Gear Ratio for Autocross - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Cuda7050 · 09-15-2013, 12:41 PM

The great thing about our Camaro's is they perform very well at the drag strip, road course and autocross at a very affordable price. My goal is to have a car that's runs mid 12's in the quarter mile while still being very capable on the road course and autocross.

I already have drag radials which are prone to bogging.I want to lower my 1/4 mile 60' times with gears. But I don't want to have to pull 3rd gear on the typical autocross course. The stock 3.45 LS3 rear ratio with stock tires will go 74 MPH in second gear. My Michelin Pilot Super Sports are shorter and will top out at 70 MPH in second. Searches suggest top speeds at the autocross to plan for are 60 or 65 mph

The question for autocross veterans is what's the typical autocross top speed that I should plan for?

tylerio · 03-22-2014, 09:57 PM

Cuda, you'll be fine. My SS has 3.91 gears and I've never had to shift to 3rd in autocross.

Cuda7050 · 03-22-2014, 10:12 PM

Hey thanks, I figured that thread was dead and buried.

600hp-lpe · 03-26-2014, 12:08 PM

I have hit 70 mph on some autocross tracks.

I have 3.73 rear gears with a 25.5" tall tire (hoosier A6). I use 2nd or 3rd gear - depending on course layout.

Primary function is autocross with my Camaro. - drags and road course as well.

Norm Peterson · 03-27-2014, 08:28 AM

Rather than plan for a specific speed at this point I'd spend a little time seeing what kind of speeds you're most likely to encounter, and gear for that (plus possibly a mph or two cushion).

All of that 2nd gear speed fine-tuning will still go out the window should you ever change tire size or step up to R-compound tires (that'll have you going faster everywhere at least because your corner speeds will get faster).

Norm

Cuda7050 · 03-27-2014, 03:37 PM

"Rather than plan for a specific speed at this point I'd spend a little time seeing what kind of speeds you're most likely to encounter, and gear for that (plus possibly a mph or two cushion)."

That's pretty much what I am trying to do. I need to know from others with more experience what speed I am most likely to encounter. I sounds like around 62-65 mph.

JDP Motorsports · 03-28-2014, 09:45 AM

The GM 1LE 3.91 gear set up works well at most autocross events. They are much better than the 3.45's but I am going to 7000-7200 RPM also... You wouldn't be disappointed with the 3.91's.

Kind regards,

Jordan Priestley
888.308.6007

09-15-2013, 12:41 PM	#1
Cuda7050 Drives: 2012 SS LS3 Join Date: Nov 2011 Location: NorCal Posts: 818	Gear Ratio for Autocross The great thing about our Camaro's is they perform very well at the drag strip, road course and autocross at a very affordable price. My goal is to have a car that's runs mid 12's in the quarter mile while still being very capable on the road course and autocross. I already have drag radials which are prone to bogging.I want to lower my 1/4 mile 60' times with gears. But I don't want to have to pull 3rd gear on the typical autocross course. The stock 3.45 LS3 rear ratio with stock tires will go 74 MPH in second gear. My Michelin Pilot Super Sports are shorter and will top out at 70 MPH in second. Searches suggest top speeds at the autocross to plan for are 60 or 65 mph The question for autocross veterans is what's the typical autocross top speed that I should plan for?

03-22-2014, 10:12 PM	#3
Cuda7050 Drives: 2012 SS LS3 Join Date: Nov 2011 Location: NorCal Posts: 818	Hey thanks, I figured that thread was dead and buried. __________________ Buttonwillow 2:23.736 Sacramento Raceway 12.89 at 112 mph Thunderhill 2:22.242

03-27-2014, 03:37 PM	#6
Cuda7050 Drives: 2012 SS LS3 Join Date: Nov 2011 Location: NorCal Posts: 818	"Rather than plan for a specific speed at this point I'd spend a little time seeing what kind of speeds you're most likely to encounter, and gear for that (plus possibly a mph or two cushion)." That's pretty much what I am trying to do. I need to know from others with more experience what speed I am most likely to encounter. I sounds like around 62-65 mph. __________________ Buttonwillow 2:23.736 Sacramento Raceway 12.89 at 112 mph Thunderhill 2:22.242

03-22-2014, 09:57 PM	#2
tylerio EXTREMZ Drives: 2015 Z/28 #891, 2012 2SS 45th Anni Join Date: Jul 2012 Location: Southern Utah Posts: 131	Cuda, you'll be fine. My SS has 3.91 gears and I've never had to shift to 3rd in autocross.

03-26-2014, 12:08 PM	#4
600hp-lpe Drives: 2010 Join Date: Jul 2009 Location: NH Posts: 4,788	I have hit 70 mph on some autocross tracks. I have 3.73 rear gears with a 25.5" tall tire (hoosier A6). I use 2nd or 3rd gear - depending on course layout. Primary function is autocross with my Camaro. - drags and road course as well.

03-27-2014, 08:28 AM	#5
Norm Peterson corner barstool sitter Drives: 08 Mustang GT, 19 WRX Join Date: Jul 2012 Location: Eastern Time Zone Posts: 6,990	Rather than plan for a specific speed at this point I'd spend a little time seeing what kind of speeds you're most likely to encounter, and gear for that (plus possibly a mph or two cushion). All of that 2nd gear speed fine-tuning will still go out the window should you ever change tire size or step up to R-compound tires (that'll have you going faster everywhere at least because your corner speeds will get faster). Norm

03-28-2014, 09:45 AM	#7
JDP Motorsports Drives: 2011 Camaro SS/ 2016 Camaro SS Join Date: Jun 2009 Location: Sandy, Utah Posts: 3,256	The GM 1LE 3.91 gear set up works well at most autocross events. They are much better than the 3.45's but I am going to 7000-7200 RPM also... You wouldn't be disappointed with the 3.91's. Kind regards, Jordan Priestley 888.308.6007