3-Car Comparison

Submitted by John Coffey

> I was at a 2 day autocross driving school over the weekend and I had

> chance to ride in and drive a number of Solo street prepared 240Zs.

> What surprised me was how each one drove differently based on how the

> owners had the cars setup. Here's what I observed:

>

> Car 1

> Springs: High rate springs, 25lb difference between front and rear

> with the rears stiffer.

> Shocks: Tokico Illumina 5 way, set for stiffer rear compression.

> Sway bars: Low rate both front and rear.

> Tires: 225/50-15 Yoko RS2s.

> Differential: LSD with very high breakaway torque.

>

> Car 2

> Springs: Low rate springs, 100lb difference between front and rear

> with fronts stiffer.

> Shocks: Tokico Illumina 5 way, set for stiffer front compression.

> Sway bars: High rate both front and rear.

> Tires: 225/50-15 Yoko RS2s

> Differential: LSD with very low breakaway torque.

>

> Car 3

> Springs: High rate springs, 75lb difference between front and rear

> with the rears stiffer.

> Shocks: Tokico Illumina 5 way, set for stiffer rear compression.

> Sway bars: Medium rate both front and rear.

> Tires: 225/50-15 Yoko RS2s

> Differential: Open.

>

> Car 1 was very balanced while under power and could be easily steered

> with the throttle. Very responsive to throttle inputs up to a point,

> too much throttle for too long would induce a spin. It did not like

> trail braking into a corner (the way Bondurant teaches it) and would

> respond with lots of understeer. Turning and braking would also

> induce a lot of understeer. Corner entrances would either be perfect

> or completely screwed up. The understeer could be fixed with a quick

> blip of the throttle and (rarely) with the brakes. Corner exits were

> the fastest of the 3 cars (if you did the entrance right) because you

> could get the power down early. This car wanted to be driven with the

> throttle.

>

> Car 2 was also very balanced while under power but was more difficult

> to steer with the throttle. Preferred to be steered with the brakes.

> It liked trail braking into a corner which was the most effective way

> to get the back end around. Understeer was prevalent but could easily

> be fixed with the brakes or a lot of throttle. Easy to get a good

> corner entrance. Corner exits were fast but had to be controlled a

> bit with the brake and throttle at the same time. Not too responsive

> to the throttle, you had to put your foot into it to get a reaction.

> This car seemed to have the typical 240Z handling traits. Overall

> balance but you needed to left foot brake to control the understeer.

>

> Car 3 was biased more towards oversteer especially under power in a

> corner. Responsive to gentle throttle inputs but with the open rear

> if you went to far, you were gone. Car had a razor edge between power

> oversteer and spinning. Understeer was common but could be controlled

> with trail braking or throttle. Car was responsive to trail braking

> but less so than Car 2. Corner entrances were fast and the car could

> be balanced through he corner pretty well. Corner exits were almost

> as fast as the other two cars but it was a result of carrying more

> speed through the corner. You had to wait a bit before putting the

> power down.

>

> Now... the question is, which of these cars had the fastest time of

> the day with the same driver? Let's hear the pundit's guesses...

>

Next post has the answer........

Continued Article -- by John Coffey

> For those that are interested, here's the answer:

>

> Car 1 was the fastest with a time of 60.322 when driven by the driving

> instructor!

>

> But, Car 3 was second with a time of 60.389 and Car 2 was third with a

> time of 60.411 with the same guy driving them! Even in autocross

> those time differences are fairly small. The person who drove all

> three cars owns Car 2 so we can assume he got everything out of that

> car that he could. I own Car 1 and my best time of the day was a

> 61.312. I also drove Car 2 and my best time in that car was a 63.4xx.

> The owner of Car 3 had a best time of 59.7xx and he was the fastest of

> all the Z drivers. He didn't drive any of the other cars and was

> stuck in the 60.5xx range until he made a heroic last run of the day.

>

> What were the guesses from the two lists:

>

> Car 1 - 5 people

> Car 2 - 2 people

> Car 3 - No guesses

>

> Sorry, no prizes for the correct guesses.

>

> What do we learn from this? Probably that there is no one correct way

> to setup a suspension for autocross. A good driver can adapt to the

> capabilities and foibles of any car and quickly get the most out of

> it. There might be more ultimate potential in any one particular car,

> but it takes some time and practice to wring it out.

>

> Thanks for playing. We have some lovely parting gifts at the door...