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.