Re: Chassis Stiffening, Suspension Ideas, Handling Improvements
Posted: October 23rd, 2009, 1:35 pm
Onlytrueromeo: infinite weight is not a practical feature, it's a theoretical standpoint. The Universe doesn't have infinite weight, so, obviously, no car will.
You use that kind of statement to illustrate a point, or, like in this case, to isolate a variable.
For a suspension system of any kind to absorb all the energy applied to it, Newton's first law (action/reaction) can NOT APPLY, since the suspended body can not absorb/dissipate any energy. For that, it needs to be infinitely stiff (so it won't ABSORB energy) and infinitely heavy (so it won't DISSIPATE energy). That doesn't mean such a scenario has to exist. It's just a way to illustrate the extreme, so you can understand/quantify the middle ground.
Cars are not designed with flex for economical reasons. They are designed to perform under a given set of circumstances.
Increasing chassis stiffness can, depending on the method used, go a long way to improve the car's handling. It makes the car more predictable, tighter, more responsive, etc. But EVERYTHING in mechanics is a compromise, and so is this.
A stiffer chassis also makes the car more unforgiving, the ride harsher, and increase vibrations.
It's actually not so difficult to understand:
The car's suspension (what isolates the car from the road) is the shocks/springs, etc. The stiffer the suspension is, the more the car will "feel" the road's bumps and cracks.
The driver's suspension (what isolates YOU from the road), is THE WHOLE CAR, so the stiffer the car is, the more YOU will feel the road's bumps and cracks.
Simple: every bump transfers a given amount of energy to the car. According to the car's design, a percentage of that energy is absorbed by the suspension. The rest of it will be absorbed by the chassis, and dissipated onto YOU, and onto the atmosphere (the car will JUMP). ANY ENERGY the chassis can't absorb (because it's stiffer), will have to go somewhere else, and the only place it can go to is you, and the atmosphere.
So, depending on the method you use, you will have a varying degree of handling improvement, and a varying degree of ride quality loss.
For example: if you weld the doors shut, you will greatly increase your chassis stiffness, while only adding a few pounds to the car's overall weight, which means you can still probably use your standard shocks/springs without any noticeable increase in body roll, so the only difference you will notice in the ride quality is that due to the stiffer chassis.
On the other end of the spectrum, if you install a full on roll cage, you will be adding quite a lot of weight ABOVE the car's CG, which will tend to have a negative effect on your car's performance, both in terms of handling and power to weight ratio. So then you will have to go for stiffer shocks/springs, to keep body roll in check, which will make your ride quality go straight to hell.
You use that kind of statement to illustrate a point, or, like in this case, to isolate a variable.
For a suspension system of any kind to absorb all the energy applied to it, Newton's first law (action/reaction) can NOT APPLY, since the suspended body can not absorb/dissipate any energy. For that, it needs to be infinitely stiff (so it won't ABSORB energy) and infinitely heavy (so it won't DISSIPATE energy). That doesn't mean such a scenario has to exist. It's just a way to illustrate the extreme, so you can understand/quantify the middle ground.
Cars are not designed with flex for economical reasons. They are designed to perform under a given set of circumstances.
Increasing chassis stiffness can, depending on the method used, go a long way to improve the car's handling. It makes the car more predictable, tighter, more responsive, etc. But EVERYTHING in mechanics is a compromise, and so is this.
A stiffer chassis also makes the car more unforgiving, the ride harsher, and increase vibrations.
It's actually not so difficult to understand:
The car's suspension (what isolates the car from the road) is the shocks/springs, etc. The stiffer the suspension is, the more the car will "feel" the road's bumps and cracks.
The driver's suspension (what isolates YOU from the road), is THE WHOLE CAR, so the stiffer the car is, the more YOU will feel the road's bumps and cracks.
Simple: every bump transfers a given amount of energy to the car. According to the car's design, a percentage of that energy is absorbed by the suspension. The rest of it will be absorbed by the chassis, and dissipated onto YOU, and onto the atmosphere (the car will JUMP). ANY ENERGY the chassis can't absorb (because it's stiffer), will have to go somewhere else, and the only place it can go to is you, and the atmosphere.
So, depending on the method you use, you will have a varying degree of handling improvement, and a varying degree of ride quality loss.
For example: if you weld the doors shut, you will greatly increase your chassis stiffness, while only adding a few pounds to the car's overall weight, which means you can still probably use your standard shocks/springs without any noticeable increase in body roll, so the only difference you will notice in the ride quality is that due to the stiffer chassis.
On the other end of the spectrum, if you install a full on roll cage, you will be adding quite a lot of weight ABOVE the car's CG, which will tend to have a negative effect on your car's performance, both in terms of handling and power to weight ratio. So then you will have to go for stiffer shocks/springs, to keep body roll in check, which will make your ride quality go straight to hell.