Suspension settings for Track
05-05-2003 | 10:50 AM
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From: Colorado
Suspension settings for Track
My RSA has not been aligned since I acquired it a few months ago. It will need to be aligned, but I have been holding off until I learned enough about its handling on the street and track to be able to make an intelligent decision about suspension settings.
Current camber (informal string measurement) is at -1.8 and -1.6 degrees front and -1.5 degrees for both rears. Car is lowered with H&Rs, but has stock sway bars. Tires are Kumho Victoracers 225/45/17 and 255/40/17, optimized at 31 and 36 pounds cold.
Car has been driven to about 7/10 on the track. Handling is predictable and solid, no mushiness. The rear can be thrown somewhat, though it takes effort. Of course there is some pushing. The car turns in nicely at high speeed, fairly well at slow speed. Handling on the street is stiff but straight -- no wandering or hunting in grooves.
Track tire rollover is about right, but wear is strongly on the outside corners. I have not checked tire temps with a pyrometer, but it is obvious where the contact patch is. The tires will need to be flipped on the wheels. I would like to see tire wear a bit more toward the center of the tread. Street tires appear to be wearing in the center of the tread, but I don't have enough mileage to be very sure of this.
I am interested to know how much camber others have in their 964s for use on the track. I don't care about AutoX, but I would like to optimize track handling without compromising street driving too much.
I'll appreciate any guidance you can offer.
Strabo
Current camber (informal string measurement) is at -1.8 and -1.6 degrees front and -1.5 degrees for both rears. Car is lowered with H&Rs, but has stock sway bars. Tires are Kumho Victoracers 225/45/17 and 255/40/17, optimized at 31 and 36 pounds cold.
Car has been driven to about 7/10 on the track. Handling is predictable and solid, no mushiness. The rear can be thrown somewhat, though it takes effort. Of course there is some pushing. The car turns in nicely at high speeed, fairly well at slow speed. Handling on the street is stiff but straight -- no wandering or hunting in grooves.
Track tire rollover is about right, but wear is strongly on the outside corners. I have not checked tire temps with a pyrometer, but it is obvious where the contact patch is. The tires will need to be flipped on the wheels. I would like to see tire wear a bit more toward the center of the tread. Street tires appear to be wearing in the center of the tread, but I don't have enough mileage to be very sure of this.
I am interested to know how much camber others have in their 964s for use on the track. I don't care about AutoX, but I would like to optimize track handling without compromising street driving too much.
I'll appreciate any guidance you can offer.
Strabo
05-05-2003 | 11:11 AM
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From: Highland Park, IL
Strabo,
On the Kumho tire pressures, I think you may be a little high. I have the same tires on my C4 and just got back from two days at the track with a pyrometer. Optimal cold pressures for my car at Road America is:
Right Front 28
Left Front 30
Right Rear 30
Left Rear 28
Hot temps varied from 34 - 36 psi. Keep in mind, cold temps will vary with track layouts, so if you want to eliminate the guesswork, get a pyro. The pyro will also tell you if you're running too much/too little camber.
Glad you're going through the fine details of suspension tuning. Not only will it make a difference in handling, but it clears your mind of any worries and lets you focus on your driving.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
On the Kumho tire pressures, I think you may be a little high. I have the same tires on my C4 and just got back from two days at the track with a pyrometer. Optimal cold pressures for my car at Road America is:
Right Front 28
Left Front 30
Right Rear 30
Left Rear 28
Hot temps varied from 34 - 36 psi. Keep in mind, cold temps will vary with track layouts, so if you want to eliminate the guesswork, get a pyro. The pyro will also tell you if you're running too much/too little camber.
