NASCAR Race Weekend Central

Tech Talk: Talking Rebound & Multi-Zone Camber with Matt McCall

Six races into the season, and the teams are getting their hands around the new aerodynamic package.

Sunday will be the first time it is tested at night. The aged track surface at Texas Motor Speedway, along with multi-zone tires that will wear out quickly, are going to be a stiff challenge for the teams and crew chiefs. Matt McCall, this weeks crew chief in Tech Talk, is going to try and set Jamie McMurray’s car to not only qualify quickly but last throughout the run and be there at the end.

McCall touches on several topics in this week’s Tech Talk. They include rebound built into shocks and how much the drivers have to absorb to keep the car on the ground, camber settings and dynamic adjustments with the multi-zone tire, pit strategy with rapid tire fall-off and the value of the education you can receive at the Kulwicki Motorsports Laboratory at the University of North Carolina Charlotte.

Mike Neff – You started 15th at Martinsville. It looked like you had a car that could contend during the day but ended up a lot further back than you wanted to. How did you see your Martinsville weekend unfold?

Matt McCall – At the start of the race we were just too loose and ended up killing the tires. We got a lap down on that first run that was 90 laps or whatever it was. We were just never able to bounce back and get back on the lead lap. We could drive back up through the field and get to seventh or eighth on the track but we were on the wrong lap. It was not that great of a weekend for that. We were somewhat ok but we weren’t nearly as good as the last race so we’ve got some work to do there for sure. The first run pretty much put a damper on the day for the most part.

Neff – Along those lines, a few fans have commented on the way the end of the race worked out. The cars on the outside line were at such a disadvantage, and that is something we see on a few different tracks. Would you like to see them go back to having the lap down cars on the inside

McCall – It doesn’t really matter to me as long as it is the same for everybody. If they went to the cone it would be interesting. The problem they’d run into is most guys wouldn’t make the decision soon enough and be playing games the whole time. I think it would be cool to see that but I don’t think they’d go that far to use the rule to let the drivers and spotters decide which line they were going to run.

Neff – On pit lane, before the race started, there were a lot of cars whose side skirts were sitting on the ground before they pulled away. We set ride heights wherever we want but are the bump stops so rigid that they won’t flex enough for those skirts to hit the track too hard or do the drivers just have to deal with it until the pressures build up?

McCall – Pretty much, you put new side skirts on to start the race and they always put a little bit to make sure you do grind some off and have the car sealed off as much as possible, even at Martinsville. The low left side air pressure there makes it look even more dramatic sometimes than it really is on the race track, especially when you get going.

Neff – We’re headed off to Texas with the new, low downforce package that we’ve had all year. The difference is we’re running this one at night. Do you feel like running it under the lights will be a different challenge than we’ve had previously this year?

McCall – I would say it is going to be a similar scenario, especially at Texas. Honestly it depends on how the tire turns out. It is a little bit softer tire, with a different construction that is similar to the Las Vegas or Fontana construction.

I don’t think it will be a ton of difference. I think there will be a lot of fall-off and tires are going to be even more important with the night race. There may be a couple of scenarios where, if it is only a six or seven lap run that maybe you could stay out or take two tires to grab yourself some track position. If there is any amount of laps left or there is possibly a long run that will probably bite you in the end. I think there will be some short pitting on green flag stops as well. I believe it will probably migrate to where Atlanta was as far as pitting way earlier than the fuel window.

Neff – We’ve seen that tires are a lot more important this year than they have been for a while. You’ve been around this game for a little bit. Do you like the fact that tires are that important?

McCall – I do, the only thing it takes away is it doesn’t allow you a lot of pit strategy all of the time. Any time you have a ton of tire fall-off it is hard to tell the driver: “Hey man, we’re going to take two tires here to gain some track position but, if you run 30 laps, you aren’t going to be happy with it at all.” For that side it makes it more challenging to make up track position, unless your car is really good and you can just drive through the field. We haven’t seen a ton of that yet. As far as the driver side, I think they like it a decent amount as far as sliding around and moving around more.

Neff – We have the multi-zone tire at Texas. What additional challenges do they present you when you are setting up your car? Does it change camber angles or is it just a matter of adjusting to how the tire reacts on the fly?

McCall – Yeah, I would say it is more of that. Obviously you go by your tire data and any information you’ve gleaned if you done a tire test with a similar tire. Once you get to the track you always seem to get a little different read as far as what camber a tire is asking for. If you have the multi-zone it definitely asks you to look under everything to ensure you haven’t incorrectly made a camber change or other adjustment.

Neff – There is a lot of character coming into Texas. We all know character translates into bumps at least somewhat. We talked about the ride heights at Martinsville. When you are setting up for a track that has serious bumps and you know you’re going to be traveling at the high rates of speed that you know you will be at Texas, do you have to build more travel and rebound into the shocks or do you have it one the earth and tell the driver to grit their teeth and deal with the bumps?

McCall – I’d say for the most part you are pretty rigid. Any time you try and add in some more travel or softer springs, you just get more of a change over the run. We’re so aero dependent that any time you have a big balance shift with the body attitude change due to the rebound it just exaggerates it over the run. It is a fine line there to how stiff you keep the car to make sure it doesn’t change a ton over the run so that the balance stays at least somewhat consistent.

Neff – There were at least some of the teams on pit lane Sunday that are only gluing on four lug nuts at this point, not even bothering with a fifth. If you put a tire on and drop a lug that means you still have to pick it up where if you had a fifth you’d have the spare there. Is it just that much of a time savings during the stop to not even look at a fifth?

McCall – I think it is everyone is practicing with four now. They get used to it, only putting four on and seating four. You see it a lot now where most of the teams are putting the bright decal on one of the holes in the rim to designate which lug they will hit first. I think it is all preference. It seems like everyone has migrated from having five on all of the time because, if you only hit four and the car comes in for the next stop that fifth one might still be hanging on the stud. The subsequent stop it might have caught threads and if they don’t hit that lug the wheel might not come off.

Neff – Texas is still a high speed track even though it is gaining character. When you have tires falling off precipitously, how much of a challenge is it to get into the driver’s head that they have to back off earlier to keep the tires from wearing out thanks to the excessive lateral load on the tires?

McCall – Yeah, for sure, there is a lot more of taking care of it from the start of the run, almost every race now. I think all of the drivers are learning how far to take it. A lot of times, just because you’re driving it harder the lap time might not be improving that much, and you’re abusing your equipment more.

I think that is still a learning process right now, and obviously Texas will be the next big step for that. I’m sure there will be some people who jack rabbit out for five or six laps but, if someone was patient enough to run behind, by lap 30 they may be significantly faster.

Neff – There are a handful of you guys who all went to school at the University of North Carolina Charlotte Motorsports program together. There are certainly many more in the garage who have come through there in subsequent years. How valuable is that program as a pipeline of people flowing into the garage area of NASCAR?

McCall – I think it is really good. I’m old now, it didn’t used to be near as technical as it is now. It has advanced a pretty good ways to allow you to get hands on even while you are in school with some of the teams. I believe they even have some professors that have worked for teams or at least are doing some research with teams. I think it is definitely a window of opportunity to go to school over there and work through that Motorsports Engineering program.

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