Square or Staggered tyre setup?
03-03-2015, 01:43 PM
#46
Racer
Join Date: May 2008
Location: Encinitas, ca PCA National DE instructor PCA San Diego chief driving instructor
Posts: 341
Likes: 0
Received 6 Likes
on
2 Posts
Hi Dave,
My sentiments exactly.
Not to change the subject too much, but I have noticed your mention of pretty stiff spring rates in several suspension threads. I am running 450F/650R, can't go much stiffer in a street car!
What size wheels and tires do you run, and what kind of lap times are you seeing at Willow Springs big track?
Thanks,
Chris
My sentiments exactly.
Not to change the subject too much, but I have noticed your mention of pretty stiff spring rates in several suspension threads. I am running 450F/650R, can't go much stiffer in a street car!
What size wheels and tires do you run, and what kind of lap times are you seeing at Willow Springs big track?
Thanks,
Chris
I run 275/40 slicks on 9" rims all around.
I haven't run this car at Willow, so I don't know, but where I have run it Fontucky and Coronado), I run with the "big" cars.
Keep in mind that like all track events, it's mostly the driver so I'm not really beating the cars.
I have resisted embarking on a full car racing program as after 30+ years of bike road racing (7 seasons as a pro) I'm burned out on all the traveling and missed sleep, so I mostly just run AX.
Of course, AX at San Diego region means something pretty different than most anywhere else as our facility is a short road course with mostly 3rd gear used, with occasional 2nd and 4th.
03-03-2015, 10:35 PM
#47
Three Wheelin'
I run 275/40 slicks on 9" rims all around.
I haven't run this car at Willow, so I don't know, but where I have run it Fontucky and Coronado), I run with the "big" cars.
Keep in mind that like all track events, it's mostly the driver so I'm not really beating the cars.
I have resisted embarking on a full car racing program as after 30+ years of bike road racing (7 seasons as a pro) I'm burned out on all the traveling and missed sleep, so I mostly just run AX.
Of course, AX at San Diego region means something pretty different than most anywhere else as our facility is a short road course with mostly 3rd gear used, with occasional 2nd and 4th.
I haven't run this car at Willow, so I don't know, but where I have run it Fontucky and Coronado), I run with the "big" cars.
Keep in mind that like all track events, it's mostly the driver so I'm not really beating the cars.
I have resisted embarking on a full car racing program as after 30+ years of bike road racing (7 seasons as a pro) I'm burned out on all the traveling and missed sleep, so I mostly just run AX.
Of course, AX at San Diego region means something pretty different than most anywhere else as our facility is a short road course with mostly 3rd gear used, with occasional 2nd and 4th.
If I ever make it back to any track (Willow Springs/Streets of Willow are the tracks I run the most, followed by Buttonwillow, then Laguna, then Pomona and Fontucky), wider wheels and tires are the next logical step. I was thinking 9" wide wheels all the way around with 255 R-comps.
I have always wanted to do a wide-open SDR auto-X, but it is hard to make it down there. Maybe someday!
03-04-2015, 12:40 AM
#48
Professional Hoon
Rennlist Member
Rennlist Member
Thread Starter
Join Date: Jan 2010
Location: Melbourne, Australia
Posts: 7,090
Likes: 0
Received 4 Likes
on
4 Posts
I acknowledge we are of course talking about fine points here and handling limits that most people don't need to consider.
At the end of the day not too many people driving their cars on here will be approaching the grip limits of their cars often enough and to the extent that it will make that much difference. As long as you are using sensibly sized and good quality tires and don't have clearance problems, go with what looks good... Paulyy's car certainly looks great and I am sure it will have more than enough grip for anything he wants to do with it!
At the end of the day not too many people driving their cars on here will be approaching the grip limits of their cars often enough and to the extent that it will make that much difference. As long as you are using sensibly sized and good quality tires and don't have clearance problems, go with what looks good... Paulyy's car certainly looks great and I am sure it will have more than enough grip for anything he wants to do with it!
my car is used as a daily. now not as much as me and mum take 1 car to work (fam business)
The car gets used on weekends, mountain runs with the PFA, Motokhanas, and maybe that track day that pops up.
Thats why i have KWv3 and nothing more serious like club sports or 4 way adjustable.
Im surprised not many has mentioned shock setting to adjust for over or understeer.
