The axle splines have one spline missing so they can only be assembled one way.
The driveshaft splines are not polarized and can be assembled wrong. Having the
yoke axes parallel means that the splines should be assembled so that the yokes
on each end are turned the same way. If you lay the driveshaft on a table the
flat surface of the yoke on each end should lay flat on the table.
If a driveshaft is cut and re-welded, it must be welded in the correct position
so the joke axes are parallel.
This is because a universal joint operating at an angle will change velocity as
it rotates. (This is why we have CV (constant velocity) joints for front wheel
drives.) The harder the angle, the more the velocity changes as it turns. The
output of the trans can be turning at a steady rate but the driveshaft will
speed
up and slow down twice with each revolution. If the yoke axes are parallel AND
the angle of the u-joint at the other end is the same but opposite, the velocity
changes will be neutralized and the diff flange will turn at a steady rate. The
TR6 driveshaft u-joints operate at a very minimal angle so it is not a huge deal
but it could vibrate if assembled wrong.
Rotating the driveshaft 180 degrees in relation to the trans and/or diff flange
can help IF you happen to have some driveshaft runout AND trans flange/diff
flange runout that happened to be in the same direction. Try one end at a time.
Richard Good
Jim Davis wrote:
> I had a problem with my car beginning to vibrate at about 65-70 mph and
> progressively getting worse as speed was increased. I tried everything
> except the driveshaft, including Panasports...still vibrated. Then I
> sent my driveshaft to Ft. Wayne Brake a Clutch in Ft. Wayne, IN and they
> sent back my driveshaft painted and balanced with a repaired yoke. I
> didn't even suspect I had a yoke problem.
> That was the culprit, so I now travel at insane speeds with no vibration
> at all.
> Oh, BTW I have no idea the which way around my driveshaft was originally
> connected to the front and rear flanges, so I would surmise a properly
> balanced driveshaft makes the relationship somewhat unimportant, except
> that according to the Haynes Manual, "the forked yokes on both shafts
> will have their axes parallel to each other". Whatever the hell that
> means.
>
> NFI,
>
> Jim Davis
> Fortson, GA
> CF38690UO
>
>
> Perhaps someone who has experienced the symptoms of an unbalanced prop
> shaft can make a comment on whether that results in the kind of behavior
> you are experiencing. I know that the shaft is supposed to be marked
> and go back the way it was installed at the factory. I know the issue
> has been discussed in the past - I just don't know what the car feels
> like if you don't put the shaft back correctly.
>
> Rich C.
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