Järn
Well-Known Member
- Joined
- Aug 26, 2015
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- The Motor City
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- Tony
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- 2019 Mustang GT Premium, Ruby Red, A10, B&O, AE
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I am curious to learn what people here think about this, specifically as it applies to the Mustang: daily driving, autocross, track.
I have copied a few key highlights from this Motor Trend article https://www.motortrend.com/how-to/modp-1104-the-bump-stops-here/
The bump stop is probably the most misunderstood part of a car’s suspension. Historically, a bump stop would be a tapered block of rubber used to stop the axle or suspension arm from traveling too far when a wheel hits a bump. The name used in the automotive engineering world now is spring aid,’ and this describes exactly what they do. They aid the spring by adding their own spring rate. They act like a progressive secondary spring and are often mounted on the damper or concentrically with the road spring.
It influences the steady-state balance of the car, usually by causing understeer, and it largely controls the balance of the car at the limit.
The bumpstop also has a strong effect on transient handling events, such as turning in to a corner and applying throttle or braking in a bend. Imagine having a car nicely balanced in a long turn, then you get on the gas. The car may already be leaning on the outer bump stops, and applying gas causes weight to transfer to the rear and it squats a little, using that outside rear bump stop even more.
...over 95 percent of vehicles now use a microcellular polyurethane elastomer MPU material.
...the key aspect of MPU is its progressive load deflection behavior, where it acts very much like a progressive spring (gaining spring rate as it’s compressed). The more an MPU bump stop is compressed, the progressively stiffer it gets.
So as you can see, the simple bump stop is far more than just a backstop designed to prevent the suspension from bottoming out. It’s actually a powerful tuning tool, since they not only stop bumps (as their name implies) but they also affect many aspects of a vehicle’s ride and handling behavior.
Here is another technical article on Bump Stop Tuning
https://www.vehicledynamicsinternational.com/features/insights-into-bump-stop-tuning.html
I have copied a few key highlights from this Motor Trend article https://www.motortrend.com/how-to/modp-1104-the-bump-stops-here/
The bump stop is probably the most misunderstood part of a car’s suspension. Historically, a bump stop would be a tapered block of rubber used to stop the axle or suspension arm from traveling too far when a wheel hits a bump. The name used in the automotive engineering world now is spring aid,’ and this describes exactly what they do. They aid the spring by adding their own spring rate. They act like a progressive secondary spring and are often mounted on the damper or concentrically with the road spring.
It influences the steady-state balance of the car, usually by causing understeer, and it largely controls the balance of the car at the limit.
The bumpstop also has a strong effect on transient handling events, such as turning in to a corner and applying throttle or braking in a bend. Imagine having a car nicely balanced in a long turn, then you get on the gas. The car may already be leaning on the outer bump stops, and applying gas causes weight to transfer to the rear and it squats a little, using that outside rear bump stop even more.
...over 95 percent of vehicles now use a microcellular polyurethane elastomer MPU material.
...the key aspect of MPU is its progressive load deflection behavior, where it acts very much like a progressive spring (gaining spring rate as it’s compressed). The more an MPU bump stop is compressed, the progressively stiffer it gets.
So as you can see, the simple bump stop is far more than just a backstop designed to prevent the suspension from bottoming out. It’s actually a powerful tuning tool, since they not only stop bumps (as their name implies) but they also affect many aspects of a vehicle’s ride and handling behavior.
Here is another technical article on Bump Stop Tuning
https://www.vehicledynamicsinternational.com/features/insights-into-bump-stop-tuning.html
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