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

[deng]

I'm not out to break records or my family's spinal cords, so I'm running Cusco Street Zero F: 7k and R: 5k (Cusco's Springs).

I think it's a nice balance between daily and track. I find that it helps rotate the car at tracks with slower speed corners like Streets of Willow. Car felt neutral at Big Willow which is a high speed course, I did oversteer in some portions, but that was due to driver error/inputs. Though, they were easily controlled by getting back on throttle. Nevermind my T9 incident. Coming from my lowering springs (f/r: 2.8k) I had a lot of dive when braking which unsettled the rear enough to cause oversteer. With the 7k front spring, the car is more flat during braking allowing me to brake later and with more confidence.

I would call Fortune Auto and confirm that they will change the rear spring rate. Fortune was my first choice as I had great experience with them for my previous vehicles, but I saw on their chart that they do not offer custom spring rates for the rear. and go with the Swift Spring upgrade. They are worth it in the daily department, so much more compliance.

I think 7k/6K would be a good start. You can always change the springs out +/- 2k before needing to be revalved, at least that's what I've heard. I also recommend the Cusco Front Pillowball Mount to eliminate the flex from the factory rubber donut. I think they should be compatible since you can use them with stock struts. And if you can, a ride height adjustment/corner balance from a local race shop would be well worth it.

[Jason@SportsCar]

You guys are in the range in the front, but far to soft in the rear. Need to get it up around 9k in the rear with that rate front.

[tmontague]

Deng, do you have a rear sway bar on your set up?

I'll be getting a corner balance at a local well known shop once everything is all set up. I'll have to ask FA about the rear spring rates but as far as I last rear they were fully custom.

[tmontague]

Originally Posted by Jason@SportsCar

You guys are in the range in the front, but far to soft in the rear. Need to get it up around 9k in the rear with that rate front.

As in a higher rear spring rate than front?

I don't know if I could handle that amount of over steer that I would expect from that set up. Would you then recommend removing the rear sway bar with a high rate in the rear?

[deng]

Originally Posted by Jason@SportsCar

You guys are in the range in the front, but far to soft in the rear. Need to get it up around 9k in the rear with that rate front.

Sadly, the Cusco's maxed out at 5k for the rear. I did want to step up my rears to 7k when I switch to Swift Springs. Heck, I might just buy some rear bilsteins, get them revalved for 9k springs and go that route. First I need a daily to replace my daily.

Originally Posted by tmontague

Deng, do you have a rear sway bar on your set up?

I'll be getting a corner balance at a local well known shop once everything is all set up. I'll have to ask FA about the rear spring rates but as far as I last rear they were fully custom.

I pulled my rear bar off when I installed the coilovers, I didn't see a need for it with the stiffer rear springs.

[Jason@SportsCar]

Originally Posted by tmontague

As in a higher rear spring rate than front?

I don't know if I could handle that amount of over steer that I would expect from that set up. Would you then recommend removing the rear sway bar with a high rate in the rear?

The stiffer rear spring help the car put power down on corner exit. No need for a rear bar when the shocks and springs are right.

[Jason@SportsCar]

Originally Posted by deng

Sadly, the Cusco's maxed out at 5k for the rear. I did want to step up my rears to 7k when I switch to Swift Springs. Heck, I might just buy some rear bilsteins, get them revalved for 9k springs and go that route. First I need a daily to replace my daily.




I pulled my rear bar off when I installed the coilovers, I didn't see a need for it with the stiffer rear springs.

Cusco can revalve. We ran 11k front and 14k rear with a Cusco setup on our 2012.

[tmontague]

hmm, good to know. Maybe I'll eventually sell the sway bar and put the cash towards some swift springs

[deng]

Originally Posted by Jason@SportsCar

The stiffer rear spring help the car put power down on corner exit.

That makes so much sense. Less squat in the rear = more contact patch on the drive wheels. The More You Know *

Originally Posted by Jason@SportsCar

Cusco can revalve. We ran 11k front and 14k rear with a Cusco setup on our 2012.

Were you running the Competition Zero 3's with the monotubes? Cusco wouldn't allow me to go with stiffer springs on my lowly twin tube fixed dampening Street Zeros.

I was going to take my rear shocks to Feal, but they said they do not do revalves on Cusco. Plus with the Bilsteins, I can just drop them off and not have to worry about any downtime with the car. Which brings up another question I have about springs...I'll make a seperate thread about it.

Originally Posted by tmontague

hmm, good to know. Maybe I'll eventually sell the sway bar and put the cash towards some swift springs

Sounds like an awesome plan.

[Jason@SportsCar]

Originally Posted by deng

That makes so much sense. Less squat in the rear = more contact patch on the drive wheels. The More You Know *



Were you running the Competition Zero 3's with the monotubes? Cusco wouldn't allow me to go with stiffer springs on my lowly twin tube fixed dampening Street Zeros.

I was going to take my rear shocks to Feal, but they said they do not do revalves on Cusco. Plus with the Bilsteins, I can just drop them off and not have to worry about any downtime with the car. Which brings up another question I have about springs...I'll make a seperate thread about it.



Sounds like an awesome plan.

Yes, they were the Zero 3s, great stuff, worked really well.

Hard to go wrong with Bilstein, lots of options and great tuners out there. Guy Ankeny at FR-Sport can do wonders with those, as can Bret Norgaard at Yawsport (he is an ex Bilstein engineer).