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Car guys are a rare bunch. We’re mechanical, left-brain thinkers when working on our cars. We also succumb to right-brain emotions at the first look of a car with a killer stance or a sniff of our favorite flavor of race fuel. There’s a deep crevice between the left and right hemispheres of our brains to which a myriad of factoids fall, seemingly never to be grasped again. Quantum physics falls into this realm, as do other mysteries such as emissions laws and the importance of your car’s pinion angle.
Thankfully, some specialize in each of these obtuse realms of thinking. Even more importantly, some can coherently explain these complex scenarios so that even those who still occasionally strike their thumbs with a hammer can understand them. Well, most of them.
In this video by YouTuber GarageFab, he takes the deep concept of pinion angles and explains the importance of keeping your driveline in proper alignment. We came across this video in preparation for lowering our S10 pickup. Like so many gearheads, we knew the importance of a proper pinion angle, but the physics behind the reasoning always eluded us.
Much time and effort went into bringing the very real, but extremely theoretical effects (and benefits) of pinion angle and universal joints into view. A case in point is the changing rotational speeds of a driveshaft as it enters and exits each universal joint. Maybe we’ve hit our thumbs one too many times, but this was mind-blowing for us.
By creating this theoretical driveline and adding simple bicycle sprockets, this video shows clearly how a driveshaft can change speeds twice during each rotation. This is a major contributor to driveline vibrations and the reason why proper pinion angle is a must. 
When you think about how much torque is transferred through a universal joint, it’s easy to assume they are quite sturdy. But they are not a constant-velocity joint, as many have incorrectly referred to them. The presenter of the video, known as MANKANDY, explains the difference by building a theoretical driveline that can be adjusted to peel back the veil shrouding differing driveshaft speeds and the ensuring vibration.
The video goes into the difference between leaf sprung suspensions and link bars, and how to set up the proper pinion angle for both. 
The beauty of this video is that it takes those complex theoretical perspectives and cements them in reality so we mere mortals can understand them. For instance, how can one end of a shaft joined with universal joints turn at a different speed than the other end? Why does the pinion angle need to be in alignment with the transmission’s output shaft? Why use two universal joints mated together (called a double-cardan joint) on the driveshafts of many vehicles?
As mentioned, this video takes a complex, yet universal theory and looks at it in a very real, mechanical example that makes sense to any gearhead. Take a few minutes and check out this informative, and sometimes funny video. It will help you understand the reason for the proper pinion angles in your ride. And, while you may not be fabricating your own suspension anytime soon, it may help you understand that annoying vibration you’ve just learned to deal with or why your universal joints may be short-lived. In our opinion, this video is well worth the time invested in making and viewing it.
