Autocross Setups

[Conedodger]

Season is starting up and SCCA will be in full tilt for the whole country in about 6 weeks. After doing a hard fought season last year, here seems to be nominal LEGAL setups for appropriate classes (note that the R is SS class due to tires and no back seats):



For you Track Pack, R, and '17+ guys, run in Sport mode, all nannies off. Track is too stiff.

I played around with shock settings and found that the car worked best on the stiffest settings. Would not put down power or transition well in normal mode.

I am still fighting with entry and middle loose but I changed the rear camber and rear toe in and hope to test at a local TnT this weekend.

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[Mach4.6]

If just stock, what's the class to run in for the GT350?

Stock GT350's run in "AS"

 

[Mach4.6]

Season is starting up and SCCA will be in full tilt for the whole country in about 6 weeks. After doing a hard fought season last year, here seems to be nominal LEGAL setups for appropriate classes (note that the R is SS class due to tires and no back seats):

A-Street

• Adjustable front swaybar at full stiff
• Upgraded front endlinks
• Bridgestone RE71R 305/30-19 square (just do it, 10.5 vs 11 makes zero difference on small courses, trust me)

CAM-C (light setup)

• A-Street
• Caster camber plates, punch everything full out as much as you can
• 19 x 11 wheels square
• Upgraded vertical links
• Rear alignment kit

CAM-C (heavy setup)

• CAM-C (light setup)
• Rear cradle lockout kit
• Bump steer correction kit

Modified

• CAM-C (heavy setup)
• Rear seat delete
• 19 x 11 wheels front, 19 x 12 wheels rear
• Hoosier A7 315/30-19 front, 325/30-19 rear
• GT350R wing or equivalent, not to exceed 8 sq ft surface area
• GT350R front splitter
• Heavy duty brake pads of your choice

Do NOT upgrade power or dial back your tune to a street related or milder tune. When you're coming out of corners, you often end up right in the meat of the torque shift around that 3200 - 4000 RPM range. It's hard to modulate and the last thing you need is more power for course running (on autocross, track is a different story).

Do NOT touch the rear sway bar except for the end links when legal. Remember autocross surfaces are rather imperfect and too much stiffness can throw you off.

For you Track Pack, R, and '17+ guys, run in Sport mode, all nannies off. Track is too stiff.

Happy hunting. You're still gonna lose to an S2000 after index... :doh:

R's can run in CAM-C also
Just finished the CAM Challenge down in San Diego

 

[nastang87xx]

I am still fighting with entry and middle loose but I changed the rear camber and rear toe in and hope to test at a local TnT this weekend.

Use Sport mode if you're having trouble in mid corner instability. The throttle response is also the same in Sport as in Track. Check your autocross surface. If there's a lot of imperfections and bumps and cracks, use Sport mode. Track wants smooth ideal conditions on the road.

 

[nastang87xx]

R's can run in CAM-C also
Just finished the CAM Challenge down in San Diego

Really...? I thought the PSC2 tires were illegal since they're 180 wear.

 

[Mach4.6]

Really...? I thought the PSC2 tires were illegal since they're 180 wear.

They are, I'm running Bridgestone RE-71R's now, much better for AX
Far as set up, I qualified 3rd, out of 16 in my stock R, .100 off a first and I'm a rookie still learning AX, the car has the potential for sure to win as is.
The field was mostly modded Camaro's, with 2 National Champions

 

[Conedodger]

Use Sport mode if you're having trouble in mid corner instability. The throttle response is also the same in Sport as in Track. Check your autocross surface. If there's a lot of imperfections and bumps and cracks, use Sport mode. Track wants smooth ideal conditions on the road.

In sport mode it was worse. Surface was very smooth. I think the fact that the car had .33 rear negative camber and zero rear toe was the real problem.

 

[nastang87xx]

In sport mode it was worse. Surface was very smooth. I think the fact that the car had .33 rear negative camber and zero rear toe was the real problem.

What tires are you on?

 

[Conedodger]

Bridgestone RE71 R 305-30 Square. 28 rear, 34 front. And yes it was better at 28 than 29 or 30 rear.

 

[nastang87xx]

Conedodger
Member


Drives: 2015 S550 PP


Are you on a GT or a GT350?

 

[Conedodger]

I knew you would ask so I updated my info ;-)

 

[nastang87xx]

I knew you would ask so I updated my info ;-)

Lol, well played. Easy on the throttle I guess. I don't know really. Are you allowed to quick spin the tires at the start for some heat? Plus if you're on an R the rear end is super light in comparison to the front. I found that a lot of courses I run on, I'm deep in the gut of the torque band in a lot of corners and I have to be extra careful feeding the power in especially on maintenance throttle. If you're sweeping at 4000RPM and you goose it, you better hold on. For perspective, at that RPM range, you're twisting out as more torque than an LS3 is and with shallower gearing.


[ame]

 

[Conedodger]

I am going to do a lot of testing this weekend. I am considering putting the non R rear sway bar on the car. I already have one and will be swapping it and doing a little A B A testing.

I know what you mean about the wheel spin. I was a little aggressive with the throttle on one run and carried the wheel spin off the corner and to the braking point in the next corner 200 feet down the strait.

 

[TDC]

I like this GT350 specific autocross thread.
Anyone experience in a tight track with fast changeovers between gas, brake and fast steering input the tendency for the electronics to glitch and put the car into normal mode??

BTW, I am nearly 100% certain that Sport mode has more aggressive throttle mapping. Need to remember where I got that info.

 

[nastang87xx]

I like this GT350 specific autocross thread.
Anyone experience in a tight track with fast changeovers between gas, brake and fast steering input the tendency for the electronics to glitch and put the car into normal mode??

It's happened to me twice on the same day. Hasn't happened since. I don't know if maybe the exhaust actuators got knocked around and freaked out the computer or...

The dual mode exhaust system is super critical for the drive modes to work correctly.

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