Suspension Tech (RE: Bushing distortion and chassis flex)
03-04-2004, 11:53 AM
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Suspension Tech (RE: Bushing distortion and chassis flex)
Hello All,
Performance suspension tuning. It is not as easy as just installing lowering springs and a sway bar. There are a lot of variables that need to be thoroughly thought about when building your suspension. We have compiled this information for you to use as a tool to building your suspension.
Bushing deflection is one area that I would like to focus on. Some people overlook this because of the installation procedure. Yes, you have to press the old soft rubber bushing out and press in the new one. When you are trying to turn your passenger car into a sportier ride you have to remember how the manufacture originally designed the car. They will incorporate some performance but more focus on ride quality. A little bit of rigidity but not too much. Factory bushings are generally made of fairly soft, compliant rubber or low-durometer elastomers. These bushings are designed to absorb energy transmitted from the road in order to provide you with a more comfy, quieter ride. In the attached link you will notice a pretty cool diagram of how the MacPherson strut design acts under load and what the soft bushings allow it to do.
http://www.elephantracing.com/techto...eformation.htm
So if you are serious about they way your car handles you might want to look into addressing this issue.
Chassis Flex - Vehicles that feature MacPherson strut are constructed in a unibody approach, which means that the vehicle "tub" incorporates a welded/frame body substructure. This means that the entire body substructure flexes to a degree as the vehicle rides over bumps, brakes, or is subjected to lateral loads during turns. The degree of flex will differ depending on the application, but some degree of flex will occur and is normal. So.... How do we fix this?
Strut Tower Brace - You can install a brace that attaches the left strut tower to the right strut tower (if possible attach to the firewall as well). By connecting right side to left side towers, this prevents a single tower from moving in relation to the opposing side tower. However there is now a slight problem. If the strut towers have now been connected, what has been done to keep them from moving together? Answer is NOTHING. By also attaching the strut tower brace to the firewall, this provides a center locating point, preventing unwanted tower movement on both sides.
Underbody Bracing - If the unibody design previously allowed a great deal of flex, the addition of a underbody bracing will be very noticeable in terms of stability and handling improvement. Even if the unibody originally exhibited minimal flex, the addition of underbody bracing will always improve handling since it reduces chassis flex and resulting wheel angle changes. This means that the grip of the tires can make better use of lateral energy instead of wasting it through excessive chassis flex.
Chassis components are especially useful when the car is equipped with high performance low profile tires. As tire grip increases, this places additional stress in the chassis "tub". This stress causes the unibody to flex and deflect. This flexing can lead to long-term weakening of the weld joints, and can result in a loss of handling performance, keeping, you the driver, from ever realizing the true potential of your suspension setup. Chassis bracing components are quick and easy to install. They are great addition if you are looking to increase the handling in your car.
We hope that we were able to expel a few misconceptions about some of the items that are typically overlooked when building your suspension. Please let us know if there are any questions.
Thank you,
Performance suspension tuning. It is not as easy as just installing lowering springs and a sway bar. There are a lot of variables that need to be thoroughly thought about when building your suspension. We have compiled this information for you to use as a tool to building your suspension.
Bushing deflection is one area that I would like to focus on. Some people overlook this because of the installation procedure. Yes, you have to press the old soft rubber bushing out and press in the new one. When you are trying to turn your passenger car into a sportier ride you have to remember how the manufacture originally designed the car. They will incorporate some performance but more focus on ride quality. A little bit of rigidity but not too much. Factory bushings are generally made of fairly soft, compliant rubber or low-durometer elastomers. These bushings are designed to absorb energy transmitted from the road in order to provide you with a more comfy, quieter ride. In the attached link you will notice a pretty cool diagram of how the MacPherson strut design acts under load and what the soft bushings allow it to do.
http://www.elephantracing.com/techto...eformation.htm
So if you are serious about they way your car handles you might want to look into addressing this issue.
Chassis Flex - Vehicles that feature MacPherson strut are constructed in a unibody approach, which means that the vehicle "tub" incorporates a welded/frame body substructure. This means that the entire body substructure flexes to a degree as the vehicle rides over bumps, brakes, or is subjected to lateral loads during turns. The degree of flex will differ depending on the application, but some degree of flex will occur and is normal. So.... How do we fix this?
Strut Tower Brace - You can install a brace that attaches the left strut tower to the right strut tower (if possible attach to the firewall as well). By connecting right side to left side towers, this prevents a single tower from moving in relation to the opposing side tower. However there is now a slight problem. If the strut towers have now been connected, what has been done to keep them from moving together? Answer is NOTHING. By also attaching the strut tower brace to the firewall, this provides a center locating point, preventing unwanted tower movement on both sides.
Underbody Bracing - If the unibody design previously allowed a great deal of flex, the addition of a underbody bracing will be very noticeable in terms of stability and handling improvement. Even if the unibody originally exhibited minimal flex, the addition of underbody bracing will always improve handling since it reduces chassis flex and resulting wheel angle changes. This means that the grip of the tires can make better use of lateral energy instead of wasting it through excessive chassis flex.
Chassis components are especially useful when the car is equipped with high performance low profile tires. As tire grip increases, this places additional stress in the chassis "tub". This stress causes the unibody to flex and deflect. This flexing can lead to long-term weakening of the weld joints, and can result in a loss of handling performance, keeping, you the driver, from ever realizing the true potential of your suspension setup. Chassis bracing components are quick and easy to install. They are great addition if you are looking to increase the handling in your car.
We hope that we were able to expel a few misconceptions about some of the items that are typically overlooked when building your suspension. Please let us know if there are any questions.
Thank you,
