As the Sprint Cup series heads back to Michigan International Speedway, the tires and aerodynamics of the race cars will be the big topics of discussion this week. The speeds at Michigan earlier this year were the highest we’ve seen all season. The tires used have been heavily scrutinized due to the repaving of the track, and issues encountered with the tires last season with the high speeds and lack of heat dissipation in the tires. The skins and the sensitivity of the cars to the air at such great speeds has the teams on edge heading to the Irish Hills this weekend.
Jason Ratcliff guided Matt Kenseth to a top-10 finish at Watkins Glen last weekend and he’s got the No. 20 team sitting third in points– the highest of any team who does not have a victory going into this weekend. With the team looking to be relatively assured of making the Chase, the focus is even more directed at putting the car in Victory Lane. This week in Tech Talk Ratcliff touches on several items that are concerns when running at Michigan. They include tire stagger, air flow under the car, keeping the car down on the track while not losing traction with the tires and the lack of flexibility on adjusting the rear spoiler.
Mike Neff: You’re coming off of a solid weekend at Watkins Glen. Not only did you finish ninth but you started in eighth. How did you manage to get Matt Kenseth qualified in the top 10 at a road course?
Jason Ratcliff: That was more Matt’s talent than anything myself or the team did. Getting on the track in a Nationwide car a little bit helped him and more seat time is a plus at any road course. Our first run in qualifying there wasn’t great; I think we were able to make some adjustments and make it better. I think getting the first lap under his belt is something Matt is really good at. Once he gets a feel for the car and the race track, he is able to adapt. I think that is where the difference was for our second effort. On the track for qualifying it was just him knowing what he had in the race car after the first run and being able to adapt and pick up some speed.
Neff: When you have a red flag that lasts and hour, and you can tell early on that it is going to be a long one, what do you guys do in the pits?
Ratcliff: That depends on the situation. If we are in a close battle for a win you’re going to spend the majority of your time thinking about what you’re going to do when the race goes back to green. Usually, especially if you sit for any period of time, you get some track changes and it gives you an opportunity to put some more thought into how the race is progressing. What you can do and, if the driver can get out of the car, you get a little face time. You can theorize a little differently. For us at Watkins Glen it was just a matter of waiting for them to fix it. There wasn’t much for us to do, as we were getting close to the last fuel stop. The car was decent so we sat around and chatted and asked how much longer it was going to be until it was fixed. It is about like the kids in the back seat waiting to get to grandma’s house — we just had to wait patiently.
Neff: So probably spent 15 minutes reworking strategy and then 45 minutes cleaning out the food in the hauler, and playing frisbee?
Ratcliff: Oh yeah, it is always a good time to clean the refrigerator out in the hauler.
Neff: We’ve gone through two road course races with the new ride height rules. In hindsight have you decided if it is better to maintain a stiffer platform or a softer platform to be fast on these tracks?
Ratcliff: I think, for us, we’re still learning. The two tracks are drastically different and we run two different tires. At the Glen you have to maintain platform pretty good because there are a lot of high speed corners. You have to be a little stiffer to maintain a good aero balance. Sonoma is quite a bit different because you are hunting grip there usually since the track and the tire combination is a lot different.
As far as the 20 car goes, the road course program needs some work. We only go to those places a couple of times a year, and it is difficult to put a lot of time and energy into it, even though we need to. While we had a decent run on Sunday we have a lot of room to grow and we need to put more effort into it in the future.
Neff: Now we’re heading to Brooklyn, Michigan to the big two mile oval that is Michigan International Speedway. When you are on a high speed track like that where there is such a premium of getting through the air, how much of a premium do you put on drafting when you are getting ready for the weekend?
Ratcliff: It definitely plays a role. The corners are so big and the same air that is a positive for the draft is not very good for balance in the corners. Once you get loaded up and start turning the steering wheel, you need all of the air you can get on the car for downforce. You may draft a guy and get an opportunity to make a pass before you get to the corner, but if you are in his trail when you get to the corner it can be difficult.
You have to play the best of both worlds from the drivers seat. It is the race within the race where you are trying to negotiate traffic and put yourself in the right spot while, at the same time, understanding what that is doing to your racecar and giving your crew the information they need to work on it. On the big tracks like that the speeds are up so high, and so is drag, especially in these cars where the spoiler is up more than it was in previous years. Drag is up and once you get to those speeds, and any reduction in drag is going to help you get down the straightaway faster.
Neff: You mentioned the spoiler. Is there a template that forces the location of the spoiler on the rear deck or are you allowed to move it from side-to-side from the driver’s side to the passenger side?
Ratcliff: No, it is set. There is a template that sits on the deck lid that comes up and runs along the spoiler and you have to maintain that shape. There isn’t any adjustability or anything that you can do in that department.
