I'm trying to control some bad oversteer during autox on my FD and have lowered the rates from 12kg to 10kg in the rear which helped a great deal but the car still has bad oversteer. I'm going to drop the rear rates again to 8kg (which is as low as the company recommends without revalving) with the front still at 12kg. I don't foresee an issue but would a 4kg difference in rates front and rear affect anything adversely?

Thanks

 

Try changing the anti-swaybar in the back to a smaller diameter one and a little more front rake.

 

The rear bars stock so I can't do much about that short of disconnecting it.

 

Disconnect one end of it then. Or add some front bar.

 

Go ahead and try it without the rear bar. I believe the effect of the rear bar is small compared to the spring rate changes you are considering. And, it's a cheap change!

My FD also has oversteer issues, much of which comes from the right foot of the driver (me!). This can be worse if you have a peaky motor with a single turbo, less so with a stock engine. Some toe-in on the rear will also help some with throttle-induced oversteer.

 

Thanks for the reply, I've got the springs already so the cost won't be the issue. I was hoping to avoid disconnecting the rear but it may come to that. I have a 30.4mm front bar which helped, if I can't get the springs on before Saturday then I'll try disconnecting the bar.

 

Well, since you have to disconnect the rear bar to change springs anyway, why not try that first? It's literally One Nut on one side...

 

Did you have this issue before the new tires?

 

What are your alignment settings, along with your ride height?

I second the disconnecting of the swaybar.

Also what do you have your shock settings at? Is your oversteer at entry, mid or exit?

Have you also tried different tire pressures?

 

This occurred before the new tires and before the chassis was stiffened quite a bit with the addition of the rollbar. The ride height is 25 inches all around, the dampers are set to very soft in the rear and hard in the front, and the over steer occurs mid corner. I have tried different tires pressures, I've been using 34 up front and 30 out back. I'll be disconnecting the bar and try it out.

 

Hmmm.... I believe you are running the Stance coilovers.

You said Oversteer at mid corner so I assume you have just hit the apex and you start to apply power and accelerate out when oversteer hits. Is that right?

Both left and right hand corners?

Are you perhaps running out of rear shock travel or completely compressing the spring on application of power?

 

Yes I am running Stance, that seems plausible as the tires in the rear have begun to rub the top of the fender well. Though the shocks have more travel than I believe there is space for the tire to travel (I'll be raising the ride height slightly) and if I remember correctly the oversteer would occur even off throttle right before I put the power on. The car was set up great for the track, it was fast, had tons of grip and was controllable but in the tight turns of auto-x its not doing to well.

edit: its mainly in left handers I believe but there was no really faster right handers

 

i dont have experiance with stance or FD coils, but my FC's tein flex will bottom out if you dont preload the springs, front and rear (with good tires). with shitty tires, there probably isnt enough cornering force to compress them that far, but thats not my case.

i discovered this when diagnosing front brake lockup, and discoverd i was bottoming out under braking over bumps.
took a look under there, and the damper only had about an inch of travel left- not nearly enough for proper handling. they are either designed to be preloaded, or designed around a lighter car with street tires (makes sense, considering japanese time attack)

i should probably make a thread about proper coilover setup one of these days.

 

Please do. It would prove to be extremely useful.

 

Just for your reference, FWIW

My car is well balanced including steady state cornering (which seems to be your problem) with these settings:

14 Kg/cm springs all around, 32 mm solid front sway bar, no rear sway bar; front neg camber maxed out and -1.25 in the rear; 0 toe front and rear

Make sure your tires are OK and shocks are well firm on rebound

- Sandro

 

Are you using a little bit of trail braking or is the car coasting at this part ( neither brake or gas)?

Maybe you do not have enough rebound stroke in the rear and you are lifting a tire... At your next event have someone watch your car going through the corners. Disconnecting the the rear bar will also allow for some more travel.

Let us know how your next event goes and pictures would be great if you can get them of the car in a corner.