Step-by-Step: Installing a Richmond Gear 6-Speed on a B-Body Mopar

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Nothing says horsepower quite like rowing through the gears in a 1960s vintage, big block powered musclecar. But like all good things, there is a price to be paid for mechanical nirvana. The acceleration-oriented rear axle gears in many musclecars can put the hurt on top-end speed (not to mention fuel economy), and the 3,000-rpm drone at highway speeds sure puts the hurt on your ears on long distance road trips.

But there is a way to enjoy the rush of a manual transmission without the speed and sound penalties: An overdrive transmission. With a five- or six-speed manual box, you get the acceleration benefits of that big rear axle gear, plus the ability to hit those big mile per hour figures and cruise at diesel-like rpms at highway speeds.

So why isn't every four-speed musclecar owner rushing to stuff an overdrive transmission in their ride? Authenticity and restoration issues aside, there are two big reasons. Most overdrives are not a simple bolt-on proposition, and most OEM boxes cannot handle the torque output of a big block V8.

But thanks to Richmond Gear's six-speed transmission, these problems are surmountable. The Richmond box has features that make it perfect for use in a 1960s-era car:
•450 ft./lbs. torque rating
•All aluminum construction—weighs just 108 pounds
•Wide range of gear ratios available—can tailor transmission for virtually any application
•Versions for popular GM, Ford, and Mopar input spline counts and bellhousing patterns

The standard Richmond box comes with 3.27 (1st), 2.13 (2nd), 1.57 (3rd), 1.23 (4th), 1.00 (5th) gears and your choice of a 0.76, 0.81, or 0.86 ratio 6th gear. But since there are dozens of other ratios available, you can tailor the transmission for specific applications—road racing or long-distance touring, for example.

A friend of ours, Ed Leung, wanted a Richmond box for his 1969 Charger R/T. Ed dumped a 492 cubic inch stroker 440, a Hemi-spec A-833 four-speed, and 4.10 rear axle gears into the factory 440/four-speed car. The combination produces neck-snapping acceleration, but conks out just shy of 120 miles per hour—and turns at almost 3,200 rpm at 65 miles per hour in fourth gear.

To better match the intended use of the car, Ed got his six-speed with a 3.04/2.13/1.57/1.24/1.00/0.76 gear set and swapped out the 4.10 gear in the Dana 60 rear axle for a 3.33 ratio gear (a rare piece, by the way). This combination matches the original A-833 four-speed's gear ratios in terms of acceleration, allows much higher top speeds, and lets the big block loaf at less than 2,000 rpm at 65 miles per hour in sixth gear.

While the Richmond box is about the same length as GM's Muncie and T-10 four speeds, installing it in the Charger was not a simple bolt-in. The Richmond's case is almost 10 inches shorter than the A-833's, requiring a longer driveshaft. The Richmond's shifter location is seven inches further back than the factory shifter. While this puts the shifter in a much better position (the factory location is too far forward for powershifting), floorpan and crossmember modifications are required to get things to fit. This chart gives you the dimensions of both transmissions for comparison.

Even though it was no walk in the park, the benefits of installing a Richmond six-speed in a classic Mopar musclecar are well worth the effort. There were no kits available when we documented this swap, but today companies like Keisler Automotive Engineering offer swap kits and components to make the job easier. When you can get 1960s-style acceleration, awesome high-speed capability, and the ability to hold a conversation at highway speeds in one package, you better grab it quick.

Fast Specs: 1969 Charger R/T
Engine: 492 cubic inch 440, Comp Cams hydraulic cam (253° duration @ .050, .305"/.525" lift), ported 906 casting iron heads, Mopar Performance M1 intake with Holley 950 cfm double pumper carburetor, MSD 6AL ignition, Hooker headers, 3" exhaust
Driveline: Centerforce Dual-Friction clutch and pressure plate, Hays billet steel flywheel, Lakewood bellhousing, Richmond Gear 6-speed transmission, Victory Performance chromemoly driveshaft, Dana 60 rear axle with Dana 3.33 ring and pinion and Powr Lok limited slip
Chassis/Suspension: Subframe connectors, front and rear anti-sway bars, police “firm feel” steering box, Wilwood 11" front disc/stock 11" rear drum brakes, 15 x 8 Weld Pro Star wheels on P235/60VR-15 front/P275/60HR-15 rear tires