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Pinion angle is the relationship between the transmission centerline and the pinion centerline, not to the ground and not to the driveshaft. Ideally, you want the pinion to become parallel to the transmission when the vehicle is under power and the pinion torques upward.

Make the pinion parallel to the transmission as a baseline, then pivot the pinion downward 2 degrees for a street car. This is referred to as a 2 degreee negative pinion angle.

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I purchased a rebuilt 8.75 clutch type power lock rear end to install on my 68' Barracuda. I knew that I would have to get the drive shaft shortened. I noticed that the pinion has a downward angle. If I put the mounting holes for the u-bolts straight up and down there is about 3/4" difference from center to center when I pull a measurement from the slip yoke. Is this ok and will I need a pinion snubber,and if so how close should it be from the bottom of the car? Thanks

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Quote:

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Pinion angle is the relationship between the transmission centerline and the pinion centerline, not to the ground and not to the driveshaft. Ideally, you want the pinion to become parallel to the transmission when the vehicle is under power and the pinion torques upward.

Make the pinion parallel to the transmission as a baseline, then pivot the pinion downward 2 degrees for a street car. This is referred to as a 2 degreee negative pinion angle.

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Quote:

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Pinion angle is the relationship between the transmission centerline and the pinion centerline, not to the ground and not to the driveshaft. Ideally, you want the pinion to become parallel to the transmission when the vehicle is under power and the pinion torques upward.

Make the pinion parallel to the transmission as a baseline, then pivot the pinion downward 2 degrees for a street car. This is referred to as a 2 degreee negative pinion angle.

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Will raising the transmission up 2° give the same effect?

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Quote:

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Pinion angle is the relationship between the transmission centerline and the pinion centerline, not to the ground and not to the driveshaft. Ideally, you want the pinion to become parallel to the transmission when the vehicle is under power and the pinion torques upward.

Make the pinion parallel to the transmission as a baseline, then pivot the pinion downward 2 degrees for a street car. This is referred to as a 2 degreee negative pinion angle.

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THE ABOVE IS ONE OF MOST CONCISE, SIMPLY PUT, and IMPORTANT concepts I've ever read on here VERY well put.

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Yet it leaves out one of the most important pieces of info - rear axle must be supporting the weight of rear of the car, as in not having the body of the car on stands with the axle hanging down.

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Common sense suggests if the pinion becomes " parallel to the transmission when the vehicle is under power and the pinion torques upward ", the angle is set with the vehicle's weight resting on its suspension.

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That is the end result of setting the angle, not how to check it.

And if people had all this common sense that you speak of, after the 1000's of posts on this, would there still be so much confusion on it?

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Pinion angle is the relationship between the transmission centerline and the pinion centerline, not to the ground and not to the driveshaft. Ideally, you want the pinion to become parallel to the transmission when the vehicle is under power and the pinion torques upward.

Make the pinion parallel to the transmission as a baseline, then pivot the pinion downward 2 degrees for a street car. This is referred to as a 2 degreee negative pinion angle.

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Picture this scenario: The rear springs have a foot or two of arch -- the car is, as we used to say, "jacked up". It would be possible to shim the axle hosing (or re-weld the perches) so that the pinion was perfectly parallel to the trans's mainshaft, but U-joint angles would be through the roof!



Cruising on the highway, you'd like front and rear u-joint angles to be complimentary, and very low (but not zero). For drag racing, you need some pinion nose-down (in relation to the propshaft) so the angles remain opposite at all times. How much of an angle? A serious drag car with only leaf springs might need as much as 4 or 5 deg., which a car with better axle windup control (pinion snubber, 4-link, quadrashocks, Caltracs, etc.) would require much less. With real street tires, there's rarely a need for more than 1 to 1.5 deg.

Rick