I'm interested in what others have to say about using the track as a tool to influence handling. With my car I noticed a reduction in understeer when adding 3mm spacers to the front (on +35 17x8 wheels).

turn-in, mid-corner, track-out, stability, etc.

I've also tried ride height changes but that didn't affect the handling as much as I thought it would.

 

Ride height is crucial, but it all depends on your suspension, brakes and suspension set up.

 

The spacers will help because it widens the stance of your car, think about a putting your feet furthur apart to increase stability when you stand. Or, like the Pontiac adds.. "Wider is better"

By widening your front track with the spacers, you have changed the ballance front to rear, helping stabilize the front in relation to the rear, reducing understeer. (had you added the spacers to the back, you would have increased understeer)

For ride-height, it is a strange beast. You will hear lots about corner weights, but it is hard to actually change the handling with this on a OEM geometry car, the best bet is to lower the car as much as you can without disrupting the camber curve (which on the Evo, doesn't take much) Many Evos i see are lowered too much, and have actually hurt their handling by disrupting that curve and the geometry of the suspension.

Best way to tune a car at the track: Shock adjustments, sway bar adjustments, camber, toe, tire pressures. Shock valving, spring rates, sway bar sizes and such can be done between events for more tuning and driver comfort.

Jon K

 

I've read lots of theory and I guess the core of my question is this:
- On the Evo, what's the disadvantage of using track to tune out understeer?

 

I guess I am trying to understand your question. By taking your car to the track it allows you an environment where you can repeat a test over and over. This will allow you to gauge whether any changes you make are helping. This can be measured by feel, lap times, tire temperatures and many other things. This can be very advantageous as it will allow you to fine tune the suspension over time.
The caveat, however, is that a good track setup is not always ideal for all environments -- such as the street or for that matter other tracks. An example is a fast track car is not necessarily going to be fast around an Auto X course.

It also requires a skilled driver / engineer to make appropriate changes rather than hoping to luck into the right setup.

It really depends on what you are trying to achieve.

 

Did you read the other posts? I meant track as in a stock Evo's track is 59.6 inches.

 

lol, now I understand your question. In my defense you were not specific so I interpreted your question to mean the race track

Widening the front stance is something that has been done for a long time with front and four wheel drive cars to improve front end response and grip. You could also try running wider tires in the front as this will also help. I am really not sure what the limit is as to how much you can run and when you might run into problems.

Keep us posted

 

We used ot use it on karts a lot too, either by changing spacers in the front or actually sliding the wheel "hubs" in the back. There, they actually had rules on how wide we could be, so we had to fit a template they would slide over the kart.

Jon

 

If you have ACD, then apparently there's only so much you can do in regards to staggering tire sizes. If the difference is too great, then ACD will step in to make "corrections".

Ref: see Mark Daddio's comments, https://www.evolutionm.net/forums/sh...&page=11&pp=15

l8r)

 

reduced overall lateral grip.

 

Sorry to stray OT, but what about playing with front & rear ride height to move the roll centers around? most people seem to lower more in the front than rear, for looks. But considering that our cars have a strut front suspension/multi-link rear, and as a consequence the front roll center moves more than the rear, this is backwards? if you look at pics of robi-spec cars (and even mitsu lowered the ride height of the 9 at the rear) the rear appears to be lowered more than the front. i'm assuming this will transfer more weight to the rear of the car (relatively speaking) as the car rolls?

 

wow, there is an advanced forumnow, just noticed.. ha ha

its been a while since my car got a suspension/chassis tune up, finally getting a new one here soon.

what you guys are saying is pretty consistant with the current set-up of my car.

track-out with front wheels, not lowered too much, specially in the front. Although soon the car will be lowered even more since I never really drive it on the streets anymore (still street legal!).

n

 

uh

 

I guess the disadvantage from a mechanical stand point would be you could adversely affect your scrub radius and accelerate the wear of your wheel bearings.

The way I see it, is the wider the track of a car the more stable it is and the longer the track of a car the easier it is to swing out the rear. I agree with what racerjon1 says, whichever side becomes wider gains more stability and overall grip. In JTB's defense I also thought you meant tuning @ the race track ...

 

Try asking Robi, he seems to love them.