[DaveC113]

Originally Posted by Msquared

Dave, it helps to think of squat as the car's suspension actually trying to pick the rear tires up off the ground rather than as the result of weight transfer. In most situations in most RWD cars, squat is caused by both. But the result is always the same: squat actually unloads the rear tires as it happens, rather than loads them. Once the suspension reaches "full squat" (static), then the full tire loading from the weight transfer occurs - but until the suspension stops moving. In any car with less than 100% anti-squat (almost all of them), you can set the parking brake and try to accelerate and the rear will still squat, even if the car doesn't roll. That's the suspension trying pull the tires up into the wheel wells, and it hurts drive traction. In cars with more than 100% anti-squat, the back end will lift up instead. That's what drag racers really want. You'll never see a serious drag racing car squat on launch - you mostly notice the front end rise.

Ahh, ok. I was definitely thinking about that incorrectly. I thought squat would help weight transfer and load the rear tires but it's the other way 'round. I'm definitely not a drag racer.

Originally Posted by Msquared

I forgot to mention that I own a copy of Race Car Vehicle Dynamics and actually did read it cover to cover. The world would be a better place if everyone did that! My son has it now.

Ordered!

[clyde]

Originally Posted by Msquared

I forgot to mention that I own a copy of Race Car Vehicle Dynamics and actually did read it cover to cover. The world would be a better place if everyone did that! My son has it now.

I have this book.

Of course, what I really need is "Race Car Vehicle Dynamics for Dummies."

And if you're up for some really light reading next, there's "The Shock Absorber Handbook."

[Msquared]

Originally Posted by clyde

Of course, what I really need is "Race Car Vehicle Dynamics for Dummies."

The closest thing I know to that is Think Fast: the Racer's Why-To Guide for Winning, by Neil Roberts. It's an uber-practical guide to how and why to set up a car. Neil is a friend of mine from college, and after getting his aerodynamics engineering degree, he went on to become a very successful motorsports engineer. His last (maybe longest?) gig was working at Honda Performance Development. When Indycar adopted rules that let Honda and Chevy develop their own aero packages, the first Honda package was designed by Wirth in England, and it was a hot mess. Neil lead the team that created the second-gen package, which was immediately successful. He also led the team that created the IMSA DPi Acura car that Penske and then Wayne Taylor Racing and Michael Shank Racing campaigned through last year, too. But this book is really down to earth. It makes a nice book-end to the Milliken tomb, and it's good to have both on your shelf.

[Badmojo]

Originally Posted by Msquared

This is true. However, that still doesn't change the fact that neither springs nor dampers can change the lateral or longitudinal weight transfer of a car during any direction of acceleration.

Springs, dampers, and suspension geometry control how the chassis moves relative to the tire's contact with the road. The stiffness and dampening of the system control the movement dynamically. Imagine the direction of the car's center of gravity (CG) during a corner. The position of the CG influences the tire load distribution based on vehicle weight and g-force, which constantly goes forward during braking, rear during acceleration, and left/right during cornering. Dampening speeds or slows down that movement. An ideal suspension system maximizes the tire load across all four tires since the friction plateaus at a specific load point.

Shock tuning alone isn't a miracle, and it's a small part of the overall system.

Grassroots Motorsports had a recent article (probably in the last 18 months) testing the degrees of stiffness of a suspension and lap times. Even racecars need some level of compression and the ability to absorb curbs, uneven surfaces, and transients to maximize grip on all four corners. Otherwise, the fastest cars would have go-kart suspensions without springs or shocks.

[Msquared]

Originally Posted by Badmojo

Springs, dampers, and suspension geometry control how the chassis moves relative to the tire's contact with the road. The stiffness and dampening of the system control the movement dynamically. Imagine the direction of the car's center of gravity (CG) during a corner. The position of the CG influences the tire load distribution based on vehicle weight and g-force, which constantly goes forward during braking, rear during acceleration, and left/right during cornering. Dampening speeds or slows down that movement. An ideal suspension system maximizes the tire load across all four tires since the friction plateaus at a specific load point.

Shock tuning alone isn't a miracle, and it's a small part of the overall system.

Grassroots Motorsports had a recent article (probably in the last 18 months) testing the degrees of stiffness of a suspension and lap times. Even racecars need some level of compression and the ability to absorb curbs, uneven surfaces, and transients to maximize grip on all four corners. Otherwise, the fastest cars would have go-kart suspensions without springs or shocks.

None of that really addresses what I wrote, either to refute it or concur. If your point is that suspensions improve grip when the road is uneven, I agree. And of course they can be used to adjust both transient and steady-state handling. My point was to rebut wenlyone's assertion that dampers somehow reduce weight transfer. While I agree that weight transfer is undesirable in lateral acceleration or braking (it's generally good for acceleration in a RWD car), I am pointing out that damping (and springs, for that matter) don't change the amount of weight transfer that takes place at a certain magnitude of acceleration in any particular example. They can affect the rate at which the transfer is applied to the contact patches, however.

[Badmojo]

Originally Posted by Msquared

None of that really addresses what I wrote, either to refute it or concur. If your point is that suspensions improve grip when the road is uneven, I agree. And of course they can be used to adjust both transient and steady-state handling. My point was to rebut wenlyone's assertion that dampers somehow reduce weight transfer. While I agree that weight transfer is undesirable in lateral acceleration or braking (it's generally good for acceleration in a RWD car), I am pointing out that damping (and springs, for that matter) don't change the amount of weight transfer that takes place at a certain magnitude of acceleration in any particular example. They can affect the rate at which the transfer is applied to the contact patches, however.

From an academic standpoint, static or steady-state methodology and concepts on a dynamic system are inaccurate. I assume that Wenlyone is considering it a dynamic system, and he is correct that the most lateral grip is achieved when the load is more evenly distributed across the four tires. I interpreted your reply to dispute that. Perhaps we are using terminology differently.

My main point to the readers of this thread is that shock tuning won't usually produce measurable results without considering the entire suspension system, including the tires. It is only one piece of the somewhat complicated puzzle.

Bringing this back on topic, several people on the forum have contacted me regarding my experiences with the DSC Sport Controller. My best advice is not to get one if you expect "plug and play" measurable lap time improvement.

[Msquared]

Originally Posted by Badmojo

he is correct that the most lateral grip is achieved when the load is more evenly distributed across the four tires. I interpreted your reply to dispute that.

No, I fully agree on that. That's literally the entire basis for chassis tuning. Again, my only point was to rebut the assertion that dampers reduce weight transfer due to acceleration.