What causes them and where do they come from?
A shake or vibration can only come from a moving part, typically a fast-moving part. Although it is possible to have a defect in your transmission or differential, it is more likely that a shake or vibration is coming from the wheels and/or tires. Vibrations can also be felt from the driveline after modifying your vehicle. Let’s dive in…
PART I: WHEELS & TIRES
Identifying where you feel the shake is crucial to figuring out the cause. Here are some questions to ask: Do you feel it in the steering wheel? In the seat or the floor? Is the whole truck shaking? Are your mirrors getting blurry? Lastly… is it felt at high speed or is it during take-off? Driveline vibration is almost always going to be felt in either the seat or at your feet. This stems from the fact that driveline vibration will resonate through the floorboard. All of the other symptoms listed are typically due to wheel and tire balance. (Yes…even if you have balanced them 3 times and/or performed a road force balance).
Newer vehicles are designed with modern materials. As vehicles are getting lighter to improve fuel efficiency, suspension is getting softer to maintain a comfortable ride. Although lighter and softer sounds nice, it also equates to a vehicle that is more susceptible to symptoms after modifying. Always make sure to choose quality name brands when selecting wheels & tires and always aim for a true balance. Static balancing (due to not wanting to put weights on the outside of wide wheels) means you’ll most likely still experience shakes and vibrations.
Wheel & tire shakes or vibrations can only happen at speed. These tend to occur due to an imbalance in a fast spinning, wheel/tire combo. A vibration at takeoff is never due to an out of balance tire as the wheels are not spinning fast enough to feel it. Typically, a wheel/tire caused vibration gets worse the faster you drive, but will not be amplified by acceleration or deceleration.
PART II: DRIVELINE VIBRATION
If you’ve Identified that the vibration you are feeling is in the seat, in your feet, or you can specifically feel that it is coming from the rear of the vehicle… then you most likely have a driveline vibration. There can be two likely causes of a driveline vibration: an imbalance in the driveline. Or U-joint angles that are out of the typical comfort zone.
Whether your truck comes equipped with a 1-piece or 2-piece drive shaft, it is still connected with universal joints. There are some standard rules of thumb that apply here. These can usually help with “trial-and-error” fixes for driveline vibrations. Rule # 1, U-joints are typically happy with 3-5 degrees of angle. In order to check angles, a digital angle finder is needed. This will require subtracting the angle of the driveshaft from the angle of the differential. (Example: the driveshaft reads +2-degrees and the differential reads +5-degrees. This means you have a 3-degree difference).
Rule #2: (Which only applies to 1-piece drivelines) Ideally you want equal, yet opposite angles between the transmission and differential.
Although following these two rules will typically make a u-joint “happy” and not vibrate, it may not always be a 100% fix. It’s good to keep in mind that not all driveline vibration can be completely eliminated after modifying your vehicle. Following the guidelines listed in this blog post is a good start when trying to solve a driveline vibration. Your results may not always make theoretical sense, but if each change you make helps or reduces vibration, then you are headed in the right direction. Please also remember: a U-joint likes to have some angle, but doesn’t know (or care) which direction that angle is.
Please feel free to reach out to our tech support department for further insight if needed. Phone# 844-535-1668 or reach us by email sales@maxtracsuspension.com
