Cosmo Steering Feel

[Berty]

Okay, so the Cosmo isn't designed as a track day monster, but that hasn't stopped me from trying. Not only this, but there really isn't much Cosmo handling advice floating around so I thought that I would get the ball rolling.

One thing that has been bothering me of late is the steering and the "feel of it".

After I put all of the bracing into the car, the front steering has become extremely light, but has also seemed to of lost the feedback it once had.

Current handling mods are...

Coilovers, 16KG front, 7KG rear
Carbing Front Brace
Carbing Rear Brace
18 x 10 SSR 3 Piece rears with Federal 595's
17 x 9 fronts (soon to be 18 x 9 SSR 3 Piece)
Custom under-bracing

So I want to give the car more responsive steering which has more feedback. Currently the car is super twitchy and the fronts tend to understeer under very fast cornering.

So here is my proposed list of changes...

KU36 Semi-slicks on the front 245 30 R18
Extended steering knuckles (increasing the steering lock)
4 degree negative front camber (currently about 2.5degree)
1.5 degree negative tow-in.
Dampeners at 5% maximum stiffness

Im pretty sure that the rear end isn't the problem, but here are the settings anyway for people to scrutinize...

2.5 degree negative camber
2.5 degree negative tow-in
Dampener's at 25% maximum stiffness

I am pretty happy with the rear end set-up at the moment and have no intention of going to semi-slicks as the 265, federal tyres are keeping traction in check.

Any thoughts on how to modify the steering?

 

[TheMAN]

16kgf/mm in the front is a bit much... reduce the spring rate and soften up the dampening..... you're not allowing weight transfer to the front and therefore losing tyre grip because of this! upgrade the sway bars also if you haven't done that!

yes, toe-in will help the car track straighter and reduce the twitchyness... you might want to get rid of power steering for more steering feel.... if not, flush the system if it has never been done with quality synthetic ATF and go from there

 

[Berty]

16kgf/mm in the front is a bit much... reduce the spring rate and soften up the dampening..... you're not allowing weight transfer to the front and therefore losing tyre grip because of this! upgrade the sway bars also if you haven't done that!

yes, toe-in will help the car track straighter and reduce the twitchyness... you might want to get rid of power steering for more steering feel.... if not, flush the system if it has never been done with quality synthetic ATF and go from there

Thanks for the reply. I have thought about getting rid of the power steering, however I don't want to go that far yet.

One thing that I have noticed with the coil-overs is despite the fact that the front end has the heavier spring rate, it is actually the rear 7KG springs that feel the tightest. When I installed the coilovers I put the fronts in first, leaving the rear completely standard. Interestingly, this was actually quite comfortable to drive around with, however once the rears went it, it became extremely firm. Any thoughts on why the "looser" 7KG rears would feel stiffer than the fronts?

 

[DMRH]

Just a theory but different rolling diameter wheels front to rear may be an issue. The rears being larger would have the tendancy to push the car in the original direction. I.E. The balance is wrong


Also my suggestion on stiffening it all up reducing steering feel may be due the lack of weight transfer on turn in thanks to a stiffer chassis. Less weight shift onto the outside wheels during a corner reduces it's tendancy to turn in.

If you reduce the rear spring rate to 5kg or less there will be a greater "roll" or pitch causing the outside tyres to bite more allowing more turn in.

Just my 2-cents & total theory from the neck-top PC.

Another thought. If you want your Cosmo to handle then study the EST Cosmo as featured insome of Antoines threads.

REgards

 

[TheMAN]

the rear end is lighter than the front... thats why the car feels more bouncy

like I said though, your front end is too stiff and not allowing good weight transfer... soften your springs and go from there
what you have is too crazy... most race cars don't even run that much!

 

[Berty]

Okay, I am going to change the fronts to 10Kg or 12KG springs for now and then try 5KG rears if I still am not happy.

 

[TheMAN]

still too crazy
why not 8kg and 3.5kg?

 

[Berty]

Well, my reasoning is it is such a big car (1650KG). Plus I will be going to 245 semi slicks on the front so that should compensate.

I have been driven around in similar size cars with 12Kg fronts and 8KG rears and they seem to behave quite well.