Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (2024)

Quick Change Gear Chart

Traditional rear axle assemblies use a fitted ring and pinion gear ratio that many consider a compromise, especially for dual purpose vehicles. Having 4.86 gears is great for the drag strip, but not so great for hitting the Hot Rod Power Tour for example, where a 3.24 gear might be more suitable for road use, fuel economy, and driveline rpm. What if you could truly live the best of both worlds by utilizing a quick change gear setup? That’s exactly what you can do with a quick change gear rear end.

This 10-spline quick change gear chart shows just how many gear ratio options are available simply by changing the upper and lower spur gears (or even swapping them from top to bottom).

So, how does a quick change rear end work? The quick change gear still uses a ring and pinion final drive ratio, but a pair of quick change spur gears (the lower driven by the driveshaft’s input and the upper connected to the pinion gear), accessed via a removable rear cover, allows you to easily change the ratio in minutes. Popular in circle track racing, quick change rear end components have seen tremendous growth for street and strip use as well.

Quick Change Rear End Diagram

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (2)

The quick change rear is easy to spot under a hot rod or race car due to the distinguishing housing design, as seen here in this quick change rear end diagram courtesy of Winters Performance Products.

We also offer a laminated 11x17-inch quick change gear chart that is perfect for your trailer, toolbox, or shop wall to help in determining the proper spur gear set number by final ratio in both low and high gear fitments.

10-Spline Quick Change Gear Set Interchange

Due to the 10-spline quick change gear set ratios available, you don’t have to worry about using only a certain brand of spur gears. This is because they are all machined to the same specs to fit the quick change rear housing. So, no matter if you use Winters Performance, Speedway Motors, , or PEM Racing gears, they are guaranteed to work together, allowing you to mix and match for the exact ratio you need based off of the typical quick change gear chart. This standardization means that even if you’re running one brand of gears you can source a different brand in a pinch and not have any fitment issues.

Quick Change Gear Ratio Formula

The idea behind the quick change axle gears is to allow on the fly gear ratio changes to suit the needs of the driving or racing application, or to facilitate engine or driveline upgrades, or changes to tire height. Any of these changes will affect the final drive ratio and rpm of the engine. Using the quick change gears to bring the engine back into its “sweet spot” of rpm use is the whole idea here. Unlike the traditional 9-inch Ford that requires swapping out the whole center section for a gear change, you can simply remove the rear cover, pop in two different quick change spur gears for the ratio you need, top off the diff oil and you’re good to go. But how do you know what quick change gear ratio you need in the first place?

Most quick change gear axle housings utilize either a 4.11/4.12 or 4.86 ring and pinion ratio, which is then further adjusted up or down the gear ratio chart via the quick change spur gears. The chart we discussed above lists these popular ratios to start, so that chart will work as both a 4.11 quick change gear chart and a 4.86 quick change gear chart. If you’re not sure which ratio your quick change rear uses it is easy to determine by marking the axle flange or tire and the pinion gear and counting the revolutions the pinion gear makes for one revolution of the axle flange or tire. Just over four revolutions denote the 4.12 gear, almost five is the 4.86 gear. We explain the full procedure of how to calculate gear ratio on a quick change rear end elsewhere in the Toolbox for all available quick change ring and pinion ratios.

Once you know what ring and pinion ratio your quick change rear is fitted with you can then move on to determine the required spur gear set(s) you will need to move the final drive ratio up or down to your needs. This is generally performed with some basic math to determine the rpm you wish to be at (or use an online calculator to calculate rpm gear ratio), whether that is a cruising rpm on the street, or max rpm going through the traps at the drag strip. That gear ratio rpm formula is as follows:

MPH x Gear Ratio x 336 / Tire Diameter = RPM

For example, we can use the following to put this formula to the test: 80 mph, 28 inch tall tire, and a 3.80 gear ratio. Plugging them into the formula would look like this:

80 x 3.80 x 336 / 28 = 4,085 rpm at 80 mph

That’s a bit much for cruising on the highway, so perhaps you want to drop that rpm down. We’d pull the 18/23 spur gears from our 4.86 geared quick change and install a set of 22/34 gears for a new ratio of 3.15. Let’s see what our rpm would look like now on the highway at 80 mph?

80 x 3.15 x 336 / 28 = 3,024 rpm at 80 mph

That’s certainly going to be easier on the engine (and most likely our ears), but you could drop the ratio further if you really wanted to get the rpm down for highway cruising, then swap back to the 18/23 spur gears for a pass at the drag strip! Using a quick change rear end gear chart makes this easy as well, though a rpm gear ratio chart would be too cumbersome to use for most, hence the need for the math formula shown here. If you are utilizing an overdrive transmission, be sure to confirm the transmission’s overdrive ratio and add it to the calculation. A 5-speed manual with a .68 overdrive 5th gear would look like this:

80 x 3.15 x .68 x 336 / 28 = 2,056 rpm at 80 mph

Use the appropriate quick change formula for gear ratio and rpm shown here to determine the best spur gear setup for your needs and quick change ring and pinion ratio.

Which Quick Change Gear Set is Best?

