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Old 09-06-2007, 05:22 AM
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Default Driver Thoughts (September 2007)

DRIVER THOUGHTS
Organized by Hollis "hollis3" Lee

For this newest addition to our motoring|underground Features section, we posed a question to various performance drivers, wishing to see the variety of answers and how each driver approaches their craft. We loved the initial response, from the simple, straight-forward answers to more detailed thoughts. We would like to thank all of those that responded.

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QUESTION
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Aside from safety, what do you think of first when preparing a car for the track?

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ANSWERS
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Jerry "Siddhartha" Bradbury (NASA)

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In the past, I have tried to remember everything I need to take to the track, but it never worked for me. I always forgot something essential. So I created a Track Day Inventory and use it every time to make sure I have all the necessities. It also contains an inventory of my toolbox which I check as well. As soon as my car has been tech inspected and signed off, I pull out a copy of my Inventory and load up. Then I tuck a copy in my toolbox in case I have to look for a tool or a part later. It saves a lot of rummaging time. I can tell immediately whether I have a 17mm open end/box end wrench in there or if I have to go borrow one.

It looks like this: Track Day Equipment (PDF)

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I am split between tires and camber. Tires because of the increased road-holding, but negative camber allows those tires to last quite a bit longer and offer increased road holding. Brakes would come after that.

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Bob "CANYON MINI" Scheer (USTCC, VARA)

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When Canyon Motorsports prepares a new race car for competition we first determine the racing series the car is being designed to race in and get the rule book for that series, then we read and study all rules & regulations for our chosen class.

After all safety requirements are addressed, we then turn our focus toward minimum weight requirements. All race series have a minimum weight both with and without driver.

At Canyon Motorsports, we take what I refer to as a top down approach to weight reduction. This approach yields us a very light chassis with a much lower center of gravity and less swing weight when the the car turns.

This means we first focus on removing as much weight as possible from as high as possible on the car. On our #4 U.S. Touring Car Championship MINI Cooper S, the first high and heavy piece to be removed was the sunroof, with a lightweight aluminum roof plug taking its place. We then removed as much of the double- and triple-layer sheetmetal on the underside of the roof, and removed every unneeded factory bracket that was revealed after the interior was gutted.

We further improved the car's center of gravity by relocating some of the heavier items that must remain. The battery box was removed and plugged with aluminum, then we installed a small Odyssey racing battery as low on the floor as we could accomodate.

During this process we kept removing weight even when minimum weight was reached. We always strived to use every available trick in our sleeve to get our car below minimum weight, then we went back and attach lead weights as low in the chassis as possible to the lightest corners of the car. This allowed us to perfectly corner-weight and balance our car while lowering its center of gravity, as we brought the car back up to the minimum weight requirement.

This was the first step of many we utilized to produce the best handling road racing chassis possible.

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Waylen Hunsucker (NAMCC)
http://www.waymotorworks.com

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The first thing I would say I would consider when preparing a car for the track would be "What is the budget?" Everyone has a budget and needs to stick to it. Some may have $100,000, and some may have $1,000. So you need to decide how much you have to spend and what you are going to spend it on.

Do you just want to make the car all-out fast by adding horsepower to it, or do you want to make it faster through the corners? A car could have all of the engine mods, but a car with the right suspension and brakes will have faster lap times. Other things will come into play in your budget are what kind of tires will you use, since the longer they last, the cheaper they will be.

Are you going to do the work on the car yourself? The labor to install some parts can be more than the part itself, so doing it yourself can save you money, but don't think doing everything yourself is the cheapest route. Having someone who knows what they are doing do it for you and in a timely manner will go a long way. You always have to value your time. Don't spend all weekend doing a job that you could have had someone else do in one day. Plus, you don't want to fall into the "I did it myself but broke this and this and it cost twice as much now" trap.

Also, track time is expensive so spending less on the car may make it so you can do more events. As you will find the more seat time you have the faster you will be; like they say, practice makes perfect. I could go on and on about things that will add cost, but bottom line is: Make a plan and stick to it.

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Eric Courchesne (Coupe Rallye)

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I would say that the suspension is the way to make your car faster and more fun to drive. But for some particular cars that already have a factory-tuned suspension such as the Cooper S, M3, and stuff like that, I would say that track tires would be of greater importance.

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I’m going to direct my answer in a manner that discusses preparing a street-driven car for track use, as I feel that it applies to the majority of members of motoring|underground. Preparing a car for racing, or solely for track use, would obviously have other considerations in addition to the discussion below. I will also be speaking in general terms. Further discussion on the specifics of each point would be helpful to those setting up a car for the track, but would take several books-worth of writing to fully explore.

The first thing I think of when preparing a car for the track is balance. When I speak of balance, I’m referring not only to (1) the balance and weight distribution of the car, but also to (2) a balance of the types of modifications done to the vehicle. I’ll break down each of the above so that you can understand why I consider both the overall balance of the vehicle and of the modifications to be so important.

