tube80z

Another idea depending on the rules would be to vent the inner fenders and put some large section screen on the holes so rocks don't get stuck on top of the manifold. Usually the wheel wells are low pressure and should help manage the radiator air. Spats or sides to the airdam will also create more low pressure. Done right this will reduce the lift and make the car faster in a straight line. if you stand in front of the car you shouldn't see any of the tire tread area. If you do it needs to be covered.

The cage was 1.5 x 0.125 for the main safety sections spelled out in the GCR. The extra bits were a mix of 0.095 and 0.065 that provided added bracing. I added 1" x 0.49 bracing in multiple areas to stop bending I found when doing some torsional and bending tests on the unibody. I personally think the car was so light as the shell was an early S30 and seemed to have thinner sheet metal in some areas compared to the later cars. The cage tied into all the normal suspension points and had a center section similar to Jon's V8 car where a tube ran down the middle connecting the front A-pillar cross bar with the rear diagonal. The strut towers had bracing that formed a Y structure front and rear that were connected into this. There were some other odd braces that looked Nascar inspired that I had thought about removing to add a passenger seat. This cage was scary and I was shocked that it ever passed tech at the hillclimb events. I found that the underside welds of most of the cage tubes were just bondo sanded over to look a weld. My guess is the PO couldn't weld upside down. I removed all this crap and completely welded around the tubes. In many areas I also added additional connections to the unibody. These all added weight but probably less than 5 pounds in total. Not on this car. That was an area of potential improvement. My V8 car has a setup somewhat like Jon's but I'm running a dry sump on the LS and mushroom flywheel. The ring gear mounts to the back of my clutch. This is a 7.25 unit and all this weighs around 13 pounds complete. I have a low ground clearance bellhousing so I can drop all this down (~3 inches lower) to the point where the transmission case is the low point. A fried has run the 5.5 clutch on an EP car and moved to a 4.75 unit. The downside of all that is you have to run the stock size ring gear. It is pretty cool hearing the motor rev like a superbike. The wheels were Diamond and Aero mini-stock wheels. They are a lighter weight steel wheel. They aren't very strong and are designed to fold up if hit too hard. They are one step above junk really. I only went this route as I was unsure about what diameter I would want to run. Most of the GT tires were 16s. At the time there was a glut of the 13 FA tires on the used market so I went this route being cheap. There was more laptime to find with a better wheel/tire combo. The Hoosier's at the time use a really light Kevlar belt construction. The sidewalls were very flimsy and made using a manual changer a breeze. The GY FA tires were more of a true radial and had steel belts and substantial sidewalls. They weighed more and were definitely faster. They ended development on these and for a long time they were not available. Avon seems to be the only valid player for the bias ply slicks. I think Hoosier still makes a semi-redial tire but I doubt it's using their latest tire technology. That seems to mostly happen in 17s and 18s. I'd never run 13s on a track. While they are light you're not going to see huge gains from this. The larger tires have a smaller tread to road approach angle and this seems key to having better grip. Assuming everything else is the same. I think for EP you're going to be limited to the cantilevered slicks unless they rules have been relaxed. At the time a new set were about $1200 new. I bought used for $50 to $80 a tire depending on how good they were.

