>Hello all triumphisti. A quick question for the all powerful all knowing
>list. I've got my driveshaft out blasted, painted and new "U-joints"
>installed and I'm wondering how this thing is supposed to go back together.
>My question is are the yolks on either end of the main driveshaft supposed
>to be in line with one another or should they be 90 deg.
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If were talking about the welded in yokes (actually it doesn't really
matter, if you have sliding yoke's this also applies, although they are
usually keyed for the following reason.) but for any one piece drive shaft
(as those used in our Triumphs) these MUST, I repeat MUST be exactly in
line. NOT 90 deg, 60 deg 10 deg or any thing but 0 deg out of phase!! The
reason for this is because when set up correctly, as designed, the joints
cancel each other out. Balancing will NOT cure an out of phase drive
shaft. One has to understand what actually goes on with a "typical", not
constant velocity type of u-joint. Any drive shaft as installed (angled),
that is, as long as the engine centerline is not exactly in line with the
rear end centerline, which is just about every front engine rear drive car
that I know of, will be at some angle. When operating at any given rpm,
the drive shaft does not actually run at a constant speed as does the
engine (or driving force) but pulses, or speeds up and slows down. This is
difficult to explain, but believe me, this is normal operation for an
angled shaft with an ordinary u-joint. Proper design will have both yoke
centerlines, the one that bolts (or slips into) to the transmission, and
the one that bolts to the rear end, parallel, to cancel out this
oscillation, delivering the constant rpm to the driven end. That's why in
engine swaps it's important to know what the engine angle is in relation to
the rear end, and preserve this relationship. Installing a drive shaft
without the original design relationship preserved will result in vibration
and premature failure of the u-joints, and in severe cases damage to tranny
castings, or bellhousings, from cracks that develop from those vibrations -
any drive line "specialist" that says otherwise, doesn't know what is
actually happening during the operation of a typical drive shaft with
ordinary, non-constant velocity type u-joints, and is giving you incorrect
information -
Barry Schwartz (San Diego) bschwart@pacbell.net
72 V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (project)
73 Ford Courier (parts hauler, rain vehicle, getting a V6 soon!)
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