NVH (Noise, Vibration, and Harshness) and Performance Modifications
Welcome to our Garagistic Tech Talk. Today's topic. Noise Vibration and Harshness (NVH) and Suspension. Not a lot of owners think of NVH when they install aftermarket parts but it is something to consider. The OEM components that are often replaced are specifically designed with driver comfort in mind. Many aftermarket parts are designed with ultimate performance in mind without considering comfort. Coilovers, exhaust, and wheels and tires are all components that can create excessive NVH as well. Most performance components will increase vehicle NVH to some extent. Here are some examples of how:
Suspension
Shocks and Springs
Suspension components are a big transmitter of NVH but OEM shock absorbers soak up all the harsh vibrations on the road to give you that smooth sailing on a cloud feeling. Going with a performance lowering spring or set of coilovers oftentimes times increases handling at the cost of OEM comfort. Why is this you ask? Suspension upgrades usually feature springs and shocks that are designed to be stiffer, therefore providing a better feel for the butt dyno while increasing NVH. Not only does this mean you'll lose ride comfort but in some cases, the increased vibration from components will require reinforcement. This is often the case when you get ready to go to the track and/or are pushing things to the limits or your just driving a BMW that has lost the will to hold itself together.
Links and Bushings
Another factor that creates NVH is suspension articulation. As suspension cycles through its travel, suspension links create NVH. NVH is these cases is often transmitted through bushings. Often times stiffer aftermarket components travel less and vibrate more as they attempt to keep the vehicle at the rest position. These vibrations can loosen components over time. A good example of a component that this tends to happen to is Adjustable Swaybar Links. The folks here at Garagistic recommend that any aftermarket adjustable endlink be installed with Red Loctite on the lock nut and have the lock nut checked every 2-4 weeks.
We went into detail on bushing durometer and NVH in a separate article (that you can find that here).
Tires
Where the rubber meets the road. Quite literally.
To keep it simple tire compounds produce NVH by how they absorb vibrations on the road. Here are some of the main differences between a comfort tire and a competition tire.
Comfort Tires
- Softer sidewalls
- Higher treadwear
- Less grip
- Less noise
Competition Tires
- Stiffer sidewalls
- Lower treadwear
- More grip
- More noise
These are the factors that you will need to look for based on your application. A comfort tire with high tread wear usually has a soft sidewall to absorb impacts. Comfort tires also have large water jackets for all weather conditions.
A competition tire has a stiffer sidewall transferring more vibrations to the suspension components. Competition tires can also be much noisier based on water jackets design and wear. Aggressive alignments can create a condition called feathering which causes tires to be audibly louder.
We will completely break down tires one day when we find a way to explain it in detail...that doesn't make your head spin. For now, just know that a tires design determines how comfortable or harsh it is. Always use the right tires for your application.
Long Story Short...
Here at Garagistic, we recommend considering your vehicles primary use and the expected NVH change of suspension components before purchasing and installing them. Always make sure to follow the recommended use procedures and if you are pushing your car to the limits, always inspect components for proper installation frequently.
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