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Mid Corner Mastery

Connor Bell, professional sim racing coach, wearing a white and blue racing suit.

Lesson by

Connor Bell

Book Coach

Now that we've mastered corner entry, corner exit, and how we structure them, it's time to talk about the next step in terms of developing the perfect corner. And that's going to be ensuring our mid-corner phase is up to the limit. In order to do that, we're going to talk about how to get to the limit of the front tires and the rear tires. We're going to mesh our learnings together on the real track later on in this workshop. And then we're going to manipulate whatever state you'd like to produce out of the car.

Understanding the Limit

Let's review the term "the limit." When we say that, we simply mean the maximum load the tires can withstand—nothing more, nothing less. Under the limit is not using the tires to their maximum capability. And vice versa for over the limit, that's going to be when we're exceeding the available grip of the tires.

What Defines a Perfect Corner?

Today, we're going to talk about the separation between fronts and rears, and really keeping all four tires on the limit for the entire corner is how we develop the perfect corner front and rear tires. In order to get closer to the limit under the rotation phases of the corner, it's important to understand the difference between fronts and rears. The perfect corner comes from equally balancing the usage of front tires to rear tires.

Front Tires

Front tires are primarily going to be affected by the steering wheel. Anytime we go over the limit of the front tires, we're going to be putting ourselves into a state of understeer.

Your cues for feeling understeer and seeing and hearing understeer include:

  • You're going to feel the force feedback lightening. We'll know when we're at the limit of the front tires—the force feedback will be at its peak torque. But as soon as we go over the limit, it's going to be a decent drop in torque from our wheelbase. This is obviously going to be easier to feel on a direct drive base, but if you are on a belt driven or gear driven wheel, it just requires a little more lightness in your hands to feel the subtle difference there.

  • We're of course going to hear the tire sound increasing.

  • Visually, we're going to see understeer. The horizon is going to stop increasing horizontally across our screen. We're visually going to see less yaw rate happening.

Rear Tires

Rear tires are primarily going to be engaged by trail braking and engine braking. Over the limit of the rear is going to put us into a state of oversteer.

Your cues for oversteer include:

  • You will also feel the force feedback lightening and weight when we get oversteer.

  • You might also have to actively counter steer.

  • We're also going to hear tire sounds increasing.

  • Opposite of understeer, the visual landscape is going to quickly accelerate. We're quickly going to gain yaw rate, and we'll see that accelerating through the horizon on screen.

Exercise One: Finding the Limit of the Front Tires

For this exercise, we'll be using Lanier Speedway (the road version, not the dirt version). If you're in the league, it's highly suggested to use the Spec Racer Ford. If you're not in the league, then go ahead and use whatever car you'd like.

Steps:
  • We want to make sure we're only lifting and coasting. So no trail braking, no downshifting whatsoever.

  • We're going to lift on corner entry to each of the corners on the oval.

  • We're going to experiment with how much steering or how much steering load the front tires can withstand.

  • Try and find the limit of the front tires by gradually increasing our maximum steering angle in each of the corners on Lanier Speedway, until we reach understeer.

The Golden Rule:

We can only apply the throttle at the apex, which in the case of Lanier Speedway is going to be pretty much exactly in the middle point of both corners.

Goals:
  • Figure out where your lift point needs to be in order to keep the fronts at the limit, while also ensuring we're only rolling on the throttle at the apex.

  • In order to find the limit of the front tires, first we have to go over and find the point at which we start to understeer. And then we can dial back down to the limit.

  • Find exactly where we need to lift in order to keep the front tires at the limit.

Exercise Two: Engaging the Rear Tires

Now we're going to talk about starting to engage rear tires at a basic level.

Steps:
  • Keep the same lift off point that you just defined towards the end of your first exercise—the lift off point that allowed you to keep the fronts on the limit and roll in the throttle at the middle point of the corner.

  • As soon as we lift off of the throttle, immediately go to around 5% trail brake and hold it up to your throttle point.

  • Now that we're going to be getting more rotation with this 5% trail brake, adjust your lift point accordingly to keep the fronts at the limit. Our lift point is going to be able to be pushed further down the track now that we're getting more rotation slash a little more deceleration with that 5% trail brake.

  • Once you're comfortable and you've got your new lift point based off 5% trail brake, then jump up another 5%, so we'll go to 5%, then 10%, then once you have another lift point, we'll go to 15%, then 20%, etc.

  • Continuously adjust your lift point accordingly.

Goals:
  • Figure out how much trail braking percentage it takes to keep all four tires at the limit while ensuring we're still rolling on the throttle at the apex.

  • In order to find the limit of the rear tires in this case, we need to go a little bit over the limit, just like we did at the fronts. Keep adding trail brake as you go through this process until you get that little bit of oversteer.

  • Try and remember what that percentile is.

Advanced Consideration:

For those that are already feeling comfortable, experiment and think about whether the limit of the front tires changes now that we're adding in trail braking. Now that we have more weight on the fronts, the limit of the front tires has increased, which means we can be a little bit more aggressive with the steering.

Exercise Three: Front Tire Limit on Chicago Street Course

Now we'll move to the Chicago Street Course (or a track of your choice). We'll be practicing through turn one. It's highly suggested to do your out lap and then set your reset point halfway down the front straight.

Steps:
  • Break to the limit under straight line braking.

