Tuning for ... "Mid-Corner" ... performance

[Sail IC]

Aiming to tune for optimum performance, like all I guess, I like to create a car that is very agile, turns and rotates very well, without being too lose in the rear risking a spin in a long one hour race.

I guess we all have our favourite methodes inserting agility through the corner. Where I'm struggling is to eliminate Mid-Corner understeer without creating excess entry/exit corner oversteer.

One way, and maybe thats the only way, is to adopt a driving style where minimizing how long time driven Mid-corner (coasting), ie break later and accelerate sooner, but late breaking often leads to overheated tires and excess tire wear.

Balancing corner exit under/oversteer I find relatively easy. I normaly start with a low LSD like 10/15/10. If I get corner exit oversteer, I just reduce the LSD-accel. What I believe is happening is that the car vents excess power through the inside wheel maintaining corner grip on the outside wheel. It works but can create some excess tirewear. I normally end up with an LSD-accel between 10-20.

Corner Entry/Mid is more problematic. In order to tune for agility through the corner (incl exit), I mostly work with the LSD (accel, decell), ridehight, and rear toe (negative vaules). In the end I normally end up with a car that when I release the breaks, I first get a very strong turn-in followed by the front losing grip and too much understeer until I can get on the accelerator. In some corners but this is fairly rear, instead of getting front tire slip after initial very strong turn-in the rear will slide out. This mostly happens in slow banked corners where the load in the suspension is very high. I normally run with a very high ridehight, so its not due to bottening out.

I think the solution to my problem lies in tuning the dampers better as when releasing the breaks there is strong weight transfering happening. I know how it should work in theory, but I have problems making the theory happen. I usually ending up just doing "trail and error", but it hasn't worked all that well for me.

I should add that above is for racing SuperGT GT500 cars Online.

I know above is rather complex, and I hope I managed to describe the problem. Appreciate any help from this very knowledgable crowd.

 

[CSLACR]

Entry can best be solved by lowering lsd decel (outside tire retains more grip, just like accel coming out) and running more front brake bias then rear, at least relative to what current settings are.

The overall trick is, you can make a car neutral by removing grip from whichever end has grip (under-steer = front, over-steer = rear) or adding grip to the sliding end. Obviously adding is the way to go, but can easily be overlooked.
When you release the brakes turning in, the front end loses weight, which momentarily gains grip, if you then experience more under-steer after the gain, you likely don't have strong enough dampers. Though I should say to a point, physics demand this slightly, so you'll have to fine balance between over or under steer, as a perfectly neutral car in all scenarios is somewhat of a unicorn.

There's also the potential driving issue you could be addressing without realizing, it may be that you're letting off the brakes to rapidly, I've no idea your driving ability or style, so this is a general possibility.

Camber and toe most certainly have an effect here, as front toe dictates how quickly the car turns in, or how slowly, and while camber can be a great tool for grip in all areas, what works best for entry may not work best for exit, so you may have to pick and choose. Steering angle is what I've found to be the prime determiner for camber, the harder you turn the wheel, the more camber you may need, of course to a point.
But then nothing eats tires like camber.

Hopefully some of that will help, I honestly haven't found great benefit from damper changes, aside from to stiff makes the car bounce, and to soft makes it sloppy, I almost always end up between 4-8 on both.

 

[Sail IC]

Thanks for your reply.

I have identified breaking as the driving area where I can improve the most. I'm rather hard on the breaks and release them pretty abrubt. The other thing I thought about is that when entering a corner lets say going from 5th to 3rd gear,, I'm doing break-4th-3rd-release. Maybe its better to do break-4th-release-3rd.

Its always hard to judge your own driving ability, but I think I'm pretty fast. Practicing for my last races my PB in a Lexus Petronas 615PP, free run Online (no slipstream) are; Laguna (1'15.7xx), Rome (1'02.071), and Trail Mountain (1'15.260). Try it, but I think for most it will be a challange to reach these laptimes.

 

[Highlandor]

The relationship between your brakes and LSD decelleration settings is important, but also, the suspesnion needs to be correctly tuned to able able to cope with this.

Tune your brakes and LSD dec setting to get the car to turn in how you want, then play with the springs, dampers and roll bars to ensure the affect of weight transfer is dealt with efficiently by your suspension.

Don't use things like camber or toe to 'cure' the problem, use these (and ride height too) to help fine tune the car.

Start with your brakes being higher at the rear for most cars on most tracks, this will get the car turning under braking, then (usually, but maybe not 100% of the time for 100% of the cars) the LSD decel settings should be reduced, sometimes quite alot or even to minimum.

This helps to get the car turning in 'early' and 'naturally', rather than 'forcing the car into the corner.

It's trial and error depending on the car, track, your driving style, suspension settings and your equiptment sensitivity settings - as to where exact figures would be best, but generally, the same 'rules' will aply to most GT500 cars, apart from maybe the NSX as this is a MR car rather than a FR car, so the LSD braking decel figure possibly might not need to be so low.

 

[CSLACR]

Thanks for your reply.

I have identified breaking as the driving area where I can improve the most. I'm rather hard on the breaks and release them pretty abrubt. The other thing I thought about is that when entering a corner lets say going from 5th to 3rd gear,, I'm doing break-4th-3rd-release. Maybe its better to do break-4th-release-3rd.

Its always hard to judge your own driving ability, but I think I'm pretty fast. Practicing for my last races my PB in a Lexus Petronas 615PP, free run Online (no slipstream) are; Laguna (1'15.7xx), Rome (1'02.071), and Trail Mountain (1'15.260). Try it, but I think for most it will be a challange to reach these laptimes.

Ironically I haven't driven any of those tracks with any GT500 car.
But yes, advanced braking techniques are about the last and hardest thing to learn, and I'm still working on them myself.

 

[zodicus]

Ive had good luck with a low compression high extension set up on the front of the car(not crazy just 1 or 2 clicks higher and lower) also back off on the rear spring rates a little, this should put and keep more weight on the out side front tire. Dont go to low though or you will overload the front tire (again not a crazy amount just a little lower than "normal")

 

[godlameroso]

If all else fails use ballast, rearward for more rotation, forwards for stability. 35-50kg is good for a road car. If you've done stage 3 weight reduction on the 02 rx7 it's at 1051kg which leaves you 49kg of ballast before you're at 1100kg. Those 50 kgs do almost nothing to hurt performance, and when you move the weight distribution to the back, amazing things happen to the car. Especially if you stiffen the side with a higher percentage of the weight.