I was standing there watching the New England Modifieds prepare for practice in the pits at Mahoning Valley Speedway on our Tour stop there and looking at the front ends of many of the cars. What I observed was what I believe to be a flawed design that I have alluded to many times in this magazine. It all goes back to a trip I made to Connecticut back in 2004.
That year I went up to see a well-known racer whose name I won’t say, but his initials are TC. He was running at Stafford on Friday night in his SK Modified and he asked me to come up. So, I arrived just before the first practice and watched him go through the turns. When he came in, he asked how it looked. I said it looked like crap.
Surprised, he asked me why. I said that the right front tire looked like it was going into positive camber through the middle. After a discussion with his then crew chief, a seasoned veteran of the Modified divisions and very smart man, we determined that the angle of the right upper control arm wasn’t enough to reduce camber loss from the 0.5- to 0.75-inch of dive and 2.5 to 3.0 degrees of roll the car was experiencing.
The crew chief told me that he had run the front end dimensions through a geometry software program and it looked good, but we determined he had used numbers that didn’t represent what the car was actually doing on the racetrack. He had entered 3 inches of dive and 0.5 degrees of roll. With those erroneous numbers, the RF camber change looked OK.
The car was redesigned the following week to correct the upper arm angles and at the same time maintain the moment center location. These changes were taken over to the Tour Modified TC drove and I think he won the next four races in a row. Getting a Modified to turn well is evidently a big deal.
Getting back to Mahoning, here were the same designs as I had observed not working in 2004 being used and on the track I could still observe, even from the pit grandstands, right front tires standing straight up or worse through the turns, at a very small, less than a quarter-mile track where you turn all of the way around the circuit.
As many times as I’ve gone over front end geometry and camber change in past issues of CT and as hard as I try to educate racers, we evidently still have far to go. And it all comes down to basics that were in place long before I came on the scene in the early ’90s.
Speed and setups are all about utilizing the four tires to their maximum. That means ending up with the best footprint, the most loading on all of the tires as possible, and consistent loading where the dynamics are balanced and no tire is overworked to make up for other tires that are underworked.
We have explained the methodology used to get those results in numerous projects and articles. And no matter what the setups are based on, such as spring stiffness and sway bar size, the goals remain the same.
The winners in this day and age are either of two scenarios, and this has been true for some time now. Either your “less than optimum” setup is slightly better than that of all of the other cars you race against, or your car is truly setup correctly to 95-100 percent of its potential and it just can’t get any better.
And when you get to the point of the latter of these two possibilities, you’ll stop fooling around with setup and endeavor to maintain what you have instead of experimenting. That’s exactly what most of the championship teams I’ve worked with have done to win time and time again.
Most of the past 10 years’ articles we’ve presented about chassis design and setup are available on our website and if not, you can dig through your past issues and reread them. There’s valuable information contained therein, I promise you. All you have to do is trust in what has worked for many racers before you.
Meanwhile, I plan on re-presenting most of that information for both the newer racers who never were introduced to it, and for the others who missed it the first, second, or third time. I guess what teachers do each year is re-teach knowledge that has been taught to past students who have gone on to higher grades. By now, some of you should be ready for graduation and that means checkered flags and trophies.
If you have comments or questions about this or anything racing related, send them to my email address: Bob.Bolles@sorc.com, or mail can be sent to Circle Track, Senior Tech Editor, 9036 Brittany Way, Tampa, FL 33619.
A Setup Guy’s Perspective
I very rarely write in due to the fact that I may look like a goofball. Like the old saying goes, better to keep your mouth shut and look like a fool than open it and confirm it. However, the letter “Disappointed in the SBBS Article” got me thinking.
I’ve been racing since the early ’90s, on dirt and pavement, and from Street Stock, to NASCAR (formally CASCAR), to Dirt Late Models. Ninety percent of the time I raced in Western Canada, and the rest in the U.S.
It wasn’t until about 1999 that we started playing with the BBSS setup on an IMCA Modified, not due to aero, but because the tracks were so bumpy.
We won a lot of races with this. I then tried it on a pavement Late Model (CASCAR). What we discovered was that once we found “the setup,” it was great. But if we went touring, I could never find the sweet spot quick enough at the other tracks, perhaps due to a lack of understanding of what was really required and what the chassis and driver wanted.
