Well, having heard nothing from other California builders, I decided to visit Exomotive in Atlanta to see a few cars up close. It was a very rewarding visit. Kevin was very gracious with his time, which gave me the most comfort of all. You may have very different questions about what this kit is all about, but for those who think like I do, this may be helpful. This answers some questions I had prior to ordering a car from Exomotive; I got my answers during a hour-long factory visit.
A little background: I have been in racing for some time, including having made a living as a driver for several years, I wanted to see the build quality and materials used before ordering a car. I have also been involved in building two 24 Hours of Lemons cars recently. Lemons has particularly strict rules for their cages. More strict than SCCA or NASA. On both cars, we overbuilt our cages, even by Lemons standards. So, that may give you some insight to my thinking. I want my good friends and team mates to walk away from a crash. So, we do not skimp on the cages. Added strength is worth the weight penalty (and generally improves handling). That said, we do our cages in mild steel, not chrome moly, which could add additional strength, but also has some downsides.
My overall impression of the chassis is this: if I could change a few things on the car, I would. Nothing major. And I am going to order a car from Exomotive. But in the effort to keeps costs and weight down, which I very much appreciate, Kevin created a car that is really very uniform without options for beefing up various components. Some of those details are important to me. I would be willing to spend more on a chassis that incorporated them. Read this with the understanding that I am picking nits here.
Specifics:
1) I might use thicker-walled tubing in the build. Exomotive builds using 1.75" x .095" DOM tubing for the cage and parts of the chassis. That is fine for a roll cage in most racing series, even for a heavier car. For our BMW 633 Lemons car, which weighs almost 2700 lbs in race trim, .095 would have been fine. We built the cage with .120-wall. There is certainly a weight penalty. For example: 1.75 x .095 is 1.679 lbs/inear foot; 1.75 x .120 is 2.089 lbs/linear foot. We probably used 80” of tubing in our BMW cage. So, that's almost 25% heavier for the 1.75" tubular strictures of the car or cage. Strength of the tubing goes up with increase in both diameter and wall thickness. The 1.75 x .120 is about 20% stronger that .095. (I am not an engineer. Just looking at some online charts.) Overall, I prefer strength over weight savings. I am probably in the minority. The tubing Exomotive uses is very strong. I would prefer a stronger, heavier car over a strong lighter one, especially in the cage—main hoop, front down tubes, dash bar, cross braces, etc. I do think the chassis structures (as opposed to the roll cages components) are fine in 1.75” x .95 DOM. Again, I am not an engineer. Smarter guys than me have worked this out. I am just stating my preferences after a few decades in racing. I’m OK with a little overkill.
2) The bends are not done on a mandrel bender. They are good bends done on a CNC machine. They are uniform and show no signs at all of kinks or pinches. I'd pay extra for a cage done on a mandrel bender. We did not do mandrel bends on our Lemons cars. So, I am certainly comfortable with the bends on our cages. Same with the cages on the Exomotive Exocet. They are good. But comparing the Exocet to our 633 is not a particularly fair comparison. As there is so little around you in the Exocet, I would do everything I could to increase the strength of the cage structures around the driver and passenger. A tubing bender, like that which can be purchased inexpensively at Harbor Freight, flattens the tube ever so slightly at the bend. A flatter bend will give more in a crash than a round, mandrel bend. One way to overcome this is with gussets. I think I will order my car uncoated and add gussets to the main hoop bends.
3) The welding is good but not top notch. I saw where the welder had ground down some welds to make them look a little better. That gives me a little heartburn. Are the welds good enough? Probably; it is impossible to tell unless you watch the welder or cut apart some of his or her work. Grinding down welds suggests a welder is cleaning up a messier weld. It's not the end of the world, but Lemons, for example, strictly prohibits grinding down welds. I asked if I could specify that no welds be ground down. I can and will when I order the car.
4) I fit! I am over 6' with unusually long legs. Kevin at Exomotive is at least an inch taller than me. I was able to fit just fine in a car with a full-containment Kirkey road racing seat. I am almost 60; so, getting in and out required some geriatric gymnastics, but a different seat will make that much easier.
5) The Track version front down tubes leave little room for my left foot. I will probably fashion some sort of dead pedal or order a different version of the car and fashion my own front down tubes.
6) The parts count on the car is much higher than I thought. There are a lot of bungs and tabs that Kevin welds on that I had not been able to see in pictures. He has thought of everything.
7) From a manufacturing standpoint, the car goes together like Legos. See the pictures below. The assembly is made much easier by notches and tabs cut into the tubes. Of course, he also has a jig set up for welding up the car. But it is very cool to see how the component parts fit together. That would be impossible without the very precise CNC bending and cutting processes Kevin prescribes.
Overall, I was very impressed with Kevin and the cars I saw. I want my chassis in yellow with British Racing Green bodywork, please.
Pictures:
This is the table or jig they use to assemble the chassis. You can see in the background the parts racks and bins.
Here you can see a little better how the parts are laid on the table.
This is one of my more interesting discoveries. The slots cut in the tubing for tabs to assemble the chassis.
You can see how precise the cuts are. Slots and tabs are both easy to see in this photo. I thought that was pretty impressive.
