Help tuning Nissan GT-R LM Race Car

  • Thread starter AudiPro
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San Diego/Calif
For the last couple days ive been trying to tame this beast of car but from what I can tell this car is all about perfection. Ive tried checking GTVault but there arent any setups I like but I was able to set the gears and other handling issues but this car still is still shaky down the straights and spins out while braking around the corners. (Note: Ive been testing it on Nurburgring of course)
 
If that tune has anything to do with the suggestions I gave you, Flynn, I would also recommend tightening the springs, dampers and stabilizers by a few clicks to adapt to the higher weight.
 
Yea I'll try that I already lowered the car as far as it would go and added some more downforce to th rear end to get some more grip around the corners.
 
Yea I'll try that I already 1) lowered the car as far as it would go and added some 2) more downforce to th rear end to get some more grip around the corners.

Two elements I want to address here:
1) Ride height actually needs to be a bit higher than the minimum, otherwise your car/suspension dynamic is going to behave too much like a single unit. That means too much alteration of the car's attitude due to road irregularity. The suspension was designed to behave like a separated buffer between the surface and the car. Your car's top priority is stability: cornering, accelerating, decelerating and across all elevation changes, and the suspension was designed to cope with the surface variables while keeping the chassis' motion shift as close to zero as possible. In order for the suspension to cope with the severely diminished stroke, the springs and dampers will need to be maxed out, and that means NO flexibility whatsoever, and ALL the energy of the road surface will be transferred to the chassis.
SUGGESTION: raise the ride height to or near the halfway point and set the springs to around 10~ish front/back (adjust to suit the static weight balance) then season to flavor for each track and according to your individual style.

2) Aero can have a significant effect on a car's handling dynamic also. If you have a car that understeers significantly, increase the aero in the front to put all the pressure on the front wheels, then reduce aero in the rear to allow for lift-throttle oversteer under deceleration. This will aid the car in getting around corners. If the car is oversteering, raise the rear downforce to keep the rear from stepping out, and/or reduce the forward aero to ease the forward-biased grip imbalance. That said, aero has a limited effect on over/understeer. Your problem may lie elsewhere, such as LSD (greatest contributor, IMHO) or suspension (moderate contributor). You could reduce the LSD-Decel to minimize grip under braking and make the rear more apt to swing around a corner. This will lead to late-apexes, but will give you more turning action on approach. Setting the LSD-Accel a bit higher will make the car tend to straighten itself out and rocket out of the corners.
SUGGESTION: Leave your aero at default (usually max) and fiddle with the LSD settings until you find something comfortable. Try reducing LSD-Decel to minimum, then stepping it up 5 clicks with each subsequent run to get it dialed in to your specific style. Then, do the same with Accel. Once you've got the rear turning how you want it, adjust the aero by 5 clicks, first forward, then rear, and measure your effect. Season to flavor.

I would also STRONGLY suggest you try to find and read Scaff's tuning manuals, if at all possible. They are priceless to tuners, IMHO. It's a shame the Emperor doesn't haunt here any more, as I'm sure he would be more help to you than I could, as all I learned was derived from his wisdom.
 
If you are trying to get rid of any understeer, try raising the rear ride height about 3-5 mm above the front ride height. Also having the rear spring rate stiffer than the front will dial out the understeer.
 
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