Client Greg Griffin at the Watkins Glen Challenge Club Racing event
The following is what I recommend as a starting point when tuning your F355 for the race track, this set up is optimized with either F355 Challenge suspension or my “sport” system for road cars or my “track” system for dedicated track cars:
When setting up the F355 with the new (revalved) shocks and springs here is the order of importance as sometimes compromises must be made:
1. Near 50/50 % cross weight
2. Level side-to-side
3. Simulate driver weight and about 50% fuel load (fuel load is not critical enough that you must drain tank, but if it’s significantly under ½ tank then fuel it to at least half full)
4. Rake setting (difference in front vs. rear ride height)
5. Toe settings
6. Camber settings
I measure ride height from the floor of the chassis just behind the front tires and just ahead of the rear tires; this is different from the Service Manual that specifies ride height measurements from the center of the inboard lower control arm mount fork.
• Ride height, Front: 85 – 115mm Rear: 85 – 115mm
• Rake: Level or close to level promotes stability and sacrifices turn-in somewhat; I suggest starting with no more than 15mm positive rake (nose lower than tail) and no less rake than zero. If the car is not turning in well start raising the rear ride height four turns at a time during testing. Do not alter front ride height at the track.
• Toe, Front: 0 – 15’ toe out total. Rear: -25’ toe in total. (NB: I’m specifying toe out in front and toe in for the rear, this is critical. Oversteer/ understeer balance can be adjusted via rear toe in settings, more promotes stability. Toe out in front helps turn-in, toe in for the front helps stability.) I’ve run as much as 45′ total toe-in for the rear suspension but you must watch tire wear. (25′ of toe is about 3.5mm on an 18inch wheel)
• Camber, Front: 2.5 – 3.0 degrees negative. Rear: 2.8 – 3.4 degrees negative (NB: should have more negative camber in rear vs. front)
This much camber may necessitate changing the lower control arm mount forks. Always torque lower control arm mount forks properly and replace the nuts with new Nylocks after a few uses. Check lower fork nuts pre/ post track events.
I also suggest using the computer controlled damping system. You may lock the shock adjusters with small hose clamps or with silicone RTV (must set overnight). If locking adjusters set rear full counter-clockwise (that’s full-hard) and fronts the same initially. If car understeers on turn-in set front adjuster 15 degrees from full hard and lock in place. Adjusters must be mechanically locked or internal hydraulic flow will eventually set them full soft (clock wise). Full hard to full soft is less than 90 degrees so adjusters are very sensitive.
For a road car the compromise is ride height, just keep it as high as practicable, but use the rake and alignment recommendations with the exception of camber/ toe. This much camber combined with this much toe will increase tire wear rates. Closer to WSM camber and toe will increase tire longevity.
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