johnc

Welcome to the world. I wouldn't say that people are cheap, just that: some just have no money some are crooks some are clueless some are still children some are liars some feel they deserve everything some are used to have things given to them some must have it their own way and the most common: some always, everywhere, all the time, in every situation MUST GET A "DEAL". For these deal people, you just have to be smart enough to structure the transaction and your behavior to make them feel like they are getting the deal they so desperately crave.

We're getting there...

That's not true. A bolt designed for 180ksi (metric grade 12.9) is equal in strength to a stud and nut combination also designed to 180ksi. The advantage studs have over bolts is that assembly is easier (assuming you've got enough room), the head is properly located immediately when installed, and the torque readings are more accurate because the fastener itself is not being turned. http://www.arp-bolts.com/media/pdf_files/CH_22-26_33-35.pdf

Jon, you're right. My explanation above was a theoretical view assuming everything in the suspension can be changed. In the real world compromise is the name of the game. You often have to do something somewhat unnatural with the suspension to get the car to go fast around a track. Previous generation VW VR6 GTIs are a classic example. In the stock racing classes they actually went faster and had reduced levels of understeer by installing insanely large front ARBs. The reduction in camber loss in roll more then offset the increased tire loadings. Ideally, you would have achieved the same and gone even faster with a bigger rear anti-roll bar, but the stock class rules didn't allow touching the rear bar.

Well, there's a 4th item that I didn't put in the list above, and that's alignment. The different parameters covered under the term "alignment" affect all aspects of handling. Adjustable struts (I assume you mean adjustable lower spring perchs) affect two alignment items: ride height and corner weights. In general, those items affect hows the springs do thier jobs so its part of setting up the basic Platform. So, to answer your question, in most cases you will not be adjusting corner weights and ride height when transitioning from the track to an autox course. Shocks, ARBs, and alignment settings are the more common items changed when going from one type of competition to another.

No reason to change. Here's one way to think of suspension tuning. Its very general but its get's you close: Springs are used to tune the steady state cornering balance of the car. Basically you're shooting for a neutral balance in medium speed corners and a slightly understeering car in the high speed corners. Think of this as "the Platform"; the foundation that the vehcile's handling is based on. Antiroll bars are used to tune the transitional balance of the car and fine tune steady state cornering balance. ARBs fine tune the Platform's balance and adjust that for track and driver specific needs. Shocks are used to fine tune the transitional balance of the car and control the Platform's natural oscillations (sprung and unsprung). Its the last, most granular level of tuning for the Platform and is the finest tuning tool for the track and driver preferences.

I thought about this diffuser idea as applicable to an ITS 240Z and I figured a wide muffler placed vertically close to the fuel cell on the driver's side would work well as one side of the diffuser. But I could never figure out how to legally (and safely and without attracting too much attention) do the same on the passenger side of the diffuser. I thought about making a fuel pump/filter bracket similar to the one in the pictures of the ROD out of some thick sheet metal, but the pump and filter would have to be awfully low to keep folks from throwing paper. I'm glad to hear that you guys had also figured it out. I like being associated with a better class of people...

Doubtful. I've been pit crew for an ALMS Viper and you can handle the wheels all you want if you just have a pair of Mechanics gloves on. In fact, I grabbed the centers to pull them off the hubs. If they were anywhere near 400F you wouldn't be able to handle them even with the gloves on. There's also enough airflow around the wheels that the 1,000F coming off the rotors gets cooled down very fast. Plus, if the hubs are getting over 400F then the wheel bearings are being cooked and the grease would break down quickly.

Your basically installing a live axle conversion kit with a rear bar that stiff.

I used to be Mr. HPDE and Mr. OpenTrack. Now that I'm doing more wheel-to-wheel racing I realize how dangerous these types of events are. Much more dangerous then the wheel-to-wheel stuff I'm doing with SCCA IMHO.

Ooops! My mistake. Nissan Motorsports lists a rear anti-roll bar part number 55611-E4622 at 25mm. It is a forward mount rear anti-roll bar and requires kit # 99996-E4010 for installation.

That's a front bar, he's just got it sitting upside down on the pavement.

