tube80z

My car is very neutral. I can set it up too neutral (note not loose) but I prefer to drive off the front end. It is really setup to change direction extremely quickly and this along with being able to put power down under cornering is why it was as fast as it was. This setup does require experience and commitment. You've got to be very careful when the back steps out. I'd almost say you need to learn to simply drive through it because if you try and steer into the slide the car will often over correct and pitch you off. Basic info. class SCCA FP using GT-2 allowance (engine setback) weight 200 pounds under class minimum with no ballast (ballasted to 2% rear heavy and almost perfect corner weights) approximately 200 WHP ride height at class rule minium track at class rule max tires: Formula atlantic front and rear (13 inch) 1.4 to 1.5 lateral Gs 1.1 to 1.2 under braking Approximately 2.5 seconds faster than a ZO-6 vette on a 49 second course (Fall enduro in Medford) Hope that helps, Cary

The setup is arrived at a completely different way really. What I now do is weigh the car ready to go to get the wheel loads and the front and rear percentages. Then I plug this into a spreadsheet that has the all the basic parameters to compute weight transfer (CG, RC, track width, camber, etc.) and use this to solve for front and rear roll angles as well as the percent of weight transfer at the front, which is referred to as a magic number. I pick equal roll angles because I'm trying to keep from loading the chassis in torsion as much as possible, which is a trick you can use when you don't have a stiff car. Then I set the front load transfer (note the terminology change -- what I'm saying is the percent of load dealt with by the springs, bars, RC) to be around 3.8 percent of the total weight transfer. What this means is I've used a systematic way to split the front rear balance of load transfer I control on the car. It will transfer weight based on the CG height and track width and there's nothing you can do to change this. All you can control is the split front to rear. You're probably wondering what's up with that number. It's biased towards understeer and the recommendation for a racing car is 3 to 5 percent front bias (understeer). If you try and setup a car with a negative front percent (oversteer) you'll quickly learn the car is impossible to drive. Even when we say we like a car loose we really have them setup front stiff to a certain degree. A car setup to oversteer will not put power down at all. The magic number is driver, track, and car dependent. But once you have it will let you play with springs, bars, track width, etc. and Keep the car balanced. If you set the car up this way it will always respond as expected to setup changes. If you have weird setups you may get into positions where you have to do the opposite of what you expect. With regards to the wider rear tires they are setup so that I can get max cornering and still get forward drive. This came from reading a number of Ortiz articles and a really long corner we have out our track. To maintain your speed on a constant arc you need forward drive. But if you've loaded the tire 100% laterally then you can't give it any drive or it will slide. In this scenario I really setup the rear tires to corner and have extra capacity for forward drive, which is the key to going faster. This works even on a 200 HP car (my old one) as well as the more powerful monsters. Cary

Wider rears will help a lot when you have as much torque as you do. The info on springs was just to show the different ranges and what stiff really is. My guess is your stiff ride has more to do with shocks than anything else. The wider rears will allow you to use more throttle while the car is turning without the car trying to step out on you. This will make a huge dent in your run times. Cary

For cars that are not generating downforce spring rates can run in the 2 to 4 hertz range. And by this I would say your setup is really on the soft end. Taking an example of a car that has a total weight of 2500 pounds (driver, fuel, etc.), 100 pounds of unsprung weight per corner, and a 50/50 front to rear distribution we get the following. 2 Hz is a wheel rate of ~215 lb/in 2.5 Hz is a wheel rate of ~335 lb/in 3 Hz is a wheel rate of ~480 lb/in 3.5 Hz is a wheel rate of ~650 lb/in 4 Hz is a wheel rate of ~850 lb/in My car is normally in the 3.2 to 3.5 Hz range. And over time I've discovered that having more rear tire is a faster setup for a autox Z. For your V8 car I think you'll find that this helps a lot with the oversteer your getting when trying to put down power in a corner. Cary

You don't need a working suspension on these cars. Just modify a gland nut and use all thread that comes up through a camber plate. Use a speed wrench on top to do a number of turns to set the ride height. I don't know if this would require changing the straps or not but you shouldn't need to move the car. Cary

Normally the suspension will be compressed under breaking (or trail braking) so this shouldn't be an issue. I guess you could have a problem if the track dropped away from you but you'd have the same issue with a front anti-roll bar holding the wheel up. So to answer your question I didn't have anymore lockup than usual when pushing it very hard. Generally the cars I see picking up wheels all the time are the guys running a lot less spring. That would be one concern I'd have about your proposed setup. The soft rear may allow it to compress enough to lift your front tire off the ground. I had a car that was setup that way a long time ago and that's what it did. Cary

My practical experience would say your theory may need a little correction. I can run true zero droop or limited droop and I don't pick up tires. The key is running spring rates that actually support the forces the car deals with, which are generally stiffer than most people think are needed (close to 1:1 corner weight/wheel rate). I ran suspension logging a couple of times to see what was going on and I could see that once the limiters topped out (very easy to see as the suspension displacement is now a straight line) the car would then roll by compressing the outer suspension. The net effect of this was a reduction in ride height. Without limiters the ride height would actually increase. I usually have .5 to .75 inches of front droop, although I've used zero at times but only when the course is extremely smooth. In the rear I usually have around 1 to 1.25 inches of droop. I've been able to even out rear tire temps and tune at mid-corner push with adjustments to rear droop travel. Here's some info from Richard Pare if ICP that I found useful. These guys gave me the push needed to try this out.