03-04-2015, 02:20 AM
#49
Three Wheelin'
In a perfect world, the chassis of a street-based track car would be set up in the following order (of course this may vary depending on what class/series the car is being built for or who you ask, but this is my take):
1. Determine the optimum overall aero/body package depending on class rules and regulations, sort out weight/corner balance issues by moving stuff around.
2. Stuff as much rubber as possible under the front and rear wheel arches as permitted by rules, with proper wheel width front and rear to maximize tire contact patches.
3. Address any suspension geometry issues that may arise from running at the desired ride height/rake.
4. Figure out the necessary spring rates front and rear for basic handling balance and to keep tires in optimal heat range, thus determining optimal damping range.
5. Determine the optimal sway bar sizes and adjustability range.
6. Test, test, and test again.
7. Change # 1-6 as necessary, rinse and repeat. Play with alignment, sway bar, and damper settings as needed to suit driver preference and track.
HOWEVER, not many of us live in that perfect world, and we address the above issues as they come. Some of us may have scored a killer deal on a nice set of wheels that we are stuck with for the time being, and need to figure out how to best make them work. Others may have been a good deal on a new or good used set of coilovers, and need to try and achieve balanced handling with that setup. Many need to compromise with a street/track combination setup, with compromise being the key phrase.
There are a LOT of good threads already posted about spring rates and balance, though of course the optimal spring rates depend on several factors, with wheel/tire setup being the most important. Basic damping rate/range is next. Since it seems you are pretty much locked in as far as coilover setup at the moment, invest in a set of front and rear adjustable sway bars to help fine-tune balance and learn what the damper settings do (I'm sure KW and others have published info on this, if not I can try to elaborate).
My best advice would be to head to an autocross, track, or at the very least, a fun, twisty driving road that you know well, and flog the car, if possible (try not to get a ticket, crash, or injure anyone). Try to get a feel for the handling of the car and whether it understeers, oversteers, feels stable during hard braking, corner entry/exit, etc. If the car does not handle as you would like in a given situation, make ONE small sway bar or damper setting change at a time and repeat the drive to see if it makes a difference.
Hopefully you will eventually arrive at an acceptable setup. Be warned that everything is a compromise, and your desired track/canyon carving setup will not be amenable for cruising around or date night (you could find a girl that puts up with punishing suspension setups as I have, however).
The bottom line is to have fun and find a setup/feel that suits you, and not some ideal espoused by myself or others (though I am happy to dispense advice)!
03-04-2015, 03:07 AM
#50
Rennlist Member
Keep in mind shock settings primarily affect transient handling, or how quickly the spring responds to weight transfer. They won't change steady state handling characteristics once the car reaches its roll angle limit. So they can be played with to affect how the car initially feels when you turn into a corner and how it reacts if you hit bumps mid corner, but the tendency of your car to over or under steer in steady state cornering is mainly a function of how your suspension is setup to handle weight transfer i.e. weight distribution, spring and bar rates, and amount of grip available at each corner etc. Shock settings have only a limited effect on your overall steer characteristics. Best to set them to properly control your springs over bumps, appropriate to your road/track conditions and spring rates and then tune steer characteristics more directly.
03-04-2015, 03:13 AM
#51
Three Wheelin'
Paulyy,
Keep in mind shock settings primarily affect transient handling, or how quickly the spring responds to weight transfer. They won't change steady state handling characteristics once the car reaches it's roll angle limit. So they can be played with to affect how the car initially feels when you turn into a corner and how it reacts if you hit bumps mid corner, but the tendency of your car to over or under steer in steady state cornering is mainly a function of how your suspension is setup to handle weight transfer i.e. weight distribution, spring and bar rates, and amount of grip available at each corner etc. Shock settings have only a limited effect on your overall steer characteristics. Best to set them to properly control your springs over bumps, appropriate to your road/track conditions and spring rates and then tune steer characteristics more directly.
Keep in mind shock settings primarily affect transient handling, or how quickly the spring responds to weight transfer. They won't change steady state handling characteristics once the car reaches it's roll angle limit. So they can be played with to affect how the car initially feels when you turn into a corner and how it reacts if you hit bumps mid corner, but the tendency of your car to over or under steer in steady state cornering is mainly a function of how your suspension is setup to handle weight transfer i.e. weight distribution, spring and bar rates, and amount of grip available at each corner etc. Shock settings have only a limited effect on your overall steer characteristics. Best to set them to properly control your springs over bumps, appropriate to your road/track conditions and spring rates and then tune steer characteristics more directly.
