1234rotor

iTrader: (1)

I just aligned my FD last week in prep to run my first track day event. I am running on Falken GRB-FK451 225/50 16 radial tires (basically a toyo T-1S).


I drive the car very little during the week and some on the weekends , so wear was not too much of a concern.

Specs are:

-1.8 front camber

+5.3 front caster

+.10 front toe-in


-1.2 rear camber

+.24 rear toe-in


I wanted the car to be stable under throttle, but have good turn-in feel with the caster set at the lower side of stock specs.


What do you run, and what do you think of my settings??


BTW, I am running some JDM KYB gearclimb shock/spring combo (non-adjustable...1.8/1.5" drops) and they seem really stiff...a good bit stiffer than R-1 sus.

gfelber

Sort of depends on the track. Where are you running? Road Atlanta?

I run about -1.8 front and -1.5 rear with +6 caster with 18x10 wheels on 285-30 rubber.

I'm assuming you have stock toe links? IF so, I'd recommend zero toe on the rear. The FD is very sensitive to rear toe on the track. I and others find the car much easier to rotate and more predictable under braking. You should be fine with .1 toe up front.


Gene

formula-mazda

Dumb guy question on my part....

Why do you run toe in at the front? I have never engineered a tin top and only have experience with open wheel. Why does this car like toe in on corner entry? Typically we run 2-3 mil toe out in the front for corner entry feel and 1-2 toe in at the rear (depending on suspension member flex) to generate a gradual exit push. I am hoping to run a gen3 on the track this year and am very interested in learning this cars sweet spot.

BTW here is my two cents on your alignment:

Castor: Since this chassis is not stiff enough to transfer weight to the rear opposite tire during turn in. It might not be a useful tuning tool. Find what is comfortable down fast striaghts and stick with it.

Camber: If you are limited to a certain spring combination and roll resistance....Purchase a pyrometer and take temps after 5 hot laps. Keep your temps within 20 degrees from inside to outside. Adjust from there...not around your driving style. Do 5 hot laps at 95% and come in to bleed down and take temps. If you do have adustable roll resistance, remember that the stiffer you make either end, the more the inside of the tire will heat up.

Ride Height: Drop it down until it scrapes then raise it 10 mil at a time. Remember that a positive rake will let the car rotate better but end up with corner entry oversteer/sharper turn in.

Toe: If other drivers like toe in at the front..then go with it. Or, be nutty and try to liven up the front end with abit of zero, or out. The poster above me mentioned 0 at the rear. That leads me to believe that the suspension does not flex aft under load. If you feel the back end coming around (not sliding but rotation) during acceleration, then gradually put more toe in at the rear. Toe in will push, toe out will rotate the car under acceleration

1234rotor

iTrader: (1)

Yes, i understand basically every thing you stated. the reason for the toe-in at the front is to offset inner tire wear alittle bit driving on the street, and to keep the car a little more stable for my first season of track/auto-x with this car. I will be going for more extreme set-ups later I am thinking.

Maybe something like

0.0- +.20 toe in front


0.0- -.05 toe in rear

and maybe even less caster in front and less camber in the rear. I guess it is time for a tire temp. gauge now though.

On the caster adjustment, My cousin Eric Foss, who instructs at Panoz, said the less caster I run the more steering feel I get and better entry steering....with a lack of bump stability and some braking quirkiness. Is that how you read it?


Also, I am looking for other FD racers coimments and suggestions on a stable first set-up, and then what to adjust toward when i am feeling more comfortable with the limits of the car on the track.


Thanks guys =)

cpa7man

iTrader: (2)

This is a good old thread. https://www.rx7club.com/showthread.p...ghlight=pettit

Ni5mo180SX

Although im in an FC, im using -2.4/-2.6 F/R camber and 1/32-3/32 F/R toe in for street and track. Very neutral handling but they may have to do with the perfect front to rear and cross weight distribution as well as the sub 2600lb weight of my car.

The only thing id try changing up is increased rear toe in to 1/8th. Good luck!

ArcWelder

I'll just address this part of your post. Toe in at the front is for stability. On high speed tracks it reduces the tendency of the car to be "darty". On low to medium speed tracks you could use less or even 0 toe in. For autocross toe out may be preferred to induce some instability for quicker turn in. 0 toe at the rear is generally preferred to keep it neutral.

Most people prefer some toe in at the front for a dual use car meaning street/track for better straight line tracking on the street. Again, all things are a compromise.