Go with a factory-remanufactured Komatsu PC100-6 final drive motor. Not new OEM. Not a no-name rebuild. Here's why.
I've managed our heavy equipment parts budget ($180,000 over six years—roughly $30,000 annually) for a mid-sized excavation and site prep company in the UK. When we lost a final drive on our PC100-6 in Q2 2024, I had quotes from three sources in hand: a new OEM unit at roughly £8,500, a factory reman from a Komatsu-authorized center at £5,200, and a local rebuild shop at £3,800. The price difference looked obvious—until I did the total cost of ownership. The factory reman saved us about 18% compared to the 'cheap' rebuild when you factor in reliability, downtime risk, and resale value. That's not a guess. I tracked every penny.
I'm not a mechanical engineer, so I can't speak to the metallurgy or hydraulic tolerances inside the motor. What I can tell you from a procurement perspective—after comparing quotes for dozens of drive motors and undercarriage parts over the years—is that the hidden costs in a third-party rebuild almost always eat up the initial savings. Not always. But often enough that our policy now is: for final drives, we go factory reman unless the timeline forces our hand. That policy came from getting burned twice (ugh).
The numbers that changed my mind
In 2023, I compared costs across eight vendors for a similar Komatsu final drive rebuild on a PC200. Vendor A (new OEM) quoted £9,200. Vendor B (factory reman) quoted £5,800. Vendor C (local rebuild) quoted £4,100. I almost went with C until I calculated TCO: C charged £450 for a 'core deposit' that had fine-print conditions, £220 for shipping each way—both ways on a 45 kg motor is not cheap—and when the unit failed 14 months later, the warranty covered parts but not labour, which cost us another £1,100 in shop time. Total: £5,870. Vendor B's £5,800 included everything: delivery, a straightforward core return process, and a two-year warranty that would have covered labour for the first year. That's a 17% difference hidden in fine print. Not massive, but it forced a policy change on how we evaluate warranty terms.
The local shop wasn't bad—they honestly tried—but their reman process didn't include the same level of testing on the hydraulic motor's internal seals and bearings. You don't notice that until the motor starts weeping or the bearing noise creeps up. On a PC100-6, the final drive motor (part number 708-2Z-00180, if you're checking) is an integrated unit with the planetary gear set. A half-baked rebuild on the motor section can kill the $1,200 gear set in six months. That's the kind of cascading failure that doesn't show up on a quote.
What 'factory reman' actually means here
People think remanufactured means 'repaired' or 'rebuilt to a minimal standard.' That's a legacy myth from a time when aftermarket shops labelled anything with a fresh coat of paint as 'remanufactured.' Today, Komatsu's authorized reman centers (and there are a handful across Europe that serve the UK market) follow a completely different process: they disassemble every unit fully, clean each component, machine the housing and bearing surfaces to factory tolerances, replace all seals and gaskets with updated part numbers, and test the assembled unit on a hydraulic bench for pressure, flow, and temperature. The unit I installed in July 2024 came with a test report showing flow rate at 98% of spec. That's not a repair—it's essentially a new motor built from reused core castings. (As of January 2025, at least, that's the standard. Verify current processes with your supplier.)
The assumption is that local rebuilds are cheaper because they use cheaper parts or less labour. The reality is they're cheaper because they skip steps: fewer gauge replacements, less rigorous testing, no machining of worn surfaces. That's fine for non-critical parts. For a final drive motor—the component that converts hydraulic pressure into 40+ kN of torque to move a 10-ton machine through clay and rubble—skipping steps is a gamble. I've seen the consequences firsthand: a 'rebuilt' motor that lasted 9 months, cost us £1,200 in towing and shop time, and left a job site stalled for two days. The client wasn't happy.
When the 'cheap' option actually wins
I don't want to oversell this. Factory reman isn't always the right answer. If your machine is a runner heading to auction within the next year, a well-reviewed local rebuild at £3,800 might make more sense—you won't capture the resale value premium of a reman unit, and the lower upfront cost improves your short-term margin. If you're in the middle of a job where downtime costs £500+ per hour, and no reman unit is available within the shipping window, you take the best available and get the machine running. I've done that (unfortunately). The exception is when the timeline is critical and the budget is tight. But for a machine you plan to keep running for 3+ years—which is most of our fleet—the factory reman pays for itself in avoided downtime alone.
How to find a reliable reman source in the UK
This is where I wish I could give you a simple vendor list. I can't—I'm not an equipment parts distributor, and UK supply chains change fast. What I can tell you from experience: start with Komatsu UK's official parts hotline (01604 576 576, as of April 2024). Ask for reman exchange options for the PC100-6 final drive. They'll route you to an authorized center, typically in mainland Europe (Germany or Netherlands) but with UK shipping handled. Pricing I've seen for that unit in late 2024 ranged from £4,800 to £5,500 depending on core condition and shipping method. Add £150-200 for return shipping of the old core, which is refundable if the core is rebuildable. Make sure they provide the test report. If they can't or won't, that's a red flag. A proper reman shop stands behind its process with data.
Looking back, I should have standardized on factory reman three years earlier. At the time, the local shops felt like the 'smart' budget play—they offered a lower quote and a friendly handshake. But given what I know now about failure rates, warranty coverage gaps, and the impact on equipment reliability for our clients, my choice was reasonable with the information I had. It just wasn't optimal. If you're weighing options for a PC100-6 final drive motor, I'd recommend you get quotes from three sources: a new OEM, a factory reman, and a reputable local reman. Run the TCO yourself—include labour for two potential failures. If the factory reman comes within 20% of the local option on total cost, go with the reman. It's not the cheapest. But it's the cheapest that works.
