Originally Posted by Johnny Wishbone
Just wondering Martin, in your opinion, what would you adjust on the car to try and get more corner speed, or free the car up. If you could give a example similar to what you have done in your App, like start with this and give five steps.
As with anything dealing with setups, there are always compromises when trying to get more corner speed. I find the main compromise is drive-ability and consistency. I will often sacrifice a little corner speed in the interest of consistency. So the point here is you can go too far in my opinion and make the car too hard to drive. Having said that here are my thoughts on obtaining more corner speed.
The first thing to look at in your car with its current setup is if the car is currently pushing a little too much or is a little too loose. To maximize corner speed you want both ends of the car to do the steering, not just the back or the front. You also want to watch how your car leans into the corner. You don't want a car that mainly rolls over on the front or mainly on the rear. You want the the car to intially roll on the front on turn-in, but very quickly get the back to roll as you start to enter the corner, otherwise the car will likely push loosing speed, or perhaps traction roll on very high grip carpet tracks. You also don't wan't the back of the car to roll more than the front at mid corner as this can make for a loose car and also cause traction rolls on high grip carpet tracks.
The next thing to focus on is to maximize lateral grip as that is what gives you your cornering abilities. to maximize lateral grip there are a number of things to try an achieve through your setup.
1. maximize contact patch of all four tires....not just the outside tires. This is managed mainly by by roll centers, spring rates, camber gain and static camber. You will need to check your tire wear to make sure you are using as much of the contact patch as possible.
2. minimize the lateral weight transfer from the inside tires to the outside tires. spring rates, roll centers and upper link lengths will affect this. Some may think that swaybars are the way to reduce lateral weight transfer but the technical journals and books I have read indicate that although it does keep the car more flat keeping more weight over the inside tire, there is a competing upward force on the inside tire caused by the swaybar that tends to negate this, and and strong increase in the downward force on the outside tire due to the swaybar that actually ends up in increasing weight transfer to the outside tire. With a higher roll center however, you can keep the car flat without creating this upward force on the inside tire. Swaybars are mainly used for car balance and car consistency and not for increasing lateral grip in other words.
3. Don't let the chassis rub on the driving surface. The moment this happens it takes away downward force from the outside tires, reducing lateral grip. Sometimes I will do this on purpose to avoid traction rolling, but that is only as a last resort.
4. Make sure that what you are asking the tires to do is gradual in nature. You want to make sure that when entering a corner you are not asking the tires to gain lateral grip too quickly both through your throttle and steering technique, but also through your spring rates, shock package, swaybars, roll centers and droop settings. A tire can reach a high level of lateral grip if it approaches that limit more gradually. For example setting up your shock bump dampening to be really stiff or really soft will cause an abrupt "ask" of grip from the tires which will reduce the overall lateral grip limits. Same thing with spring rates...too soft and too hard are not good for the same reasons...you need to experiment and get a feel for what works best at any give track.
5. slip angle is another key factor in achieving lateral grip. In order for a tire to reach it's maximum lateral grip it needs some slip angle. Some tires like a larger slip angle than other tires to achieve their maximum grip. This is a function of the rubber compound and the overall shape and sidewall strength of the tire. Only testing will tell you what works best for a tire. The slip angle is affected by rear toe-in and also by the static toe-out in the front and dynamic toe-out caused by the ackerman settings you use. There is no one right answer here as it really depends on the tire...testing is the only way to find the optimal static and dynamic slip angles for a given tire.
As for the order of how I would approach this...and there are many ways to do this...but here is my personal approach.
1. first start with dialing in the spring and shock dampening package so that the car is not too floppy and not too flat and can transition smoothly into and out of corners. I spend a lot of time on spring rates and shock packages.
2. I then focus an equal if not greater amount of time on my roll centers. My goal is to keep the roll center as high as possible without making the car feel too edgy or traction rolling (on carpet). Lower roll centers will feel smoother during transitioning into and out of corners which is equally important as ultimate lateral grip in terms of driving consistency. In general I tend to drive a medium type of roll center as i find that to be a good compromise between ultimate lateral grip and a smooth driving car.
3. Now I focus on my rear toe-in and often do this in conjunction with the roll center. I was enough rear toe to make the car feel stable on entry and have good forward bite off the corner, without making the car loose all of it's momemtum in the middle of the corner. Again as I said above I want the front an the rear of the car to do the steering..so I work a lot with combinations of front and rear roll centers along with rear toe to find the right amount of roll, rear and front steering. For example if I notice the car is pushing too much in the middle of the corner because the front seemed to be rolling and back of the car was not rolling enough, I would lower the rear roll center (perhaps 0.5 to 1.0mm) and maybe even decrease my rear toe-in by 0.5 degrees as a second step.
All of these concepts are explained in more detail within my app (www.setupworkbench.com
), yes I know shameless plug...but I keep hearing from people how much it helps them
Sorry for going on so long...but hopefully this gives you some of idea of how I approach things. Hopefully my ramblings made some sense.