Spring Mechanics Question

Hello all,

I have a question regarding springs and overall load transfer.

I have been reading up on vehicle dynamics, specifically load transfer, and understand that the magnitude of load transfer is only affected by the physical geometry of the car, while how the distribution takes place depends on the springs, roll bars, dampers etc…

My first question is: During braking the backwards force on all four tires and normal force on the back tires all cause a moment about the CG in the same direction. The front tires’ normal force is the only force opposing this moment, thus we obviously have more load transfer to the front tires as they need more force to compensate for this longitudinal roll. I have been reading that stiffer front springs compared to rear springs means that some of the load transfer stays on the back tires (to equally distribute the braking force). This doesn’t make sense to me. Braking at a certain force REQUIRES the front tires to have a certain normal force to counteract the longitudinal roll, if some load is transferred to the rear then the car would roll over as the moment wouldn’t equal zero (given all things “equal”).

My question is: How and why does stiffer front springs and softer rear springs bring about this differentiation in longitudinal transfer? ( I understand their effect in lateral load transfer)

My second question is: During a right turn, if both the front left and back left tires are over their limits then, the driving style and line is wrong, correct? The magnitude of lateral transfer stays the same and i cannot redistribute it in any way as both tires are already at their limit. Correct?

Thank you for any help in understanding.

John

take all of what you have learned and toss it , in forza you can do some really crazy things that physics say should not happen. and since this is not a sim game we will never be able to manage the longitudinal bias of the cars .

as for the tires being over the limits according to the telemetry menu are a bit off . if we still had the ability to watch replays on the leaderboards you can clearly see that many of the fastest people on forza are pushing tires well beyond their limits . the only thing you should be worried about is how your driving affects your lap times .

Ah man;(

I’m consistently 1-1.5 seconds off the number 1 time on all tunes. Just can’t seem to figure out that last oomf. I tend to “see a problem” and tune the car to my driving style.
How can the telemetry be wrong? Isn’t that the data directly read from how forza is perceiving it?

Ignore telemetry, tune by feel.

Also. 90% of the time is build, tune just makes it better. So you may have the wrong build on your car.

Here comes the next problem:

Sometimes, the fastest build isnt the easiest to drive. You need to adapt to the car, not the car to you.

2 Likes

Indeed, I’ve previously done some cars that feel like they could spin at any moment and would be super competitive with laptimes.

I think tuning by feel is the way to go. Without the game code, we don’t really know how the calculations for physics and each tuning section truly effects the vehicles performance. What we do know is that if you go by… “If I change this one thing and see what happens… OH, it does this…”. You will learn ‘the way of the game’ and tune to your own preferences.