The Process, Part 3 the Cage
Are you excited? This is the part where we finally start making something that looks race car-ish. I’m also going to let you buy some things at this point, but still not “go fast” parts. Building the cage is another step where we need to know where we are going. Different classes and different organizations have different regulations with respect to roll cages. Typically your basic minimum roll cage will be compliant across most organizations, however adding on complexity above and beyond the minimum is not always legal. There are what we call cage tie-in points, or just “points.” When you hear someone mention a 6 point cage or an 8 point cage what they are talking about is in how many places the cage is welded to or attached to the original car. The minimum you will find is a 6 point cage this would be two rear down tubes attached at the rear wheel wells usually, two main hoop tubes attached right behind the driver to the floor, and then two down tubes attached to the floor in the front of the car. However, I am not aware of any classes that limit you to only 6 these days, most allow two more attachments from the front down tubes to the firewall area. That would be an 8 point cage. The rules for your class come in when you want to go above and beyond that. Often times people want to go through the firewall to the strut tops to stiffen up the chassis, in many classes this is not allowed, you could spend a lot of money adding in these extra attachment points and at the same time knock yourself out of a class that you want to run in.
Yes, yes, I said I was going to let you spend money on “parts.” Okay, let’s talk about it. You will want to have picked out your race seat before you have the cage built. The reason for this is because often times the cage can intrude on the space you need for you seat, especially in tight cars. Your cage builder needs to know what seat you are going with, and a close approximation of where you will want it mounted. You should also talk to your cage builder about how you will mount the seat itself. More on that shortly. Other parts that would be smart to consider at this time are your harnesses, and any nets that you will run inside the car.
A sparco full containment fiberglass shell racing seat.
Now, let’s talk about safety equipment a little bit. This is no place to cut corners or slash the budget. You can replace a car, but you can not replace a you. I always recommend going with a full containment FIA style seat for a road racing car. And you’ll want the associated seat mounts that go with it. I would also recommend using head containment nets along with your window net. This adds some complexity and expense, but it’s about keeping your head mounted on top of your neck, and your neck in one piece. So you have the FIA seat mounted to the style of bracket it was designed for, and then we add in the head containment nets. THESE NETS SHOULD BE WRAPPED AROUND THE SEAT. It is not useful to have a head containment net that does not fully contact the seat, a net flapping in the breeze mounted in the center of the car touching nothing is not capable of doing it’s job. Read the instructions and follow them.
On this note, let’s talk a little bit about the contrast between what we see in road course racing and what we see in circle-track racing like NASCAR. a NASCAR style seat is a rigidly mounted seat that is attached to the cage in several points, it’s a solid aluminum or carbon composite piece that does not flex or give. They are large, very large, because they have to have multiple inches of energy dissipating foam inside them. Because the seat is so solidly mounted a lot of the crash energy is transferred right into the seat shell, so in order to protect the driver’s body we have to have 4 or 5 inches of foam around the driver. This is not something that can be easily accomplished or even needs to be easily accomplished in most road racing cars. Our crashes are different, very rarely does a road race car hit a solid concrete wall, and if it does it’s rarely at the same speeds that you see in NASCAR. Most of our crashes in road racing will have lots of opportunity to scrub off energy in little bits along the way, rather than one huge whack. The FIA seat and it’s mounts along with the properly installed head containment nets, are designed to flex and move around during a crash. Most of them are flexible carbon or fiberglass, and they are mounted on seat brackets that are designed to deflect and bend so that the energy doesn’t reach the driver’s body. So you want as much empty space around the seat as you can find, and you want to follow the manufacturer’s instructions on seat mounting, do not try to outsmart these guys, and don’t let your circle-track buddy give you a hard time about it, it’s apples and oranges.
Okay, so back to the cage again. We have our seat, and we are going to the cage shop. Talk to your cage builder about how the seat will be mounted. I highly recommend having the cage builder assist in this process. I would remove all the factory seat mounting, podiums and boxes and what not, and build your own mount. I prefer, and I recommend building a little mini cage for the seat mount that exists on it’s own. Plate 4 places along the sides of the seat area, two on the center tunnel and two on the side sill/rocker area. Then between each of those weld in a cross bar that goes from left to right between the pads, and once you have that. Weld on two rails that go fore and aft to those cross bars. This gives you a solid seat mount that is not reliant on a floor pan for structural integrity. I believe this is one of the most overlooked areas in amateur road racing. People mount their seats on garbage. If you absolutely must mount the seat to the floor, please please reinforce the area somehow.
The seat mount in my car, Hector, after I welded it in.
I have built a lot of race cars in my day. I don’t know how many, a bunch, mostly for other people. I have never built a complete cage. I have modified cages when they don’t suit me or a client, but I’m not a cage builder. There is no economy in building one cage for yourself. You will spend so much time trying to figure it out and still probably do a poor job of it, no offense. Have a trusted cage builder do your cage. I know several great cage builders on the east coast. There are three in my immediate area that I trust, and more in the mid atlantic and south east. Plenty of accomplished people who know what they are doing. Don’t try to save money on this, just don’t do it. Budget about $2000-$3500 for yourself and you will get a beautiful, legal, and safe cage that will make you proud when people peer into your car in the paddock. Within that range you can get on the low end your basic minimum requirement MIG welded cage up to on the high end a TIG welded cage with fancy gussets and so on. There is nothing wrong with a MIG welded cage, by the way, most cages are mig welded. It’s not as pretty, but it is perfectly safe.
This is another place where you may want to look around at some cages and see what styles you like and compare what you see with the rules for your class and etc. Most professional racing series allow very complex cages that are tied into multiple points on the chassis and incorporate fancy finish panels, gussets, and lots of dimple die work. Often times most of that stuff will not be legal in an amateur level club racing class. So shop around, but don’t forget to pay attention to what you are allowed.
Top Quality builds always include a nice finish on the interior of the car.
Depending on how busy the cage shop is, and how well you planned your delivery and etc. the car will probably be with the cage builder for a number of weeks. This is the perfect time to get some other work done. Next time we’ll discuss what can be done while the chassis is away at the cage builder.