NASCAR Race Weekend Central

Tech Talk: Matt McCall Talks Spring Rates, Pit Selection and Sway Bars

While Matt McCall’s team didn’t win the race in Michigan last weekend the win did come within the organization, and that has to be a boost of confidence for his No. 1 team.

McCall’s group, and their driver Jamie McMurray crossed the line in eighth place and gained some points in their effort to qualify for the Chase without a victory. As they get ready for Darlington they face some completely different challenges than they did in Michigan.

The unique shape of Darlington and the challenging line that drivers are forced to run are a challenge in and of themselves for the Cup series. McCall discusses the spring rates of tires and springs themselves. He looks at pit stall selection and the need to unload with a solid balance for running the race. In addition he speaks about sway bars, twist rates and the combination of the bump stops used to make the front of the cars stick to the track.

Mike Neff, Frontstretch – We like to look back at the previous race to start the column each week and you had a strong run at Michigan. Your teammate won the race so it was a great day for Chip Ganassi Racing with Felix Sabates. How do you feel about your Michigan effort?

Matt McCall – I think it was pretty good. We made some gains from the first Michigan race and obviously the No. 42 won the race so that was good for the company. Everybody has obviously been working really hard to get some more speed in our cars. I think it was a timing thing. Our cars have gotten better and HMS (Hendrick Motorsports) has worked hard on the motors so I feel like it just ended up where we put together a solid weekend for us and for the 42 to win was really good.

Neff – Everyone seems to be of the mindset that the aero package at Michigan is probably where we are headed for next year and beyond. With CGR getting the win that is obviously a good thing. How did you feel like the package ended up racing?

McCall – It is hard to tell. The tracks they picked, between Kentucky and Michigan are probably not the only two tracks to analyze some type of an aero package, but it was fine. It was a similar deal. It isn’t like it created a ton of passing or anything. I am pretty sure that is the package they are going to next year, with perhaps a tweak or two. For the most part that will be the package from my understanding.

Neff – So now we head to Darlington, the track with multiple nicknames. You only get one shot at this place each season. When you look and see Darlington coming up on the schedule, what is the first thing that comes to mind as you are headed to the egg-shaped oval?

McCall – I think the biggest thing is you need to start somewhere close, balance-wise, and keep up with the track. We normally start with very little rubber on the race track, or very little. You only practice during the day and then you go from starting in the afternoon to a night race, so the track changes a lot. The prep work ends up being even more in-depth to try and have a game plan to keep up with the track. That is the biggest challenge.

Neff – Are the tires that we are running this year the same as they were when they used the low downforce package here last year?

McCall – The left side is the same, the right is different. We’ll see if that changes very much. They are still going to wear like crazy. The pace is going to get slow but it is a different right side than we ran last year.

Neff – When you set up, knowing you’re going to have quick fall off in the tires, is there something you can tweak in the balance of the car to try and reduce the wear or is it predominantly between the driver seat and the gas pedal?

McCall – I would say most of it is definitely up to the driver. You can do minimal stuff car wise but any time you start trying to take things away to make the tires last longer you’re going to take speed out. It is sort of a trade off. If you take speed out the driver will probably drive it harder and the tires may end up wearing more. It is more in the driver’s hands and their approach and which lines they take.

Neff – When you get ready for Darlington you hear about the egg shaped oval but you don’t necessarily hear about the difference in radius of the corners. The banking is about the same however. Does the similar banking alleviate some of the challenge in setting up for the two corners that are so significantly different?

McCall – The way you approach the corners is extremely different. Turn one is a lot of throttle and it basically ends up breaking into two corners. You almost get wide open then have to let out of the throttle and then get wide open again. Three and four is almost a normal corner. You come in, use the brake, roll around and pick the gas up again. The hardest part is to get the handling somewhat similar on both ends. It is easier to fix one end if you can avoid making the other end worse.

Neff – The repave of Darlington wasn’t that long ago but the track is beginning to get some of the character back. Are you able to set the car up close to the ground from the jump or do you have to build in some more play since it has started to regain some character?

McCall – I’d say, for the most part, your wheel rates are still pretty stiff. Aero is still super important. Mechanical grip is still there but if you go full blown mechanical it is not going to work out very well for you in traffic.

Neff – When you look at choosing pit stalls at Darlington, there is a small group of pit stalls on the turn four end of the track before you get to the cross over tunnel. Is it a detriment being down there or is it actually helpful since the pit lane is so difficult to get onto, that you’re already whoa’d down to pull into your pit stall?

McCall – Last year we had decent success pitting down there. The way they have the timing lines now there really isn’t as much of a value trying to jump in and out. They have them so tight, as far as the distance between the lines, most tracks the importance is getting onto and off of pit road and having an opening in or out. If you don’t have that you have to work with the cars around you. You want an opening but if you can’t have that you have to work with your competitors close to you. Now they’ve pretty much eliminated benefits of one end or the other unless it is a two tire call at the end of the race, but there is a slim chance of Darlington being a two tire call.

Neff – With the weather being a factor this weekend and, as you just told me, we’re going to have a reduced schedule, how much more importance does it put on rolling off of the truck with a good balance that is ready to race?

McCall – That is the key for sure. We don’t technically have that many sets of tires to practice with. Especially if we end up still qualifying, so that makes it a little bit of a challenge. So starting close to race ready is super important.

Neff – A general question about the cars we are running this year. With the fact that you’re on bump stops and you are down on the earth almost the whole time, do the rates of the springs matter anymore? Do you even use heavy springs anymore?

McCall – It all works together. It depends on which track and what you’re trying to accomplish with bar twist and bump stop load and that type of stuff. You can run really stiff chassis springs and get almost the same result of running soft springs and bump stops.

Neff – What size sway bars are you running when you roll into Darlington?

McCall – It is all over the board. They rate everything rather than going by size. In a roundabout way you’ll be between an inch and a half and two inches, that’s a pretty standard size bar. They all go by rates now rather than inches. The bar size is a minimal part of it now. You can change the way the bar twists or the synergy works when you set the heights so it is a pretty small part of just that number.

Neff – So they have the science down now to where they can make the bar stiffer or more flexible with the same diameter?

McCall – Correct, it obviously depends on what track you’re at and that type of stuff. You may try and have a more lightweight bar if you have a place where you want to run less nose weight. If you are running a ton of nose weight at a track where it doesn’t really matter you may have a bar with the same rate but it weighs 20 pounds more.

Neff – You mentioned the folks at Hendrick Motorsports have been working on power. Do you feel like you’ve caught up some to the Toyota camp or does the Chevy powerplant still have a ways to go to catch them?

McCall – We’ll find out in Chicago. I don’t believe Toyota has been pushing it. I think they’ve been running about 85% if I was a betting man. We’ll see once the Chase starts how that rolls back around. I feel like HMS is doing a great job and we’re in a good spot but I’m not sure we have a 100% comparison yet.

Neff – On Sunday night, coming to the end and you are looking at a restart with 10 to go thanks to a caution. Are you going to take four tires, two tires or stay out?

McCall – That really depends on how many laps you’ve run, where you are running and how many cars are on the lead lap. There will be a ton of stuff that comes into play to figure that out. If you stay out with 20 laps on your tires I think there will be a huge wreck in turn one. I would say that is a very slim chance unless you have a bunch of followers to help you.

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