(1) Weight Distribution/Balance

Many people want to set up their vehicles for track days in the least expensive way possible. This is not, in and of itself, a bad thing, but lack of consideration of the overall balance of the vehicle can lead to negative handling characteristics.

For example, some MINI owners like to remove the rear seats, replace the exhaust with one that is much lighter, replace the battery with a lighter one (or relocate it to the front of the vehicle and remove the battery box), remove the rear wiper and motor, and replace some of the rear suspension components with lighter aftermarket parts. Again, none of these changes individually make a big difference in balance or handling. However, when combined, these changes can make a difference of over 100 pounds in the rear of the vehicle. The addition of an M62 supercharger and a water-to-air intercooler (for example) could add multiple pounds to the front of the vehicle as well. A lighter vehicle is a positive, but large disparities in cross-weights, left-right balance, or front-rear balance can upset handling characteristics. An R53 MINI Cooper S has (approximately) a 60.5% front and 39.5% rear balance. Removing 100 pounds from the rear and adding 20 pounds to the front changes this balance to approximately 63.1%/36.9% F/R, even though the car has had an overall weight reduction of 80 lbs.

Weight and balance changes can be overcome by suspension tuning, but the use of stock springs, or springs created and sold for a close-to-stock vehicle, may result in some interesting handling characteristics. Essentially, what I’m saying is that all weight changes affect the handling of the car in some manner, and the consequences should be considered before making major cumulative changes.

(2) Balance of Types of Modifications

The balance of the modifications performed on a vehicle is, I feel, one of the most important parts of preparing a vehicle to be competent at, and to survive the rigors of, track use. Many focus on engine modifications for increased horsepower as a first step. While it can help lap times, horsepower can also mask bad driving and bad suspension setups. Additionally, added horsepower can overwhelm brake and suspension systems, which can lead to dangerous on-track situations.

I would say that for every modification made to the vehicle, one must understand the effect on the vehicle and the driver. With greater horsepower comes greater speed, which places greater demands on the braking system and drivetrain. A car that has multiple power upgrades would most likely benefit from an upgraded brake setup, such as a big brake kit or simply upgraded rotors, pads, and cooling (brake ducts). Putting the increased power to the ground is also important, and some sort of limited slip differential would help in this regard. Another, often overlooked, example would be a tire upgrade. With increased traction comes greater demand on the braking system as well as the suspension system. Upgraded brakes and increased roll stiffness, through a sway bar or springs (or both), would be recommended to accommodate the greater forces generated by the stickier tires.

I can offer examples all day, but the overall idea, again, is this – For every modification made to a vehicle, one must think of the overall effect and additional demands placed on the systems of the vehicle and on the driver.

In closing, each car has different characteristics and demands in creating the ultimate track setup. When setting out to make a car track worthy, one must consider the overall balance of the car, as well as the balance of the modifications performed on the vehicle.

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Click the image to open in full size.

This one is easy. No car is fun to drive (or race) on the track without a suspension that is suited to the vehicle. Of course I am rather biased as I get paid to tune race car suspensions. Regardless, beyond pure speed a car is significantly more enjoyable to drive when you have a good suspension, and that suspension is properly set up for the particular track you are on and the tires you are using.

It really pays to do your homework before buying a suspension for your car. Ask around what people are running for particular applications and try to decipher what is good and bad because not all suspensions are created equal. This last weekend I was tuning the suspensions on two virtually identical E36 M3 race cars. Both cars had the same motors, same roll cages, weighed the same and had the same springs rates and alignment settings. The only real difference was the dampers they were using. Both had double adjustable dampers produced by well known manufacturers and were supposedly valved for the spring rates on the cars. But when I drove both cars back to back I noticed a rather surprising difference. One car felt light and quick and responded well to my every input. The other car felt slow to react and oscillated annoyingly over bumps. "Ok", I thought. "Maybe the rebound is just set a little low". All the shock settings were set at about middle so I made a big change and stiffened everything up to 3/4. The car definitely felt better and oscillated less but it still felt relatively slow to react. So I cranked all of the shock settings up close to maximum. Now the car felt a lot quicker on turn in and didn't oscillate much but it couldn't soak up any bumps and would wash out after its now-quick turn in. I played with the dampers all day but never could make the car feel as good as the other one. In the end the difference in lap times was really only 0.5 seconds, but the first car was just so much more FUN to drive.

So the point of that overly long story was that if just the manufacturer of two similar dampers can have that much of a difference on the feel of the car and how much fun the car is to drive then the suspension of a track car needs a lot of thinking and time to make it absolutely right.

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If you are an active driver in sanctioned events and would like to participate in future Driver Thoughts columns, please send an email to hollis3 @ motoringunderground.com. We would love to add your thoughts. µ

Last edited by iDiaz; 09-11-2007 at 11:30 PM..
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