Best Gear Box For Go Kart: Compare 30 and 40 Series Kits

#1 · Best Overall

1. maXpeedingrods Go Kart Gearbox Kit

• Weight: 12.35 lb
• Dimensions: 7.87 x 7.87 x 7.87 in

Best for: 30 Series chain-matching builds.

Why it ranks #1: Its 30 Series fit covers engines up to 14HP and includes sprockets for #35 and #40/41/420 chain, with a 5/8-inch shaft.

Included 12-tooth #35 and 10-tooth #40/41/420 sprockets let this maXpeedingrods kit address two chain setups in one 30 Series gearbox package. Its forward and reverse functions add maneuvering options for compatible go-karts and utility vehicles, while the specified shaft and keyway help identify the required connection.

The 5/8-inch shaft with 3/16-inch keyway gives builders concrete dimensions to compare with their drivetrain, and the included sprockets cover #35 and #40/41/420 chain configurations. The 1540 mm shifter cable provides a stated length for planning the control route. Forward ratio is 1:1.3 and reverse is 1:2.6; the gearbox speed is 5/13 of clutch speed. It is specified for 30 Series use and engines up to 14 HP, so those limits matter when selecting a setup.

Skip it if you need a 40 Series gearbox; the GXYWADY 40 Series replacement is specified for that class of setup.

Choose this kit if your 30 Series build needs forward and reverse plus sprocket options for the listed chains. Check engine rating, shaft dimensions, and chain choice against your drivetrain before installation.

Listed on Amazon as: maXpeedingrods Go Kart Forward Reverse Gearbox Kit 212cc 30 Series

#2 · Three-Mode Shifting

2. VEVOR 30 Series Gearbox

• Weight: 12 lb
• Dimensions: 5.5 x 4.33 x 8.34 in

Best for: 30 Series multi-chain DIY karts.

Why it ranks #2: This 30 Series kit specifies forward, neutral and reverse, a 5/8-inch shaft, 2300 RPM and sprockets for two chain formats.

Three shift positions—forward, neutral, and reverse—combine with included 12T #35 and 10T #40/41/420 chain options in this VEVOR 30 Series gearbox. That pairing gives kart builders both maneuvering modes and a choice of listed chain setups, with a 5/8-inch shaft and 3/16-inch keyway.

The two included sprocket specifications let a builder choose between #35 and #40/41/420 chain configurations, while the 5/8-inch shaft and 3/16-inch keyway provide dimensions for checking the drivetrain interface. Forward, neutral, and reverse positions support repositioning and neutral selection during operation. VEVOR lists a 1:1.3 forward ratio, 1:2.6 reverse ratio, and 2300 RPM, and describes the kit as suitable for DIY installation. Its stated engine range is 2–13 HP.

Skip it if you need a 40 Series unit for an 11–18 HP engine; the GXYWADY 40 Series replacement lists that range and 530 chain.

This fits DIY kart or utility-vehicle builders seeking three shift modes and either of the listed chain choices. Keep its 30 Series designation and 2–13 HP range in view when checking the engine and existing drivetrain.

Listed on Amazon as: VEVOR Go Kart Forward Reverse 212cc Gear Box, 30 Series Torque Converter, 10T #40/41 12T #35 Go Karts Accessories TAV2 30 40 41 for 2HP-13HP Engine, Transmission Local Honor, 3 Shift Modes

#3 · Broad Chain Fit

3. GXYWADY 30 Series Gearbox

• Weight: 12.45 lb
• Dimensions: 7.87 x 7.87 x 7.87 in

Best for: 30 Series low-horsepower builds.

Why it ranks #3: The 30 Series replacement covers 2–13HP engines and lists 12T #35 plus 10T #40/41/420 chain compatibility and three shift modes.

Three shift modes and two listed sprocket setups make this GXYWADY gearbox a flexible 30 Series option for engines rated 2–13 HP. Forward, reverse, and neutral add maneuvering choices, while compatibility with 12T #35 and 10T #40/41/420 chain helps identify suitable drivetrain arrangements.

Forward, reverse, and neutral modes give operators a choice beyond forward-only running, while the listed 2–13 HP range identifies the intended engine class. Compatibility with 12T #35 and 10T #40/41/420 chain gives builders two stated sprocket configurations to consider. The 5/8-inch shaft and 3/16-inch keyway supply useful interface measurements, and the kit is specified for a 30 Series torque converter and four-stroke engines. Those limits help avoid treating it as a universal gearbox replacement.

Skip it if you need a 40 Series gearbox for a higher-powered engine; the Leyuncot 40 Series kit lists 11–18 HP applications.

This is a match to consider for a 30 Series, four-stroke build within the stated 2–13 HP range. Its chain options and shaft dimensions aid matching, but the series and engine-type restrictions matter.

Listed on Amazon as: GXYWADY Forward Reverse Gearbox Kit Replacement for 2HP-13HP Go Kart

#4

4. Silscvtt 30 Series Gearbox

• Weight: 12.35 lb
• Dimensions: 11.81 x 10.24 x 7.87 in

Best for: 30 Series three-mode operation.

