The Frontstretch: Tech Talk: Darian Grubb Breaks Down Kentucky by Mike Neff -- Thursday June 27, 2013

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Tech Talk: Darian Grubb Breaks Down Kentucky

Mike Neff · Thursday June 27, 2013


Darian Grubb is a Cup Series champion crew chief who has worked at Joe Gibbs Racing with Denny Hamlin for the last year and a half. He was part of the No. 48 team when they won a championship for Hendrick before turning wrenches for Casey Mears and the Tony Stewart. He finished in 6th place in the points with Hamlin last year in their first season together. He now faces the unenviable task of trying to guide his team to three wins and numerous high finishes in order to qualify for one of the two Wild Card slots in the Chase.

Grubb and his No. 11 crew have been searching to regain their victory contending form since Hamlin sustained a broken back at California in the fifth race of the season. Grubb has led the team to two pole positions since the return of Hamlin, but the finishes in the races have been elusive. As Grubb tries to turn the corner and put his team on the kind of meteoric rise it will need to make the Chase and then contend for the title he took a few minutes to talk with Frontstretch about last weekend at Sonoma and this coming weekend at Kentucky, along with testing and the logistics of moving teams and equipment around the country.

Darian Grubb will be trying to steer the No. 11 Toyota and Denny Hamlin back into Chase contention, beginning with this Saturday night’s intermediate track race out in Kentucky.

Mike Neff: Just got back from Sonoma and the twists and turns of the road course. How do you think your sojourn to the wine country worked out?

Darian Grubb: It is one of those things. We had a decent car. I think we could have finished somewhere between fifth and tenth. We didn’t have a winning car I don’t think. We just left with frustration. You get bumped and spun out into the grass and you spend all day trying to make it back and you never get the finish you want.

Neff: Saw that a fire actually started after you guys spun into the grass. Assuming that comes from the heat that is generated by the headers and it caught the grass on fire once you ended up out there.

Grubb: It was actually from when the car stalled. When he restarted the car it blew a large flame out the exhaust pipe and caught the grass on fire. Everything out there is so dry that it ignited immediately. I feel bad about that but it did bring out the caution which allowed us to get caught up there.

Neff: Every time we go to a road course we hear about the dreaded wheel hop. In the grand scheme of braking with a 3,400 pound stock car that is going over 100 miles per hour, Is there anything that could be done with the brake system like an anti-lock braking system or is that against the rules and would it actually work if they did it?

Grubb: It is not allowed by the rules and we would love to have some technology like that. Everyone drives with something like that in their street car every day. However, this is a performance business so we have to try and do everything we can to get around that. You don’t have the ability to do it so, most of the wheel hop comes from the setup parameters that we have in the car to try maximize forward drive which is a big issue at Sonoma. The tire life there is not the best so we struggle for grip which means drive off of the corners is at slow speed. So, you end up running truck arm geometries and rear springs that actually aggravate the wheel hop conditions so it is kind of playing the best of both worlds to get the best braking and the best drive off that you can get.

Neff: We’re heading off to the bluegrass state of Kentucky. The track is known for being a little bumpy and it is old enough to be well aged. Are we running the same tires we have the last couple of years since we’ve been doing there?

Grubb: It is a different left side but everything else is pretty similar. It isn’t a drastic change, just a small change, so I don’t think it will make much of a difference.

Neff: The character of Kentucky, and everyone knowing it is a bumpy track, are you able to go into the track with the new car traveling a lot more in anticipation of the bumps and knowing the new car likes that or do you have to kind of suck up the bumps a little bit to get more speed?

Grubb: We’re not really sure until we get there. We’re looking forward to learning that. The car acts a little different at every track we have been to so far. Just because of the bumps and the aero platform, I think you’re going to see a lot of differences between the single car runs in practice and qualifying and what you’ll see in the race. We’re just trying to keep building the notebook of everything we THINK we’re learning and we hope we’re hitting on some trends. We haven’t had the performance as the 11 team that we’ve wanted over the last few weeks but we do think, in most aspects, we’ve learned why and we hope to get back on the right track this weekend.

