NASCAR Race Weekend Central

Tech Talk: Tire Spring Rates, Five Minute Clocks and Engine Temperatures with Justin Alexander for Michigan

Heading to the Irish Hills of Michigan will test the reflexes of everyone with the fastest racetrack NASCAR competes at during the season. The teams have quite a few different challenges facing them, with the track that is still holding onto the newness of the repave that happened several years ago. In this week’s edition of Tech Talk the crew chief of the No. 3, Justin Alexander, will break down several of the things that are on his mind as he heads to Michigan International Speedway.

Looking back at Watkins Glen, may people were talking about Joey Logano‘s issue and the confusion over the five-minute clock. Alexander explains how most people approach wreck damage on a car. He then gets into Michigan looking at engine and oil cooling, stress on suspension components and spring rates of tires, yaw and its impact on sideforce and downforce along with General Motors hospitality also come up during the conversation.

Mike Neff – This past weekend was a lot of twists and turns both on and off of the track. You seemed to be headed for a great day before a problem that ended up throwing your whole day for a loop. What happened?

Justin Alexander – It was actually in Turn 10, he got in too hard racing at the end on older tires. It was either wreck the car in front of him or wreck himself. He didn’t want to end someone else’s good or bad day or whatever. I think he locked them up and slid through the gravel. That put us a lap down and we kind of just rode there the rest of the day. All-in-all it was just an OK day. We really didn’t have the car, it wasn’t exactly what he needed. We tried some strategy things to get him out front and do some things. He stayed out front for a little bit and then older tires caught up to us so we ended up where we ended up.

Neff – A general question rather than something specific for the No. 3, we saw the problem that Joey Logano had. There was discussion about the communication of the five minute clock. If NASCAR puts you on the five-minute clock, does your official that is covering your pit stall let you know that you’re on the clock or is it up to the team to be aware of the rules and make the judgment that they should be on the clock?

Alexander – Typically, they do let us know we’re on. Really, any time you’re involved in an incident on the racetrack, any type of crash in any form or shape, you can assume you’re on the five-minute clock. The only way you’re not on the clock is if you have pure mechanical damage. I think they were involved in an incident and then had mechanical damage as a result of it. I’m not exactly sure what went on there. Usually, the official will come and tell you that you’re on the clock. He doesn’t always do it. I forget if he does it right away. We usually have one official for every couple of boxes. I believe they get around to tell you, but sometimes they don’t tell you right away. I guess it could be confusing for those guys not really knowing. I always assume we are on the clock until an official says we aren’t.

Neff – Saturday we saw the XFINITY cars with rain tires on. If the opportunity presented itself would you like to see the Cup series utilize rain tires?

Alexander – Yeah, I think it would be fun. I think rain situations make the races that much more interesting and that much more exciting. I know the drivers like to be out there driving on the wet pavement because that isn’t something that they normally get to do. I thought it was a good race, and unfortunately, the caution came out right when they were getting to the part where guys were going to make the decision to go to slicks. That makes it an even more interesting race when guys are on two different types of tires. It was going to be really interesting and then it played out to where it wasn’t as interesting. Definitely, if we ever got the chance to do it I would love to do it.

Neff – Next up is Michigan, arguably the fastest track on the circuit because we don’t run plates there. They repaved the track several years ago and the surface doesn’t really seem to be aging. It has been a very tight groove the last few times there. When we get to Michigan this time will we have two working grooves or will we still be at one-and-a-half?

Alexander – I think you’ll have a couple. This track is still fairly smooth. It is wearing out a little bit, but certainly not as fast as some of the other tracks we see. You’ll definitely see a couple of grooves I think. You may see some guys run way up high by the wall. You’re probably going to get a couple of grooves. Michigan is such a fast place. It should be a decently exciting race.

Neff – We saw transmission coolers on cars this past weekend thanks to the time spent in low gears and the associated higher RPMs. At Michigan, with the high speeds and so much time spent on throttle, do you have to worry about transmission temps just because there isn’t a respite from the high RPMs for very long?

Alexander – No, usually transmission temps aren’t an issue at places like Michigan. You’re really worried about those transmission temps at places where you’re shifting a lot. Road courses, maybe Pocono, or other places that we do shift. Places where we don’t shift we really don’t run into issues there and so we never run coolers.

Neff – On the engine side, when you’re at sustained RPMs for so long, with very little time off of them, is engine cooling a greater concern this weekend than some of the other Intermediate tracks where there is more time off of throttle?

