tube80z

Sorry no pics of this one. My car has a 280Z style adjustable rear bar that currently hooks to the control arms. As I have a fuel cell in the back a good portion of the floor was removed. My plan was to attach my new rear roll bar to the rear cage tubes (these go back towards the bumper section) and have it go through the floor to the strut. When I measured this I get links around a foot long. So this is more of a do what I say than a do what I do :-) Cary

One of the largest performance increases for me this past year was moving to nitrogen. Why I like it is that I can use the ideal gas law to determine my starting pressure for a given ambient temp and a target hot pressure. I made a chart in excel and printed it off for use on race day. To see if nitrogen would help use the ideal gas law to determine what your pressure rise should be. If you're much higher than this, which I'm guessing 260DET may be then you can benefit from nitrogen. To get your tires onto nitrogen you need to purge them of air before. Smith has a procedure and a lot of tire shops are moving over to it. For slicks I have found I lose less pressure over night on nitorgen and it is not reactive. I spend a lot of time taking care of my tires and this is one step. It also comes in useful to run air tools as well. I need help to run my car and nothing works better than to offer "air" and the use of an impact gun on race day. Once you've bought the cylinder and regulator it doens't cost that much to use nitrogen. It was also very handy when I had a flat on the trailer on the way to a race. Someone stopped to help me out and I pulled out the impact and went to work and they just kinda watched dumbfounded. I don't have any magic info here but I've seen the same thing. I do know a tire has a rate that varies with camber and pressure and this probably has something to do with it. I stumbled across this last year when I had tires that had given up on me. I tried lowering the pressure to overheat them and soon found more performance. Up to that point I was floundering trying to figure out how the car went from really good to really poor. See -- I'm no expert :-) I can't say that they run any hotter this way, at least from taking temps but they do provide more grip and work better. This may be something to do with spring rate. I do think they heat up quicker at least from how they work. I'm running Hoosier tires in R25A and R35 compounds. If you plot lateral acceleration to tire temp you'll find that slicks have a couple of operating windows with a noticeble dip in the middle. I'm guessing that lower pressures may help you cross this window more quickly, which is especially important in autox and hillclimb type events. To get more heat into the tire you can raise the RC, the car, increase toes, and play with pressure and camber. Pressure and camber are the two items I spend a lot of time messing with between runs once I get the car balanced. The key is to always get the car balanced and see an even pressure rise before you start tweaking too many things. Otherwise you'll soon be chasing your tail. Cary

You don't have to do all this but starting to do more and more really helps. If you only do two things I'd say keeping track of track temperature and your pressure rise are the most critical. Even if you don't want to do anything else you can make meaningful changes playing with those two. I race in White City, Oregon. It was used to train troops for desert warfare in WWII and is only fit for insects in the summer. So I know what you mean about heat, but at least it is a dry heat. As far as ride height changes,etc. if you keep good notes about weather conditions (like ambient and track temps) it can help when you find that magic sweet spot. You can always make the change at home when you think you know what the condidtions will be when you run. Or if they are almost always the same then you don't have much to worry about. At the end of the day this is just autox. Cary "who was hoping for a Rory Byne :-)"