At this time I started working for a race shop in Calgary and started to learn more about the computer programs that were available. After buying several of them, and as many books as I could get my hands on (the only ones prior to this were Paul Van Valkenburgh, and some Steve Smith), the teams I worked with became more successful.
I believe at approximately this time your programs and book came out and some of the blanks got filled in (this isn’t a kiss Mr. Bolles’s a$$ letter).
After a few more years we started having more questions about how to do better. So I started getting into the tech schools, taking classes in the U.S. from RaceWise with Mark Bush, to the three-day class with Claude Rouelle this winter. The reason was to see and learn new views on the subject, other than books and programs, by talking to other racers. Even if we don’t race in the same class or type, it might spark a new idea.
The point of all this is that since the early ’90s to today, the understanding on how the cars work has changed as much as computer technology has. Also it seems to me that what works for one driver doesn’t seem to work for another. The gentleman who wrote the “Disappointed” article finds the BBSS setup works great for him and his team. I’ve found a mix here.
Same car, same setup, same track, same day, three different drivers—one loves it, one didn’t find that much of a difference, the last hated it. All were within 0.003- second on a 1⁄3-mile track, with about 7-degree banking in the corners. Working with a lot of drivers over the years also makes for a good learning experience. Some are great, and others, not so much.
I’ve learned over the years that taking advice from a guy who talks like a expert when he’s running 15th all the time isn’t the same as talking to guys who are successful every week. Everything changes, the latest hot idea may or may not be the best idea, but I think racers need to have more of an open mind.
On the subject of drivers, I’ve found that most of them have no idea about what the car is doing. This isn’t a knock on drivers. I completely suck as one, and do admire what they do. When you try to get info from them, some try to sound like an F1 racer, others just shrug their shoulders and say, “I don’t know.” What does a driver really feel? Weight transfer, tire spin, aero?
I might be wrong here but I believe the driver only really feels a few inches of weight transfer (his back side) and feedback from the steering wheel (hands). The rest he sees (the cars pitching over) and hears (tire spin, tire chatter, brakes, and so on). One of the reasons I believe I suck as a driver is that I’m pretty much deaf. I’d love to read an in-depth article on that—what does a driver feel and how it related to setup and crew communication.
I do enjoy reading your tech articles and your book. I might not always agree with your conclusions, but do agree with your methodology. They always get me thinking about stuff, and believe that’s your real idea. I hope this letter makes some sense, and on behalf of most of the racers out there, thank you, not only for sharing your experience, but talking to other racers and sharing theirs as well.
Thank you again for your time,
Your letter is much appreciated. Those of us who have worked with various teams and drivers will connect with what you’re saying. I agree with you, technology has changed and I think we all have a better understanding of how the car wants to be setup. After all, it’s what the car wants that’s most important. And then there’s the driver.
A driver’s ability to feel the car is, in my opinion, a born-with quality. I don’t think it can be easily learned. This comes from my own experience with driving and my experience with lots of drivers. Some take to the race car naturally and some just never are comfortable. The natural drivers can be the hardest to read because they so easily adjust to the way the car is. Unnatural drivers never can adjust and seem to complain more.
In my experience, once you give the driver a comfortable car that reacts correctly to the steering, brake, and throttle input, he’s happy. But a strange thing happens right about that time. He/she gets more acute about the things the car is doing. Instead of saying it has a push at mid-turn or it’s loose off, drivers start telling you, “Just as I get into the throttle, it has a slight push up off the corner,” or, “It’s just a bit loose right at the apex…”
This refinement of the driver’s input tells us we are very close to where we need to be. Many drivers don’t know what to tell the crew, sometimes because they have never felt a good setup to know the difference. It’s up to the crew chief or consultant to observe the car, look at the tire temps and shock travels and make a determination about the setup and what needs to be changed.
You’re also correct about our goals here at CT. We try to get racers thinking first and foremost. I don’t expect everyone to agree with my presentations and the way I think, but if they start thinking about their car and come to understand what it needs, then we will have done our jobs.
Width Versus Left-Side Weight
Here’s my question: Do we want a wider track, or more left-side weight? Given an option between a car that is 78 inches wide with 58 percent left-side weight and a car that is 80 inches wide with 56.5 percent left side weight, which would you prefer?
