Jimmy Fennig tells the story of race car ingenuity

Mark Martin and Jimmy Fennig created cars with trick suspensions and trick bodies to outsmart the officials and the competition

Race car engineering. Back in the day racers would try anything to get a leg up on the other guy. It was part of racing and always will be.

That stuff is still here today. It’s just highly regulated. The box is smaller and it’s rare to see large advancements like the one’s here.

Mark Martin and Jimmy Fennig worked together long before they reached the cup level. In 1985, Fennig left the NASCAR Cup Series to become the crew chief for Mark Mark at the ASA level.

The next year, they both rose to the NASCAR Cup Series, together. The following year they seperated until they were re-united in 1997, winning 14 races.

“I’ll never forget the story at the Minnesota State Fair,” Jimmy Fennig opens the story via the Mark Martin Podcast.”We had a little rain delay. And we had a little trick in our car. We’d bounce it — More or less illegal.”

“We’re sittin’ there and they got a little rain delay. We’re parked down in turn 1 and old Ed Howe, he come looking up there. He couldn’t figure out how our splitter or valence [was sitting so close to the race track].”

“He went home scratching his head. He could never figure it out.”

“It was two pieces of conduit basically.”

Mark Martin: “So cool. We’d push it through tech with that conduit in the front end. Then, once you got passed tech you’d just kinda bounce it a little bit. That conduit would fall out and that thing would sit right.”

Jimmy Fennig: “Yeah. That thing was perfect. And they guys right behind it that were pushin’… They’d drop their rags right on top of the conduit. We had it timed perfect. Pick it up, away we go.”

“But, we’re not the only one’s like that. That’s racing.”

Martin: “Yeah. We were havin’ to race against people like that.”

Mark Martin 1984 - Michigan International Speedway - ASA
Mark Martin 1984 – Michigan International Speedway – ASA


The stories could go on forever. One year, Five Star came out with a spec body. It’s similar to what the NASCAR Xfinity Series has currently. The only difference is it didn’t have the honeycomb security stamps. That left a window of opportunity for a way around that rule book.

“I just don’t want to say we’re cheaters all the time,” Fennig says before telling part two of the story.

Martin: “Yeah. But, this is the good stuff.”

Fennig: “Anyway, at Anderson, we went and qualified. All the cars got done with qualifying. We backed up.”

“Our spoiler — Bob Senneker’s car is parked behind us. He’s running a Ford. We’re running a Ford. Our spoiler ended up being about 2 inches higher than his. They finally figured out — We cut it, re-glassed it and re-stickered it.”

With a spec body, everyone is suppose to be running the exact same stuff. There’s was modified slightly and made to appear like the original. The spoiler was the giveaway.

“Stuff like that — I mean, that was racin’ back then. We had some great times.”

Mark Martin and Bob Senneker
Mark Martin and Bob Senneker (ASA)


“Bob Senneker used to have like a 3-link with a leaf spring. Me, Mark and my brother that was working for us. Day and night we worked on the race car in the shop.”

“We were trying to copy what he had because he would always kick our tail. We’d go to Michigan. Whenever the track would lose tires, he would always keep running.”

“We tried copying it. When Mark gets in the car in the garage, we’re all excited. We got this thing figured out!”

“He drives out of the garage, turns left and the rear tire just drove right into the battery. Killed everything.”

“We had to go back conventional. But, we kept working on it. But, we beat him sometimes. There’s a lot of stories like that. It was fun back then.”

NASCAR inspection tent
NASCAR inspection tent

These stories still exist. It’s just on a much smaller scale because the cars are tech’d to a much higher degree. Chase Elliott’s team installed tape on the rear spoiler for more downforce. Kevin Harvick might or might not have allowed his roof to collapse on purpose.

Martin: “You were just trying to figure something out. That’s the thing with the competition today in NASCAR. You’re in such a tight box.”

“I talk about this all the time. Dave Watson, he was ASA champion in 1977. Then, he built a Cup car up there in Wisconsin. He took it down and raced some NASCAR races with it.”

“You can’t do that now. I don’t see how you could build a Cup car without a Hawkeye to look at it. Every thing has to be so precise. It’s amazing.

The Hawkeye system has removed a lot of the ingenuity. It’s the black tent also known as the ‘room of doom’. NASCAR rolls the cars through the tent before they hit the track.

It’s an optical computer scan. It gives a printout of every point on the race car body. It measures the positive and negative of the body tolerances. NASCAR allows .150 in either direction.

But, the teams are now multi-million dollar corporations and they’re trying harder than ever to find an advantage.

Jimmy: “Yeah. You come up there. You hit it, you look at it and it’s green. If you got red spots, that means you’re over the .150 [tolerance}. NASCAR makes you fix it.”

“But, that’s what NASCAR’s gotta do nowadays. Now, we’re looking at how to beat Hawkeye. The guy next door’s looking at how to beat Hawkeye.”

“It’s a tool NASCAR’s gotta police to keep the competition together. But, in this business, everybody tries to see how they can beat NASCAR. Whether it’s anything, tires.”

“In ’98, they’d stick pins in sidewalls. Cause bleeders are illegal in NASCAR. So, they’d have pins in them. We got beat by that a couple times.”

“Right now, NASCAR’s got it pretty tight on building these cars. Jack [Roush] bought a Hawkeye. They’re not cheap. But, we take advantages of all the tolerances. We’re right there. Without that tool, some guys wouldn’t be able to do that.”

Jimmy Fennig retired from the NASCAR crew chief role in 2014. He still works at Roush Fenway Racing to this day.

Jimmy Fennig
Jimmy Fennig

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