For the sway bar you can weld a mount to the strut tube (should be fairly wide) to distribute the load. Another way that works well is to build a special collar that is on the spring perch. I'll see if I can dig up a picture. Ride height divided by air density ratio is more or less a constant. I use this relationship to change the ride height as the temperature/humidity/barometric pressure change (I have a small weather station with me when I race). In reality I only make changes for large swings. Where I race there often changes in track temp of 40 degrees from morning to afternoon. If you were racing a ground effects car you live or die by this (think about this when you watch F1 this weekend). If you don't like doing this you can use my second trick. That's to only practice when the conditions are similar to when you'll typically race. I do this a lot of the time and watch my competitors chase their tales for a lot of the day. Then they find a demon setup and are really fast. When we race the conditions are often not close and they wonder what happened. Another item that isn't well understood is that to see the effect of a spring change you need to adjust ride height. If you don't then you have changed more than one variable. Here's the key: wheel rate =(motion ratio)^2*spring rate wheel rate (at the contact patch) (WRc)=(wheel rate)*(tire spring rate)/(wheel rate + tire spring rate) or WRc=1/WR + 1/TR Ratio 1 = WRc/Corner Sprung Mass WRc/ground clearance is a constant This gives you a formula for the ride height change you need to make when you change springs. Along these same lines are a few more formulas called magic ratios. These can be used to look at any setup and make another that works similar that has different sway bars and springs. Here are what I'd recommend for records at each race. 1. setup sheet. This is all the car settings before the race. 2. Run sheet. Use this to record lap times and variables while you are running. I have one of these for each run and use it to watch tire pressure rise, temps, etc. I also make notes about how the car worked and what I'd like to try next. 3. Setdown sheet. This is used to record all the settings after you have completed a race. As you make changes during a run or if something has changed that you didn't know about you find it here. 4. Tire record sheet. I keep track of each tire and how much use it has. After every three events I flip them on the wheels to maximize life. And if you run bias ply tires (slicks) you need to keep records of tire circumference. Bias ply tires grow as they are ran. You'll need to adjust ride height to compensate for this. I also get the car off the tires when I bring it in from a run and scrape the crap from them while they are still hot. So you're probably thinking I'm totally full of crap by now. But if you have ever driven your car one day, didn't really pay attention to the weather conditions, etc. and it worked perfectly. Then another day, which you would swear is similar, and the car drives like crap. These are some things you can try to keep the car working well. Good setups are the product of hard work done in a systematic manner over time. Don't expect to master this in a season, let alone a few races. Good record keeping of setups, changes, and variables at the track will help you make the car fast and help you make changes when it is not. Cary

For let's start from the beginning: 4) car set-up as per John Coffey: Camber - 3 degrees neg front and 2.5 neg rear Caster - 6-8 in front (you can decrease camber if you have more caster) General rule of thumb is one half KPI (steering axis inclination). When running this much caster you also need to check to make sure you don't have too much caster trail (mechanical trail). You'd like to have around half an inch. Also try to have no more than 20 percent of tread width as scrub. Toe - 1/4 to 3/8 out in front and 1/16 to 1/8 in in the rear For tight track try rear toe out. Ride Height - 4.5 to 5 inches at the rocker Springs - 225 to 250 front and 275 to 200 rear 400 all the way around. You'll need proper shocks to make this work. Helps to quicken transition times and keep suspension gemoetry for going all over the place. Sway bars - 1-ich front and 5/8 rear 15/16 front max -- both need to be adjustable and connect to the strut, not the control arm. Sway bar should be in a low friction mount, which is not poly or other form of pinch block. Ideally at least one is driver adjustable for when you need to make the last minute tweak between runs. Offset bushing - yes Will be needed for street prepared but should be avoided in other classes. Poly - yes Never. Poly has too much friction. These need to be low friction pieces to help with mechanical grip. Good advice on notes deleted. A tire pyrometer is good to indicate wear but not a lot more. But tire pressures are more accurate on how the tires are used. You should work on a setup that gives you an even rise in pressures. This is where good notes and understanding what you need for a hot tire pressure is important. You can switch to nitrogren to help eliminate the effects of water vapor in the tires. To adjust chassis balance you can change the rake. Rule of thumb is two turns of the spring collar to start. If the effect is too much try one turn. You lower the end that isn't sticking. Make sure you keep the arms near lever and don't end up too low. The car should be corner weighted. Make the front level and the front weights as close as you can and live with what you get in the rear. Move as much weight down and towards the back as you can but not behind the rear wheels. Remember you need to make ride height changes to compensate for weather conditions to keep a balanced chassis. Also consider using shims for camber/caster plate alignment. These allow rapid known changes and/or allow you to get the car put back together without having to do a major alignment. Before an event always know all your settings. Keep notes of any changes that you make at an event. And at the end of an event do a setdown. This last step is important and few people do it. If you're using the same size tires all around keep notes on how hard they were used and rotate to keep the use as close to the same as you can. Do all chassis etup work on old tires. New tires will mask a lot of the changes until you have killed them. By doing all this you'll end up having a car that is kinder to its tires. Test, test, test, and have lots of fun. Hope this helps, Cary