Horsepower is the holy grail of high performance. We love it. We want more of it. We can never seem to get enough of it.
So why do many people waste horsepower once they find it?
In the seemingly endless search for more horses, muscle car and race enthusiasts often squander existing horsepower by using an improperly sized ring and pinion gear set. The right gear set will help transfer more power from the engine to the asphalt, improve engine acceleration or top-end speed (depending on your vehicle’s purpose), and play a large part in the final cruising rpm of your vehicle.
That’s why more and more gearheads are benefitting from gear swaps. You can, too. We’ve outlined four key factors you’ll need to consider when choosing a ring and pinion set. Armed with this information, your sales rep will be able to help you harness more horses with the right gear set.
1. Rear-End Type
First, you’ll need to tell your sales rep your rear-end type. There are two main types of rear-ends: conventional and banjo-style.
Also known as “integrated,” conventional rear-ends usually consist of a bolt-on style cover and C-clip axles. Common conventional rear-ends include the GM 10- and 12-bolt, Dana, Ford 8.8-inch, and Chrysler 9.25.Banjo-type rear-ends usually include bolt-in axles and a completely removable center section, or third member, which is loaded from the front of the housing. Some examples of banjo-style rear-ends are Ford 8-inch, Ford 9-inch, Chrysler 8.75-inch, and GM 8.2-inch.
2. Series of Carrier
To determine which gear sizes are compatible with your current rear-end setup, you need to know the series of differential carrier, especially when dealing with GM and Dana applications. The carrier is the internal portion of the differential that is attached to the ring gear and is responsible for the distribution of power between wheels. Carriers are categorized by series, and the easiest way to determine differential carrier series is to simply look at your original gear ratio.
If you don’t know your current gear ratio, the easiest way to calculate the ratio is by using the following formula:
Number of ring gear teeth/number of pinion gear teeth
Example: 39 ring/11 gear teeth=3.54 ratio
Most gear manufacturers will give a range listing of what gear ratios go with each series of carrier. In general, the carrier series follow these guidelines:
- 2-Series Carrier: 2.73-Lower Gear Ratio
- 3-Series Carrier: 3.08-3.90 Gear Ratio
- 4-Series Carrier: 4.10-Up Gear Ratio
Typically, you’ll want your gear ratio to match the carrier series, but you may be able to use a higher gear ratio range with your current carrier by using a ring gear spacer (pictured at right). For example, a ring spacer may allow you to use a 3.08-3.90 gear ratio with a 2-Series carrier. However, you should never have more than a one series difference between the gear ratio and the carrier. For example, never use a 2-Series carrier with 4-Series gear ratio.
3. Vehicle Purpose
With your rear-end type and carrier in mind, you can now zero in on your desired gear ratio. Ask yourself: What is the purpose of my vehicle? This information will help determine a general range for your optimum gear ratio. Here are some general guidelines:
- Daily Driver: 2.55-3.23 Gear Ratio
- Street/Strip: 3.42-3.90 Gear Ratio
- Race: 4.10-Up Gear Ratio
Your sales rep will be able to help you find the gear ratios and components you need, but you can also narrow down your choice using this Gear Ratio Calculator found at SummitRacing.com.
4. Gear Style
There are two basic styles of aftermarket gears: performance and pro.
Performance gears are ideal for most street, strip, or off-road applications. They are made from hardened steel and are much more durable than stock. This allows them to handle higher torque applications. Chances are your application is a perfect candidate for a performance gear set.
Pro gears, like the ones offered by Strange Engineering, are for drag racing only. These gears are softer than a performance gear, so they can absorb the torque impact of the engine. However, the softer design of these gears will cause them to wear out more quickly than performance gears.
Here’s one last bonus step: call Summit Racing’s full-time technical staff at 330-630-0240 if you have any questions. Just make sure you’ve taken the first four steps to lay the groundwork for choosing the right ring and pinion.
[…] Also, you can read our earlier post on how to choose a ring and pinion in four steps. […]
How can I find 2.55-3.23 for my 1971 BMW e10 m10 or what do I have to do to get low set of gear.
It’s nice when an article addresses a topic that I’d previously made a decision about based solely on “gut feelings” and it turns out I made a perfect choice.
3.42:1 rear-end FTW!
Doesn’t the transmission final gear ratio also play into this decision especially given the number of OD transmission swaps going on?
I agree, Joe. Looks to me that the guidelines listed apply only to a 1:1 final trans ratio.
I totally disagree with ur gear selections based on vehicle purpose. I run a 4.33 ring and pinion in my street driven chevelle with a turbo 350 trans and 29 inch tall tires. Its the perfect street gear. The car spins around 3200 rpm at 60mph. With the 3800 stall non lockup torgue convertor. I run a can shaft with a 2000 to 6000 rpm range. If u go by the cam manufacturer recommended minimum gear ratio. Just remember this is based off a 26 inch tall tire. Mine was 3.90.
Ur right. My 65 Chevelle has a 4.88 with a 30″ tall tire. Cam is a comp 274s xtreme energy with a 2000-6400rpm range. Turbo 350 with a 3,000 stall . 65mph is around 3500rpm. Ran a 4.11 in my daily driven 87 Monte Carlo with a turbo 350 and a super street fighter convertor. Loved that combination. I’m not afraid of cruising the highway spinning 3500rpm and getting 10mpg. Street racing requires more gear because u are only running stop light 2 stop light
My 81 camaro does fine with 4.10 gears running a 454 backed by a Th400 with a 3800 stall. I don’t generally drive it very far on the street bit it does fine driving around when it does see street time. I’m running a 29 in tire on it though
Ive bought many parts from summit including rear end gears and there tech guys always make sure that you know what you are buying and how it should or should not be used. Never had a problem with any recommendations:-)
[…] hear more about choosing gearing for your vehicle. Then you can take a more in-depth look at How to Choose a Ring and Pinion in 4 Steps, and then check out our video showing you a step-by-step gear swap from the experts at Motive […]
[…] How to Choose a Ring and Pinion in 4 Steps […]