Glad you're going through the fine details of suspension tuning. Not only will it make a difference in handling, but it clears your mind of any worries and lets you focus on your driving.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
05-05-2003 | 12:21 PM
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From: California Boardwalk, Skanderborg Denmark
For reference, the recommentation for the Carrera Cup track cars by Andial was:
Front: -2 degrees 30 minutes (-2.5) with 2.5 minutes toe in total
Rear: -2 degrees 20 minutes (-2.33) with 15 min toe each wheel
Ride height: 103 mm at front jacking points and 122mm at rear jacking points
Corner weighs were set with the 167 pounds in the drivers seat, the rear weights were adjusted to be equal which meant the right front was the light wheel.
Tires were 235/45-17 front and 255/40-17 rear Toyos
Anyone found that this set up works for them? <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />
Front: -2 degrees 30 minutes (-2.5) with 2.5 minutes toe in total
Rear: -2 degrees 20 minutes (-2.33) with 15 min toe each wheel
Ride height: 103 mm at front jacking points and 122mm at rear jacking points
Corner weighs were set with the 167 pounds in the drivers seat, the rear weights were adjusted to be equal which meant the right front was the light wheel.
Tires were 235/45-17 front and 255/40-17 rear Toyos
Anyone found that this set up works for them? <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />
05-05-2003 | 02:21 PM
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From: Blacksburg, VA
Strabo: It may be difficult to meet your goal of optimizing track handling without compromising street driving too much; but then it may depend on exactly what you mean by that. You may aleady be near that compromise setting right now, with about 1.5-1.8 degrees. Optimizing track performance means over 2 degrees (see above post by Cupcar), but that will have a negative affect on street driving and tire wear. I have about 1.2-1.3 degrees all around, and definitely consider that a compromise. But the uneven tire wear is barely noticable at those settings, and so is the extra steering attention that I have to pay driving down the highway. In fact, I've been thinking that closer to 1.6-1.7 would be the better compromise for me. You didn't mention your toe settings, but that would be part of your compromised system too.
I tend to agree with Joey on the pressures in the Victoracers based on my experience (I have the same tire sizes on 8 and 9X17" rims, on a RSA also). On my car the 36 cold in the rear would become something like 44-46 hot on a warm day, and I'd probably be sliding a little. But then, if they are optimized for you at those pressures, I can't argue with that.
I tend to agree with Joey on the pressures in the Victoracers based on my experience (I have the same tire sizes on 8 and 9X17" rims, on a RSA also). On my car the 36 cold in the rear would become something like 44-46 hot on a warm day, and I'd probably be sliding a little. But then, if they are optimized for you at those pressures, I can't argue with that.
05-05-2003 | 03:44 PM
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From: Colorado
I pushed the rear tire pressures up to 36 pounds cold to loosen up the rear end and help the car rotate. Seems to work fine, and it could probably take a bit more.
The long-term fix will probably be a bigger rear sway bar, but I'm trying to take a very gradual approach to things. Also, I'm aware that I may need to take another look at tire pressures after I change suspension settings.
Strabo
The long-term fix will probably be a bigger rear sway bar, but I'm trying to take a very gradual approach to things. Also, I'm aware that I may need to take another look at tire pressures after I change suspension settings.
Strabo
05-05-2003 | 04:38 PM
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From: California Boardwalk, Skanderborg Denmark
I find that the needs for track and street are opposite in terms of even tire wear.
What works for even wear on the street will wear out the outside of the tire at the track, what works on the track will wear out the inside of the tire on the street.
The compromise that works financially best for you depends on the duty cycle of your car, is it mostly track or mostly street.
Your trophy shelf will be best served by as much negative as you can dial in. This may be limited in a stock car by the car's adjustment capabilities before the optimum is reached for the track, so this limitation may serve as your compromise dictator. <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />
What works for even wear on the street will wear out the outside of the tire at the track, what works on the track will wear out the inside of the tire on the street.
The compromise that works financially best for you depends on the duty cycle of your car, is it mostly track or mostly street.
Your trophy shelf will be best served by as much negative as you can dial in. This may be limited in a stock car by the car's adjustment capabilities before the optimum is reached for the track, so this limitation may serve as your compromise dictator. <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />
05-06-2003 | 06:47 AM
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From: Virginia Beach, Va.
