Performance alignment
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Joined: Oct 2000
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From: SoCal
Cdelena: From http://www.egroups.com/message/S2000-Motorsport/96
"Randy:
Try about 35 psi all around, maybe a little more in the front and less in
the rear.
Alignment:
Front- straight toe, -1.5 degrees camber
Rear- toe in 1/4", -2.5 degrees camber
I believe the caster is about 5 degrees
If you have the stock bar and stock shocks, be prepared to have trouble
keeping the rear in line. I don't think you can get much help on that from
alignment and tire pressures.
Steve Sucsy
----- Original Message -----
From: Randy Petschauer rhjp@y...
To: S2000-Motorsport@egroups.com
Sent: Tuesday, October 17, 2000 9:58 PM
Subject: [S2000-Motorsport] Alignment and tire pressure settings
> The season is drawing to a close here in NY and have two or three
> more autox's before I go into autox hibernation. I just had a set
> of
> 225/245 Kumhos mounted and had hoped I might find a suggestion or two
> concerning alignment and tire pressure settings. Another message
> board did have some postings concerning this a while back. But I
> haven't managed to find it again.
>
> Other than the tires, the car is stock.
>
> The first event is this weekend. So I must get the car to the
> alignment shop by Friday.
>
> Can anyone help.
>
> Much thanks in advance."
That's a good site for performance msgs about S2K esp for autocross.
Also, since I put HKS on which moves weight forward, I sense less tendency to rotate into turns, i.e. understeer feeling. I will decrease tire pressures in rears to help compensate. That's after I get back from this meeting in Conroe, TX.
"Randy:
Try about 35 psi all around, maybe a little more in the front and less in
the rear.
Alignment:
Front- straight toe, -1.5 degrees camber
Rear- toe in 1/4", -2.5 degrees camber
I believe the caster is about 5 degrees
If you have the stock bar and stock shocks, be prepared to have trouble
keeping the rear in line. I don't think you can get much help on that from
alignment and tire pressures.
Steve Sucsy
----- Original Message -----
From: Randy Petschauer rhjp@y...
To: S2000-Motorsport@egroups.com
Sent: Tuesday, October 17, 2000 9:58 PM
Subject: [S2000-Motorsport] Alignment and tire pressure settings
> The season is drawing to a close here in NY and have two or three
> more autox's before I go into autox hibernation. I just had a set
> of
> 225/245 Kumhos mounted and had hoped I might find a suggestion or two
> concerning alignment and tire pressure settings. Another message
> board did have some postings concerning this a while back. But I
> haven't managed to find it again.
>
> Other than the tires, the car is stock.
>
> The first event is this weekend. So I must get the car to the
> alignment shop by Friday.
>
> Can anyone help.
>
> Much thanks in advance."
That's a good site for performance msgs about S2K esp for autocross.
Also, since I put HKS on which moves weight forward, I sense less tendency to rotate into turns, i.e. understeer feeling. I will decrease tire pressures in rears to help compensate. That's after I get back from this meeting in Conroe, TX.
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Joined: Oct 2000
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I'm no expert, but here goes....
To get the optimum camber settings on your car you need a pyrometer. Take it to the track, skid pad, parking lot. Then take a few laps to heat up the tires, probably as fast as you can safely go. Then stop and immediately take temperature measurements of the inside and outside of the tires. The optimum setting should be when both areas measure identically. If the inside is hotter, then too much negative camber. If outside is hotter then not enough negative camber. This procedure should insure maximum contact patch of your tire. Taking into consideration, suspension, weight, track conditions etc.
To get the optimum tire pressure settings, same thing. Take measurements at the middle and both sides of the tire. If the middle is hotter, then its overinflated, if the sides are hotter then its underinflated. Now, camber and tire pressure becomes compounded at this point. You can have too much camber and overinflation, if the inside and middle of the tire is hotter than the outside, and that goes for all the possible combinations. Ideally, you want to have identical or as close to identical temp. across the tire contact patch.
More rear toe-in gets less oversteer. More front toe-in get more understeer. Ideally, there should be no toe-in, to reduce drag. Wrong toe-in settings can make the car unstable at high speeds.
It is not advisable to adjust oversteer and understeer conditions with camber and tire pressure settings. This takes away from maximum tire contact. An adjustable sway bar would be ideal. More front bar is less oversteer, more understeer same thing with less rear bar. More rear bar, gets more oversteer, less understeer same thing with less front bar.
This procedure would get your car to be at neutral. Now, the slight oversteer condition or understeer condition can make the car handle better through a course, it depends on the driver's preferences. However, rest assure that you've maximized your tire contact patch.
It would be great if you had the occassion to try this procedure out, pls. share the info. With the resources available, we could probably get optimal settings for each racetrack, car setup, etc.
To get the optimum camber settings on your car you need a pyrometer. Take it to the track, skid pad, parking lot. Then take a few laps to heat up the tires, probably as fast as you can safely go. Then stop and immediately take temperature measurements of the inside and outside of the tires. The optimum setting should be when both areas measure identically. If the inside is hotter, then too much negative camber. If outside is hotter then not enough negative camber. This procedure should insure maximum contact patch of your tire. Taking into consideration, suspension, weight, track conditions etc.
To get the optimum tire pressure settings, same thing. Take measurements at the middle and both sides of the tire. If the middle is hotter, then its overinflated, if the sides are hotter then its underinflated. Now, camber and tire pressure becomes compounded at this point. You can have too much camber and overinflation, if the inside and middle of the tire is hotter than the outside, and that goes for all the possible combinations. Ideally, you want to have identical or as close to identical temp. across the tire contact patch.
More rear toe-in gets less oversteer. More front toe-in get more understeer. Ideally, there should be no toe-in, to reduce drag. Wrong toe-in settings can make the car unstable at high speeds.