Why it ranks #4: Its 30 Series specifications include a 5/8-inch shaft, 3/16-inch keyway, 2300 RPM and three shift modes for engines up to 13HP.

Forward, reverse, and neutral selection gives this Silscvtt gearbox a useful three-position control layout for compatible go-karts. Its 5/8-inch shaft, 3/16-inch keyway, and stated 30 Series limitation make drivetrain matching explicit, while the listing covers engines up to 13 HP.

The three shift modes provide a neutral position alongside forward and reverse, so operators can select among the listed gearbox functions. A 5/8-inch shaft and 3/16-inch keyway give builders concrete interface dimensions, and the 1540 mm shifter cable length helps with control-routing plans. The specified 1:1.3 forward and 1:2.6 reverse ratios, plus 2300 RPM, describe operating parameters. Compatibility with #35 12T or #40/41/420 10T chain is listed, but use is restricted to 30 Series.

Skip it if you have a 40 Series drivetrain; the Leyuncot 40 Series gearbox lists a 3/4-inch shaft and 530 chain.

This suits a 30 Series kart or utility-vehicle build needing three shift positions and a stated cable length. Its 30 Series-only limitation is decisive, so do not select it for a 40 Series drivetrain.

Listed on Amazon as: Silscvtt 30 Series Go Kart Forward Reverse Gearbox

#5

5. labwork 30 Series Gearbox

• Weight: 5600 g

Best for: 30 Series sprocket replacement builds.

Why it ranks #5: This 30 Series kit is listed for 2–13HP engines and specifies 5/13 clutch-speed gearbox speed plus replacement sprockets for both chain formats.

Compatibility with both 10T 40/41 and 12T 35 sprockets gives the labwork 30 Series gearbox two listed chain configurations for a 2–13 HP replacement build. Its 1540 mm shifter cable and 5/13 clutch-speed specification also help builders plan controls and transmission matching.

The 10T 40/41 and 12T 35 sprocket compatibility addresses two common chain arrangements listed for this kit, while its 30 Series designation narrows the intended gearbox class. A 1540 mm shifter cable gives a stated length for routing the control, and the gearbox speed is specified as 5/13 of clutch speed. The product is presented as an easy-install assembly for 2–13 HP engines, but buyers still need to check their engine and existing drivetrain against those parameters.

Skip it if you need a specified shaft and keyway dimension to verify a replacement; the VEVOR 30 Series kit lists both.

Consider this for a 30 Series replacement where the engine falls within 2–13 HP and the listed sprocket options match. Its cable length is specified, but the supplied details leave shaft dimensions unstated.

Listed on Amazon as: labwork Go Kart Forward Reverse Gearbox Kit Replacement for 2HP-13HP Engine

#6

6. ALL-CARB 30 Series Gearbox

• Weight: 12.28 lb
• Dimensions: 7.09 x 7.09 x 7.09 in

Best for: 30 Series compact cable routing.

Why it ranks #6: The 30 Series replacement lists a 5/8-inch shaft, 3/16-inch keyway, 2300 RPM and compatibility with 2–13HP engines.

A 130 cm shifter cable sets this ALL-CARB gearbox apart for builders planning control routing on a 30 Series setup. It also lists a 5/8-inch shaft, 3/16-inch keyway, and compatibility with 10T #40/41 or 12T #35 sprockets for engines rated 2–13 HP.

The 130 cm cable length gives a concrete control-routing measurement, while the 5/8-inch shaft and 3/16-inch keyway help check the gearbox interface. Its listed 10T #40/41 and 12T #35 sprocket options address two chain configurations on a 30 Series setup. Forward and reverse ratios are 1:1.3 and 1:2.6, with operation at 2300 RPM. The 2–13 HP engine range helps buyers assess whether this replacement belongs in their go-kart or off-road vehicle build.

Skip it if you need a longer listed cable; the maXpeedingrods 30 Series kit specifies 1540 mm.

Choose this for a 30 Series engine setup within 2–13 HP when its sprocket choices and 130 cm cable suit your layout. Check control routing carefully, since cable length is a specific constraint.

Listed on Amazon as: ALL-CARB Go Kart Forward Reverse Gearbox Replacement for 2HP-13HP

#7

7. JNDO 30 Series Gearbox

• Weight: 12.1 lb

Best for: DIY builds needing three shift modes.

Why it ranks #7: This forward-neutral-reverse kit is described for engines up to 13HP or 420cc, though the provided specifications omit shaft and chain details.

Forward, neutral, and reverse give the JNDO gearbox three distinct shift modes, addressing the lack of reverse on basic go-karts and helping drivers reposition in confined spaces. Its listing specifies support for engines up to 13 HP or 420cc, making engine capacity an important selection point.

The three shift positions let a driver select neutral as well as forward or reverse, adding maneuverability without relying on forward-only operation. JNDO lists compatibility up to 13 HP (420cc), which helps builders assess whether the kit belongs in their engine class. The product is described for DIY assembly enthusiasts, so it is aimed at people adding gearbox functionality to a build. The supplied details identify it as a 30 Series kit, a key constraint when matching a drivetrain.

