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.

 

[BumprHumpn]

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.

I

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.

I upped my natural frequency to around 3 to 3.2 and it seemed to help out a lot. In my gr4 silvia, we'll it's no longer a gr4 car. It was kicked out of gr4 races after I put the r38 nismo and ultra high rpm turbo in it. Coming down 1st Str8 on Nurburing, hitting that hump at 190 mph leaves my staring 90 degrees up in the air . Thye next section running down hill thru the woods was the worst for me.. If I even tapped brakes, I was done. Bouncing like I was in a ditch, but raising my frequency to 3.1 on both. Some cars don't go that high so try 2.5 or so.keep them the same and dont forget if you add side skirts or bigger tires , you need to change your dampers and springs . I did 35 and 40 . This is for racing tires but I adjusted my ride height down , got rid of side skirts, 18inch wide tires ,and my Nissan still rides a wheelie but hitting 200mph zig zagging down hill and slamming brakes,my car does bounce around. IT reminds me of a magnetic race track car trying to come off thr ground ,but it never does... I'm blabbering .lol...have fun ..works great on silvia , demon, and the r33

 

[lbpomg95]

I

I upped my natural frequency to around 3 to 3.2 and it seemed to help out a lot. In my gr4 silvia, we'll it's no longer a gr4 car. It was kicked out of gr4 races after I put the r38 nismo and ultra high rpm turbo in it. Coming down 1st Str8 on Nurburing, hitting that hump at 190 mph leaves my staring 90 degrees up in the air . Thye next section running down hill thru the woods was the worst for me.. If I even tapped brakes, I was done. Bouncing like I was in a ditch, but raising my frequency to 3.1 on both. Some cars don't go that high so try 2.5 or so.keep them the same and dont forget if you add side skirts or bigger tires , you need to change your dampers and springs . I did 35 and 40 . This is for racing tires but I adjusted my ride height down , got rid of side skirts, 18inch wide tires ,and my Nissan still rides a wheelie but hitting 200mph zig zagging down hill and slamming brakes,my car does bounce around. IT reminds me of a magnetic race track car trying to come off thr ground ,but it never does... I'm blabbering .lol...have fun ..works great on silvia , demon, and the r33

All of those have a lot of downforce, thus they don't suffer as much. This issue is generally worst on classic cars that don't have front and rear aero options.

 

[bigmull]

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.

It would help if you can list the worse cars and your tunes.This way we can see if there is a simple solution or not.The majority of cars that I drive don’t have any aero and skinny tyres some even have “ stock” brake pads.Most of them will be doing over 170 mph down Mulsanne,a few can hit 200+ and are pretty stable.

 

[OldandSlow]

All of those have a lot of downforce, thus they don't suffer as much. This issue is generally worst on classic cars that don't have front and rear aero options.

bigmull has some great tunes for these cars.

 

[bigmull]

To illustrate how stable they can be here is a short video of the Maserati Merak,no aero at all.

 

[bigmull]

The Aston Martin DB3S is not an easy car to tune or drive. It has tons of power,skinny tyres,standard brake pads,but can be tamed as you see in the video,in the rain as well.