DE, understeer and body roll
12-21-2009, 12:54 PM
#1
Three Wheelin'
Thread Starter
DE, understeer and body roll
It is now time for the winter maintenance and projects.
First on my list is to find a way to control the understeer when I am on the track (DE events). My car has the M474 option with red boge shocks - changed 35,000 miles ago and I really like the way it feels on the street but sure needs more control on the track.
After reading a bit, I saw that by stiffening the rear sway bar, it can help quite a bit. Louie Ott's rear drop link kit is an inexpensive way to do that
Second, I would like to control the body roll. This also can be done by stiffening the sway bars. Since the rear will be done with Louie's kit, I was looking for DR's front sway bar.
My question is : by doing changes on the front and rear sway bar, I will control the body roll but what about the understeer? Is there enough adjustment on the sway bars to be able to control the understeer and body roll?
Should I start doing only the rear sway?
I forgot to mention that the suspension is completely stock.
First on my list is to find a way to control the understeer when I am on the track (DE events). My car has the M474 option with red boge shocks - changed 35,000 miles ago and I really like the way it feels on the street but sure needs more control on the track.
After reading a bit, I saw that by stiffening the rear sway bar, it can help quite a bit. Louie Ott's rear drop link kit is an inexpensive way to do that
Second, I would like to control the body roll. This also can be done by stiffening the sway bars. Since the rear will be done with Louie's kit, I was looking for DR's front sway bar.
My question is : by doing changes on the front and rear sway bar, I will control the body roll but what about the understeer? Is there enough adjustment on the sway bars to be able to control the understeer and body roll?
Should I start doing only the rear sway?
I forgot to mention that the suspension is completely stock.
12-21-2009, 06:28 PM
#2
Addict
Lifetime Rennlist
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Lifted from Roger KRAUSE Racing..." .Understeer Corrections
Push, plowing, front tires slide out first.
Usually slight understeer is safer.
Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks. Stiffen Bump.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.
Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.
Increase positive caster.
Soften front springs.
Stiffen rear springs.
May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
Drive a different line.
Use weight transfer to your advantage."
Having ridden with many students I find that understeer is often made worse by the driver....smoothness is the key. If the turn in is made too quickly harshly it upsets the car and the tires go into bad understeer (high slip angle) same with early apexing a corner sets you up to run out of track and to make a tighter turn to try to stay on track, the line is so important. The 50/50 weight distribution of a 928 is NOT ideal just better than a nose heavy muscle car
Push, plowing, front tires slide out first.
Usually slight understeer is safer.
Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks. Stiffen Bump.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.
Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.
Increase positive caster.
Soften front springs.
Stiffen rear springs.
May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
Drive a different line.
Use weight transfer to your advantage."
Having ridden with many students I find that understeer is often made worse by the driver....smoothness is the key. If the turn in is made too quickly harshly it upsets the car and the tires go into bad understeer (high slip angle) same with early apexing a corner sets you up to run out of track and to make a tighter turn to try to stay on track, the line is so important. The 50/50 weight distribution of a 928 is NOT ideal just better than a nose heavy muscle car
12-21-2009, 07:13 PM
#3
Race Director
"needs more control on track"....is a bit vague.... then you mention understeer..... so I would guess the problem you are experiencing is a bit to much "bounce" on rebound (classic sign of old shocks) and understeer (common on street 928's).....
Here is a great inexpensive combo I used for the Lemons racer 928 (1984 auto).....Bilstein shocks with Eibach springs cut 1 (rear) to 1.5 (front) coils...so I would say the rate is 600lb front a shade under 400lb rear....with stock sway bars on stock 225/50-16 street tires with camber maxed out at about 2.5' per corner handles pretty well.....the "bounce" is well controlled and it does understeer a bit...but I think we can reduce that by increasing the rear sway bar....
Here is a great inexpensive combo I used for the Lemons racer 928 (1984 auto).....Bilstein shocks with Eibach springs cut 1 (rear) to 1.5 (front) coils...so I would say the rate is 600lb front a shade under 400lb rear....with stock sway bars on stock 225/50-16 street tires with camber maxed out at about 2.5' per corner handles pretty well.....the "bounce" is well controlled and it does understeer a bit...but I think we can reduce that by increasing the rear sway bar....
