Looking back, the build on Jeremy Croiset’s Spec Z seems like it was finished before he had time to enjoy it. It’s kind of like sending your first child off to college, and asking yourself, “Where did the time go?”
When it comes to building a car or raising a kid, the days are long, but the months are short.
NASA’s Director of Sponsorship, Croiset never had the chance to drive the car when it was street legal. As soon as he got it, he began gutting it and preparing it for Spec Z class racing, just in time for a trial race at Southern California’s Auto Club Speedway before making a few tweaks and hauling it —and his Honda Challenge car — to Mansfield, Ohio, for the NASA National Championships.
Just after qualifying that Saturday, Croiset hoisted the car on jack stands in his pits, pulled off the catalytic converters and substituted them with replacement pipes from Berk Technology. The process was fairly straightforward, although it did involve a few ratchet extensions and universal joints. Croiset finished the job and made it to grid in time for qualifying.
“I don’t know the lap time differences between the two, but seat-of-the-pants feel, the car definitely had more oomph,” he said. “It had more go with the test pipes installed. It was 5 mph faster on the banking. It was 145 before and then it was 150. Now, those are indicated speeds, so who really knows what it actually is.
“Then coming out of each corner, the car definitely had a little more grunt,” he added. “It just made the car more fun to drive. It’s always more fun when you have more power, right?”
Spec Z gives NASA members one more spec class to consider. The rules governing the class are fairly well established, although Croiset, who wrote the rules with input from Nissan, said he is considering allowing aftermarket camber adjustment devices to prolong tire life. He also added that building the car himself led him to write a new rule allowing differential coolers. One difference between Spec Z and NASA’s other spec classes is that Nissan’s 350Z is a cut above a momentum car.
“The cars are fast. They’re fun to drive,” he said. “They seem to be fairly reliable, and a lot of that is a testament to the fact that they are so stock.”
There are some rule changes coming that don’t add to the expense of building the car. For example, the shock tower brace at the rear obscures the adjustment knobs for the shocks, so Croiset will issue an update that allows racers to cut a hole in the brace over the shock, which will allow them to make quick adjustments.
He also is going to do some research on ways to remove the heaviest parts of the air conditioning system, such as the compressor, which runs off a serpentine belt that runs everything else. Spec weight with a driver is 3,300 pounds, and his cars tipped the scales at 3,485 pounds. Clearly, he has more work to do. Croiset said you could start with a 2003 or 2004 car, add the cage and the minimum requirements and be on track for $16,000.
“The great thing is once it’s built, it’s built,” he said. “You don’t have to do anything else. There are no rule changes on the horizon, with different suspension kits. There is not going to be a new differential that comes on the market that’s better that you have to upgrade to. They’re all spec parts, so in reality everybody runs the same thing and you just have the cost to build the car and then you just have to maintain it.”
Over the course of the build, Croiset learned a few things that would be good for prospective Spec Z racers to know. For example, the sound-deadening “tar” that Nissan uses in the Z cars is especially gooey and a nuisance if you don’t remove it all before you install the cage, after which it becomes increasingly difficult. Search YouTube for a handy way to use dry ice and hammer for removing tar based sound deadening. A mallet might be a better choice than the claw hammer the guy in the video uses.
Croiset also learned the nuances of installing the Wavetrac torque-biasing differential. Long story short, you need two short-stub axles with flat ends to do the install. Most Z cars equipped with an open differential already have the two short-stub axles.
Long story longer, Cars equipped with a factory viscous limited-slip differential typically have one long-stub and one short-stub axle, so you’ll need to pick one up from Nissan. However, on an undetermined number of cars with factory open differentials, some have “mushroomed” ends, not flat ends, so you’ll need to replace both. Knowing that going in will keep you from feeling lost.
Once you get the car built, NASA, Nissan and BF Goodrich have created contingency programs that should get any racer’s attention.
“The way it’s set up right now, with the contingency available from BF Goodrich and from Nissan, if you win in this class, and you’re running with three or more cars in your region, you basically have no costs to run,” Croiset said. “You’ll get basically a free set of tires from BF Goodrich every single weekend in prize money. You’ll get $500 cash from Nissan every weekend, so that’s pretty cool.”
Once the class gets up and running, there likely will be surge in the use of the Brembo brake packages found on the track-spec Z and the NISMO model. The braking systems consist of four-piston Brembo calipers up front, two-piston models at the rear and uprated rotors. Still, the focus of this spec class will remain on keeping it as affordable a class as it can be, Croiset said.
“Making this series affordable is what attracts potential people to running in the class,” he added.
Just be sure to have your kids college fund squared away first.