Best Gearbox For Go Kart: Compare 30 and 40 Series

#1 · Best Overall

1. maXpeedingrods Forward Reverse Kit

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

Best for: 30 Series Multi-Chain Builds.

Why it ranks #1: For 30 Series setups, it supports engines up to 14 hp, states both ratios, and includes #35 and #40/41/420 sprockets.

Support for engines up to 14HP, plus two included sprocket options, gives this maXpeedingrods gearbox a useful range of 30 Series applications. It accommodates #35 chain with a 12-tooth sprocket or #40/41/420 chain with a 10-tooth sprocket, helping builders match the drivetrain chain they use.

The 5/8-inch shaft with a 3/16-inch keyway provides a defined interface for a compatible 30 Series setup, while the included sprockets cover two chain configurations. Its shifter cable measures 1540 mm, giving the control a specified reach for installation planning. The gearbox is listed for go-karts, utility vehicles, and other applications using engines up to 14HP; that ceiling and the 30 Series-only note are important boundaries when selecting it.

Skip it if you need a 40 Series gearbox for a larger engine; GXYWADY's 40 Series 11–18HP replacement is the closer match.

Choose this for a 30 Series go-kart or utility-vehicle build that needs forward and reverse and can use either listed chain option. Keep the 14HP engine ceiling and 30 Series restriction in view before planning the drivetrain.

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

#2 · Best Chain Options

2. GXYWADY 30 Series Gearbox

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

Best for: 30 Series Three-Mode Replacement.

Why it ranks #2: The 30 Series replacement covers 2–13 hp, offers forward, neutral, and reverse, and specifies #35 and #40/41/420 chain sprockets.

Forward, reverse, and neutral give this GXYWADY gearbox three selectable positions for easier operation in a go-kart or utility vehicle. Its stated 2–13HP range and compatibility with a 30 Series torque converter make it a broad-power replacement option for smaller-engine builds.

The three shift modes help accommodate maneuvering and stopping needs, while the 5/8-inch shaft with a 3/16-inch keyway specifies the connection for a compatible assembly. Chain choices are also identified: 12T for #35 or 10T for #40/41/420, helping buyers match the gearbox to their chain setup. The kit is described for 2–13HP four-stroke engines and 30 Series torque converters, so its stated range provides a clear boundary for selection.

Skip it if you run a 40 Series engine above 13HP; Leyuncot's 40 Series gearbox is listed for 11–18HP applications.

This is a fit for a 30 Series, four-stroke build in the stated 2–13HP range that benefits from neutral as well as forward and reverse. Keep the converter series and chain option aligned with the rest of the drivetrain.

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

#3 · Best 40 Series Fit

3. GXYWADY 40 Series Gearbox

• Weight: 20.8 lb

Best for: 40 Series 530-Chain Builds.

Why it ranks #3: Its 40 Series fit covers 11–18 hp, including Predator 420cc, with a 3/4-inch keyed shaft and 12-tooth 530-chain sprocket.

A 3/4-inch jackshaft and 12-tooth sprocket for 530 chain make the GXYWADY gearbox a clearly specified option for larger 40 Series go-kart drivetrains. Its listed applications include 11–18HP engines, including Predator 420cc and Duromax 11HP-and-over engines, pointing it toward higher-powered builds.

The 3/4-inch shaft with a 3/16-inch keyway supplies a defined connection for compatible 40 Series components, while the 12T sprocket and 530 chain specification identify the chain arrangement. A forward ratio of 1:2 and reverse ratio of 1:2:6 describe its gearing for buyers planning operation in both directions. The stated 11–18HP range and named Predator and Duromax applications help distinguish it from 30 Series gearboxes intended for smaller engines.

Skip it if you have a 30 Series 212cc build; maXpeedingrods' 30 Series gearbox lists #35 and #40/41/420 chain sprockets.

Pick this for a 40 Series kart or utility vehicle using a listed 11–18HP engine and 530 chain. Its 3/4-inch shaft and chain specification make drivetrain matching essential; it is not the smaller 30 Series option.

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

#4 · Clear Ratio Details

4. Leyuncot 40 Series Gearbox

• Weight: 23.1 lb

Best for: Predator 420cc 40 Series.

Why it ranks #4: This 40 Series kit lists 11–18 hp fitment, a 3/4-inch keyed shaft, 12 teeth, 530 chain, and forward and reverse ratios.

Compatibility with Predator 420cc and Duromax engines rated 11HP and above makes this Leyuncot gearbox a targeted 40 Series choice for heavier go-kart and utility-vehicle setups. It pairs a 3/4-inch shaft with a 12-tooth sprocket and 530 chain for a clearly stated drivetrain arrangement.

