JThor

Trying to keep my car in F Street this year, but want to upgrade springs if legal. I want to get the benefit of the full 2010 track pack car if reasonably feasible.

Do any of you have the spring rate specs for a 2010 GT Track Pack II car? I have a vin for a 2010 Track Pack II car and my vin for the Track Pack I car (3.73 rear axle package) So far, the springs and sta-bars seem identical. Both cars call for AR33 5310 F (Yellow) for front and AR33 5560 D* (Tan) for the rear from the dealer catalogue. I know the rears have a rated spring rate of 156 lbs. I don't know the spring rate for the Yellows. Both have 36.4 mm sta-bars in the front. If this is true, the only difference seem to be the the strut assembly between a Track pack I and II car. Any additional info would be helpful.

Norm Peterson

If the two Track Packs are calling out the same front spring by part number and tag color there is nothing to gain there, and even if there was I think you'd have to convert the rest of the car to match whichever Track Pack you picked the springs from. Aftermarket springs are out for FS and the 2014-only FSR class; they'll send you to STU, ESP, SM, or CP.

The strut assembly probably doesn't matter, since you're free to swap struts and shock absorbers (there may be some limits - I'm not entirely sure what damper allowances exist in F Street).


Norm

Fabman

Very entertaining read, let me bring this to a head.
Where can a guy get a good set of track day springs in stock OD for a set of Koni yellows?
Car makes a bunch of power and has all good arms and K member etc. on R compound tires. It just rides on Pro Kit springs and it's way too soft.

F1Fan

For stock style struts? No such animal, the closest were the linear rate Steeda Comps but they can't be considered high rate springs really but at least they did not slam the car and have you bouncing off the bump stops.

For track level spring rates you need to go with coilovers. It is easy enough to have your Koni Sport struts modified to use 60mm to 2.5" ID race springs and both front and rear dampers re-valved to handle the higher spring rates. Some of us are running mild 450 to a less than mild 650in/lb linear rate race springs on our coilovers for street use and the difference in pitch and roll is huge and it only gets huger as the tires get stickier.

HTH!