High Speed Stability on Tuned Road Cars?

[lbpomg95]

Hi there, I've looked it up but not had much luck finding anything. I mostly drive road cars, which I either partially or fully upgrade, and I generally use a one-size-fits all set-up for driving them. Mostly I'm happy with how all my cars handle on twisty tracks, but I've noticed issues with stability at high speed (around 160mph and above), and was wondering if anyone else has noticed, or cured it?

It's worse when using racing tyres, but it's very much still there with sports tyres. I usually run maximum rear downforce, but for cars like the classic Alpine A110 and the Lamborghini Miura with no front aero, the front end is very light and unresponsive, but then loads up and gets very twitchy. Certain cars are undriveable on bank turns, or on the final sector of the Nurburgring at the end of the long straight.

Are there any tweaks I can make to my set-up (other than using less grippy front tyres) to improve stability at high speeds? Thanks in advance.

 

[bread82]

Almost certainly an aero effect at those speeds. Ride height differences can affect balance there too. Toe in can also help stability.

Springs and damps can alter the timing of load transfer so can either be set harder or softer depending on when the driver feels the car misbehaves in relation to control inputs. Too twitchy is bad but an unresponsive car which then bites you after you've fed in even more input is bad too. This is very much a personal preference.

Banked turns are a menace on some of my cars, it can be very hard to tune out. If the rear end lets go I've found more rear camber makes the grip loss more progressive.

Also at the mega speeds you mention, and with sticky tyres... Might be worth checking she's not bottoming out.

It's sometimes possible to set aero balance one way (eg understeer) but have the springs and other mechanical suspension set for oversteer. The car then becomes schizophrenic when changing speeds since the aero dominates at high speed, this can cause problems.

Good luck.

 

[lbpomg95]

Almost certainly an aero effect at those speeds. Ride height differences can affect balance there too. Toe in can also help stability.

Springs and damps can alter the timing of load transfer so can either be set harder or softer depending on when the driver feels the car misbehaves in relation to control inputs. Too twitchy is bad but an unresponsive car which then bites you after you've fed in even more input is bad too. This is very much a personal preference.

Banked turns are a menace on some of my cars, it can be very hard to tune out. If the rear end lets go I've found more rear camber makes the grip loss more progressive.

Also at the mega speeds you mention, and with sticky tyres... Might be worth checking she's not bottoming out.

It's sometimes possible to set aero balance one way (eg understeer) but have the springs and other mechanical suspension set for oversteer. The car then becomes schizophrenic when changing speeds since the aero dominates at high speed, this can cause problems.

Good luck.

Thanks for the advice. Generally I set my cars up to be fairly neutral and stable.. Spring rate, anti roll bars etc are almost always higher at the front, rear downforce is usually maxed, I run a fair amount of rear toe-in on most RWD cars too. Ride height is normally 10-20mm above the minimum.

 

[OldandSlow]

What I learned from Praiano: ballast 100, set at -50. I've used this on many FR and MR cars.

Also, Pizzacato1985 and Vule have tunes for some difficult cases.