angle at the u-joints to prevent vibration. I do not know
> if CV joints need offset. A real mechanic will probably know the answer.
> --
> Larry Dilk
> Indianapolis, IN
> 76 Eleganza II
> Patterson 455,Turbo City TBI,
> Just LOVE It!
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