Start looking for Subura STis and you might have better luck. Cary

You don't need a wind tunnel to do this. Use a simple water manometer and do the test yourself. Then drive the car at various speeds and have a passenger record the pressure results from inside the car. Easy and cheap. Your local Home Depot or Lowes has everything you need. Cary

Here's a pic from a friends car. It has a one inch front swaybar and is at maximum turn-in. Based on this I'd say go for swaybars first then see what it looks like. He's running stock springs BTW. Why are you trying to climb into the passenger seat C

This pic reminds of me of Scott Charters Z. He ran a set of schoenfield headers turned around just like this and didn't really have the majority of the issues seen in the GRM article. The car was a definite beast. Cary

Good point Jon!

Do you have a real pic in a corner? This looks like you're about to lose it and have lifted off the gas. Often when the suspension is compressed and you do this it makes the roll look worse because the suspension has overshot on rebound. When you start looking at putting on sticker tires, etc. you will need to increase spring rate. They should be used to support the chassis. So if you increase the amount of traction the they will need to increase. I guess the trick is figuring out how to do this in the best way. Probably swaybars first. You can also try to raise the RC and that will help cut down the roll angle. The problem will be the lowering the car causes this to go down too. So on one hand lowering both helps and hurts you. If part of your roll is caused by the suspension jacking up you can try and use the droop limiting crutch. It's worked for me and is cheap to implement. Many people don't understand how it works very well and like to claim it's BS. It can really help with turn-in. Cary

If you tune to a specific suspension frequency it takes this into account. C

The posts above have some good info but it will be hard to find an ITS or GT-2 car in Australia since those are specific US classes. If you don't have money to add a cage and still want the suspension to work best I would suggest working out your spring rates so that the car has equal front and rear roll angles in a corner. This will help with a car that's not as torsionally stiff. If you don't know how to do this you might consider contacting the folks at http://www.racing-car-technology.com.au, they are located in NSW. Cary

My sentra was rear steer so the rack would move the opposite direction you need. Take a look at the rack pinion. If it's the same as the Z (on top) then it will probably work if it's the correct width. If it's on the bottom, like I expect it to be then the rack won't work in a front steer location. Cary

Can you vent into the fenders? GT rules and prepared autocross rules allowed this but I couldn't add the vents into the hood that have been talked about. Cary

Nice work Phil! For the oil cooler why could you move it the left side of your box and let it vent out the core support? Sort of a bookmarked type arrangement. I've seen this one on a number of racing cars over the years where they have a central duct. Cary

When I have no clue I first calculate the magic number for the suspension and use a few rules of thumb. What this gives me is a baseline to test from. The magic number is the concept taught in Rouelle's (also in Milliken) seminars and is nothing more than the percentage of total weight transfer seen at the front of the car. The idea being that this percentage should generally be in the 3 to 5 percent higher than the percent of static weight on the car. 5 being for sporty street car and the 3 to 4 range for racing cars. This is driver and course dependent but will almost always be in a .1% range. You can use this number to play with track, spring, bar, RC changes to your hearts content and keep the balance the same. I made simple spreadsheet to do this that makes many assumptions but works reasonably well (no tire stiffness or chassis stiffness is used). My rules of thumb are to try and not go more than 60% of the front stiffness with bar and no more than 30% in the rear. For track cars I prefer to use half that, YMMV. My guess, without knowing too much about your car, is that you have too much front percentage and it will end up understeering more than you want. I'm not seeing an option to attach a doc to this post. If you want I can send you my spreadsheet but be forewarned it was quick and dirty and I didn't try and make it user friendly. Just PM your email. Cary

Here are a few of my favorites: Dave Kipperman warming up his brakes. Check out the guy on the left (Peter Brock) One quick Z car The pit crew in action. I did this shot by panning the car as they jumped the wall. Father and son on a Sunday drive (Morgan and Gavin Smith) One of my all time favorite shots. Taken at dusk on a practice day. We'd been telling Dave that sideways was fast Here's Dave lapping more slow cars at PIR And sometimes I even get my picture taken.