Behind the Scenes: The NASCAR Peak Antifreeze Series powered by iRacing.com – For Those “Uh Oh” Moments
May 26th, 2016 by Matt Holden
Sometimes you begin a race with a lot of confidence, you’re pretty certain that you got the car set up properly and you won’t come across any serious issues for the next 100 laps or so. Many times, things go just as planned, but every once in a while you go through the first corner and realize that the laps between you and the checkered flag are going to be a struggle. With the new aero package on the digital NASCAR Sprint Cars throwing a lot of us a curveball, these early-race issues occur frequently in the NASCAR PEAK Antifreeze Series. I’m going to go over some of the most common issues we’ve faced this year, so if you missed the last article on in-race adjustments, check it out HERE!
Before diving into how to address various issues, we need to know how to diagnose them. In most cases the driver will mis-diagnose an issue initially, no matter how experienced they are. There are lots of things going on during the first five laps of any race, from heavy traffic and car contact, to funny aerodynamic issues with all the cars. For example, drivers may say the splitter is hitting the track, but don’t wait to see if pressure buildup clears it. Adjusting too soon can create unnecessary issues and snowball into bigger issues that you literally cannot solve during a race. Waiting is often the best policy, since most issues will either get better or worse as a run progresses. Patience, young grasshopper.
Once you’re certain that the car has an issue, checking the tires is the next step. Obviously, you’re only going to see the tires that came off the car, so it’s basically guesswork until you have some solid evidence. Tire temperatures are the only way the car can communicate what’s going on during a race, so that black box is worth a ton. Here is a picture of a set of tires that came off of Nick Ottinger’s car during the Richmond race a few weeks ago:
For most situations, tire wear is completely irrelevant. A hot, overloaded tire can wear in just the same way as a cold, unloaded tire, and the wear will typically reflect whatever the driver is saying. If he says loose, the right-rear will be worn. Tight, and the right front will be worn. That doesn’t necessarily mean that’s what’s going on with the car, as is the case with the Richmond tires. Nick said the car was loose with those tires, but further checks showed something different. I’ll use these temperatures for the next few examples.
Obviously, start with camber checks. Does anything look “wrong” with the tire temperatures? Yes! Immediately apparent is that the right-front and right-rear tires are cambered out. That’s bad enough, but I can at least let Nick know that this is going on, and he can try to adjust accordingly. Usually, this shows up on stiff-spring front ends in traffic, since we don’t have enough rebound to keep the nose pinned down. The nose lifts in dirty air, and the camber goes positive. I couldn’t fix this issue, but getting closer to the lead would clean up the air a bit and help this. If your alignment checks are good, we need to average the temperatures.
Load in a tire produces heat. It’s that simple. We need to get an average temperature on the tire to see how the tires are performing. For the example, we have the following averages:
LF: 206.7° RF: 228.3°
LR: 208° RR: 224.7°
We can gather from these temperatures that the car may have too much crossweight in it. Nick was saying the car is loose, and the right-rear had the lowest wear numbers, which contradict the temperatures. Combining all the evidence, we can determine that the car is actually tight, with a snap-loose on corner exit, the infamous “push-loose” condition. So, even though Nick was saying the car was loose, I adjusted crossweight out of the car with the rear perches, and dropped the left-rear tire 1.0psi. After these adjustments, Nick said the car was neutral. Typically, push-loose conditions are diagnosed as simply loose from the driver’s seat because the “push” is very mild and not necessarily something the driver can feel. If I had adjusted the car without checking the temperatures first and tightened the car, it would have gotten worse during the next run.
Once you’ve got a solid idea of what the car is doing, addressing the issues is fairly simple. Here are some of the most common early race issues we’ve faced during this simracing season and how to fix them.
1) Splitter Contact
This is extremely common, especially with the low front-end ride heights that can be run in the Cup cars. Cooler temperatures can change front end travel a lot, and since the splitter unloads the front tires as well as adds a lot of drag, it needs to be fixed as soon as possible. The biggest thing to remember is that, when the splitter does clear the track the car will become incredibly loose since the front tires are suddenly working. Because of that, you need to be sure to do something to tighten the car up so it’s drivable.
There are two adjustments that can clear the splitter, some drivers prefer one over the other. My go-to is to add 1psi to both front tires. This will add a bit of spring rate to the front tires and raise the front end without adjusting the car’s suspension. In longer races, like this week’s 300-mile NASCAR PEAK Antifreeze Series race, I’ll make this adjustment alone without any chassis adjustments, but shorter races will combine a chassis adjustment with the pressure adjustment. The other adjustment is to go positive on both rear perch adjustments. This will lower the rear of the car and raise the splitter a small amount. Since this changes both the rear end suspension characteristics and the aerodynamic platform, it can be a major adjustment. It will both loosen the car as a result of the splitter raising at the time it loosens the car aerodynamically from a lower rear end, so there have been cases where Nick left pit road and I wasn’t sure if the car would be pointing in the right direction after he turned the wheel.