When it comes to quick change gears there is a difference between brands, including the materials used, machining tolerances, gear finish, and more. The gear quality should be a consideration based upon the actual usage, your budget, and other factors. A street driven car that will travel limited miles may not need the best quality gears possible when compared to someone racing every Saturday night and putting hard laps and high rpm loads on their quick change gears. So, determining usage, initial cost, wear, and more will help you to decide on what quick change gear brand may be best suited for your application. In a “good, better, best” summation, we are listing the following gear brands we offer.

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (4)

Winters Racing quick change gears offer a great value for the price point.

Good

The Winters Performance brand of quick change gears is the perfect starting point for those new to quick change rear ends and those on tighter budgets (or may be purchasing multiple sets). The Winters quick change gear sets provide a dependable, properly machined gear at an affordable price.

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (5)

The PEM Racing gears offer polished gear surfaces, lightening holes, and more while still at an attractive price for most users.

Better

Moving up a notch is the PEM Racing manufactured quick change gear sets. The PEM Racing gears are a step in the right direction quality wise, using improved materials still at an accessible price for most and feature lighting holes along with a REM polished gear face to reduce friction.

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (6)

The Speedway Motors Premium Lightweight quick change gears offer REM finished surfaces, lightening holes, and best in class materials to take high horsepower runs lap after lap.

Best

For those seeking the best quick change gear sets we offer our own premium lightweight quick change gear sets with all the best features, including lightening holes, REM finished surfaces and crown shaved gear teeth profile to reduce friction and run cooler, and are machined from 8620 steel for utmost strength. While initial cost is a bit more, these gears make up for it in durability and longevity in high horsepower and heavy load conditions, saving you money in the long run.

Lightweight Quick Change Gears

Any racer will tell you that if you can save weight on a race car component it is most definitely worth the extra cost often found on the lightweight component’s price tag. The same can be considered for light weight quick change rear end gears. Not only do they shave some weight from your race car, but they provide a higher strength to weight ratio, and their reduced rotational mass also improves acceleration and throttle response. While lightweight quick change gears come at a premium price, costing more upfront, they provide more performance for that price compared to standard heavy weight quick change gear sets that prioritize durability over performance.

REM Finish Quick Change Gears

REM stands for Rapid Electropolishing Method and is a chemical process where machined parts are placed in a tank filled with heated electrolyte and an electric current is passed through the machined parts. The machined parts thus have a thin layer of metal removed, smoothing the metal’s surface in the process. In simpler terms it is essentially the opposite process of electroplating. This smoother finish reduces friction and wear on the parts, which is why the REM process is so popular on high load surfaces like gears and bearings. REM finished gears provide cooler operating temperatures and longer life with potentially less frequent maintenance or replacement.

Quick Change Rear End Oil Capacity

Oil capacity for most quick change rear axle assemblies will fall between 1.5 and 3 quarts of differential gear oil. That said, it is always best to refer to the manufacturer’s specs to confirm total fluid capacity of the rear axle assembly. Most manufacturers recommend 80W140 standard gear oil or full synthetic 75W90 differential oil, but again, it is best to consult the manufacturer as to preferred viscosity use. Fluid levels should always be checked with the differential at a level position, which may require raising the vehicle and temporarily adjusting the pinion angle to level out the axle housing via a floor jack. Most quick change rears utilize a fill plug and a level plug. After removing both you would top off/fill the differential from the fill plug location until the fluid begins to exit the level plug location. If the fill plug is not accessible due to suspension or body components it is acceptable to fill the differential from the level plug location.

Best Tools for Quick Change Gear Set Service Parts

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (7)

While we focused on the quick change spur gear aspect of these popular rears in this article, Speedway Motors offers ring and pinion gears and service parts for most quick change axle brands.

While Speedway Motors offers a complete range of internal service parts for popular Winters quick change rears, including ring and pinion sets, we’re going to maintain our focus here on the quick change gearsets themselves.

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (8)

Make quick change gear swaps quick and mess free with a drain pan designed to hold the spur gears being swapped out.

Obviously, you’ll need a drain pan for draining differential fluids to access your quick change spur gears. Our aluminum oil drip pan for quick change rear end service is a great solution here. We also offer a plastic version as well if that’s your preference.

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (9)

Light, yet durable, our plastic spur gear storage boxes are available in several colors to store your gear sets to keep them clean and ready to go.

When it comes time to swap your quick change rear end gears, you’ll want to keep your gear sets stored in a clean and orderly manner. Our quick change gear case storage boxes are the perfect solution. Their strong, yet light, plastic construction holds a pair of spur gears, keeping the gears free of dirt and debris. Simply note directly on the case the gear ratio number (found on the typical quick change gear chart) to keep your gear sets organized.

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (10)

Often it is not easy to get a differential fluid bottle into place to properly fill or top off the rear axle. Using a hand fluid pump like this makes the process a breeze.

Once you’ve swapped out your quick change spur gears and it’s time to button up your rear end, don’t forget a new quick change differential gasket (if needed) and refill your differential housing using a hand fluid transfer pump to make topping off your differential housing a breeze.

Quick Change Gear Chart | RPM Gear Ratio Formula for 10-Spline (2024)
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