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We all start out building custom rides somewhere, and it’s usually in a driveway. Whether it’s our parent’s or the parking lot of our first apartment, those times wrenching on our project when we have no idea what the heck we’re doing can be a lot of fun. Thing is, they can also cause some real damage if we don’t do things right.
Now while sure, we could be talking about safety issues or making sure your jack stands are solid, this isn’t that post. No, we’re talking about pinion shims because we see our fair share of folks come through our doors with lifted or lowered trucks and busted u-joints wondering what the heck happened. Fortunately, we’ve got the answer.
It’s all about the angles
Take a moment and go look at your truck (or car, if you’ve got something with a rear leaf spring setup). Now pay attention to the driveline. If your truck was moving down the road, you would see that while your transmission stays still, your rear axle travels up and down. Your driveline has to transfer that power from the transmission to the axle, and if your driveline were straight, your axle wouldn’t be able to move, thus giving you a horrible ride.
The solution that manufacturers came up with decades ago is the u-joint. This allows the driveshaft to rotate and pivot at an angle. It’s pretty cool to watch, as it’s this fancy mechanical connection moving just right. But, like everything else, it has limits.
A u-joint will only allow the driveline to tilt so far. Get past a certain point and either the u-joint breaks, or gets close enough that vibrations become a nightmare.
Pinion shims to the rescue
This is why pinion shims are so important. When you lift your truck, you’re changing the angle between the rear axle and the transmission, thus changing how far that driveshaft has to adjust. If you add the proper amount of pinion shims, then you have a driveline that happily transmits power, keeping you chugging down the road.
The same thing applies to lowered trucks. Going lower puts your driveline at the opposite angle, but you still have to consider how the driveline will function. If it’s bent too far or the pinion of your axle doesn’t go the right way, you will bind that driveline up. It’s guaranteed.
We can fix that
Of course, we do have a solution. If you already have blocks or other suspension modifications that require them, we have pinion shims ready to go. All you need to do is ask. And by installing a set yourself, you’ll be able to eliminate the vibration and save yourself from the hassle of buying a new driveshaft. And believe us, that’s not a lot of fun.
Point is, if you haven’t fixed your pinion angle yet, take some time to do it now. Your u-joints will thank you.