Neff: The Kentucky race is at night again this week That will obviously cause the track to be cooler. Does the track temperature affect shocks and springs as much as it does tires?

Grubb: I say it does a little bit just because you’re having to maximize grip a little bit more because the track is going to be hot and slick. Then, when you go back in the evening, tire wear is still going to be a big factor either way, just because of the track abrasiveness and the old asphalt. The grippy shocks you end up with during the day typically will just add that much more grip at night. Then you have more grip in the tire because the track surface isn’t so slick. You have to kind of play the game a little bit and learn a few things. Make sure your ride quality is good and make sure you aren’t abusing those tires and hopefully all of those things will just get better at night when you gain more grip and get more speed out of it.

Neff: Curious on the shock side of things. There is oil or some other kind of fluid inside of a shock. Obviously it is close to the brakes and tires, so there is heat that gets in there. Does the heat that transfers into the shock have an impact on the rebound or overall performance on the car?

Grubb: It really does. That is something that I think we do a really good job of predicting. A lot of the testing we do we actually pre-heat the shocks. As soon as you put those shocks on your dyno or on the car and go out there and beat them up a little bit they create a lot of heat. That is how they disipate the energy, they create heat in themselves and you have to disipate that heat somehow. The bumping curve and the rebound curves do change a little bit as the viscosity of the oil changes from the temperature and the brakes do transfer a lot of heat. They’re really close to the headers and a lot of that stuff does transfer. So you’re trying to keep the heat out of them and keep consistency so that you know from the start to the finish what you have as a cool shock and a hot shock the better you can set your car up.

Neff: NASCAR loosened up the testing rules this year. How much testing have you done so far?

Grubb: We’ve actually done none. We’re going to our first test as Joe Gibbs Racing organization on Monday at Indianapolis Motor Speedway. We’re going to come home for Sunday with family and then head up to do a Monday-Tuesday :test at Indy before we head off to Daytona.

Neff: Curious on the logistics of tests like that or even coming home from California to go to Kentucky. Loading up Trucks and things like that, do y’all have spare haulers? Do you just have everything lined up at the shop and when the hauler rolls in you just swarm over it and change it out? How does the logistics of swapping from one race to another or one test to another when there is such a tight time constraint.

Grubb: It is interesting because we really don’t have a lot of the equipment sitting around. Especially after we didn’t have the testing for several years, so it is hard to keep all of that equipment sitting around in your shop , making no money for you. So a lot of those things got sold off through a lot of the teams. Now you’re doing it with a lot less equipment. Now that the series has opened testing up you need to reacquire some of that equipment and use some of our four car test haulers and things for hauling equipment back and forth. It is honestly one of the reasons we’re doing the testing on Monday and Tuesday at Indianapolis, that way we have Wednesday to get the truck back hone and get the truck cleaned out and get it down to Daytona for parking Thursday morning. Just because we don’t have enough equipment to have extra trucks and transporters sitting around to do a Tuesday-Wednesday test like we’d normally like to do it. All those trucks have to go straight from Kentucky to Indy. The test trucks will meet them there. We’ll do a swap out and they’ll haul the race cars and backup cars back home from Kentucky. They’ll leave the test cars up there. Then they’ll be back in full process again Wednesday morning. We’ll wait for the truck to be at Joe Gibbs’, we’ll meet them here on Wednesday, do a swap out of all of the speedway stuff to go to Daytona on Wednesday afternoon.

Neff: I believe this is the first time I’ve talked to you since Denny had his back issue. Have you had to do any extra modification to his seat or add additional padding or is it just the way it started?

Grubb: Everything is where it was when he started the year. We haven’t really changed anything. We’re working on some areas with the seatbelts and things like that, just trying to figure out ways to increase safety. Things that utilize the new technology that is coming out there so that we can make things better and try them out. Other than that, we’re in development mode and his master is DEVO.

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