A9 is still the Adelaide keeper: 1:12.018 best, 1:11.848 theoretical, 232.09 km/h peak. Since the last log it survived a wing trim test, a no-third-spring package, a clean rear camber test, and a three-setting diff preload bracket. The biggest lesson of the week was not a setup value at all.
The Wrong Front End
A full lab day of camber testing ran with the rejected front P-rod position (-25.0 mm, the A11 front end) left in the car overnight, plus off-spec rear camber. Every session that day sat 0.16-0.39 s above the keeper's theoretical with identical weather.
The clean single-variable decomposition, from the night the keeper was set (rear camber -2.5 deg and rear P-rod 7.0 mm held constant):
| Front P-rod | Best lap | Session theoretical |
|---|---|---|
| -24.0 mm | 1:12.018 | 1:11.848 |
| -25.0 mm | 1:12.284 | 1:12.109 |
The front position alone cost 0.27 s best / 0.26 s theoretical, essentially the entire deficit. Sector stitching was not the limiter; the ceiling was.
Operating lesson:
- Rejected tests get backed out control by control before the next session.
- Every comparison against a keeper now starts with a full setup diff against the keeper session, not selected field checks. Field checks missed this twice.
Rear Wing Trim Rejected
Setup change: rear upper flap 21 -> 20 deg (garage trims: downforce -1.2 pts, drag -0.5 pts, aero balance 43.2 -> 43.5 percent).
Measured result:
- Best lap: 1:12.545.
- Split minima: 23.528 / 19.318 / 29.687.
- Peak speed: 232.1 km/h, no measurable straight-line gain.
Decision:
- Rejected. The drag relief never showed up at peak speed and the lap lost about 0.4 s. Reverted within the hour.
No-Third-Spring Package Rejected
Setup changes, three at once: rear third spring removed (150 -> 0 N/mm), rear camber -2.3 -> -2.5 deg, diff preload 50 -> 45 Nm.
Measured result:
- 1:13.009 in the only timed lap.
- Garage rear ride height collapsed from 38.3 to 30.8 mm without the third spring carrying the rear.
Decision:
- Rejected as a package. Three variables moved at once so no single-variable conclusion exists, but the rear platform clearly needs the third spring at the 166 N/mm corner-spring rate.
A9 Re-Baseline Confirmed
Full A9 spec restored and verified by setup diff: front P-rod -24.0 mm, rear camber -2.5 deg.
Measured result, 8 timed laps:
- Best lap: 1:12.049.
- Theoretical lap: 1:11.902.
- New all-time S1 best: 23.135.
The ceiling returned with the front end, closing the attribution. The remaining S3 giveback concentrates in two places: the corner at 75 percent lap distance and the final-corner exit. The session's best lap took the 75 percent corner faster than the keeper lap itself, so that corner has more in it on this setup.
Rear Camber -2.3 Rejected Clean
The camber question rerun as a true single variable, back-to-back with the same-evening re-baseline, front end confirmed by setup diff.
Measured result, 7 valid laps each:
| -2.5 deg | -2.3 deg | |
|---|---|---|
| Best lap | 1:12.049 | 1:12.171 |
| Best-5 average | 1:12.210 | 1:12.373 |
| Theoretical | 1:11.902 | 1:12.127 |
Decision:
- Rejected. Slower S1 and S3 minima, equal S2. Rear camber stays at -2.5 deg. The earlier apparent -2.3 advantage existed only on the wrong front end. Seat call before the data said the same thing; the data confirmed it.
The Preload Map
Diff preload tested at 40, 45, and 50 Nm on the verified A9 platform, single variable per session. All three settings sit within 0.07 s at the best lap over short runs, and no setting separated at the theoretical. What separated is the shape of the lap:
| Preload | Holds the record for |
|---|---|
| 50 Nm | best lap and ceiling (1:12.049 / 1:11.902) |
| 45 Nm | best S2 (19.239) and best S1+S2 (42.578) |
| 40 Nm | best hairpin zones and best S3 average |
The 40 Nm trade, measured against the same-evening 50 Nm re-baseline: hairpin zones 0.07-0.08 quicker, S3 faster on average and more repeatable, S2 consistently paying 0.03-0.04, and net zero at the theoretical.
S2 anatomy explains the trade: S2 contains exactly one corner, the chicane-exit right at about 34 percent distance, and then the full run to the end of the back straight. The entire 40 Nm S2 deficit lives in that single corner, whose exit speed taxes the whole straight. The straight itself is identical across all three settings, peak speed is 232 km/h on every one, and the lap ends the straight 200+ RPM under the limiter. Together with the wing-trim null result, straight-line gains are not available at Adelaide from wings or gearing. The remaining time is mid-corner.
Cross-setting sector bests now stitch to 1:11.781.
Current State
- Keeper: A9, unchanged. 1:12.018 best / 1:11.848 theoretical.
- Preload is a shape call until longer stints separate the settings.
- Front ARB blade testing has started from a measured balance read: the car gives the same slight-understeer signature at the hairpin, the 75 percent corner, and the chicane exit. First short run on a softer front blade favored the softer setting in both problem zones; unresolved at this sample size.
- Still open behind that: dampers, coast ramp, front camber and toe, and a full 8-12 lap mini-stint on A9 to confirm repeatability.