Drive shaft alignment?

[Daryl]

Look at the white clothes line I have tied at the yokes, The shaft will not be parallel to the frame rails. Is this ok? Both yoke are at the 12:00 position.

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[Daryl]

Well to answer my own question and after an hour or two of reading, the angle is there to keep the needle bearings moving. I read from a couple of driveline places that 2 degrees is optimal. No less.

[Mo's70MCs]

The old drive angle dilemma...up there with the same dilemma as the ackerman effect.

[wallaby]

it's pretty interesting. The U-joints go through a process of slowing down/speeding up as they rotate when there is a bend in them. The idea is to phase the u-joint at the other end of the shaft so it does the identical thing 180 degrees from the first, thereby cancelling out any vibrations. A constant velocity u-joint does the same thing all in one package.

 

If you stretch a line through the differential centerline forward, and a different line through the engine centerline rearward, the two lines should be parallel and not meet. (if the rear joint has to bend 2 degrees, the front should also bend 2 degrees). The same applies to the difference in up & down position when viewed from the side. I see lots of 4x4 lift setups where the rear axle has been rotated so the pinion points upward towards the trans output...that's wrong. If the trans centerline is level with the ground, the rear pinion should also be level so the u-joints will run at their smoothest. With constant-velocity u-joints, these angles are much less important: that's why CV joints are used in front-drive cars, it's there to provide a smooth rotation of the tire despite the changing angles of steering.

You can mock up an assembly with a ratchet extension and a typical u-joint flex extension at each end...as you rotate it through your fingers you can feel the effect that different angles cause. If one end is straight and the other has a bend, you will feel a "kink" as the shaft goes around.

 

Here is a constant-velocity joint:

 

 

[Daryl]

Found a great video that puts it in perspective. I also found that Tremec has an app for smartphones that turns them into a drive line angle calculator.

[Dans '70 Z20]

(OOOPs just reread and you were speaking of Left/Right alignment but figured I would leave this article in case anyone needed it)

 

Here is an article that explains how to set pinion angle.

 

Pinion (center section) sits nose down at rest. When accelerating hard it will rise with torque of motor and grip of tires. The more HP/Torque your motor is the more rise. Usually most pinion angles are set in the 3 - 5 degree range based on HP/Torque. The goal of proper pinion angle is to insure driveshaft and yoke are parallel during hard acceleration. Therefore exerting less stress on the u joint.

 

Here is the article: Car Craft - How to set pinion angle article.

 

Dan

 

[monte0]

Good info, actually have to set this myself

[wallaby]

I like the video.

They forgot to rev that demonstrator up above 3000 rpm to show how the vibrations easily destroy the table and classroom.

[dbreese]

I like the video.

They forgot to rev that demonstrator up above 3000 rpm to show how the vibrations easily destroy the table and classroom.

 

 

That would send people running!!

 

David