2) Rear Contact
Depending on your rear spring choices, you could run into an issue where the rear of the car is slamming into the race track if the weather produces higher speeds. Usually, small contact is okay as long as it’s not for a sustained period of time. If the car is just popping the track a few times, it will usually clear later into a run as speeds decrease, but heavy contact can produce a lot of drag and make the car extremely loose. While the splitter is made of composites and produces a dull groan as it hits the track, every part of the car’s underside is metal, so the sound is very noticeable…plus the sparks are a good giveaway as well.
The fix is extremely simple: negative on both perches. This will raise the back of the car up and change the car from a sled back into a car. In every case I’ve experienced, the driver has not reported the massive swing from clearing the rear of the car as he did when the splitter cleared, so it typically doesn’t need a second adjustment to compensate for new issues. This happened during the NPAS race at Atlanta, where the right-rear of the car was hitting the race track whenever Nick ran the highest lane in the turns. Since the nose of the car started low, I added some air to both front tires to raise the splitter as well, since raising the rear of the car lowers the splitter.
3) Uneven Pressure Buildup
This issue is extremely common, and is often a result of the track’s progression through the race, or where the driver likes to run. If a driver starts moving up to the top, for instance, the right-front tire will usually start building pressure very quickly. If a track starts to rubber up heavily, the right-front and left-rear may start building up quickly. It’s hard to identify these things during a race since hot pressures are not included in a black box, but enough experience can usually help a driver to point to that being the problem. There are two big flags, however, that point out a pressure issue. First, if a driver says the car “flips a switch” and unexpectedly becomes tight or spins without warning, there’s a very good chance that a tire has built up enough pressure to lose grip. In most cases, this is one of the right-side tires. The other flag is if the driver reports a handling change late in a run, or one that wasn’t present during the first few laps but is very apparent late in the run. Tire pressure is directly related to tire spring rate, so changes in pressure will have a direct effect on how the driver “feels” the car.
Identifying the problem tire is simply guesswork at this point. It’s often better to wait and look at the tire temperatures before making a pressure change to correct pressure buildup, taking a bit of air out of a tire that is showing a lot of heat. Or, if that tire is at the minimum, add it to the other tire on the same side of the car.
4) Cross Buildup
This one’s rare, and the crossweight is not actually changing – it just seems like it is. That said, it’s happened twice during the 2016 NPAS season on the #05 car, at Texas and Richmond. Interestingly, those were the two tracks where simracers were reporting heavy rubber buildup, so it could be the link. Regardless, the car needed a crossweight reduction as the race progressed, which showed-up in the tire temperatures. This can be corrected by either inflating the tires that are not gaining heat, or reducing crossweight with the perches. For instance, if crossweight is building in the car, the left-front and right-rear tires could be inflated to match the pressure buildup on the right-front and left-rear.
Where you can run into issues is the rear perches. I mentioned in the last article that your crew should keep the rear springs in mind when making perch adjustments, and not doing so could get you into a world of hurt. If you were to run springs like 250 lb/in on the left-rear and 1000 lb/in on the right-rear, the same amount of change would have a huge effect on the chassis relative to the left-rear adjustment, so you have to make sure to keep the adjustments balanced to prevent major issues.
5) Bumps upsetting the car
This hasn’t happened on Nick’s car yet, but it has happened in my Class B car this year. On some extremely bumpy tracks, the car could get tossed around by the bumps. Typically, this is from having a very stiff spring that doesn’t allow the wheel to move over a bump. In my case, this happened at Las Vegas, where the bumps in Turn 1 were dictating where the car wanted to go. To fix this, I made a “positive” adjustment on the right-rear perch, which reduced some of the preload on the spring. Since it was then sitting in the car with less load on it, the force to move the spring was reduced, and was able to go over bumps with a lot less “excitement.” If you tend to run extremely soft rear springs, such as the 100 lb/in rears we can put in the Class A cars, make sure you aren’t binding that spring over a bump, or the adjustment I made to my car will make the problem 10x worse!
Hopefully you can take these small issues and make them a non-issue in future races. It can be a little frustrating, but taking the time to work out what is causing the issue and properly diagnosing will work wonders in making these little nagging problems go away. Best of luck, and keep the painted side up!