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At Munro & Associates, we recently conducted a detailed teardown of the Ford Mach-E’s rear motor, inverter, and transmission assembly. Our objective? Understand how Ford’s design stacks up against competitors like Tesla and Volkswagen—and where it may be adding unnecessary complexity, weight, or cost. While the Mach-E’s system shows a few thoughtful touches, our analysis reveals several missed opportunities for refinement and lean design.
Magnet Arrangement and Rotor Insights
The Mach-E’s rotor includes eight magnetic poles, each housed within heavily glued slots. A notable design choice here is the skewed magnet arrangement—a technique used across the EV industry to reduce acoustic noise and improve torque smoothness. While some claim skewing also marginally improves motor output, the real benefit is quieter operation.
Unfortunately, Ford’s use of excessive adhesive to retain the magnets contrasts sharply with Tesla’s barb-style retention method, which uses mechanical interference (like fishhooks) for secure, efficient assembly. We also noted 507 individual laminations in the rotor—a surprisingly high count. While electric motors are indeed simpler to assemble than internal combustion engines, part counts like these remind us that they are not necessarily “simple” in structure.
Stator and Hairpin Winding: A Step Forward
Where Ford scores points is with its stator. The Mach-E utilizes hairpin winding—a flat-wire technique that supports automated manufacturing and enhances thermal efficiency. This is a better approach than Tesla’s hand-wound stators in terms of production speed and consistency. From both an energy and automation perspective, Ford’s choice here is strong.
However, this progress is undermined by the unnecessary inclusion of certain components and connectors, particularly in how electrical leads connect the inverter to the stator.
Extra Parts, Extra Problems: Power Lead Design
Rather than routing power leads directly from the inverter into the motor, Ford introduces an intermediate component—essentially a copper-heavy junction block. This design adds weight, cost, and complexity. With the inverter already mounted directly above the motor, there seems to be no functional reason for not using a direct path. Competitors like Tesla avoid this inefficiency, opting for more integrated, streamlined electrical connections.
Cooling and Packaging Inefficiencies
Ford’s cooling approach further complicates the rear motor assembly. Inside the housing, a plastic ring and an oil jet spray gear oil onto the rotor for thermal management. This method is bulkier than both Tesla’s and Volkswagen’s designs. Tesla employs a more compact and efficient cooling ring system. VW goes a step further by eliminating the oil pump entirely—a brilliant move to reduce both part count and energy losses.
The Mach-E also features an unusually large housing, which raises questions. It adds weight and suggests that packaging optimization was not a top priority. This is a recurring theme: good ideas overshadowed by overengineering.
Parking Pawl: An Outdated Add-On?
The inclusion of a mechanical parking pawl is another head-scratcher. While common in traditional transmissions, modern EVs typically use electronic parking brakes. This part adds unnecessary complexity and weight—especially when software could easily handle the function. Volkswagen and Tesla have already eliminated it.
This kind of legacy carryover indicates a mindset more aligned with adapting ICE architecture than fully embracing EV-native design.
Transmission and Planetary Gears: A Bright Spot
Not all is critical. One strong point is Ford’s use of an inline planetary gear system for the Mach-E’s transmission. This configuration avoids the space inefficiencies of offset designs and delivers quieter operation. Though slightly heavier and more expensive than alternatives, planetary systems are well understood and reliable. We applaud Ford for this design choice.
Inverter Assembly: Complicated and Costly
The inverter teardown was revealing—and frustrating. The design includes multiple levels of manual assembly, welding, and non-automated fastener installation. Instead of using modern push-fit or snap-fit components that facilitate clean, automated workflows, Ford relies on a patchwork of screws, springs, welded busbars, and soldered connections.
We noted over 90 pins requiring manual alignment and soldering. This increases the risk of misalignment, failure, and costly rework. In some cases, circuit boards are secured using screws that don’t align well with automated feed systems, further complicating assembly.
A more modular approach using board-to-board connectors or snap-in MOSFETs could greatly simplify this process and improve yield.
High-Cost Materials and Over-Engineering
The inverter’s design features premium fasteners—double-washered, stainless-steel bolts—and even thick EMI shielding plates that seem redundant given the casting’s inherent shielding properties. In many cases, it felt like Ford “gold-plated” the design without fully assessing whether the cost or mass added any real-world value.
Moreover, components like the upper cover only receive half the number of screws as the lower circuit board—an inconsistency that seems more like oversight than engineering logic.
Serviceability and Maintenance Concerns
Maintenance accessibility is another area where the Mach-E falls short. Oil filters and pumps are buried within the motor housing, making them difficult or impractical to service. By contrast, Tesla exposes their filters for quick replacement. Again, VW wins points for removing the oil pump altogether—a clever way to reduce cost and improve reliability.
Recommendations and Takeaways
From a lean design and manufacturing standpoint, Ford’s rear motor assembly feels overbuilt. Key takeaways for engineers, investors, and EV designers:
- Reduce Redundant Components: Eliminate intermediate power connectors and parking pawls that add weight and cost without meaningful function.
- Simplify Inverter Design: Shift toward push-fit and board-to-board connections to reduce manual labor and improve assembly consistency.
- Reconsider Thermal Management: Streamline cooling systems by studying Tesla’s ring-style cooling or VW’s pump-free solution.
- Enhance Serviceability: Ensure filters and pumps are accessible without full motor disassembly.
- Weight Reduction Matters: Every part counts in an EV. Focus on light, cost-efficient, easily assembled components.
Conclusion: A Mixed Bag from Ford
The Ford Mach-E rear motor system blends competent engineering with several avoidable missteps. While the hairpin stator and inline planetary gears are highlights, the use of extra components, overly complex assemblies, and legacy thinking hold back the overall system’s cost-effectiveness and manufacturability.
Munro & Associates champions smart, efficient, lean engineering. As EV competition intensifies, optimizing every connection, weld, and fastener isn’t just a matter of preference—it’s a necessity for long-term success. If Ford can take the feedback and evolve, the next generation of the Mach-E could be a standout.
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