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Modified Masterpiece

HOLY JEEPERS.”

That’s the phrase Ron Ver Mulm uses to describe the acceleration of his SCCA E Modified Chevrolet Camaro autocrosser.

The fact that he says it in a delicate, polite Midwestern accent completely belies the weapons-grade ferocity of this single-purpose automobile. But when we give you some of the objective numbers, you realize that no amount of filthy language could possibly do justice to this automobile’s insane performance.

“We’ve measured 1.8 to 1.9 sustained lateral gs, 1.6g braking, and”–wait for it–“1.7 gs for eight-tenths of a second in sustained acceleration.” Those are numbers usually endured by rookie Air Force recruits thrown into some sort of plane crash simulator, but Ron and his wife, Sonya, strap themselves into this rocket voluntarily.

Iowa residents Ron and Sonya are regulars on the Midwest autocross circuit, and they’ve spent almost two decades campaigning a Camaro in the already heavily modified C Prepared class. “But there were a lot of things that we were solving with Band-Aids, and we kind of wanted to take it to the next level,” says Ron. Don’t let the modest tone fool you: Ron’s idea of “next level” is several levels beyond what the typical car owner envisions.

Purpose-Built Performer

“We started with a clean sheet of paper,” Ron explains. “I had all sorts of files with examples of GT1 cars and various race cars that I drew inspiration from, but mostly this is a clean-sheet design.”

The E Modified class is for heavily modified production-based cars or tubeframe silhouette copies of production cars. Those purpose-built machines take a scant 50-pound weight penalty over their production-based counterparts.

“With a GT1 car, the priorities are safety, crash resistance, durability, stiffness and performance, basically in that order,” says Ron. “But with an autocross car, I could reverse that 180 degrees and concentrate on stiffness and performance along with low weight and not have to worry about crumple zones or impact.”

Behind the Curtain

There’s not a single piece of Camaro chassis anywhere in this car, although the dimensions have to meet certain Camarobased standards. That gorgeous fiberglass shell, a replica of a 1970 body, came from a vintage racer who intended to use it in an old IMSA car restoration. However, he went with a reproduction made from his car’s original metal instead. So Ron took the body back to Iowa and set about designing a chassis that would support it.

The most noticeable feature of this Camaro isn’t really noticeable until you peel away that skin. The beating V8 heart, much like the heart in your own body, is offset significantly to one side. The entire engine also lies quite a bit behind the front axle, although still ahead of the midpoint between the front and rear axle line as prescribed by the rules. Still, it sits closer to where a passenger would than it does to its original location.

This placement required a custom-fabricated rear end, offsetting the differential severely to the right. “The driveshafts are something like 16 inches on one side and 34 inches on the other side,” Ron figures. But thanks to the three-link arrangement’s carefully placed forward-connected suspension links, the offset doesn’t place any unusual torque strain on the chassis.

Indeed, one of the areas where the car truly excels, according to Ron, is powering through and out of corners.

“Packaging was a huge consideration in this car,” says Ron. “The only major component that lies outside the wheelbase is the radiator.” The view with the skin off shows most of the large and heavy components situated in or around what would normally be the passenger compartment of this pseudo-Camaro.

“Center of gravity is much lower compared to the CP car. The roll centers are very low, and the polar moment is obviously very low as well,” Ron says. “I’d like to get the engine even further back, but according to drawings, that would run the headers right through the steering wheel.” He chuckles, adding, “So we probably couldn’t do that very well.”

Although he drew some inspiration from more mass-produced GT-style cars, this Camaro truly was an original build. “I taught myself SolidWorks and designed the car in that,” says Ron, with all of the casualness of somebody mentioning what they made themselves for breakfast.

When we pointed out that one does not simply teach himself SolidWorks, Ron clarified, “Well, it took me seven months. I watched a lot of YouTube videos.” When pressed further on how he managed to master such a complex program and design such a complex piece of machinery in such a relatively short amount of time–all with self-training–Ron offered, “I’m a nerd.” Maybe so, but he’s a nerd with a Camaro that all the jocks would envy.

Ron did encounter a few challenges with his design’s extremely low center of gravity. For example, because of the engine’s low placement, he had to cut off a portion of the transmission bell housing so it would properly clear the ground. This also necessitated a “low ground clearance” clutch–basically a very small-diameter, multi-plate unit that feeds power from the engine to the two-speed transmission. Again, to keep the package small and the rotating mass compact, Ron used the third and fourth gear cogs instead of the larger first and second ones. This required the use of an extremely low 7.33:1 rear end.

Great Expectations

Now in the car’s second full year of competition, sorting has gone pretty well. “Out of the box it was basically what we expected it to be. The brake system had to be completely redone, though,” Ron recalls. “We basically swapped over from the CP car, and it didn’t work at all. We were getting all sorts of brake hop, uneven lockup. We just ended up replacing nearly everything except for the front rotors.”

Aside from that, sorting has mostly been a matter of dialing in the suspension to get the most out of the computer-designed chassis. This mostly involved switching to stiffer and stiffer springs until Ron found a package that was amenable to the extremely stiff chassis.

“I’m also having to recalibrate my driving, as I’m having trouble with corner entry at this point,” Ron admits. “That’s personally, not so much the car. It just gets from corner to corner so quickly. We’ll exit a corner at 30 mph, and in less than a second we can be hitting nearly 70 mph. That takes a whole different mindset.”

Still, our guess is that Ron and Sonya are in this Camaro for the long haul. They spent nearly two decades in C Prepared, where their other car earned them a wall full of national trophies and two championships.

“Ultimately I’d like to see this car have some success,” says Ron. “On paper it really appears to have what it takes to compete, even though E Modified is populated with lots of very small cars. [The Camaro is] physically a lot bigger and quite a bit over the minimum weight, but on paper there should be some situations where we can compete favorably.”

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Comments

View comments on the GRM forums
Rubens
Rubens New Reader
2/19/16 1:54 p.m.

I wish I could see more photos of the engine set up. That is totally new to me.

HunterJP
HunterJP HalfDork
2/19/16 2:15 p.m.

Ron and Sonya are, simply put, amazingly awesome people. This car build is simply an external, material expression of that awesomeness.

Ed Higginbotham
Ed Higginbotham Editorial Assistant
2/19/16 2:40 p.m.

In reply to Rubens :

Here's a shot of the bottom if that helps any.

cmcgregor
cmcgregor Reader
2/19/16 2:41 p.m.

That thing is bananas.

In a good way, of course.

Rubens
Rubens New Reader
2/22/16 9:52 p.m.

In reply to Ed Higginbotham :

Thanks a lot. The pic does help to understand the whole set up a little better. Amazing idea to bring the power train in between the axles... But how is the lateral weight distribution? Isn't the car way heavier on the right side?

Fueled by Caffeine
Fueled by Caffeine MegaDork
2/22/16 10:08 p.m.

Mental in every possible way.

OHSCrifle
OHSCrifle HalfDork
2/25/16 5:34 p.m.

looks like Loosecannon's MGB - and damn impressive.

Keith Tanner
Keith Tanner MegaDork
2/25/16 5:46 p.m.

He's totally destroyed the spirit of the Camaro. It's not meant to be an autocrosser, or have the engine beside the driver. The car is ruined.

bentwrench
bentwrench Dork
2/25/16 8:57 p.m.

Look how long the front control arms are!

84FSP
84FSP HalfDork
2/26/16 3:28 p.m.

That thing is a pure beast. Awesome smells of smoking hoosiers and race fuel.

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