How to get ride of understeer?
01-09-2007, 11:14 AM
#1
Race Director
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How to get ride of understeer?
This has been a pretty bid problem with my C5 since I put a new front sway bar on. The car pushes extremly hard. I do not mind a little understeer, but feel that I scrub way to much speed sliding across the track.
I undertand how to correct it while moving, by opening the wheel and less loud pedal, but want to correct the problem from happening is the goal...
The only suspension mod I has is the Addcco 32mm front sway bar. I have a Z06 rear sway bar or a Z51 to play with. I plan on putting one of these on to mess around with, but want some help as I feel that the rear sway bar may cause more push (just a thought though.)
Thanks!
Adam Boca
I undertand how to correct it while moving, by opening the wheel and less loud pedal, but want to correct the problem from happening is the goal...
The only suspension mod I has is the Addcco 32mm front sway bar. I have a Z06 rear sway bar or a Z51 to play with. I plan on putting one of these on to mess around with, but want some help as I feel that the rear sway bar may cause more push (just a thought though.)
Thanks!
Adam Boca
01-09-2007, 11:46 AM
#2
Le Mans Master
Adam,
This sounds simplistic and you can disregard at any time, but what's the condition of your front tires? I ran 275/315 V700 Victoracers this past year, and when they go off, it's pretty dramatic.
Also, depending on the size tire you're running, you could go up a bit on width. I'm now running 275/305 RA-1s on wagon wheels with good wear and balance (slight understeer on corner exit, and better turn-in than I had with the 315s).
HTH, and have a good one,
Mike
This sounds simplistic and you can disregard at any time, but what's the condition of your front tires? I ran 275/315 V700 Victoracers this past year, and when they go off, it's pretty dramatic.
Also, depending on the size tire you're running, you could go up a bit on width. I'm now running 275/305 RA-1s on wagon wheels with good wear and balance (slight understeer on corner exit, and better turn-in than I had with the 315s).
HTH, and have a good one,
Mike
01-09-2007, 01:08 PM
#3
Le Mans Master
Without making any complimentary changes, increasing the
front sway bar stiffness moves handling tendencies toward
understeer.
Your bigger front sway bar has made your car understeer more.
Options
1) switch to larger rear bar to help balance increased front bar.
2) switch back to OEM front bar
2a) switch back to OEM front bar and add larger rear bar for even
. less understeer/more oversteer.
3) increase rear spring rate.
and so on.
I agree that tires, shocks and other stuff contribute to balance
but here my vote is that the culprit is obviously the bigger front
bar.
.
front sway bar stiffness moves handling tendencies toward
understeer.
Your bigger front sway bar has made your car understeer more.
Options
1) switch to larger rear bar to help balance increased front bar.
2) switch back to OEM front bar
2a) switch back to OEM front bar and add larger rear bar for even
. less understeer/more oversteer.
3) increase rear spring rate.
and so on.
I agree that tires, shocks and other stuff contribute to balance
but here my vote is that the culprit is obviously the bigger front
bar.
.
01-09-2007, 02:50 PM
#4
Race Director
relatively speaking, you need to take some grip out of the rear. As above, if you can, stiffen the rear. You can modify the stiffness of your rear bar SLIGHTLY by adjusting the heim joints. In other words, when the joint is at a 90 deg angle to the bar, it is softest. If you can adjust it all the way in/out to make that angle tighter, it will effectively stiffen the bar.
The other option is to take come camber out of the rear. Will cause the car to rotate more in the corner, and may also help get more grip accelerating out.
I personally think GM does a good job matching their bars, so I would stick to a package: ie, T1 front-T1 rear, Z51front-Z51rear, etc.
The other option is to take come camber out of the rear. Will cause the car to rotate more in the corner, and may also help get more grip accelerating out.
I personally think GM does a good job matching their bars, so I would stick to a package: ie, T1 front-T1 rear, Z51front-Z51rear, etc.
01-09-2007, 04:30 PM
#5
Le Mans Master
http://fbodyeurope.org/phpBB2/viewtopic.php?t=5568
If you have to ask "what is understeer / oversteer?", it’s quite simple: if you approach a fast bend in the road, turn the wheel, but the car just plough straight on into a ditch, then you suffer from understeer. If you leave the same bend spinning backwards into the ditch, then you suffer from oversteer. Of course oversteer can easily be provoked when there is an idiot at the wheel, so don’t always blame the car.
For those of you who understand your car’s dynamics well enough not to make the typical beginner’s mistakes that will upset the handling, here is a list of changes that will guide you to tune your suspension to a neutral-steer for superior high-performance handling.