You'll find that higher negative camber settings will be a thing of the past.
With the onslaught of the new Hoosier that's due out this Summer and the Michelin Pilot Sport Cups requirement for less camber than usual "track" tires, and it's proven prowess on the track with Club Racers and the sort, you probably won't see neg. camber settings in excess of 1.8, maybe even 1.5??
The Cupcar, the car itself, that is, settings are becoming obsolete with these new and "improved" tires.
I am going in for an alignment on a high-tech rack today, to see how well my home tactics work...I want to see how the numbers compare with the laser sights on the machine and my bubble gauges/turn plates.
I have been using the GAC (Grand American Cup) Hoosier lately that supposedly requires less neg. camber, and I want to tryout the Michelins soon, so I may keep my neg. camber at 1.5 front and 1.75 rear...may reverse the numbers though, 1.75 front, 1.5 rear, just to see what happens, as I see others are doing this on their 964s, and I wear out the outer edge on my fronts quite often.
Where the trick seems to be is how much toe OUT in the front, and slight toe in at the rear do we use??
Well, there is a guy here at the local P-Car facility that is crew chief for a winning GT3R/GT2R team, he says he wants to "experiment" a little with my car today...sure, the tire wear will come out of my wallet, but we may learn a thing or two over the next couple of events??
With the onslaught of the new Hoosier that's due out this Summer and the Michelin Pilot Sport Cups requirement for less camber than usual "track" tires, and it's proven prowess on the track with Club Racers and the sort, you probably won't see neg. camber settings in excess of 1.8, maybe even 1.5??
The Cupcar, the car itself, that is, settings are becoming obsolete with these new and "improved" tires.
I am going in for an alignment on a high-tech rack today, to see how well my home tactics work...I want to see how the numbers compare with the laser sights on the machine and my bubble gauges/turn plates.
I have been using the GAC (Grand American Cup) Hoosier lately that supposedly requires less neg. camber, and I want to tryout the Michelins soon, so I may keep my neg. camber at 1.5 front and 1.75 rear...may reverse the numbers though, 1.75 front, 1.5 rear, just to see what happens, as I see others are doing this on their 964s, and I wear out the outer edge on my fronts quite often.
Where the trick seems to be is how much toe OUT in the front, and slight toe in at the rear do we use??
Well, there is a guy here at the local P-Car facility that is crew chief for a winning GT3R/GT2R team, he says he wants to "experiment" a little with my car today...sure, the tire wear will come out of my wallet, but we may learn a thing or two over the next couple of events??
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05-06-2003 | 09:56 AM
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From: TX
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"><strong>You'll find that higher negative camber settings will be a thing of the past.
you probably won't see neg. camber settings in excess of 1.8, maybe even 1.5??
Where the trick seems to be is how much toe OUT in the front, and slight toe in at the rear do we use??
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Michelin says the camber on the cups should be 1.5-3 degrees, max 4 degrees negative.
Where toe gets tricky....my alignment guru, who is/has been the lead tech for Porsche and Grand Am racing teams, is especially in the rear. He likes to set the toe to offset some of the Weissach axle effect (I've previously posted my alignment settings). For those who want to control that without playing with toe, you can install the RS control arms, at $1200 each, or the ERP bearings, at $610/pair. The bushings themselves are not Porsche-available parts.
you probably won't see neg. camber settings in excess of 1.8, maybe even 1.5??
Where the trick seems to be is how much toe OUT in the front, and slight toe in at the rear do we use??
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Michelin says the camber on the cups should be 1.5-3 degrees, max 4 degrees negative.
Where toe gets tricky....my alignment guru, who is/has been the lead tech for Porsche and Grand Am racing teams, is especially in the rear. He likes to set the toe to offset some of the Weissach axle effect (I've previously posted my alignment settings). For those who want to control that without playing with toe, you can install the RS control arms, at $1200 each, or the ERP bearings, at $610/pair. The bushings themselves are not Porsche-available parts.