For hillclimbs my car weighed 1850 with 5 gallons of fuel in 10 gallon cell. Car had a basic fire system and extensive cage (12+ points). The shell was an early 240 with nothing in it that wasn't required by the rules. It came from Montana and had been stolen and set on fire. Custom fiberglass doors and stock hinges (heavy), one piece FG front end (JC Whitney), and the rear hatch was a FG skin bonded into the car (total pain in the butt). All glass (windshield and hatch) were eighth inch Lexan. Engine was an old EP motor with the weirdest cam I have ever seen. Engine was equipped with dual modified SU carbs, a Stahl style header, and a short exhaust that ended just behind the driver (yes it sucked). Engine was a 2.8 all balanced with a 6 pound flywheel and stock type clutch and connected to 4-speed running a stock style driveshaft. This hooked up to a R200 LSD using stock style half-shafts. The car had a run-flat electrical system after my alternator sheared off at a hillclimb. I ended up using the battery from my trailer's winch and that was a very heavy (~60 pounds) marine deep-cycle optima. It was setup so I could quickly remove it and stick it back on the winch. A lot of people have told me that it is impossible to be that light. Where the magic was (not much) in this car was the wheels, tires, and brakes. Tires were from a Formula Atlantic and Kevlar belted, and had 13x10 wheels up front and 13x12 in the back. The brakes were 10.325 vented front rotors with Wildwood 4-piston dynalites in the front and 10.25 rear rotor with 2-piston dynalite calipers. Just changing to GY tires would add almost 40 pounds to the weight (steel belts versus Kevlar). But they GY tires were faster by almost a second on a 46-second lap of the local track. Few people pay close attention to what tire/wheel/brake weight adds to a car and it can really add up. I never set out to try and build a super-light car and figured it was in the 2 to 2.2K that most of these cars were. So I was rather shocked when we weighed it a buddies who had scales. Getting this car into the 1700s would have been possible with normal parts that are available now. But it would have been expensive to go much beyond that. My easiest area of weight loss would have 7.25 dual disc rally clutch and a lithium battery. Those two items alone would have allowed me to save about 50 pounds of weight. The other easy thing to do would have been to remount the cell so the sump was at the back and could run a gallon or two of gas instead of needing to be almost full. From there it gets really expensive really quickly to shed weight. Carbon parts, lighter versions of everything, etc. I'm sorry but that Porsche in the video seems scary, especially looking at the seats.

In response to the Coleman rack I'll add that they are heavy, need to be greased often, rely on small friction surfaces to keep play down, and if you're using hydraulic steering the servo lacks feel. I have seen a bunch of them with bent racks that are often felt as a stickiness in the steering. I got two of them used and had to do a bunch of press work to get them straight. One was listed as bent so I knew that but was surprised that the "good" one also had a smaller bend in the rack housing. Perhaps Coleman has fixed all this and they are somewhat decent these days. I think they are great for dirt cars but I'd prefer one that has proper seals on the rack and had a better system to take up any play between the rack and housing. Cary

Those Coleman racks are not very nice. They are a cheap dirt car setup meant for serious abuse. Do yourself a favor and buy a Woodward steering rack. They will custom build to your specs or you can use one of many pre-built setups. If you're not using electric power steering their servo allows you to change the force level of the assist but doesn't have any production car damping. Jon went this route on his car. Awesome news on the Bosch motorsports ABS. Totally jealous of that purchase.

I've seen some Porsche cup cars that use a booster and a dual master bracket that bolts to it. John Coffey used to sell a setup like this years ago but I seem to recall that he deleted the booster. The downside to this is it takes up additional space in the engine bay. For my street car I'm looking at using the Bosch i-booster, which uses an electric motor rather a vacuum assisted booster. Here's a video from Bosch, These are used on Teslas, which is where I first saw them. The good news is they are on many new cars and fairly cheap on ebay. And don't worry about sensors as this will run in limp home mode and act like normal vacuum assisted brakes. The good news is these come on a lot of cars that have cheaper parts then a Tesla (Honda, Toyota, etc.) In this video jump to it shows the wiring setup and some cheaper alternatives, Hope this helps, Cary

Have you looked at other ratios for the 8.8 that are not mustangs? "2.47 is 83-86 f150 and 2.26 is 79-81 ford Lincoln mercury passenger cars." I have not verified this but did see what looked like 2.47 gears for sale on a few sites.

