Adelaide Street Circuit

A9 with rear P-rod lowered one more step.

• Aero unchanged: 21 deg front flap / 21 deg rear upper / 12 deg rear beam.
• Front P-rod length offset: -24.0 mm.
• Front ride height: 17.4 mm.
• Rear P-rod length offset: 7.0 -> 6.0 mm.
• Rear ride height: 37.8 -> 37.4 mm.

Best lap: 1:12.099. Theory: 1:12.063. Peak speed: 231.84 km/h. Loaded bottoming dropped, but lap time, theory, and peak speed were worse than A9.

A10 with front ride height lowered.

• Aero unchanged: 21 deg front flap / 21 deg rear upper / 12 deg rear beam.
• Front P-rod length offset: -24.0 -> -25.0 mm.
• Front ride height: 17.4 -> 16.9 mm.
• Rear P-rod length offset: 6.0 mm.
• Rear ride height: 37.4 mm.

Best lap: 1:12.097. Theory: 1:12.067. Peak speed: 231.66 km/h. S3 minimum: 29.538. Front bottoming increased versus A10. A follow-on session the same night, front -25.0 with the A9 rear restored, measured 1:12.284 / 1:12.109: the front position alone costs about 0.26 s versus A9. The front P-rod was not returned to -24.0 afterward and silently carried into the next lab day.

Rear camber tests run while the rejected A11 front P-rod was still in the car.

• Front P-rod -25.0 mm (A11 position, left in overnight) instead of A9's -24.0 mm, found in the second setup audit.
• Rear camber: -2.2 deg in the first two sessions, then -2.3 deg.
• Aero, springs, diff, rear platform, front camber, and toe identical to A9 throughout.

The front P-rod alone measures 0.27 s best / 0.26 s theoretical (single-variable, same night as the PB) and explains essentially the whole day's deficit. At constant front -25.0: -2.2 deg gave 1:12.247, -2.3 deg 1:12.143 / 1:12.010 theoretical, -2.5 deg 1:12.284 / 1:12.109, so -2.3 was fastest of the three at that front height. Rear inner-edge heat (the motivating concern) ran 10-15 C over the outer at -2.5 and narrowed only 1-3 C at -2.3, with no pace fall-off in any -2.5 run.

A12 with the rear upper flap lowered.

• Rear upper flap: 21 -> 20 deg.

Best lap: 1:12.545 in 4 timed laps. Peak speed unchanged at 232.1 km/h, so the drag relief never showed up. Reverted within the hour.

Three changes at once from A12.

• Rear third spring: 150 -> 0 N/mm (removed).
• Rear camber: -2.3 -> -2.5 deg (the A9 value, unknown at the time).
• Diff preload: 50 -> 45 Nm.
• Garage rear ride height collapsed 38.3 -> 30.8 mm.

1:13.009 in the only timed lap; abandoned after 2 laps. Three variables moved at once, so no single-variable conclusion, but the rear platform clearly needs the third spring at the 166 N/mm corner-spring rate.

A12 with lower diff preload.

• Third spring, camber, and P-rods restored to A12.
• Diff preload: 50 -> 35 Nm.

Best lap: 1:12.283 in 4 timed laps; S2 matched the day's best. Within execution noise of 50 Nm. Needs 8-12 lap stints per setting to separate.

The A12 question rerun as a single variable on the verified A9 front end.

• Front P-rod -24.0 mm confirmed by setup diff.
• Rear camber: -2.5 -> -2.3 deg, both corners.

Back-to-back against the same-evening A9 re-baseline: best 1:12.171 vs 1:12.049, best-5 average 1:12.373 vs 1:12.210, theoretical 1:12.127 vs 1:11.902. Slower in S1 and S3 minima, equal in S2. Driver call before the data: -2.3 kills the setup. Confirmed. Rear camber stays at -2.5 deg.

Diff preload 50 -> 45 Nm on the verified A9 platform.

• Everything else A9; back-to-back with two 50 Nm sessions the same night.

45 Nm, 8 laps: best 1:12.180 and the best S1+S2 ever recorded (42.578). 50 Nm, 4 laps each: 1:12.289 and 1:12.226. Within execution noise. Rejected by driver call: the seat never preferred it and 50 Nm holds the lap and ceiling.

Diff preload 50 -> 40 Nm, single variable verified by setup diff.

• Everything else verified A9.

Best 1:12.107 vs 1:12.049, theoretical 1:11.908 vs 1:11.902: net zero at the ceiling. The shape moved: hairpin zone 0.07-0.08 faster with the four best hairpins of the combined set, S3 average 0.08 better, S2 consistently 0.03-0.04 worse. All three driver reads confirmed. A closing 45 Nm session then set the all-time S2 best twice (19.239 / 19.240). Evening picture: 50 holds the lap and ceiling, 45 the S2 records, 40 the hairpins. Rejected by driver call: the shape trades never earned the seat's preference. The preload chapter closes at 50 Nm.

One front ARB blade step softer on the preload-40 base, single variable.

• Front ARB: Soft bar / Medium arms, blades 2-3 -> 2-2.
• Diff preload held at 40 Nm; the clean comparison is the 2026-06-09 22:41 session (40 Nm, blades 2-3).
• ARB changes are garage-only: the manual's in-car F8/FARB claim does not match the sim.

Direction came from the seat: slight understeer everywhere, and one blade softer is the manual's less-understeer step. First read, 3 laps, leaned positive. The deciding run went three steps softer on the ordered blade ladder (2-3 to 1-5): 1:12.380 best / 1:12.263 theoretical over 8 valid laps, lazy and slower by the driver's read with the stopwatch agreeing. Rejected; the understeer is not front-roll-stiffness-limited and the blades returned to 2-3.

Rear ARB arm length Position 1 -> Position 2 (1 = longest/softest, 7 = shortest/stiffest; the keeper runs full soft).

• Everything else pure A9; verified by setup diff.

Two sessions, 17 valid laps: theoreticals 1:12.027 and 1:12.243 vs the A9 references at 1:11.902-1:11.978. The hairpin rotation gain was real (+5 km/h apex, zone faster than the PB lap) but every loaded corner after it paid it back: 0.15-0.30 per lap lost from hairpin exit to the line, S1 never near its best, S2 0.03-0.04 down. Driver call and stopwatch agree. Both ARB directions measured dead on the A9 platform; the platform stood until the A23-A25 package changed it underneath.