No time for rest if you're a Penske crew chief.

Although they do not command as much fanfare as their NASCAR counterparts, an IRL IndyCar Series crew chief is just as important to his or her driver as 'Zippy' is to Tony Stewart, or 'Fatback' to Ricky Rudd.

Rick Rinaman and Matt Jonsson are the respective crew chiefs for Marlboro Team Penske teammates Helio Castroneves and Sam Hornish Jr. and this is a typical race weekend from their perspective.

The crew chief's job does not start at the beginning of a race and end when the chequered flag drops. Countless hours are spent planning, studying past results and checking and rechecking each and every part on the racecar to determine its functionality and durability.

In addition, Rinaman and Jonsson orchestrate the effort of their entire pit crew, while at the same time work with team engineers to determine the correct car set-ups for each track and practice session. The Marlboro Team Penske crew chief's main objective is to insure that the racecar and pit crew are always running at their optimal levels.

During a typical race weekend the work begins as soon as the team arrives at the track. On Thursday, it's the crew chiefs' responsibility to make sure the cars get through both their tech and safety inspections smoothly. Once that's accomplished the crew chiefs then insure their respective crews complete the set-ups of the cars, so they can hit the ground running during Friday's practice sessions.

For the rest of the race weekend, Rinaman and Jonsson are hard at work recording each and every change to the car during practice sessions as well as keep in constant communication with their respective engineers so that adjustments can be made quickly and efficiently. After each session, the crew chiefs work to insure changes are made per the engineers' direction.

Typically, Friday is a day for the team to work on its race set-up. At the end of the day, Rinaman and Jonsson oversee the changing of the cars from race set-up to qualifying trim. Once qualifying is over, the cars are switched back to their race set ups and after the final warm-up, both crews perform a "nuts to bolts" inspection of the car to make sure each and every part is up to standard before the race.

Once the car has been prepared for Sunday, the crew chiefs shift their focus to preparing their crews for the race. When the Marlboro Team Penske cars come in for a pit stop, the average fan sees one team working together as a cohesive unit to get the car back out on the track in the most efficient manner possible. What they don't get to see is that the crew chiefs are hard at work laps before the car comes in to make sure each member of his crew knows exactly what to do and when to do it.

Before the Marlboro Team Penske Dallara/Toyota even hits pit lane, the crew is in position and each of them knows exactly what needs to be done. If the engineer has decided to make a change to the car, it is Rinaman or Jonsson's responsibility to prepare their crew and make sure they are ready to make the change. In addition to prepping their respective crews, both crew chiefs also change the right front tyres on the racecar.

"My main job as crew chief is to prepare the pit crew for the upcoming pit stop," said Rinaman. "When you surround yourself with good people, you can depend on them to know their roles and responsibilities during these crucial points in the race. My guys are pros; you don't have to remind them what they're doing and I always have the utmost confidence in their abilities."

Once a pit stop is concluded, the driver has to be released out of the pits. For Castroneves, Rinaman is the one to tell him when it's safe to leave the pit. After Rinaman has changed the front right tyre on the #3 car, he quickly moves into position at the front of Castroneves' car so he can monitor the remainder of the pit stop to make sure that everything goes smoothly and all changes have been made. As soon as the car is ready to go, Rinaman waves him out of his pit box.

In Jonsson's case, he executes his tyre change and oversees the remainder of the stop from the side of the car and Roger Penske calls Sam Hornish Jr. out of his pit box once the stop has been executed and the traffic is clear.

During the race, the crew chiefs are constantly talking to their engineers as well as Tim Cindric (Race strategy for the #3 car) and Roger Penske (Race strategy for the #6 car) to determine what needs to be done to the car, so the team can prepare for the next pit stop.

Once the race is concluded, the Marlboro Team Penske cars are loaded up and brought back to the race shop in Reading, Pennsylvania. After a race weekend, the primary cars are completely disassembled so that each part can be inspected for cracking, wear and tear. It's important to get the car apart efficiently, so that the painters can begin repainting the tub. Since the cars are repainted every two races, it's necessary that they get started quickly, because the process takes a few days and in cases of back-to-back races, extra time is something the Marlboro Team Penske crew does not have.

"You don't want to have a failure, when you take into account all the costs of a simple mistake," says Jonsson. "If something goes wrong during the race that could have been avoided by an inspection, it makes that extra time worth it. It's also important when you think about the fans who've paid good money to see the race and can watch the Marlboro Team Penske cars cross the finish line."

Within 24 hours of the trucks returning, the team has had an opportunity to examine every inch of the car. Each Tuesday after a race, the crew chiefs meet with management, reps from the engine shop, the technology shop and other various departments to go over the problems each team may have encountered during qualifying and on race day, as well as discuss what needs to be done for the next race.

Once the crew gets back the freshly painted tubs, they begin to reassemble the car and make the changes from the previous track set-up to the upcoming track set-up. In the most recent case the cars' Chicago set-up is quickly switched to the one they will use for Fontana. After the cars are prepared for Fontana, they will be loaded onto the transporters and driven out West. Once they arrive at California Speedway, the process will begin all over again.

So, how does one become a crew chief for an IndyCar team? Both Rinaman and Jonsson got to where they are now in a similar fashion.

In 1975, Rinaman started working in racing with his brother in-law, John Caldwell, on Paul Newman's SCCA entry. Rinaman's job with the team at that time was to do whatever was needed, from simply carrying tools to waxing the car. After a couple of years with Paul Newman, Rinaman moved to California with Caldwell to work with Toyota's entry in the IMSA Series. When Toyota moved on to work with Dan Gurney, they took four guys from the previous team with them, one of them being Rinaman.

One year later the team competed in an Indy car race with Jeff Wood at Caesar's Palace in Las Vegas. At the race, Rinaman spoke with personnel from Penske Racing, and he got a call shortly after the race asking if he would like to work with the team.

Because Rinaman had family in Pittsburgh, it was even more of a reason to move to Reading, Pennsylvania and work with Penske Racing. Rinaman started with Penske Racing driving the transporter and doing minor mechanical work. At that time there weren't very many employees, so everyone did whatever they had to, whether it was repairing the car, or driving the transporter to the next destination.

From 1983-1989, Rinaman was a mechanic with the team until being named crew chief in 1989, where he was in charge of Al Unser Sr.'s pit crew. Beginning with the 1990 season, he was the crew chief for Emerson Fittipaldi until 1996; and from 1997 1999 he was Al Unser Jr.'s crew chief. Since 2000, Rinaman has been Castroneves' crew chief. In his tenure as crew chief for Penske Racing, Rinaman's cars have earned three Indianapolis 500 wins, 22 race wins and 24 poles.

Jonsson has always been employed in the racing world. A native of Sweden, he started by helping his brother in go-karts in 1985. In 1994, Jonsson moved to America to work for Bettenhausen Motorsports.

"Once I started working for a smaller team like Bettenhausen, I was constantly looking over the fence to see what Penske was doing, that was where I really wanted to be," remembers Jonsson.

In 1995, he left his job with Bettenhausen to take a chance and send a resume to Penske Racing. The team called him that fall and offered him a job as a mechanic. Jonsson was named crew chief in 2000 and was in charge of Gil de Ferran's pit crew. With de Ferran's retirement at the end of the 2003 season, Jonsson now works with Sam Hornish Jr. In his time as crew chief for Marlboro Team Penske, Jonsson's cars have earned two CART Championships, one Indianapolis 500 victory, ten race wins and fifteen poles.