05-06-2003 | 10:44 AM
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From: Colorado
Jeff,
Tire technology marches ahead, but so does the cost. I know that the current Hoosiers are expensive, and don't last long. Michelin Pilot Sport Cups are also expensive, though I hear that their longvity may be better than Hoosiers. And it's hard to believe that a new Hoosier would be "inexpensive".
So what does this do to the folks running Kumhos, that are 1-2 seconds slower, but last quite a bit longer? Does this mean that we will be even behinder than we are now?
Strabo
Tire technology marches ahead, but so does the cost. I know that the current Hoosiers are expensive, and don't last long. Michelin Pilot Sport Cups are also expensive, though I hear that their longvity may be better than Hoosiers. And it's hard to believe that a new Hoosier would be "inexpensive".
So what does this do to the folks running Kumhos, that are 1-2 seconds slower, but last quite a bit longer? Does this mean that we will be even behinder than we are now?
Strabo
05-07-2003 | 06:47 AM
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From: Virginia Beach, Va.
Yup, believe I put my foot in my mouth and made an incorrect statement. <img border="0" alt="[icon501]" title="" src="graemlins/icon501.gif" />
I thought I remembered a good buddy of mine saying that the Michelins didn't require as much neg. camber...the more I think about it, I think he was referring to the ECSTA Kumhos.
The Hoosier rep. told me that the new Hoosiers won't require as much either...but I have yet to see the release of the new tire...surely to compete with the Michelins!
Strabo, the inquisitive fellow here lately - eh?? <img border="0" title="" alt="[Wink]" src="wink.gif" />
...and yes, as technology marches forward, so does cost. <img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" />
A handful of buddies, including Manny, that are running the new Michelins in Club Races say they are getting about THREE times the heat cycles out of them, seems they may run out of heat cycles before they do rubber?? ...I dunno.
To the person that says the Michelins are "too expensive", with that simple fact (the three times claim) I say that they'd be an IDIOT to say they are too expensive.
A Hoosier = $200 ...a Michelin Pilot Sport Cup = about $245
The Hoosier is finished in three weekends, the Michelin in 8 or 9??
You do the math.
You will NOT see many Club Racers in the stock classes running Kumhos, the turn-in is horrible when compared to that of a Hoosier, even FAR more pitiful when compared to a Michelin Sport Cup.
Some of the guys in the GT classes, with the older, lighter cars and more rubber underneath might be seen running the Kumhos.
THAT, my friend, is what I've noticed...I'm no pro...but I do keep my eyes open. <img border="0" title="" alt="[Eek!]" src="eek.gif" />
I thought I remembered a good buddy of mine saying that the Michelins didn't require as much neg. camber...the more I think about it, I think he was referring to the ECSTA Kumhos.
The Hoosier rep. told me that the new Hoosiers won't require as much either...but I have yet to see the release of the new tire...surely to compete with the Michelins!
Strabo, the inquisitive fellow here lately - eh?? <img border="0" title="" alt="[Wink]" src="wink.gif" />
...and yes, as technology marches forward, so does cost. <img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" />
A handful of buddies, including Manny, that are running the new Michelins in Club Races say they are getting about THREE times the heat cycles out of them, seems they may run out of heat cycles before they do rubber?? ...I dunno.
To the person that says the Michelins are "too expensive", with that simple fact (the three times claim) I say that they'd be an IDIOT to say they are too expensive.
A Hoosier = $200 ...a Michelin Pilot Sport Cup = about $245
The Hoosier is finished in three weekends, the Michelin in 8 or 9??
You do the math.
You will NOT see many Club Racers in the stock classes running Kumhos, the turn-in is horrible when compared to that of a Hoosier, even FAR more pitiful when compared to a Michelin Sport Cup.
Some of the guys in the GT classes, with the older, lighter cars and more rubber underneath might be seen running the Kumhos.
THAT, my friend, is what I've noticed...I'm no pro...but I do keep my eyes open. <img border="0" title="" alt="[Eek!]" src="eek.gif" />