The 3/4-inch intermediate shaft and 3/16-inch keyway define the connection, while the 12T sprocket and supplied 530-chain specification give builders a concrete chain configuration to plan around. Its forward ratio is 1:2 and reverse ratio is 1:2:6, supplying gearing information for both directions. The 11–18HP application range includes the named Predator 420cc and Duromax 11HP-and-over engines, helping buyers distinguish this 40 Series unit from smaller 30 Series options.

Skip it if you run a 30 Series converter and a smaller engine; GXYWADY's 2–13HP 30 Series kit lists matching chain options.

This suits a higher-powered 40 Series kart or utility vehicle using a listed engine and 530 chain. Confirm that the 3/4-inch shaft, keyway, and sprocket arrangement match the rest of the drivetrain.

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

#5 · Best 30 Series Modes

5. Silscvtt 30 Series Gearbox

• Weight: 12.35 lb
• Dimensions: 9.06 x 7.68 x 7.68 in

Best for: 30 Series Neutral-Shift Builds.

Why it ranks #5: For engines up to 13 hp, it specifies a 5/8-inch keyed shaft, three shift modes, 2300 rpm, and multiple chain options.

Three positions—forward, reverse, and neutral—make the Silscvtt gearbox useful for drivers who want a neutral selection alongside directional travel. It is listed for engines up to 13HP and offers a 5/8-inch shaft with chain options for common 30 Series go-kart setups.

The 5/8-inch shaft with a 3/16-inch keyway gives a defined connection for compatible components, and the 1540 mm shifter cable provides a stated length to consider when positioning the control. Its 12T sprocket supports #35 chain or its 10T option supports #40/41/420 chain. Forward and reverse ratios are listed as 1:1.3 and 1:2.6, respectively; the product is explicitly limited to 30 Series use, not 40 Series.

Skip it if you have a 40 Series 11–18HP setup; GELUOXI's 40 Series gearbox lists a 3/4-inch shaft and 530 chain.

This is suited to a 30 Series go-kart within the 13HP limit when neutral selection and the listed chain choices fit the build. Its explicit 30 Series restriction makes series identification essential.

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

#6

6. ALL-CARB Forward Reverse Gearbox

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

Best for: 2300-RPM 30 Series Builds.

Why it ranks #6: This 30 Series replacement lists 2–13 hp fitment, 5/8-inch shaft, 2300 rpm, and #35 or #40/41 chain sprocket options.

A specified 2300 RPM operating figure and a 130 cm shifter cable give this marddpair gearbox concrete installation details for a 30 Series build. Its listed 2–13HP range and sprockets for both #35 and #40/41 chains extend its relevance across several smaller-engine setups.

The 5/8-inch shaft and 3/16-inch keyway identify the gearbox interface, while its 12T #35 and 10T #40/41 sprocket options help match a compatible chain arrangement. A 130 cm cable gives a stated length for planning shifter placement, and the listed forward and reverse ratios are 1:1.3 and 1:2.6. The 2300 RPM specification and 2–13HP range add further boundaries for a 30 Series go-kart or utility-vehicle installation.

Skip it if you need a 40 Series gearbox for a Predator 420cc; Leyuncot's 40 Series kit lists that engine and an 11–18HP range.

Choose this for a 30 Series build within its 2–13HP range when the chain options, cable length, and 2300 RPM specification suit your plan. Its power limit is the key boundary for engine selection.

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

#7

7. SEBLAFF 30 Series Gearbox

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

Best for: Compact 30 Series Replacement.

Why it ranks #7: Its listed fit is a 30 Series torque converter on 2–13 hp engines, with #35 12T and #40/41 10T chain options.

A compact assembly and stated 30 Series compatibility make the SEBLAFF gearbox relevant to go-karts using 2–13HP engines. It lists both a 12-tooth #35-chain option and a 10-tooth #40/41-chain option, giving builders two stated chain arrangements to consider.

The specified 30 Series torque-converter application narrows the intended setup, while the 2–13HP range helps buyers assess engine suitability before installation. Its two chain and sprocket combinations let a builder select between #35 with 12T and #40/41 with 10T rather than treating those as interchangeable. SEBLAFF describes the gearbox as lightweight and wear-resistant, and calls out compact assembly and convenient installation as practical construction and setup considerations.

Skip it if you need a 40 Series gearbox for an 11–18HP engine; GELUOXI's 40 Series 530-chain gearbox covers that application range.

