Pinion angle.

[Doug_Guilds]

What would be a good recommended pinion angle for a stock 4 Mustang? And is there a disadvantage to running to much pinion angle (like 2 or 3 degrees) handling or forward bite wise?

[84Dave]

Doug....... Some time ago, Bob Bolles, of chassis fame, ran some tests with a Super Late Model V-8(pavement) on a chassis-dyno to observe what happens to TQ/HP at the rear tires with changes in pinion & transmission tail-shaft angles. He tested angles from 0-6 degrees. Even he was shocked at a couple of his findings. In terms of vertical angles, he found the greatest power transfer with angles in the area of 2-3 degrees at each end of the drive shaft. Any angle over 4 degrees did not improve the power transfer. The shocker? At angles of 0-degrees, the power transferred actually decreased slightly. And the U-joints at each end of the driveshaft revealed a terrible beating. Laterally, any angle, in conjuction with either vertical angle, also decreased the power transfer slightly. As though the U-joints were 'binding' slightly. Which, over time, also would not serve well for reliability. Bottom line? It appears vertical angles in the area of 1.5-2.5 degrees is about as good as it gets for power transfer & U-joint reliability. -Dave-

[RACEMAN]

Doug....... Some time ago, Bob Bolles, of chassis fame, ran some tests with a Super Late Model V-8(pavement) on a chassis-dyno to observe what happens to TQ/HP at the rear tires with changes in pinion & transmission tail-shaft angles. He tested angles from 0-6 degrees. Even he was shocked at a couple of his findings. In terms of vertical angles, he found the greatest power transfer with angles in the area of 2-3 degrees at each end of the drive shaft. Any angle over 4 degrees did not improve the power transfer. The shocker? At angles of 0-degrees, the power transferred actually decreased slightly. And the U-joints at each end of the driveshaft revealed a terrible beating. Laterally, any angle, in conjuction with either vertical angle, also decreased the power transfer slightly. As though the U-joints were 'binding' slightly. Which, over time, also would not serve well for reliability. Bottom line? It appears vertical angles in the area of 1.5-2.5 degrees is about as good as it gets for power transfer & U-joint reliability. -Dave-

Dave,

Do you have any numbers to post? There is such a thing as test-to-test variability and I'm curious as to what the difference would be.

Thanks.

[84Dave]

I don't remember the exact numbers from the article, but my memory thinks the gain/loss TQ/HP numbers were high single-digit and/or very low teens. Not a lot for an engine that was making about 540HP & 470TQ, minus the loss through the tranny. -Dave-

[drtlvr]

I've heard people say that more pinion angle helps get more bite off the corner. I've always thought while under power and the suspension loaded there should be just enough angle to load the needle bearings. Do people mistake more pinion angle giving them more bite when it's actually binding up the driveline?

[84Dave]

According to the Bolles testing, that can be the case. Depending on the angle. Excessive pinion angle is/can be a 'crutch' for more bite off a corner. I highly recommend Bob Bolles' HPBooks titled "Stock Car Setup Secrets-Advanced Chassis & Suspension Technology for Asphalt & Dirt". ISBN:1-55788-401-3 . Your knowledge base will be expanded considerably with the above book as part of your racing library. -Dave-