How is pulling a transmission with that setup? I know that may seem like a stupid comment but I also like to think about how hard it is to do basic maintenance items and changing the transmission clutch and pulling the motor are on my list. Cary

Personally I think ARBs are just as useful to road racing as they are to autox. I know a lot of people like to argue that point but they are a tool help with setup. I can tell from my hillclimbing days that my car was easier/nicer to drive when using ARBs to balance the fast corners. You can spring the car stiff enough to not need them but if you don't have a really smooth course it will not put power down as well and the car will have a lot more of a snappy feel when loaded up and ride over bumps. In the end it's all down to how you like the car to feel and what makes you confident in how the car behaves. If you have no confidence and feel is crap it doesn't matter how fast XYZ driver is with a similar setup. What I learned about the splined bars is that you need to rate test them about 3 times before they will read the same. If a bar is used then it will probably do this. I bought some from Roush years ago that were supposed to be used and came in new packaging. You can rate test them on the car locking the other opposite side at level ride height and then handing weights from the spindle or weld a hook to an old steel wheel and bolt that on to simulate the best experience and then hang weights from a chain and use a laser level on the wall or piece of plywood or similar. Your just looking for what happens hole to hole. And you can run both sides in different holes to split the rate (most people forget this). The advantage to this method is you will know what the installed rate at the wheel is. That's what you need for all the spreadsheets that calculate wheel loads. You might as well make some droop limiters too while you are there. If you add a forward facing arm you can build a stop using a pivoting foot bolt (https://www.mcmaster.com/leveling-pads/). Or use the arm side and capture how far it can extend. Just make sure there's enough clearance for the wheel/tire combo. Hope that helps, Cary

Don't forget ebay for these too. You can search for NASCAR sway bar and find lots of options. Ideally you test these as they often take a different rate after being used a few times. I wasn't aware of this until I saw it in a youtube video explaining how to use bars with bump rubbers. You can also look at some of the big race teams for used parts. Really high end stuff for pennies on the dollar.

SuperDan has now fixed this. It was a problem with an expired certificate. Nothing malicious. Cary

The one thing I would add is a pin in the middle. Unless you are doing a lot of work to close up the front end and exhaust the pressure. I have may pictures taken over the years with various Zs that have the center of the hood bulged up looking like a guppy. Love watching the progress, Cary

I'd personally do plywood until you get the design all figured out. It's cheap and easy to work with. When you want to go all out you can route out big sections and use foam to fill them in. Then put some Kevlar on the bottom and some carbon or s-glass on the top and you'll have a very strong splitter. For the splitter frame make it adjustable and sprung so it can move up if the car gets too low. I see a lot of solid mounted splitters that people grind off. Done right you can make this a performance adjustment but that may get you in trouble with the rules. Leading edge treatment (flexible skirt or radius) depend a lot on what the rest of the car has going on underneath. If you have mostly a flat floor and not anything hanging down to act as a sail them you want air to go under the splitter. This helps to reduce pressure and leads to higher downforce numbers. If you don't have a flat floor or there's a lot of stuff to catch the air then you are better off blocking it off and using the edge like in Greg's pic above. Either way seal off as much as you can under the car and back to the wheel center line. And if you can exhaust the radiator into the fenders (assuming you can do hood vents) and add some s-flaps that are adjustable. Hope that helps, Cary

You're welcome. I'm learning lots from your build too. Every time I build anything I always find a better way to build it and make it lighter next time. I love watching the progress. I still come to see what people are doing and what the latest things people have found on newer cars and to keep the Zs going better than ever. My latest find is the Bosch i-brake system. Electronic brake booster rather than needing any vacuum. More later on that. Keep up the good work, cary

Unless there are some missing tubes a strut tower brace is still going to help. On my old car I had the cage tied in similar to this and did some push/pull testing using a hydraulic ram and found the towers would still move. It will be a lot less but they will still move. And I could tell when it wasn't attached, as the car seemed a little slower to respond. I don't know if historic or SCCA EP will let you do this but if you reinforce the top of the tower and connect it to the vertical you'll lose another area of movement. Another way would be to use a thicker camber plate top plot that's connected to your vertical tube. If you are going to use spacers for bumpsteer that are longer than an inch on the steering arrm, I'd recommend TIGing the largest spacer to the arm. As stupid as that sounds it makes a difference. If you bend the arm down then you probably don't need to worry about it. Cary