A Class

[JG4tr]

This thread will contain setups and discussions for the A class cars

[JG4tr]

First on the menu:

1998 Tommy Kaira Subaru M20b

The TommyK seems to be among the best overall AWD performers in A class that do not have their origins in a powertrain swap. It has been a couple of months since I was running the grip tracks over in Exhibition mode and that was before I started documenting my builds and setups on paper so, I had to get back into the game for this one.

The fact that I had run Suzuka in Exh with the then under development Audi S4 V8 and the fact that it hadn't stretched its legs for awhile led me to take it out for a spin before posting the setup. I'm glad that I did. If you've ever gone back to a car that you tuned up months ago and been surprised by the handling characteristics, you understand why.

No doubt that I had grown accustomed to it and drove it in such a way as to compensate for its less than stellar tuning. I made some quick adjustments to the gearing, alignment and most significantly the Diffs to get the car a little closer to where it should be. It had a pretty bad throttle lift understeer which some more rear diff decel took care of for me. I reran the Suzuka Exh race and took almost 7 seconds off my Audi time.

I figured as long as I was futzing with the thing, I would take it back to the upgrade shop and see how it might do with some alternative builds. It was originally built out as a pure grip build with all stock powertrain ( 350HP ) and full racing platform. Weighing in at 2416lbs with the lightest 20"Volk rims and Pirelli slicks it ratings of speed 5.0, accel 5.4 and Handling 5.9 @ PI849. I 'downgraded' to 19", slightly heavier Volk se37k rims and was able to upgrade two tire brands to the Hoosiers which brought me to an even 850PI @2420lbs but increased handling to 6.0 so, this would be my revised grip build.

I tried alternatives like going to BFGoodrich DOTs and adding sport cams for an increase in power to 384. This resulted in stats of 5.2,5.7 and 5.6 which turned out to be about 1.5 seconds slower at Suzuka.

I then tried a Goodyear slicks, sport weight, sport cams and race fuel which netted 405HP and stats of 5.4, 5.3 and 5.8 @ 2828lbs. This was an improvement at closer to 0.5 seconds off the pace of the Suzuka grip build so, maybe a possibility for a slightly more power oriented track as is an untested option of just reducing the tire widths and adding a couple of extra HP to fit.

For Suzuka however, the full grip build seems to be the way to go for this car. I will do a little more tweaking over the next couple of days to see if I can continue to improve the handling any more before posting the full build / tune specs.

[JG4tr]

I've made some pretty significant changes to the tune on my TommyK since it's previous runs in Exhibition mode. Interesting what a few additional months of tuning experience and perspective can do for you...

The most significant changes came in the form of suspension and Diff settings. The rebounds got softened and the spring percentage increased to improve response. I also added more spring and reduced bar on the front to improve turn-in and contact patch. Then I reduced the front diff accel and reproportioned the torque split from a rear bias of 45/55 to an even 50/50, all contributing to a more 'neutral' package.

The Build

     Powertrain: Bone stock to leave PI for all those grip goodies
     Platform: Full race from soup to nuts
     Aero: Forza race for all three components
     Rubber & Rims: Hoosier 255/30R19 slicks front & rear on Volk SE37K rims
     350HP & 2420lb curb weight, PI850

The Tune:

Tire Pressure:
     Front: 29
     Rear:  30
Gearing:
     Final Drive: 3.63
     (1): 3.33
     (2): 2.05
     (3): 1.49
     (4): 1.23
     (5): 1.05
     (6): 0.93  ( not used )
Alignment:
     Camber Front:-0.5
     Camber Rear: -0.5
     Toe Front:0.2
     Toe Rear: 0.2
     Caster:    6.0
Anti-Roll Bars:
     Front:  07.74
     Rear:   38.00
Springs:
     Front: 361.2
     Rear:  512.0
Ride Height:
     Front: 3.9
     Rear:  3.9
Dampers:
     Rebound Front: 8.0
     Rebound Rear:  6.8
     Bump Front: 3.4
     Bump Rear:  3.4
Aero Adjustment:
     Front: 125  max
     Rear:  165
Brake Bias:
     Bias:       44 %
     Pressure: 80 %
Differential:
     Front:
         Accel: 25%
         Decel:  0%
     Rear:
         Accel: 50%
         Decel: 50%
     Split:  50 / 50

This works out to be a weight bias of 41.4% @ 72.2% springs

The engine has a medium width powerband which is strongest between 6000-7500RPM so, I wouldn't rule out gearing it as a six speed but, as with most AWDs, the Tommy doesn't shine at the high end of the speedometer so, it might have very limited applications.

Also, the springs are a little firmer than usual for me. I've felt for awhile now that softer suspensions are more forgiving of my driving style, allowing me to recover quickly from small mistakes without losing much time. A firmer setup can improve potential performance but, also seems to narrow the line between in and out of control. It also seems that once you step over that line , it costs you more time trying to get back. Maybe I should just learn to drive smoother... In any case, the car was originally run at about 71% springs, for those who might be curious and the diffs should provide some good opportunities for adapting the car to various driving styles.

It's no missile to be sure but, should be a good choice for grip tracks. I was able to run it in its current form last night, further improving my Suzuka Exhibition race time and it's spot on the hotlap leaderboard.

[fndrbndr]

Interesting build.  I wouldn't worry about making this a speed car, as it's AWD, but if you want more speed, putting more power on the rear wheels might help. 

[JG4tr]

I'm afraid that 350HP just isn't enough to make this a true high-speed car, no matter how you divide that power up. It looks as though the RS4 that Bimmer has posted benches out pretty well for speed tho...

[Ske]

I've been running the Mitsubishi GTO in A, and it looks like it could be a decent alternative if you want an AWD with a bit more "go". I still think the R34 Skyline has potential as well, but I can't get it to perform as well as the top cars in class. It's not horrible but it's a good half second off the Evo 8's pace.

If drivetrain isn't a concern I'd recommend looking at the Saab 9-3 for a good intermediate car.. it'll pack about 480HP at 2400 odd lbs on 245 Avons (probably close to 500 on "lesser" slicks/heavier wheels), so it should be pretty fast. The handling's not top notch, but it's decent enough.

[JG4tr]

Thanks for the suggestions Ske, The Mits GTO should have a higher top speed due to it's smaller frontal area and reduced aerodynamic drag compared to the Subaru. The Saab, I might not have considered in A class until you mentioned it but, for a RWD car, I've got a Nissan Fairlady Z Version S twin turbo to try out first.

[Snyder005]

I find it's interesting that you feel more at home driving a grippy car on Suzuka.  It's representative of the different driving styles and is what makes it such a great game.

For this track i found that, like Mugello, my fastest times came from unrealistic power builds.  Suzuka East is scary trying to keep that much power on the ground though, lol.

I would suggest moving the torque balance more toward the rear, as that's where the weight is transferred under acceleration and it should help some.

[JG4tr]

Before I re-tuned the car to it's posted state, I was running a significantly more rear-biased torque split. I enjoy an AWD with a RWD flavor to it but, felt that a more neutral handling 50/50 split had more consistant handling characteristics and might be better suited to others.

In an AWD car, the diffs can have a pretty significant effect on driving characteristics and are good for driving-style type adjustments. For other drivers, the posted setup might be just a good starting point that they may want to 'season to taste'...

Thanks for your suggestions.

[Snyder005]

"season" -you mean like  "I'll have some garlic and maybe some other spices".  Now i'm hungry 

jk, lol.