Pinion Angle

I found this on Rossler Trans

"Tired of breaking cases and drive shafts? There are many books that misled you on setting the pinion angle. For Drag Racing this is simple. You are trying to set the pinion angle to be parallel with the centerline of the engine & transmission on hard acceleration. To achieve this you must first figure out the parallel setting of the rear end to correspond to the angle of the engine & transmission, then add the proper amount of pinion angle. Add 1 deg. for 4-Link vehicles, 2 to 3 deg. for ladder-bar vehicles."

[torkflight]

I have found this to be a much better way to set pinion angle, it is sometimes hard to acheive the proper operating angle but the end resault is much better, eliminating vibrations and getting the most power through your drivetrain,

Operating angles in a driveshaft are the angles between the pinion, driveshaft and transmission centerlines. The optimal angle for any driveshaft to run at is 0 degrees, where many vibrational and frictional problems are non-existent. In order to minimize power loss and vibration in an offset configuration, the pinion centerline and the transmission centerline need to be parallel. In general, the largest angle for racing applications should 2 degrees and the centerlines should be parallel within 1/2 degree. With suspension movement the operating angle will increase, but should not exceed 15 degrees. If the centerlines are off too far, the u-joints travel at uneven operating velocities, causing vibration (this is the same problem induced by poorly phased end yokes). This vibration is hard to distinguish from an unbalanced driveshaft.


Critical speed is the speed at which a spinning shaft will become unstable. This is one of the single largest factors in driveshaft selection. When the whirling frequency and the natural frequency coincide, any vibrations will be multiplied. So much that the shaft may self destruct. Another way to think of this is that if a shaft naturally vibrates at 130 times a second, and one point on the shaft passes through 0 degrees 130 times a second (7800 RPM) then the shaft has hit a critical speed. There are several ways to raise the critical speed of a driveshaft. You can make it lighter, stiffer, or increase diameter without increasing weight. This is the reason carbon fiber makes a good driveshaft, it is stiff and light and can be made to any diameter or wall thickness. Aluminum, while it has a very good critical speed is not quite as strong as steel. Steel, with good strength characteristics will have a lower critical speed.

[Z28SSMAN]

Good article.

I put a fancy adjustable BMR torque arm on my Camaro and set it at what I thought was -2 deg. It doesn't hook any better than the non adjustable Edelbrock I took off. In fact, the non adj worked better.

I should have saved my money.

[Red Rocket]

Both Tork and Jolly hit the nail on the head. By far the best and ONLY way to set up a driveline angle.

Good read here too. Source of Tork's info above. Small changes in driveshaft length and composition make for big changes in critical speed.

http://www.markwilliams.com/driveshafttech.aspx

Critical speed when achieved gets ugly...