The rule book calls for max track width of 81 inches, so both are within the rules. My car is a 2,600-pound IMCA-type pavement Mod.
I’ve always felt that wider is better but many people feel differently. All the ballast in the car has been placed for maximum left-side weight.
Wider track offers less load transfer through the middle of the turns and therefore more retained left-side weight. If the wider track reduces the load transfer by more than the difference in left-side percentage, then it would be best to go with the wider track.
If the difference in left-side percent is more than the load transfer difference, then obviously you would go with the higher left-side percent. The difference here is 39 pounds.
If all were equal, I’d go with the wider track. With the low center of gravity of your Modified, there’s less load transfer than would be seen by a Late Model or stocker. But, why not try for both?
You say you have the ballast placed for maximum left-side percent at what I assume is the 78-inch track width, but if you increase the track width by 1 inch on each side, your left-side percent should remain the same.
If you increase the track width by extending the right-side tires by 2 inches, your left-side percent will increase and you can move ballast to the right to bring the left-side percent into the rules limits.
Tire Soaking Dangers
I’ve been witnessing an alarming trend at some of the local tracks. I’m not sure, but I think it falls in the area of safety, although it affects handling. A lot, if not most, of the local racers are treating their tires with chemicals that I’ve been told have carcinogens in them. Being a cancer survivor, it scares the heck out of me.
I know that not all are using the proper handling procedures and I’m also sure that their (young racers) kids are around these chemicals. Are they really necessary to improve performance or are the racers just too lazy to work on setup?
What tools other than a Durometer are needed to keep this in check? Please answer in one of your tech columns and I would appreciate name withheld.
It sounds like the racing is kart racing? Most of the kart tracks and sanctions tend to ignore tire soaking. This comes both from an aspect of lazy tech’ing and the reluctance to enact a tire rule where the racers are required to run new tires purchased at the track on race day.
Yes, many of the chemicals used to treat tires, as are many household cleaning chemicals, are dangerous to breathe. There are warning labels on many products that instruct us to use in well ventilated areas. The problem with tire soaking is that it’s illegal or against the rules in most places and must be done in places that are hidden and closed in, i.e. improperly ventilated.
There are other dangers too. I heard a funny story, only because no one was injured, where someone was soaking in the basement of their house and the furnace came on and the fumes ignited burning the house down. The insurance company did replace the house but refused to replace the rotisserie that was used to soak the tires.
Mini Cup Tire Temperatures
I recently purchased and read your book, Stock Car Setup Secrets. I noted that you illustrated ideal dynamic weight transfer with two equal small left-side circles and two equal but larger right-side circles. The circles represent ideal dynamic weight distribution. Can dynamic weight transfer be related to tire temperature?
The last time on the track for testing a new setup adjustment, my grandson’s suspended Super Mini Cup car was run three times for 10 laps each. After each of the three sessions, three tire temperatures were taken on each tire (inner, center, and outer). I averaged all of the temperature readings for each tire and they are as follows: LR 106.6, LF 96.6, RF 126.8, and RR 129.4.
Do my grandson’s tire temperatures represent the same as your dynamic weight transfer circles? If so, the right side seems nearly equal but the left side is consistently hotter in the rear by about 10 degrees. If the left-side temperatures need to be closer to equal, how to I get the left side equal without messing up the right side? Thank you for your time and advice.
David M. Gangel
You have asked the million dollar question. There is a correlation between loading of the tires and tire temperatures. What you see in your tire temperatures is an imbalance in the roll angles in your car. I have talked a lot about roll angles in various articles in CT.
Your rear suspension is trying to roll more than the front suspension. This serves to transfer more load from the left front onto the right front tire than what is needed. Since the LF is less loaded, it works less and is cooler. Inversely, the LR tire is more heavily loaded and therefore is working harder and it has more heat.
The average rear temperatures are hotter too meaning your car is tight/loose. This is a condition where the car is tight in the middle and with excess steering input to overcome that, goes loose off the corner producing the hotter average rear tire temperatures.
The solution is to do one or more of the following: 1) Stiffen the RR spring rate and/or soften the LR spring rate, 2) Raise the Panhard bar (if that’s allowed and possible), 3) Soften the RF spring rate and/or stiffen the LF spring rate. When your left-side tire temperatures are within a few degrees of the same, your setup will be balanced and the front-to-rear averages will be almost the same.