7. Caster can be tweaked from side to side as needed. This stagger helps the car through turns. For the downtown Savannah race track, which features mostly left-hand turns, we add a bit more caster to the right: 2 degrees on the left, 2 3/8 on the right. Your stopwatch--and data system, if you're running one--will help reveal the correct answers here. How do we adjust caster? We run Jaguar XJ6 ball joints. They're similar to the Triumph pieces but are a little slimmer, meaning we can shim them back and forth by about an eighth of an inch.
8. This is our old-school toe gauge, which works well for comparing two reference points. On a relatively short track like Savannah, we set our TR3 with 5/32-inch toe-out for improved turn-in.
SETTING TIRE PRESSURES
We like to set our tire pressures first, using a method gleaned from Andy Hollis, a multi-time SCCA autocross national champion who often does the tire testing for our sister magazine, Grassroots Motorsports.
- Inflate all tires to the same high psi estimate.
- Time three hard, clockwise laps around a skidpad.
- Drop the pressures by 4 psi all around.
- Repeat steps 2 and 3 until the lap times point toward an ideal pressure range.
- Note the range of pressures that produced the fastest laps.
- Inflate all tires to the highest pressure in that range.
- Time three hard, counterclockwise laps around the skidpad.
- Drop the pressures by 2 psi all around.
- Repeat steps 7 and 8 until you hone in on the fastest pressure.
- Use a probe-type pyrometer to confirm the fastest pressures. Ideally the tire temperatures will be close to even across the entire tread. If they’re a little bit cooler on the outside edge, that’s okay, too. If the temperatures in the center are too high, though, the tire is running too much air. “When in doubt, trust the clock, not the pyrometer,” Hollis adds.
- Tires cool as they sit, so waiting even a minute to measure a tire’s temperature can render the data almost useless. That’s why we recommend having at least one helper, so one person can take measurements on each side of the car. We record our data in an old-school notebook.
ALIGNMENT BASICS: CAMBER. CASTER & TOE
Negative Camber
