Quick-change rear ends, born from the high-stakes world of circle track and drag racing, have rapidly become a favorite among street and strip enthusiasts. Their ability to quickly swap final drive ratios through a simple gear change has long been indispensable for racers seeking optimal performance on varying tracks. This adaptability also benefits hot rodders, allowing them to seamlessly transition between highway and race gearing. This article provides an in-depth look at gear types and an overview of how quick change rear ends function.

What Is a Quick Change Rear End?

The basic principle behind a quick change is straightforward: an additional set of gears is positioned between the driveshaft and the differential at the rear end. These extra gears can be easily swapped out to adjust the final drive ratio depending on how and where you're driving. Racers of all types—including short track, drag, and drifting—can optimize their car's power delivery at specific points on the track by using quick change gears for precise adjustment. And for hot rodders, it means you can quickly switch from a daily driving-friendly ratio to something way more aggressive for those stoplight showdowns or quarter-mile runs.

How Does a Quick Change Rear Work?

A quick change rear end still utilizes the ring and pinion final drive ratio, but incorporates a pair of quick change spur gears. One spur gear is driven by the driveshaft, and the other is connected to the pinion gear. You can get to these gears through a removable rear cover and change the ratio in minutes, making it exceptionally handy.

To explain deeper, think about a regular, fixed-ratio rear end. The driveshaft connects to the rear with a splined yoke that combines with the pinion gear. Power is transmitted to the rear axles and wheels as the pinion turns the ring gear, which is bolted to the differential or spool.

In a quick change rear end, the driveshaft yoke connects to a lower shaft that's splined on both ends and extends from the front to the back of the rear. A change gear slides onto the splined end of that shaft at the back. Positioned directly above the lower shaft and running parallel to it, the pinion enters from the back of the rear. Another change gear slides onto the splined end of the pinion and connects with the first gear on the lower shaft. The pinion then drives the ring gear, similar to a fixed-ratio rear, transferring power to the track or street through a differential, spool, or live axle.

Quick Change Rear End Gears

There are many different gear ratios available, from 1.20s all the way up to 9.14s and even higher from some manufacturers. The ratios have tiny differences, so racers can make the perfect adjustment to get the most power out of their engines based on the track they're running and the conditions at race time.

Most racing teams have a huge collection of gear sets for any track they race on. Divers who run quick change equipped street cars that don’t hit the track, or only occasionally do autocross or drag, only need one or two sets. Sometimes a single gear set can be flipped upside down to totally change how the car drives. One popular gear set, when installed one way in these rears, can create a 4.11 final drive ratio. Flipping the same gear set over produces a 3.48 final drive ratio. Changing gears on a quick change rear end takes approximately 10-15 minutes for the typical hot rodder, and only a few minutes for seasoned racers.

How To Choose the Right Quick Change Gear

When choosing quick change gears, remember that different brands use different materials, have different machining tolerances, and gear finishes. Think about the gear quality based on factors like how you'll use them, wear and tear, and your budget. If you're just driving your car on the street and not putting a lot of miles on it, you probably don't need the best gears out there. But if you're racing every weekend and pushing your gears to the limit, you'll want something more durable. Some of the best racing brands out there are Winters Performance, SCS Gearbox, and PEM Racing—they make tough and reliable quick change gears.

Winters Performance quick change gears are machined properly and are more affordable and dependable than other brands, making them ideal for budget-minded racers and those who need multiple sets.

PEM Racing produces mid-priced quick change gear sets constructed with high-quality materials and designed for affordability. The gears feature REM polished faces and lighting holes to minimize friction and enhance performance.

SES Gearbox is the go-to choice for racers seeking premium quick change gears because of their excellent reputation and track record. Although they cost a little more upfront, they are more durable and last longer under heavy loads and high horsepower, saving you money over time.

Quick change rears can make a difference in how you run on race day. Trust Behrent’s Performance Warehouse for quick change rears from the best brands on the market.