DECREASE UNDERSTEER..... CORRECTION.....DECREASE OVERSTEER
higher pressure........................tire pressure - front......................lower pressure
larger contact area....................tire section - front...............smaller contact area
more negative.........................wheel camber - front.......................more positive
softer.................................. ..........springs - front................................... ......stiffer
thinner (softer).............................swa y bar - front.........................thicker (stiffer)
larger.................................. .........spoiler - front................................... ....smaller
lower pressure.........................tire pressure - rear.....................higher pressure
smaller contact area.................tire section - rear..................larger contact area
more positive.........................wheel camber - rear......................more negative
stiffer................................. ...........springs - rear.................................... .....softer
thicker (stiffer).............................sw ay bar - rear.........................thinner (softer)
smaller................................. .........spoiler - rear.................................... ....larger
weight bias rearward................weight distribution..............weight bias forward
A few words of warning: if you are unsure about what you are doing, rather get help from an experienced person. Make your changes in small increments and first test the result in an open area where you can do little harm (like at one of our slaloms). Rather tune towards neutral-understeer, since an oversteering car is quite a dangerous beast that needs a fast hand to catch it. Have fun.
For those of you who understand your car’s dynamics well enough not to make the typical beginner’s mistakes that will upset the handling, here is a list of changes that will guide you to tune your suspension to a neutral-steer for superior high-performance handling.
DECREASE UNDERSTEER..... CORRECTION.....DECREASE OVERSTEER
higher pressure........................tire pressure - front......................lower pressure
larger contact area....................tire section - front...............smaller contact area
more negative.........................wheel camber - front.......................more positive
softer.................................. ..........springs - front................................... ......stiffer
thinner (softer).............................swa y bar - front.........................thicker (stiffer)
larger.................................. .........spoiler - front................................... ....smaller
lower pressure.........................tire pressure - rear.....................higher pressure
smaller contact area.................tire section - rear..................larger contact area
more positive.........................wheel camber - rear......................more negative
stiffer................................. ...........springs - rear.................................... .....softer
thicker (stiffer).............................sw ay bar - rear.........................thinner (softer)
smaller................................. .........spoiler - rear.................................... ....larger
weight bias rearward................weight distribution..............weight bias forward
A few words of warning: if you are unsure about what you are doing, rather get help from an experienced person. Make your changes in small increments and first test the result in an open area where you can do little harm (like at one of our slaloms). Rather tune towards neutral-understeer, since an oversteering car is quite a dangerous beast that needs a fast hand to catch it. Have fun.
01-09-2007, 09:17 PM
#6
Drifting
Adam:
Another set of questions to help you reach a satisfactory solution - break down the corner into three elements - corner entry - midcorner - corner exit.
Is the car reluctant to turn and then it just carries that through midcorner? Or does the car turn in well, and then push as you reach steady state?
Another set of questions to help you reach a satisfactory solution - break down the corner into three elements - corner entry - midcorner - corner exit.
Is the car reluctant to turn and then it just carries that through midcorner? Or does the car turn in well, and then push as you reach steady state?
01-09-2007, 09:51 PM
#7
Le Mans Master
Lancer033, I've seen that info in that format somewhere else before.
It may have been a driving sim site.
In 2005 there was a post about an online setup guide. This turned
out to actually be a reference for a driving sim, too.
Online Chassis Setup Guide
BUT, have a look at the detailed discussion before dismissing the
possibility that there is chassis knowledge available from a computer
game site.
The "ULTIMATE"
Racing Car Chassis Setup Guide and Tutorial.
.
It may have been a driving sim site.
In 2005 there was a post about an online setup guide. This turned
out to actually be a reference for a driving sim, too.
Online Chassis Setup Guide
BUT, have a look at the detailed discussion before dismissing the
possibility that there is chassis knowledge available from a computer
game site.
The "ULTIMATE"
Racing Car Chassis Setup Guide and Tutorial.
.
01-10-2007, 12:37 AM
#8
Le Mans Master
Adam:
Another set of questions to help you reach a satisfactory solution - break down the corner into three elements - corner entry - midcorner - corner exit.
Is the car reluctant to turn and then it just carries that through midcorner? Or does the car turn in well, and then push as you reach steady state?
Another set of questions to help you reach a satisfactory solution - break down the corner into three elements - corner entry - midcorner - corner exit.
Is the car reluctant to turn and then it just carries that through midcorner? Or does the car turn in well, and then push as you reach steady state?
I agree, this is a really good question to ask yourself. Z06s really respond well on turn-in to a little bit of trail-braking. A little extra trail braking right into mid-turn is great for getting a little bit of car rotation and then you can start applying power to really drive hard out of the corner early.
Driving technique and the condition of the tires has a profound impact on the handling characteristics of the car I have found.
01-10-2007, 10:18 AM
#9
To improve mechanical grip at the front :
Increase front toe out at the track - up to 1/4"
Increase front camber
Lower the front of the car 1/8"-1/4"- more rake and lower CG will help, especially on turn in.
Also use the biggest rear bar you have, and consider a wider front tire.
Increase front toe out at the track - up to 1/4"
Increase front camber
Lower the front of the car 1/8"-1/4"- more rake and lower CG will help, especially on turn in.
Also use the biggest rear bar you have, and consider a wider front tire.
