04

How this sheet was built

What it knows, what it assumes, and how far to trust it
Front endRear endRace day

What this is

A setup sheet for the 04 that lives on your phone and works in the trailer with no signal. It holds the whole car, front and rear, one saved setup per track. After every run it takes tire temps, hot pressures and what the driver said, and gives you one change to make first. Everything you do goes in a log so a good night at one track comes with you to the next one, and a bad change can be undone with confidence.

It was built for a crew that tunes between races with a jack bolt, a tire gauge, a pyrometer and a tape, not for an engineer with a data system. The language is the language of the pits on purpose.

Where it started

It began with four questions, answered by someone who did not yet know the car:

AskedAnswered
What does the driver measure at the track?Nothing yet, starting from scratch
What car and chassis?Tour-type asphalt modified, chassis builder unknown
Which tracks?The New England bullrings: Thompson, Stafford, Waterford, Seekonk, Lee, Star, Monadnock
Who uses it, where?The driver, on a phone, at the track

The first version was a camber calculator and a shopping list. It then grew in this order: the full toolbox (pyrometer, camber gauge, scales, toe plates, stagger tape, durometer), so every number became a real measurement; the Car page, so the guesses above could be replaced with the real car, the real chassis builder and the real starting numbers; the quick-adjust levers crews actually reach for between a heat and a feature; the rear end as its own page; and the Race day page: tire sets with heat cycles and durometer, a lap timer with a ledger of what actually won, gear and RPM, the forecast for the track with a pressure pre-set, a session clock and the checklists. Every one of those first-day guesses is now yours to change on the Car and Tracks pages.

Where the numbers come from

The starting camber, caster, toe, pressures, stagger and cross weight are generic tour-modified rules of thumb, the kind a veteran crew chief would hand a new team as a place to start. They are not your chassis builder's numbers. When you get the builder's sheet, put those numbers on the Car page under My starting numbers and every baseline in the app follows.

The "which way is tighter" logic on the fast levers and the rear end was checked against material racers already trust:

Track lengths and banking came from published track data. Two banking figures, Thompson and Star, could not be confirmed and are marked approximate on the Tracks page. Fix them from the track's own tech sheet.

How it thinks after a run

  1. Short run, no verdict. Under eight laps the tires never came up. It will tell you that and hold the camber and balance calls.
  2. Air first. Middle of the tire hotter than both edges is too much air, cooler is too little. It also checks hot gain: rights should build about 2 to 4 psi, lefts 1.5 to 3.
  3. Then camber, from the edges. Right front wants the inside edge 10 to 20 degrees hotter than the outside. Left front wants outside even to a little hotter. Outside those windows it moves a quarter degree, a half after a long run, and never past the safe window on the Car page.
  4. Then balance. Fronts much hotter than rears is a tight car working its fronts to death. Rears hotter is loose. A left front as hot as the right front, or a left rear hotter than the right rear, means that corner is carrying too much of the car and it says so.
  5. Then the driver. Tight or loose at entry, middle and exit picks the lever: cross weight, stagger, bar height, arm angle, third link, rubbers, shocks, bias. In practice it gives the proper fix and names the fast fix as a fallback. In a heat or feature it leads with the fast fix because there is no time to scale the car.
  6. One change. It always names the one thing to do first. Do that, run it, ask again.

What it will not do

Things the crew should know

Wish list

Want the sheet to do something it does not? Tell us in one line and we try to have it for the next race. The button in the corner does the same thing from any page.

How to make it better

Tell the person who set it up three things and the sheet gets sharper: the chassis builder and their setup sheet, the tire brand and compound you run, and the real banking on any track where the number looks wrong. Anything that comes up at the track that the sheet gets wrong, write it in the driver notes on that run so it can be fixed.