Florida Test with Michelin and Police Safety First

MICHELIN TEST, JENNINGS FL

BIKE: 2007 Police Safety First Suzuki GSXR600 in AMA Suspersport spec.

RIDER: Bobby Fong, second year with SFR,

TARGET LAP TIME: 1:16

TRACK RECORD: Geoff May, 1:14.7 M4 AMA SUPERSTOCK GSXR 1000.
DAY ONE:
Arrived 7.15am to a wet track with standing water in places. Prepped the bike and then took time with Brian Stokes who graciously provided a walking commentary lap while the track dried out – very informative! The track opened at 10am, with ambient temp at 50 degrees F.
- 1st session on an old 07 PRC front and new 07 C rear to learn the track.
- 2nd session on second used 07 PRC front and same rear tire.
- 3rd short session at pace on same tires as S2, running lap times of 1:22’s.
- Lunch.
- Riders meeting and announcement re: 10 sets of tires to be tested. Format of 1 out lap, 10 fast laps, 1 in lap at pace to return to the pit for tire temp data collection and completion of rider evaluation sheets on the set of tires just tested.
- 4th session: - focus Bobby on getting laps times down to within .5 of a second in each session to allow him to focus on tire side grip and corner entry feel thereby providing qualitative feedback. After completion of the session with the bike back on the stands, the front tire was wearing very well and when I read the rear tire wear characteristics it was obvious that there was too much abrasion, too much rebound damping, too much low speed compression damping. We changed rebound from15 to 17 out and low speed compression from 5 to 8 out, both from full stiff.
- 5th session, reviewed tire wear, improved on compression and rebound but abrasion still too pronounced. We removed the Penske shock to change the spring from a 525lb spring to a 500lb. In checking the Penske shock thoroughly, it was discovered that it was leaking so a new 08 Penske was shock installed with the 500lb spring, with 8mm installed preload.
- 6th session running mid to low 17’s and settled into a rhythm. Tire wear improved significantly, but abrasion still somewhat excessive – this was accredited to the track surface by Michelin technicians based on their experience.
- 7th session Bobby complained of a lot of front tire push only when under most duress off throttle and trail braking in turns 1 and 10. Gone as soon as the throttle was applied. The GP Suspension forks were removed as per test plan and Traxxion gas cartridge forks installed. Geometry was changed significantly to put more weight on the front wheel with forks raised 10mm from previous position (15mm through via GP Suspension billet extended fork caps) and 5mm of ride height put into the shock (previously with zero ride height).
- 8th session bike turned much more responsively, held the line better going into the corner but push was still evident under duress. Chassis far more neutral and responsive overall.
- decision made to work further on geometry with fork positioning and rear ride height, based on 180 tire measurements for day two (see specs below)


DAY TWO
Arrived at a dry track with a very cold 45 degrees due to a solid cold wind. The SFR GSXR 600 has no thermostat, so we placed two and a half strips of tape onto the radiator to minimize airflow through it in order to keep the engine temp at 190 degrees to avoid cold seize damage. Forks were lowered to the OEM stock position and 2mm of ride height was added to the shock.
- 1st session with slicks in at 2 laps to add one more piece of tape as the engine was running too cold and then back out to complete the session. Bike handled better, even more quick turning but push still evident and now running wide on the corners. Changed low speed compression to 8 clicks out.
- 2nd session with slicks saw Bobby drop into the 16’s for the first time but the running wide problem was amplified with compression change. Changed low speed compression to 16 out and changed the rear sprocket to a 42 as at this pace the rev limiter was frequently reached.
- 3rd session with DOT’s running at flat 17’s. Improved the running wide but still present. Front push still present. Change Penske low speed compression to 16 out.
- 4th session on DOT’s at low 17’s. Still running wide, slightly better.
- Lunch, sun came out so all tape removed.
- 5th session. S1 slick front with new 180 DOT D rear. 5 laps out, ran high 16’s and focused on forks and corner entry re push. Added ¼ turn of compression and push eliminated. Cause: forks compressing too quickly to the bottom of the stroke.
- Still running wide in corner exit, so half a turn of preload removed and 2.5 turns of ride height added to the Penske shock. In after three laps saying corner exit was improved but the rear tire spun far more easily. Half the ride height removed with the expected results – bike ran slightly wide and rear tire spun up a little less easily. CAUSE: shock spring too stiff, and when the throttle was applied the shock stopped working an consequently took weight off the front wheel.

TEST SUMMARY:
- Bobby did incredibly well to get down into the 16’s with brand new tires and a track he had never ridden before. A testament to his ability to put a new track together and ride hard and smart.
- the chassis set up from 07 was far too tall in the front fork position with the rear shock at stock length and the axle all the way to the back of the slot causing the front tire to push as there was not enough weight on it going into the corner. With geometry reset, the chassis became neutral and turned very easily.
- the bike would not finish the corner as the 500lb shock spring was too stiff and we didn’t have the opportunity to change it to a 475lb to see if this would solve the problem as there were no more tires available.
- We have a good baseline for geometry and spring rates to use as a platform for further refining the chassis and testing with different valving combinations.

08 Front Tires:
- V slick tire provides more grip and more compression over DOT settings.
- V slick tire gave most consistent and trustworthy feel.
- V DOT stable but feels like it is ready to fold under max load.

08 Rear Tires:
- 190 E DOTgave best side grip.
- 180 D slick gave better hook up/drive.
- 180 D DOT gave best short term drive (8 laps) and fastest lap time 1:16.8.