November 7, 2023

Urethane Be Gone

As part of the 2023 driveline rebuild all the worn suspension bushings throughout the car were replaced. This was a good opportunity to remove all the urethane bushings that has crept in over the years.

Replacing rubber suspension bushings with urethane is generally considered to be a performance upgrade, however the impact this has on noise and vibration should not be ignored. If you're building a racing car then urethane bushings may provide some performance benefit, but for a street-driven car there is no performance benefit at all, while the added noise, vibration, and harshness (NVH) is significant! The added vibrations will also loosen every nut and bolt on the car.

When I purchased the Corvette in 2018, I knew that a urethane mount had been fitted to the snout of the diff housing. I then (foolishly) added urethane engine mounts (Tuff Mounts) when the engine was rebuilt in 2020-2021. When the gearbox was removed in late 2023, we discovered that the gearbox mount was urethane too! So, it turned out the entire driveline was mounted on urethane!

Removing all the urethane and replacing with quality rubber bushings had an almost miraculous effect on the Corvette's NVH. It's significantly quieter in the cabin, and it feels super tight and smooth on the road. It literally feels like a new car, not an almost 60-year-old one.

The lesson from all of this? Don't fit urethane mounts and bushings to your street-driven Corvette, it will make your car less enjoyable to drive and provide no performance benefit.

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