Not stainless, just regular steel. I glued put neopreme(sp?) rubber to the inside of the straps after I took the pictures.

The copper tube should be ok with heat but it might throw off the readings. You can wrap the tube with Fire Sleeve which should reduce the heating of the tube from the header.

In my 240Z with a Quaife trans I had a 2.39 first gear and even with a 4.38 rear gear the car was hard to get going, especially with a 5.5" double disk clutch. Most of the time it involved a small burnout or a stall. It was better with a 4.63 and almost tolerable with a 4.88.

Dimensionally my cell was an 18 gallon one. But, when filling it for the first time, I couldn't get 15 gallons into it.

When my 240Z had stock fenders and coil overs I measured and had Monocoque make custom 15 x 8 wheels for the car. The rims had 4.5" backspacing and I could get the tip of my little finger between the tire/rim and the lower spring perch without any spacers. I also had to roll the rear fender lips when running 225/50-15 tires.

The only power coating related failure I've seen had to do with some BBS 3 piece wheels on a Viper. The owner took them apart sent the centers out to be powder coated. The coater wasn't told or forgot to mask off the mating surfaces and bolt holes that held the 3 wheel pieces together. The owner reassembled the wheels and drove them on the street for a few days. That weekend he went to a Viper Racing League event and in the second race the front wheels feel apart at 100+ mph and the Viper was totally destroyed. The owner luckily survived with just a few broken bones. Seems that the powder coating under the bolt head and nuts softened under the brake heat and wheel loads causing the bolts to lose torque and the wheels to break apart. The lawsuits are still in court.

Wrought aluminum allows (6061 is typical) are artificially aged/hardened via heat treatment. The initial heat treatment is at 1,000F for for 1/2 hour and then quenched in water. This gives a temper designation of T4 and gives 6061 significant strength over as wrought (T0). An additional heat treatment (generally referred to as "aging") of 400F for 2 hours brings additional strength and is designated as T6 temper. Any additional heating of the material to 400F is considered an additional aging process. In the case of a T6 temper, an additional aging will reduce the tensile strength of the material and is considered "overaging." In the case of 6061 T6, the ASTM minimum specified strength is 40ksi. Any additional aging process will reduce the tensile strength some amount and the material can no longer be considered in T6 temper. There are additional temper designations for aluminum beyond T6, but T7, T8, and T9 require cold working to increase strength. Using heat again (artificial aging) on T6 material reduces the temper to T4 (if you're lucky) and more frequently to T0. When welding 6061 aluminum that has to meet specs its much better to weld 6061 T4 and then post weld age (PWA) it for one hour at 400F to get a T6 temper. If 6061 T6 is welded the material has to go back to square one and go through the 1,000F and 400F aging processes again to get back to a T6 temper. EDIT: T7 temper is not reached via cold working. T7 temper is reached via precipitation which is heating the material to a bit under 200F and keeping it at the temperature for 24 to 48 hours.

A custom fuel cell with a 7 degree rise bottom in basically the stock location will work wonderfully as the top of your rear diffuser. That's what the Rusty Old Datsun had.

Here's what the Rusty Old Datsun had for fuel cell mounting: Try .049 or .063 sheet. You'll kill yourself trying to properly bend .120. The straps you see in the picture above are .049.

Move the tank as far forward as you can while still leaving enough room to get a wrench on the nuts holding the diff to the moustach bar.

Dang. I stopped by your car and looked at it for a bit. Nice car. Sorry I didn't put you with the car, but I don't think you were around when I was admiring it.

For a road race vehicle, weight distribution is more important then yaw inertia. In fact, as Dennis learned, a little yaw intertia is a good thing. It makes a car more forgiving and stable because the same inertia that causes bad things once the car starts rotating also makes the car harder to rotate to begin with. For an autocross vehicle, low yaw intertia is more important then weight distribution because autocross is all about transient response. During a run at an autocross the vehcile is rarely in any kind of steady state cornering. Quick transient response will give faster course times then good balance, if the driver can stay ahead of the car. From one of Mark Oritz's newsletters:

People are already digressing... Here's a hint: Which is more important: balance or transitional response? The answer may depend on the intended use...