Alexander – I wouldn’t say it is too much different from any Intermediate track where we go. The demands are obviously really high on the engines everywhere we go with the RPMs up. Michigan is a place where we run higher minimum RPMs than we typically do at some of the other places that we go. Certainly you have to run a little more cooling to the radiator and oil cooler to keep everything at operating temperature, so the demand is probably a little higher but we’ll compensate for that with how much tape we will run on the nose.

Neff – You touched on the smoothness of the track earlier. With the kind of speeds that we’re running there you are getting a ton of downforce on these cars. How much strain does that put on your bumpstops and other suspension components with that much pressure on it with such sustained periods throughout the race?

Alexander – Yeah, it is a lot. Michigan is a pretty heavily loaded place, especially with the speeds we’re carrying on entry and even through the center of the corner. Springs, bumpstops, shaft springs, the tires, everything is really heavily loaded at Michigan. You really have to work your suspension around being stiff enough that you don’t bottom out or hit the race track. As you said, Michigan is a smooth place so we can run a little bit stiffer spring or a little bit stiffer shock and it not upset the driver that much as far as mechanical grip goes. It is a little bit of a balance, but we tend to err on the stiffer side for Michigan for sure.

Neff – You did mention tires and with most of your other components you have a controlled environment where those items can be tested out well before they get to the race track and get put on the race car. With the tires, they’re given to you at the track and there is a spring ratio that is supposed to be consistent with the tire. However, they are a hand built tire out of Akron Ohio. How much fluctuation do you tend to get with your sidewall spring rates, from one set to another, with the tires that Goodyear gives to you?

Alexander – Since they are handmade, they are definitely a different spring rate from tire-to-tire. When we get to the racetrack and they give us all of our tires, we go through and measure the circumference of each tire and we put them in sets based on their spring rates. We can kind of control a little bit of how we manage the spring rates, when we put them on and how we put those spring rates together in sets. Definitely little differences from tire-to-tire and from set-to-set that we will have, because they are handmade. We definitely compensate for that and put them in the sets we want to see, based on whether we want to run them for qualifying or whether you want to have a softer rate for a certain part of the race, the first or the last run of the race. It is a variable that we definitely look at we spend a lot of time controlling.

Neff – Does Goodyear let you know the spring rate of the sidewall of each individual tire? Is that something they test before they ship them to the race track?

Alexander – Yes, they come on the tire or with the tire. We do know the spring rate of each one and that helps us put them in sets.

Neff – Dealing with the yaw or attitude of these cars from their midpoint. The rear housing is supposed to be at zero degrees and there are some tolerances involved that can come into play. How much do you try and get rear steer into these cars knowing how long the straightaways and the track in total are to maximize side force?

Alexander – That is certainly something we try and optimize and get as much as we can. Most every track that we run at nowadays we try to get as much rear steer as we can because it helps with sideforce and helps us build more speed into the car itself. We try to get as much as we can here. Michigan is a place where drag and downforce are critical. If you run your car more pitched up in the rear, you’re going to add more drag. Because Michigan is so fast and there is so much throttle time the drag can end up slowing you down if you’re not careful. There is an optimum attitude that you want to run around at. That varies from track-to-track. Michigan is one of those places where you have to keep drag in mind in the back of your head.

Neff – There are a lot of things that go on around the race tracks when the Cup series rolls into town. When we get to Detroit there is a lot of pressure on the teams, especially Ford and Chevrolet. At the same the manufacturers can do some special things for their teams. Does GM and the Chevrolet brand do anything extra special for the bowtie teams when you get to Michigan?

Alexander – GM does some things from time-to-time for us and sometimes when we’re up here they’ll take us and show us around and do some different things. For the most part when we get here, we’re kind of focused on the racing and have very little time to do much anyway. Every once in a while they’ll treat us to something nice, but most of the time it is just getting up here and going racing, and doing our thing on the weekend. It is fun and we appreciate every single thing they do for us. We love being up here and hopefully we can get to Victory Lane for them this weekend.

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About Mike Neff

Mike Neff
What is it that Mike Neff doesn’t do? The writer, radio contributor and racetrack announcer coordinates the site’s local short track coverage, hitting up Saturday Night Specials across the country while tracking the sport’s future racing stars. The writer for our signature Cup post-race column, Thinkin’ Out Loud (Mondays) also sits down with Cup crew chiefs to talk shop every Friday with Tech Talk. Mike announces several shows each year for the Good Guys Rod and Custom Association. He also pops up everywhere from PRN Pit Reporters and the Press Box with Alan Smothers to SIRIUS XM Radio. He has announced at tracks all over the Southeast, starting at Millbridge Speedway. He's also announced at East Lincoln Speedway, Concord Speedway, Tri-County Speedway, Caraway Speedway, and Charlotte Motor Speedway.

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