Skip it if you need stated shaft and sprocket dimensions before choosing; the maXpeedingrods 30 Series kit lists both chain sprockets and shaft size.

This suits a DIY builder seeking three shift modes for a listed engine class up to 13 HP or 420cc. Make sure the 30 Series designation matches your existing drivetrain; detailed shaft and sprocket dimensions are not supplied here.

Listed on Amazon as: JNDO Go Kart Forward Reverse Gearbox Kit 30 Series for 212cc 420cc Engine

#8 · Higher-Power Fit

8. GXYWADY 40 Series Gearbox

• Weight: 20.8 lb

Best for: 40 Series higher-horsepower swaps.

Why it ranks #8: This 40 Series replacement targets 11–18HP engines, including Predator 420cc, and lists a 3/4-inch shaft with a 12-tooth sprocket.

A 3/4-inch jackshaft and 12-tooth sprocket for 530 chain distinguish this GXYWADY 40 Series replacement from smaller-shaft gearbox kits. It is listed for 11–18 HP engines, including Predator 420cc and Duromax 11 HP and above applications, helping target buyers narrow fit by engine and drivetrain.

The 3/4-inch jackshaft with 3/16-inch keyway gives a specific interface to compare with a replacement setup, while the 12-tooth sprocket is specified for 530 chain. Its 40 Series designation and stated 11–18 HP range direct it toward higher-powered applications than 30 Series kits. The listed forward ratio is 1:2 and reverse ratio is 1:2.6, helping buyers consider the transmission behavior alongside compatibility with go-karts and utility vehicles.

Skip it if you run a 30 Series setup or need #35 chain; the VEVOR 30 Series gearbox lists sprockets for #35 and #40/41/420 chain.

Pick this replacement when a 40 Series 11–18 HP application calls for a 3/4-inch shaft and 530 chain. Its shaft, keyway, and chain specifications make drivetrain matching essential before replacing an existing gearbox.

Listed on Amazon as: GXYWADY 40 Series Forward Reverse Gearbox Replacement for Go-Karts

#9

9. Leyuncot 40 Series Gearbox

• Weight: 23.1 lb

Best for: Predator 420cc 40 Series swaps.

Why it ranks #9: The 40 Series kit targets 11–18HP engines and specifies a 3/4-inch shaft, 12 teeth and included 530 chain.

A 3/4-inch intermediate shaft, 12 teeth, and supplied 530 chain define this Leyuncot 40 Series gearbox for higher-powered replacements. The listing names Predator 420cc and Duromax 11 HP and above engines, giving buyers concrete application references alongside its 11–18 HP engine range.

The 3/4-inch intermediate shaft with 3/16-inch keyway specifies the connection dimensions to compare against a replacement, while the included 12-tooth 530-chain setup narrows chain compatibility. Its 40 Series designation and 11–18 HP range suit applications such as the listed Predator 420cc and Duromax 11 HP and above. Forward ratio is 1:2 and reverse ratio is 1:2.6, giving buyers transmission figures to consider when selecting a gearbox for a go-kart or utility vehicle.

Skip it if you need a 30 Series gearbox or #35 chain sprocket; the VEVOR 30 Series kit lists a #35 option.

Choose this for a 40 Series replacement matching the stated 11–18 HP range, 3/4-inch shaft, and 530 chain. The Predator and Duromax references help narrow application, but drivetrain dimensions still need to align.

Listed on Amazon as: 40 Series Forward Reverse Gearbox 11-18hp Fit for Predator 420CC 530 chain

#10

10. RedCap Reverse Transmission

• Weight: 8.27 lb

Best for: GY6 external reverse-box replacements.

Why it ranks #10: This external transmission is intended for most GY6 150cc engine-based vehicles, a distinct fit from the listed small-engine 30 and 40 Series kits.

Forward at a 1:1 ratio and reverse capability make the RedCap external gearbox a distinct option for compatible GY6-based 150cc and 250cc vehicles. Its listed applications include go-karts, ATVs, UTVs, quads, and named Hammerhead, Carter, and other models, directing buyers toward model-specific replacement use.

The external gearbox provides forward and reverse functions, with a stated 1:1 forward ratio that buyers can consider when matching the transmission behavior. RedCap identifies compatibility with most GY6 150cc engine-based Chinese go-karts, buggies, ATVs, and UTVs, and names models including Hammerhead Twister GTS150, SS150, Carter Talon 150cc, UM150, and LM150. This makes the application list central to selection; it is not described as a 30 or 40 Series gearbox kit.

Skip it if you need a 30 Series gearbox with chain sprockets; the VEVOR 30 Series kit lists shaft and chain specifications.

This suits owners of listed GY6-based 150cc or 250cc go-karts, buggies, ATVs, or UTVs needing an external reverse box. Match the named vehicle and engine application; 30 Series chain details are not supplied.

Listed on Amazon as: RedCap Complete Reverse Transmission Gearbox Kit for Hammerhead Twister GTS150 SS150 Carter Talon 150cc UM150 LM150 150cc 250cc Go Kart ATV UTV Quad Buggies