Neff: Since we don’t have to raise the car back up to a minimum ride height these days, with the smoothness of Michigan after the repave, do you build any rebound into your shocks or do you make them basically solid sticks since you want the car down and solid the entire time?
Ratcliff: Since you can run the car down and you might have a little more selection in springs than you did in the past, you certainly don’t have to add shock. Since you can start it right there at the ground, there isn’t anything you have to hold there. You can still put some shock to it for the race. Mechanical grip is still a factor and it is something you have to look at. You can certainly over do it; it’s not like you can go out and just pile a bunch of shock to it and expect that to be okay. At the same time, you can take all of the rounds out of the car now and just set it right on the race track. You don’t need a lot of rebound to keep it there like you had to in years past.
Neff: Kevin “Bono” Manion mentioned this last week and I’m sure most fans have no idea that this occurs, so hopefully you can explain it a little bit. Does NASCAR take the shocks off of the pole and race winners’ cars and lay them out, disassembled, for you guys to check out?
Ratcliff: Yeah, they have been doing that for a few years now. That is another way for them to try and keep the garage area a little closer on something you can’t see. That stuff is typically enclosed in the shock body so you can’t see what is in it on the race car. That is something they have been doing for a while. They take the shocks apart and lay out all of the pieces. They don’t allow you to touch them or move them around or really even take pictures. However, for a shock specialist or someone who knows what they are looking at, it can be valuable.
But, at the same time, people can get creative and put a bunch of stuff in their shocks to send you in the wrong direction (laughs). You know how this sport is. There are some very creative people in it. If they think they can put a spin or trick on you to send you the wrong way they are going to do it. Either way, it is something that is a little bit different than most other sports that is very unique. You certainly see a crowd around the table every week inspecting just to see what is going on. Once you see one team’s shock up there several times, because they qualify well, you’ll find out that what a team does in the shock area they tend to remain very consistent. Every time they put them up there they tend to look just like they did last time.
Neff: Still dealing with the suspension of the car, with the car not having to lift the car up to a ride height are you using a softer spring that easily compresses down to the ground or a stiffer spring that just forces it to the location you want?
Ratcliff: It all depends on the race track. The closer you put the car to the race track, the stiffer you are going to need to be to keep it off of the race track. It depends on rough race track or smooth race track and how much body movement you can allow. That is still very open, no different than in years past; it is a variable that changes pretty often. It is more of a track size and track surface kind of thing. We always want to maintain the best platform we can, at the same time, you can’t beat yourself to death on a bumpy race track trying to do that and lose all of your mechanical grip having the car bounce all over the place. It is a give and take situation. You can’t say you want one or the other, you want a little bit of both depending on where you are going.
Neff: Along the lines of the air coming through the front of the car. When you are at a track like Michigan and doing 210+ going into the corner, you are pushing a bunch of air with the front of the car. Does having brake duct openings in the front allowing the air to come through and bleed out through the wheel well improve the car going through the air or do you want to have the nose as sealed off as much as you possibly can?
Ratcliff: You want it sealed off. You don’t want any more air than you absolutely have to under the hood, you want it to stay on top of the car and create downforce on the outer body. You need that pressure difference between the outer body and the under body and you need all of the working together. You try and keep the air on top of the car and keep the splitter working. That is the most effective way to create front downforce. Putting holes in the nose, and especially putting air under the hood, is typically not a good thing…
Neff: In keeping with the duct theme, do the ducts that direct air to the rear tires, do they have to come through the side windows or are you allowed to pull air from under the car or through the nose all of the way to the back?
Ratcliff: Any air that goes to the rear brakes or the rear tires has to come through a quarter window NACA duct. There are some exceptions where they will allow you to run a scoop on the truck arm or something where it can be directed up to the brake caliper. It can’t have a fan in it. It just has to be a little scoop, a directional piece that has a hose on it. 99% of the air that is going to feed underneath the car for the rear tires and brakes must come through the rear window NACAs.
Neff: Are you limited to the material that is used for the side skirts on the car? Do they have to be plastic or are you allowed to use different materials?
Ratcliff: They really don’t specify. Around the exhaust you have to use aluminum because it gets so hot. Most of the time we use the plastic, or EBS. You can use Lexan as well but it can get a little more brittle. It is open…most guys will run a Lexan or plastic skirt with an aluminum piece there at the exhaust outlet in order to take the heat.
Neff: We use radial tires that don’t vary much at all from the diameter of one tire to the next. With the curvature of the long straight at Michigan, is there enough of a variance between some tires that it allows you to pair different rights and left to add some stagger and help the car turn?
Ratcliff: No, Goodyear sets the stagger based on the molds that they use for the given tires chosen for the track, based on the tire code selected. Of course, radials don’t really have any variance in them anyway. The stagger does differ every week depending on what tire combination they choose every week and what molds are used to construct the tires and that can differ quite a bit. On any given weekend though, they are fairly consistent from set-to-set and especially all of the lefts and all of the rights.
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