Here is an article from our blog that should be helpful for those of you considering a gear swap. All of the information concerning cruising RPM and torque gain are included. Feel from to shoot me a PM if you have any questions.
Swappin’ Gears
Added Dec 31, 2010, Under:
Camaro
Warning: Installation of rear end gears should only be performed by professionals.
As owners of the 5th generation Camaro continue their pursuit of more performance, many are swapping to a more aggressive set of rear end gears. While not an inexpensive modification, the bang for your buck with a rear end gear swap is hard to beat and the improvement in performance is dramatic. Making this sort of modification can be intimidating because many people don’t understand differentials and gearing. In this post I will try to provide some basic information to at least try and help get you pointed in the right direction.
How It Works
The rear differential is the device that transmits torque and rotation from the driveshaft to the rear axles which then drives the rear wheels. The rear end gears contain a ring and pinion gear that can be swapped to different ratios. The stock Camaro comes with either a 3.27 (all V6 models and the automatic SS) or a 3.45 (manual SS) rear end gear ratio. This means that for every 3.27 or 3.45 rotations of the drive shaft your rear wheels will turn once. A lower gear ratio means increased torque and increased acceleration without the engine having to create any additional power.
This all sounds great but the are some potential draw backs. A lower gear ratio means that your engine has to turn faster at cruising speeds which means fuel mileage can suffer. In the case of the 5th generation Camaro, the new six speed transmissions help mitigate the impact of this. Camaro owners that do a lot of highway miles have been reporting a loss of about 1-2 MPG, while those who drive mostly in town are reporting no change and even an increase in some cases due to the engine not having to work as hard to get up to speed.
The other potential draw back is that a lower gear ratio will shave away top end speed. This is not important to the average Joe since the Camaro is capable of speeds well beyond the speed limit right off the showroom floor, but for competitive drag racers it can be. It is possible that while the lower ratio will cause your car to accelerate faster it can also cause you to have to shift gears one more time before you cross the finish line, potentially sacrificing the gains made. Careful calculations should be made when selecting the correct ratio for these sorts of applications.
The Numbers
Camaro V6 Models
Currently, there is only one gear ratios made specifically for the 5th generation V6 Camaro. For the V6 Camaros Richmond manufacturers a 3.55 gear ratio. With the stock 3.27s the automatic (A6) equipped V6 runs 1750 RPM at 70 MPH. Swapping to the 3.55s provides an equivalent torque gain of approximately 10% or 27.3 ld.-ft. of torque at the rear wheels and will raise 70 MPH cruising RPM to 1949.
The V6 Camaros equipped with the manual transmission (M6) come with 3.27s and run 2000 RPM at 70 MPH. Swapping to the 3.55s provides an equivalent torque gain of approximately 10% or 27.3 ld.-ft. of torque at the rear wheels and will raise 70 MPH cruising RPM to 2167.
The rear end in the M6 equipped V6 Camaro is similar enough to the SS that their gears will also work. Apex Motorsports recently had a customer install Richmond 3.73s in his car. The result was an equivalent torque gain of approximately 15% or 41.2 rear wheel lb.-ft. of torque at the rear wheels and will raise 70 MPH cruising RPM to 2277.
Camaro SS Models
The Camaro SS models currently have three aftermarket gear ratios available for them; 3.73, 4.11, and 4.33. When equipped the the automatic transmission (A6) the SS comes with a 3.27 rear end and cruises at 1795 RPM at 70 MPH. By upgrading the factory 3.27s in the stock A6 equipped Camaro SS to the 3.73s you will realize an equivalent torque gain of approximately 15% or 61.5 rear wheel lb.-ft. of torque and cruise at 2050 RPM at 70 MPH. By upgrading the A6 to the 4.11s you will realize an equivalent torque gain of approximately 27% or 110.7 rear wheel lb.-ft. of torque and cruise at 2250 RPM at 70 MPH. By upgrading the A6 to the 4.33s you will realize an equivalent torque gain of approximately 33% or 135.3 rear wheel lb.-ft. of torque and cruise at 2377 RPM at 70 MPH. The A6 transmission is geared more aggressively than the M6 SS so we have found that 3.73 is the ideal gear for most A6 equipped SS applications.
When equipped with the manual transmission (M6) the SS comes with a 3.45 rear end and cruises at 1612 RPM at 70 MPH. By upgrading the factory 3.45s in the stock M6 equipped Camaro SS to the 3.73s you will realize an equivalent torque gain of approximately 10% or 42 rear wheel lb.-ft. of torque and cruise at 1750 RPM at 70 MPH. By upgrading the stock M6 equipped Camaro SS to 4.11s you will realize an equivalent torque gain of approximately 20% or 84 rear wheel lb.-ft. of torque and cruise at 1915 RPM at 70 MPH. By upgrading the stock M6 equipped Camaro SS to 4.33s you will realize an equivalent torque gain of approximately 25% or 105 rear wheel lb.-ft. of torque and cruise at 2025 RPM at 70 MPH. We have found that the 4.11s are the ideal gear for most M6 equipped SS street applications. Once the 550-600 rear wheel horsepower range is reached we recommend dialing back to 3.73 unless the vehicle has a very solid suspension package and a very competent driver.
Make It Happen
Hopefully, the information in this post has helped you better understand gear swaps. If you think a gear swap may be right for your project be sure to consult a professional during your decision making process.