As we noted in <A HREF="http://my.is/forums/f41/lexus-c-f-2013-united-states-444825/">our previous Front Page story</A>, the 2013 Lexus IS F receives "refined suspension tuning", without further elaboration. We reached out to Lexus and promised a follow-up as soon as we received more information. Now, thanks to the good graces of Jason Schell, Senior Product Planner for the Lexus IS, GX and LFA lines and, most specially, Paul Williamsen, National Manager of Lexus College, we have our answers.
The overriding goals were further improvements to turn-in response and dynamics (roll, pitch, ride, comfort, etc.). Based on notes from Lexus IS F chief engineer Yukihiko Yaguchi, we can inform you of the following component changes:
- All springs and shock absorbers have been revised and are new parts.
- The front coil spring rates are reduced, and are now about 2.5% softer than in 2012.
- The rear coil spring rates are increased, and are now about 13% stiffer than in 2012.
- The rear suspension control arms & bushings are new and retuned, but Lexus did not provide any further information on what this entails nor how they compare to 2012.
- As was the case <A HREF="http://my.is/forums/f41/lexus-c-f-2012-including-u-s-pricing-433939/">in 2012</A>, the IS F shocks absorbers are supplied by German supplier ZF affiliate Sachs. In their 2013 iteration both front and rear shocks (or dampers) are retuned for increased damping force in compression at mid- to high-speed motions. There are changes to the rebound springs inside the Sachs shocks, which resist motion of the shock at large extensions. The front rebound springs have lower rates and the rear rebound springs discontinued, which increases ride comfort during low piston-speed motions. The 2013 IS F rear shocks may well be the only ones in the Lexus lineup without rebound springs.
Left unchanged amidst all this are the front and rear stabilizer (or anti-roll) bars.