  • Release the brakes immediately once you get to the turn-in phase. As soon as you're about to put the first degree of steering angle in, completely drop off of the brakes.

  • Do no downshifting whatsoever. You'll be entering turn one with fourth gear. Stay in fourth gear the whole time.

  • Since we're not doing any downshifting or any trail braking, we're simply going to be rotating the car by using the steering wheel only.

Goals:
  • Find the limit of the front tires by gradually increasing our maximum steering angle until we reach understeer. Once we get to that understeer, dial down and figure out the exact limit—exactly how much maximum steering angle we can use to get to the limit of the front tires.

  • Figure out where your braking reference needs to be if you're limited to the front tires for rotation.

The Golden Rule:

Roll on the throttle at the apex, no later, no earlier.

Exercise Four: Combining Trail Braking with Steering

This exercise is similar to exercise two on the oval, but applied to turn one at Chicago or whatever track you're practicing on.

Steps:
  • Continue braking to the limit under straight line braking. Keep the same braking point you just had at the end of the previous exercise.

  • Release the brakes upon initial turn-in and drop right down to 5% pressure. We don't want any blend in our braking as we normally would with trail braking. You're just going to jump from your straight line braking down to 5% trail brake as soon as you turn in.

  • Obviously, we're getting more rotation now and a little bit of extra deceleration. So it means you'll have to adjust your braking point to keep the tires at the limit.

  • Adjust your braking point based on the 5% trail brake. As soon as you're consistent and comfortable, increase by 5% again, up to 10%. Once you get comfortable with that and consistent and have found a new braking point, go up to 15%, etc.

Goals:
  • Find the limit of the rear tires by gradually increasing your trail brake until you get to oversteer.

  • Begin combining your understanding of front tire and rear tire limit by retesting each when using both at the same time.

  • The limit of the front tires is probably going to change now that we have more weight on them with trail brake. I suggest leaving that step or completing that goal towards the end. Once you're fully comfortable with the right trail braking pressure, then you can go and retest the steering.

Exercise Five: Adding Downshifts

We're going to further test the rear tires at a more advanced level. It is indeed time to add in downshifts.

Steps:
  • Break to the limit under straight line braking and trail brake. Our trail braking is going to be based off of what we learned the last time around.

  • Start with adding in our downshifts as late as possible in the cornering phase. For example, if you're coming in in fourth gear and you want to be second gear exiting turn one at Chicago, we're going to do both downshifts right before our throttle point, very, very late in the corner. That way we're not inducing too much rotation.

  • We're looking to start at an under the limit state, and each time we reset, start to downshift earlier and earlier in the cornering phase.

  • As we begin to downshift earlier, we're going to be further testing out the rear tires. We're looking to find that point where you continuously downshift earlier, and then you eventually go a little bit over the limit of the rears. Once we find that, we're over the limit, and we can dial down from there.

Goals:
  • Find the limit of how quickly we can downshift before going over the limit of the rears.

  • Find the right balance between all three tools for rotation. We want the car to be in a balanced state, not understeering, not oversteering, but still using the fronts and the rears, both at the same time, hopefully to the maximum each of those tires can handle.

  • Make sure we're rolling on the throttle at the apex.

  • Now that we're downshifting, try and see if your braking point also changes.

Advanced Technique for Multiple Downshifts:

If you have a corner where you need to do two downshifts, what works well is doing one of the downshifts quite early during your straight line braking phase. Do one of the downshifts early under straight line braking because it's going to help decelerate the car. And then you'll still have somewhat higher RPMs under initial turn-in. You'll get a little more rotation at the start. Then sort of delay your second downshift and only use it when you need rotation coming into the apex.

If you notice that you're not rotating quick enough, and you're on a trajectory to miss the apex, then downshift a little bit quicker just to get some of that rotation going earlier. And then if you're already on a trajectory to rotate correctly, and you don't need any extra rotation, or if you take another downshift you're going to oversteer, then delay that second downshift to the point where you're just about to get on throttle.

Dynamic Brake Bias:

Depending on where you downshift will affect your dynamic brake bias. It's basically changing—you're sending more rearward bias, depending on where you downshift. So sometimes you actually don't have to change your brake bias. You can just dynamically adjust it with the timing of your downshifts.

Key Philosophy: Fast In, Fast Out

The fastest way to take 99% of single apex corners is to roll in the throttle at the apex. A lot of traditional coaches will say momentum matters, and we want to get on throttle as early as possible, but that comes back to the philosophy of slow in, fast out. But anytime we're rolling on the throttle way before the apex, we're probably losing a lot of time on entry because we're braking so early. And then you're also probably getting some understeer on exit that you're having to manage as you apply the throttle.

The philosophy here is fast in, fast out. And the best way to do that is to brake to the limit on entry and figure out the braking point that only allows you to roll on the throttle at the apex. The whole slow in, fast out momentum philosophy might work for really, really slow cars, but it's a little bit outdated with today's level of driving.

Important Reminder: Causing and Preventing

It comes back to the idea of if you can cause it, you can prevent it. Basically we're looking to cause 1% over the limit, and then because we're able to purposely do that, we can very consistently drive at the limit and prevent any big moments of over the limit.

Tire Management

The best thing you can do for tire management is drive at the limit. When you don't know exactly where the limit is, you're more prone to driving over it. And that's when you cook your tires—when you're understeering and really leaning on the front tires.

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