Perk,

You said something in your list that is THE SINGLE MOST IMPORTANT bit of tuning advice. I real bit of wisdom that I have long since learned to live by... Do you know what it was?

Tune ONE THING at a time.

It is a chassis tuner's creed. Basic setup aside, dialing in for a specific track or handling characteristic is much easier and more consistant when you make one single change at a time and mark its effect. That way you know if it helped or hurt.

I see alot of guys that change tire pressure, adjust camber, adjust toe and change the weight package and then when the car starts behaving badly, they GUESS on what adjustment is at fault.

Even Tire Pressure is an adjustment. Tire Pressure is a component of supension. Softer tires are in effect, small adjustments to your shocks as well as greatly affecting grip levels. Tire compounds as well.

While we are on the subject of compounds, I have found that while a BFG Comp T/A is a pretty good track tire, it is only good to a point... then it gets really bad really fast. Plus, once they break traction, they are really really hard to get back and the break traction suddenly!

Yokohama AVS Intermediates on the other hand have just a bit less lateral grip than the T/As but it's totally and completely predictable. When they break traction, they slide very slowly and are much more able to be brought back with throttle control. Plus, if there ever was a tire to help out the driftability of the Fiero, I think the AVS Intermediate is that tire... You still can't drift that well but it IS much easier with them. Down side is that you can really eat up a set at the track.

Just thought I'd throw that in there to complicate things

See you all at the track!

DKOV -
DMS

quote Originally posted by 84Bill: Will I was mulling over your tire size theory. I dont know if you considered that a tires side load grip changes with rotational speed. In other words a nonrotating tire will have more lateral grip than a tire rotating at 1100 rpm. I wonder if there is a mathmatical formula to determine the percentage of slip for a given load and tire RPM. Bill

Irrelevant. It affects all 4 tires the same way, unless you're running grossly different diameters front to rear.

quote Originally posted by Will: Irrelevant. It affects all 4 tires the same way, unless you're running grossly different diameters front to rear.

Ahh
That makes sense

Oops, too late. my 2M4 has a battery moved to the front. Of course there will be a 4.9 in the back later. With more weight up front I am closer to the magical 50/50 weight bias, even though I hear that's not always desirable. What I did do was put in poly bushings and end links on the front sway bar. I don't see a need for a rear bar yet until I get that motor into the back. Now, I have a new question... the Cadillac had a larger diameter wheel/tire that I would mimic for the visual balance with the bigger rear wheel gap. (15's front/16's rear).

So what is the effect and how does one compensate for the larger rear wheels (height)?

I'm advocating lowering the rear suspension
half an inch lower than the front but with taller tires/rims out back to bring the car level. A RCC bump steer correction kit once I get that on (with the V8).

quote Originally posted by 84Bill: One other thing perk Before you go spending loads of money chasing down these theories try running the car with all that stuff (trunk carpet ect. ect.) removed and check the results against a simmular suspension setup with all that heavy stuff in place. Basicly set basic suspension up and record the corner speed and G if possible then lighten the rear and go again...

I am going to try to document as much of the process as possible. You will be able to follow my progress here on PFF (just look for upcoming threads with "Lab Rat" in the title) and on my site (eventually I will have a whole section dedicated to the Fiero).

perk - todd's hot rods

[This message has been edited by perkidelic (edited 07-30-2003).]

quote Originally posted by 84Bill: "why does the Fiero rear step out so unpredictably?" Inexpierence There are literally a million reasons why, they range from the ground and end at the drivers head and every tangable thing in between and even the intangable thought process of the driver. Ultimatly it is the responsibility of the driver to recognize and prevent it from happening. [This message has been edited by 84Bill (edited 07-27-2003).]

Amen.

4 or 5 years ago (can't quite remember when I got my car now, it's like a member of the family. ).. anyway...

The first week I had my car, I hadn't quite put new tires on it.. (bald) it was raining, I jumped it a little too fast going into second making a LEFT hand turn off a traffic light.. broke it loose.. Not only was this my first mid-engine car, but my first time losing traction in a rear-drive car (BAAAD combo).. hit a curb..

Needless to say, that was a few years ago, my driving skills have greatly increased to the point where I can break it loose in a similar situation and generally keep the car going the right direction.

Best thing I ever did was take my car to a LARGE empty parking lot in the snow one year, and took about a half tank of gas that day learning how to handle traction loss.