S197 pushing badly

[TeeLew]

TeeLewism #936: Robert Duvall has contributed to more poor handling race cars than any other person on the planet (He even beats Steeda). Everyone laughs at the racing in _Days of Thunder_, but I've heard people who are too young to even remember the movie quote me, "Loose is fast.." They rarely complete the quote, "...and on the edge of out of control." What they NEVER acknowledge is the lesson of the scene. It was 6 seconds slower.

 

[bnight]

Interesting - I've always heard faster drivers want a sharper front end because you can manage the rear end with steering and the pedals....but what you're saying is backwards, right?

It goes both ways: Verstappen a lot of front end actually more front end than anyone on the Grid, Hamilton on the other hand prefer a rear end car (Reason he was struggling with ground effect cars and with the Ferrari car last season.) Both styles make for a fast driver Hamilton - 7 titles vs Verstappen - 4 titles. So overall it's a personal preference. Regarding the Mustang the car is a point and shoot car (heavy car, big engine) if you set it up to be able to spend as little time in the corners as possible it will be generally faster which means you need rear end to exit the corners fast. But you also need frontend to rotate on entry which makes the brakes the single most important part on the Mustang (brake as late as possible, trail into the corner and step on the gas as soon as possible).

 

[TeeLew]

You're not wrong, but the pinnacle of the sport has very little in common with what we do and NONE of us have Max's skillset. We are mortals.

 

[Mad Hatter]

I found it easier to understand in terms of weight transfer. As we brake, we transfer the load on to the front tires increasing the grip. The term "Nascar turn" stuck in my head from some one here on TMO. To turn our big heavy cars we need to load the front tires up and at the same time, our rears lighten up, ounce we got the car rotated and we start to accelerate, we want some squat so that the weight transfer to the rear and we blast out of the corner. I can get 4 to 5 car lengths on a Cayman GT4 on corner exit. At least in my setup, if I take a neutral stance through the corner the car will understeer horribly. It likes it either on the brakes for corner entry and on the accelerator for exit, no coasting.

 

[TeeLew]

I believe the best approach is to try to carry enough entry speed that the car requires you to have a slightly pause between the brake release and throttle application in low-speed corners. By low-speed, I mean 2nd and 3rd gear. In the higher speed stuff (4th and up), get back to throttle immediately to settle the rear and keep the rolling speed up through the middle of the corner. If you find you have to immediately got back to throttle in low-speed corners to settle the rear, then the car is probably trending to be too loose.

You mentioned the diff earlier. For me, the torsen is the simplest answer, but not the preferred one. We have to have preload across the rear axle and the torsen inherently doesn't have much, especially as delivered. That's nice for a grocery store parking lot, but it doesn't stabilize the rear axle during braking (which allows inside rear locking/micro locks inducing instability). Once on the throttle, things improve, but the torque bias ratio is relatively low and it's easy to get the inside rear lit up, especially if there is bad pavement, you skip it off a curb or drop a tire.

Our cars have a relatively high CG and relatively low rear weight distribution. The inside rear gets very light on the way into the corner. If I were setting up an Mustang GT (broad term GT, not the model) car, I'd start with a minimum of 200 Nm preload and all the ramp/plate I could get. I can almost guarantee I'd end up with something resembling a spool. All you really need it to do is crack open just a little in the brake release/coast phase. EVERYTHING else is better when it's locked. Well, that's not true...it can be a real PITA to push around the paddock when the diff is going click-click-click every time you try to turn the steering wheel, but, regardless of the wive's tales, that's about the only place at a racetrack it will increase understeer. In most scenarios, it actually helps to turn the car.

Drivers will fight like hell against locking the diff because they think it will just make dump-truck understeer. If you're just driving around town in the linear range of the tire, that's what it does. We shouldn't be spending much time in the linear range of the tire while cornering at race track pace. Once we've introduced a bunch of load transfer, have the appropriate slip angle to the tires and have gone to throttle, it *helps* to turn the car.

The Challenge guys are stuck with the torsen. If I were running one of those cars, it'd be built tighter than a frog's arse. If it were open to change, I'd be on an OS Giken.

 

[DAVECS1]

I have working quite a bit on my setup and my last visit to Putnam Park in Indian I was genuinely very happy with my car's response. It favored braking late with generous trail breaking keeping the front end loaded until the last second. My toe is 0 my camber is 3.1 degrees and Caster is at 6.8 degrees. I have tie rod adjusters to move that point down. I also have raised my lower trailing arm mount by an inch using the Steeda subframe. I also am using the longer ford performance trailing arms. Here is where my setup differs quite a bit from everyone elses. I run 1550lb/in front springs and 700lb/in rear springs. I am running hyperco's all the way around 3" up front and 2.5" in back On Mike's adjustable setup. I am currently running Fortune Autos dampers with custom valving but Iay bug Tee Lew to adjust them. The soft rear spring with very stout rebound damping is allowing me to come out of the cornes super aggressively. I can get on the fuel super early and if the cars starts to slide, it is extremely predictable. I also run 2.9 degrees rear camber with a 1/32nd toe in. Square 305/40R18 setup.