Consider this for a 30 Series go-kart using an engine within the stated 2–13HP range and one of its listed chain combinations. Its series and power limits make it a poor match for larger 40 Series drivetrains.

Listed on Amazon as: 30Series Forward Reverse Gear Box Kit 35Chain 12T 2300rpm

#8

8. GELUOXI 40 Series Gearbox

• Weight: 20.4 lb

Best for: 40 Series 530-Chain Replacements.

Why it ranks #8: The 40 Series replacement targets 11–18 hp engines and specifies a 3/4-inch keyed jackshaft with a 12-tooth 530-chain sprocket.

A 3/4-inch jackshaft, 12-tooth sprocket, and 530 chain identify the GELUOXI gearbox as a specific 40 Series replacement for larger-engine go-karts. Its listed 11–18HP range includes Predator 420cc and Duromax 11HP-and-over applications, helping buyers target the right engine class.

The stated 3/4-inch shaft with a 3/16-inch keyway provides a concrete interface for a compatible 40 Series assembly, while the 12T sprocket and 530-chain detail define the listed chain arrangement. Its stated use covers 11–18HP engines and names Predator 420cc and Duromax 11HP and over. Those application details make it easier to distinguish this gearbox from smaller 30 Series units, though the supplied information does not give gear ratios.

Skip it if you need listed forward and reverse ratios for a 40 Series kit; Leyuncot's 40 Series gearbox specifies both ratios.

This matches buyers seeking a 40 Series replacement for a listed 11–18HP engine with 530 chain. The shaft and sprocket details clarify the drivetrain arrangement, but buyers needing stated gear ratios should consider that information boundary.

Listed on Amazon as: Gearbox for 11hp-18hp 3/4" with 3/16" Keyway 12 Tooth with 530 Chain

#9

9. Blast 40 Series Gearbox

• Weight: 22 lb

Best for: 40 Series 420-Chain Builds.

Why it ranks #9: This 40 Series gearbox is listed for 11–18 hp applications and offers a 3/4-inch keyed jackshaft with 530 or 420 chain options.

The 10-tooth sprocket with 420 chain makes this Blast gearbox a distinctive 40 Series option for a build using that chain arrangement. It is listed for heavier applications with 11–16HP engines, including Predator 420cc, and specifies a 3/4-inch jackshaft with a 3/16-inch keyway.

The 3/4-inch jackshaft and 3/16-inch keyway give the assembly a defined connection for a compatible 40 Series setup, while the 10T sprocket and 420 chain suit builders using that listed configuration. The product also mentions a 12T sprocket with 530 chain, providing a second stated arrangement. Its 11–16HP feature listing sets the relevant engine range, and the gearbox kit is shipped without the driver or driven clutch, which must be accounted for separately.

Skip it if you need the driver and driven clutch included; GXYWADY's 2–13HP 30 Series kit lists gearbox and mounting accessories.

Choose this for a 40 Series build in the stated 11–16HP range that uses 420 chain or the listed 530-chain option. Plan separately for the driver and driven clutches, which this gearbox kit does not include.

Listed on Amazon as: Go Kart Forward Reverse Gearbox Kit Compatible with 11-16 hp Engines, Predator 420CC- 3/4" jackshaft (10T Sprocktet 420 Chain)

#10

10. JNDO 30 Series Gearbox

• Weight: 12.1 lb

Best for: Three-Position DIY Builds.

Why it ranks #10: It provides forward, neutral, and reverse modes and claims support up to 13 hp, but the supplied details omit shaft, chain, and ratio specifications.

Forward, neutral, and reverse shift modes give the JNDO gearbox a practical advantage for tight-area maneuvering: drivers can select neutral or back out rather than relying on forward travel alone. Its listed engine range reaches 13HP and 420cc, making it relevant to DIY go-kart builds in that class.

The three shift positions address maneuvering needs directly, while the stated support for engines up to 13HP (420cc) identifies the power range this kit targets. JNDO also describes rugged aluminum-alloy construction, a material detail relevant to builders weighing gearbox construction. The product description calls out DIY assembly enthusiasts, but the supplied details do not specify shaft dimensions, sprocket sizes, or cable length, so those points remain important to resolve for a particular drivetrain.

Skip it if you need stated 5/8-inch shaft and chain details before choosing; maXpeedingrods' 30 Series 212cc kit lists both sprocket options.

This suits a DIY builder seeking forward, neutral, and reverse on an engine listed up to 13HP or 420cc. Check the drivetrain interface details against your build, since the supplied specifications do not give shaft or sprocket dimensions.

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