Coil over spring rates

[tmontague]

I've reviewed the short threads that were archived on here but I wanted to get some input from those of you that regularly track your Yaris and what your preferred spring rates are and why.

I will be pulling the trigger mid winter on some Fortune Auto 500's and am trying to nail down what spring rates I want to go with. I will also be installing all of the TRD hardened rubber mounts front and rear as well as rear axle beam bushing collars.

I do DD the car but my main focus is for it to be built for the track. In other words, I don't mind a bumpy ride but I don't want the spring rate of a purely dedicated track car so that it is virtually non DD'able. I like the car to have slight over steer bias which I am currently used to as I'm running MicroImage springs (4/3kg F/R) with stiffer Tokiko blue's in the rear and oem KYB's up front. I have a TRD rear sway bar as well. Currently the car understeers probably a little too aggressive for ultimate handling. I feel like a reduction in oversteer on my current set up would make it ideal for fast track times.

What I have in mind is something like a 7k F and 6k R. The 500 series coilovers do have dampening adjustment (25way) so I have some wiggle room to play around with the over/under steer characteristics. I will also have a clutch type LSD installed within a couple weeks so that may or may not factor into the spring rates. My track tires are currently r compounds and will typically be running nothing higher than a 100 treadwear tire.

Let me know what you guys have experienced on the track, I open to hearing your experiences/thoughts