Transmission Rebuild Kits for Heavy Equipment: Overhaul Kits, Master Kits, and Seal and Bearing Kits for Allison, CAT, and Komatsu

What Separates a Complete Overhaul Kit from an Incomplete One

The most costly mistake in a transmission rebuild is discovering a missing component after the assembly is already disassembled and the machine is committed to the overhaul cycle. A kit that covers 85 percent of the rebuild positions leaves the operator sourcing the remaining 15 percent individually at full unit pricing, with individual freight costs, and with the machine sitting in pieces during the additional wait time.

A genuinely complete transmission rebuild kit covers the following component categories without exception:

• All friction plates and steel separator plates across every clutch pack position in the assembly
• All sealing rings, O-rings, and lip seals at every shaft, piston, and housing interface within the transmission
• All gaskets at every housing joint and cover interface
• The full bearing set for every shaft position included in the overhaul scope
• All snap rings, retaining clips, and small retention hardware specified for replacement in the manufacturer's overhaul procedure
• The filter and any associated hardware are specified for replacement as part of the fluid circuit refresh

A kit that covers all six categories for your specific transmission variant is a complete overhaul kit. A kit that omits any one of them will require supplementary individual component orders before the rebuild can be completed. When reviewing a kit, the transmission service manual for your specific variant is the reference; the OEM overhaul procedure lists every item specified for replacement, and that list is what the kit should match.

Allison Rebuild Kit Range

Allison 1000 Rebuild Kit

The Allison 1000 rebuild kit is the most widely sourced transmission overhaul kit in the heavy equipment and heavy truck segment, a consequence of the Allison 1000 platform's dominant deployment across off-highway construction equipment, articulated machinery, and vocational trucks operating in mixed job site and on-highway environments. The Allison rebuild kit in our range is compiled to the Allison service specification for the 1000 series six-speed platform, covering all friction and steel plates across the clutch pack positions, the complete seal and O-ring set, all sealing rings at the piston and shaft interfaces, and the gasket set for all housing joints and covers.

The Allison transmission overhaul kit variants in our range are available across the standard production build configurations of the Allison 1000 series, with the specific variant confirmed against your transmission serial number before the kit is dispatched. Transmission serial number verification is particularly important for the Allison platform because the 1000 series has been produced across multiple build revisions with changes to clutch pack count and friction material specification between production generations.

Allison Transmission Overhaul Kit: What the Build Revision Determines

The Allison 1000 has undergone several production revisions that affect clutch pack count, piston travel, and friction material specification. An Allison transmission overhaul kit compiled for an earlier build revision installed into a later-generation transmission will contain friction plates of the wrong thickness and count for the clutch pack dimensions of the assembly. The result is a rebuilt transmission with incorrect clutch pack clearances that produces shift quality below the rated standard from the first shift event after reassembly.

This is why Allison transmission serial number verification is not a formality it is the step that determines whether the kit you receive matches the transmission you are rebuilding.

CAT Transmission Rebuild Kit Range

CAT Transmission Rebuild Kit Coverage

The cat transmission rebuild kit range at Imara Engineering covers the CX series powershift platforms used across CAT dozers, motor graders, articulated trucks, and wheel loaders, with kit variants available for the CX31, CX38, and TA22 transmission models as the primary coverage platforms. Each cat transmission rebuild kit is compiled to the Caterpillar overhaul service specification for the relevant transmission model, covering the friction and steel plate sets, piston seals, housing gaskets, O-ring sets, and the bearing set positions specified for replacement in the CAT transmission overhaul procedure.

CAT transmission rebuild kits are also available as transmission seal and bearing kit configurations for operators who are completing a targeted seal and bearing overhaul without replacing the friction plate set, a valid approach for transmissions where shift quality is still acceptable, but a fluid leak or bearing noise has triggered the service. The transmission seal and bearing kit consolidates all seal, O-ring, and bearing positions into a single order without including the friction and steel plates, reducing kit cost for applications where the clutch pack components are still within serviceability.

Komatsu Transmission Rebuild Kit Range

Komatsu Transmission Rebuild Kit Coverage

The Komatsu transmission rebuild kit range covers the TorqFlow powershift transmission platforms used across Komatsu D-series dozers and WA-series wheel loaders, as well as the transmission configurations used in PC-series excavator travel drive applications. The gearbox overhaul kit heavy equipment variants for Komatsu platforms are compiled to the Komatsu service specification for each transmission model, with friction material grades and seal compound specifications matched to the operating temperatures and hydraulic pressures of the specific torqflow circuit configuration.

Komatsu transmission overhaul kits for the TorqFlow platform require particular attention to friction material grade selection, as the TorqFlow circuit operates at higher sustained hydraulic pressures than many other heavy equipment transmission designs. Using a friction plate from a kit compiled for a lower-pressure application introduces glazing and premature wear from the first operating cycle of the rebuilt transmission. Our team verifies the friction material grade specification against the Komatsu transmission serial number as a standard step on every Komatsu transmission rebuild kit order.

Selecting the Right Kit Configuration for Your Rebuild Scope

Not every transmission overhaul has the same scope, and selecting the correct kit configuration for the work being carried out avoids both overspending on components you do not need and under-specifying a kit that does not cover the full overhaul requirement.

The three main kit configurations and when each applies:

1. Transmission Master Kit: The most comprehensive configuration, covering every replaceable wear item in the full overhaul scope, including all friction plates, steel plates, seals, gaskets, bearings, snap rings, and filter hardware. The transmission master kit is the correct choice for a complete overhaul where the transmission has been fully disassembled, and every wear position is being renewed simultaneously.
2. Transmission Overhaul Kit: A standard overhaul configuration that covers friction plates, steel plates, seals, and gaskets but typically excludes bearings and snap rings. The gearbox rebuild kit configuration is appropriate when the bearing set is being individually assessed and sourced rather than replaced as a blanket overhaul item, which is a valid approach when bearing condition has been confirmed as serviceable before the rebuild commitment.
3. Transmission Seal and Bearing Kit: A targeted configuration for rebuilds limited to the fluid sealing and bearing positions appropriate for machines entering overhaul due to an identified seal leak or bearing fault, where the friction plate set has been assessed and confirmed serviceable. The transmission seal and bearing kit is also used as a supplementary order alongside an overhaul kit on transmissions where the bearing set was excluded from the standard kit.