Vibrations represent one of the main ways to tell if you have a driveline problem. However, your driveline can produce different types of vibrations depending on the particular issue it's having. Here's what you need to know about driveline vibrations and what they're trying to tell you.
Speed Related Vibrations
The speed you're driving when vibrations occur can give you a good indicator of the type of driveline problem you have.
Low speed vibrations – If vibrations occur around or under ~30mph, it's a low speed vibration. Typically, these vibrations indicate problems mechanical problems.
One or more of the components of your driveshaft is weakening or out of alignment with the rest of the driveline. This usually means that one end of the driveshaft is not rotating in harmony with the other end.
Mid to high speed vibrations – Vibrations that occur at higher speeds typically indicate a drivetrain balance issue. Vibrations at high speeds can also mean the driveline is approaching its "critical speed."
These are just broad categories. But knowing if you have low or high speed vibrations will help you dig deeper into the particular driveline problem.
Vibrations from Mechanical Problems
Vibrations caused by mechanical issues can mean any of a number of issues.
Phasing – When the yokes at each end of the drivetrain are out of synch with each other, they cannot cancel out your speed fluctuations. That energy has to go somewhere, so it turns into a vibration.
A fix for phasing usually involves just turning the yokes back into alignment. They even sometimes have little arrows to show exactly where the yoke and yoke ears need to meet.
Alignment and angle – When the driveshaft isn't sitting at the proper angle, it will cause vibrations. If the drivetrain is straight, it will cause vibrations. Sometimes this occurs with an improper install. Sometimes it happens over time as the U-joints start to loosen. Alternatively, vibrations can also occur if the u-joints are too tight.
There are ways to diagnose and deal with alignment problems yourself, but it's better to let a professional do it for you. You can repair most mechanical issues without needing to replace your drivetrain. However, if issues persist or keep returning, you may need a new drivetrain to handle the stresses your vehicle are putting on it.
Balance - The balance of your drivetrain encompasses every component that makes it up. An imbalance can damage your drivetrain, your transmission, and other parts of your car.
Balance deals with the length of driveshaft, the condition and proper function of the joints and yokes, the weight of the drivetrain components, even the materials the drivetrain parts consist of. These things must remain in balance if you want a smooth ride. Balance is of the utmost importance, and you should definitely see a professional about balance issues and rebalancing.
Vibrations from Driveshaft Critical Speed
If very high speeds cause vibrations, it usually means your driveshaft is approaching its critical speed. Critical speed is the point at which the driveshaft is at its highest tensile threshold. It will vibrate violently and can even completely break. In most cases involving critical speed vibrations, you have to replace the driveshaft.
Is It Time for Custom Driveline Components?
Many of these vibration-causing driveline issues can occur because you have driveline components that do not match how you use your vehicle. You may also have aftermarket components that aren't fit for your vehicle. In cases of critical speed vibrations, you need a driveshaft that can handle greater RPMs anyway.
In all of those cases, you may want to speak to a professional about custom drive shafts. Contact a business, such as Jons Shafts and Stuff, for more information. A custom shaft built for your specific needs will serve you far better than constant repairs or replacements.