GR40 SLA Suspension Wins First Time Out
Bruce Griggs Passes David Smith in Turn 1 to take the lead on his way to victory.
The new GR40 SLA (short-long arm) suspension system was installed on the front of
?Old Blue,? the venerable Fox bodied Mustang stabled at Griggs Racing and used for
development of GR40 Chassis systems and components for over 12 years. It resulted in a
race win and new SCCA Infineon Raceway track record. Starting from the last position
on the 32 car grid due to a drive line vibration which precluded a qualifying run, Bruce
Griggs took the lead from the current record holder, BMW M3 driver David Smith, 3 laps
from the end of the 30 minute race and ran uncontested to the finish.
Close examination of the Hoosier SO4 tires
showed even wear, and tire temperatures
throughout the weekend within 5-8 degrees of
each other on all 12 points (3 per tire). Griggs
stated after the event that he is almost
embarrassed at how well the car works for a
simple bolt-on system. ?We hit a home run on the
first pitch with this design.?
The GR40 SLA system was CAD
designed, fully FEA (finite element
analyzed), thermal and stress tested
for the growing needs of the
Mustang performance aftermarket
that continues to place increased
demands upon its vendors for high
quality and value in chassis
performance. The system is the
latest in a long line of developments to the GR40 product line. ?This geometry is another.leap forward in Mustang enthusiast chassis development? said Griggs. ?Basing the
camber, roll center and roll couple curves on what we have learned over the years racing
on DOT legal tires, we were finally able to package the tire?s optimization requirements
into the front end of the Mustang chassis like we have been doing all along with the rear.
Not that what we had before didn?t work, this is just so much better.?
?We set the car up in the shop with the static camber set at the baseline design and tested
on the NASCAR course at Infineon (mostly right turns), Thunderhill (mostly left turns),
and again at Infineon on the full course (left and right). We then raced it at Infineon.
Camber/caster, and toe settings never required change from the initial shop settings, and
the only requirements for fine tuning the chassis between tracks was adjusting the watts
link to maintain balance, which is to be expected. We tested on last years Hoosier S03?s
and raced on the new steel belted SO4s. No changes were needed between tire types
Exiting Turn 10 at speed, under high lateral load the GR40SLA affords a flat stance.
The SLA system is currently available complete, or as an upgrade to an existing GR40
chassis utilizing the current design GR40 K Member. It is suitable for street, open track,
autocross, and road race. It also would serve well in high output drag cars as it would
facilitate the removal of the shock towers for more room around big-power motors.
Griggs has applied for multiple patents related to GR40 SLA geometry and design
For further information, contact Griggs Racing Products 707-939-2244
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