It is not advisable to adjust oversteer and understeer conditions with camber and tire pressure settings. This takes away from maximum tire contact. An adjustable sway bar would be ideal. More front bar is less oversteer, more understeer same thing with less rear bar. More rear bar, gets more oversteer, less understeer same thing with less front bar.
This procedure would get your car to be at neutral. Now, the slight oversteer condition or understeer condition can make the car handle better through a course, it depends on the driver's preferences. However, rest assure that you've maximized your tire contact patch.
It would be great if you had the occassion to try this procedure out, pls. share the info. With the resources available, we could probably get optimal settings for each racetrack, car setup, etc.
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Joined: Oct 2000
Posts: 1,445
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From: Chicago
Proper suspension tuning is a very 'black' art in that it's something that takes a long period of time testing to optimize. Not everyone has this time, so people tend to compromise on settings that are nearly optimal. BBSpoon had some great points about suspension tuning.
We have been discussing this allot recently in National Autocross circles, and concensus seems to be that you tune on a skidpad first, basically a big circle. Tune until you can get the best cornering speed and car balance/feel on the skidpad. Then you make sure that the car works well in a slalom, and possibly make some fine tuning adjustments to make that better.
As simple as this sounds, it involves allot of time, crew and equipment. First, timing equipment, then tools to make adjustments, and crew to effect thos adjustments. We will be doing that to a certain extent with our shocks and swaybar, but Alignment is much more difficult to adjust at a testing session.
Our baselines could possibly be something like this:
Camber 1.7f / 2.0r
Toe -1/8"f / +1/32"r
With '-' = Toe out, '+' = toe in. Of course this is just a guess, and we'll probably make changes as we go. It all depends on how much camber you lose as the suspension compresses. I suspect that 2.5 is too much in the rear, as it may begin to hinder putting the power down, a problem these cars tend to have. We'll post our experiences when we begin testing. And the Egroup linked above is a good site... I happened to start it!
We have been discussing this allot recently in National Autocross circles, and concensus seems to be that you tune on a skidpad first, basically a big circle. Tune until you can get the best cornering speed and car balance/feel on the skidpad. Then you make sure that the car works well in a slalom, and possibly make some fine tuning adjustments to make that better.
As simple as this sounds, it involves allot of time, crew and equipment. First, timing equipment, then tools to make adjustments, and crew to effect thos adjustments. We will be doing that to a certain extent with our shocks and swaybar, but Alignment is much more difficult to adjust at a testing session.
Our baselines could possibly be something like this:
Camber 1.7f / 2.0r
Toe -1/8"f / +1/32"r
With '-' = Toe out, '+' = toe in. Of course this is just a guess, and we'll probably make changes as we go. It all depends on how much camber you lose as the suspension compresses. I suspect that 2.5 is too much in the rear, as it may begin to hinder putting the power down, a problem these cars tend to have. We'll post our experiences when we begin testing. And the Egroup linked above is a good site... I happened to start it!
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From: Honolulu
Jason,
I run -2.5 in the rear and -1.6 up front and the last time I checked my tire temps I'm still "hot" on the outsides. I'm now running the Kumho streets (vs the RE-730 before and the S-02 before that). I was borrowing a needle probe type pyrometer but am considering purchasing a laser IR type. I've only got one autox on the kumhos but have found them to be very unforgiving at the limit (a MUCH lower limit I might add) than either Bridgestone tires before. I suspect I need the pyrometer to help me get more out of these tires and find the "sweet spot" on the inflation pressures. I know you guys run race tires, so your experiences are different than those of us who run streets.
I run -2.5 in the rear and -1.6 up front and the last time I checked my tire temps I'm still "hot" on the outsides. I'm now running the Kumho streets (vs the RE-730 before and the S-02 before that). I was borrowing a needle probe type pyrometer but am considering purchasing a laser IR type. I've only got one autox on the kumhos but have found them to be very unforgiving at the limit (a MUCH lower limit I might add) than either Bridgestone tires before. I suspect I need the pyrometer to help me get more out of these tires and find the "sweet spot" on the inflation pressures. I know you guys run race tires, so your experiences are different than those of us who run streets.
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Joined: Oct 2000
Posts: 1,445
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From: Chicago
RT... 1/8" toe out shouldn't feel that twitchy on the road. It will, however, kill your tires faster. If you want longer tire life, go with 1/16" toe out in the front. You definitely want some toe out to help turn-in.
Colin... I'd be careful with tire temps on street tires. The tread design can cause the readings to be skewed. The tire will gain more heat where there is more tread. Also, stick with your probe style pyrometer. They give more accurate readings. As the tire cools, the surface cools first. With the probe, you can get in there where there is still temperature. The temp on the surface equalizes quicker.
Is 1.6/2.5 the most camber you can get in an S2K? We don't have ours yet, but one of the first things we will do is put it on the rack. I'd worry about traction with 2.5 degrees of camber. We'll see what works, though... I'll keep everyone posted. Although Colin makes a good point. What works for me with adjustable shocks, a big front swaybar and race tires might not work for those with street tires.
Colin... I'd be careful with tire temps on street tires. The tread design can cause the readings to be skewed. The tire will gain more heat where there is more tread. Also, stick with your probe style pyrometer. They give more accurate readings. As the tire cools, the surface cools first. With the probe, you can get in there where there is still temperature. The temp on the surface equalizes quicker.
Is 1.6/2.5 the most camber you can get in an S2K? We don't have ours yet, but one of the first things we will do is put it on the rack. I'd worry about traction with 2.5 degrees of camber. We'll see what works, though... I'll keep everyone posted. Although Colin makes a good point. What works for me with adjustable shocks, a big front swaybar and race tires might not work for those with street tires.
