Tesla's New Hairpin Stator Revealed in Drive Unit Teardown, Sandy Munro Missed the Moment

The love-and-hate relationship many people have with Tesla is a show to watch. Many complain about multiple issues with their cars, but say they still love them. Others have quality and manufacturing problems and are annoyed by incompetent Service Center technicians, but still love the brand. And others just hate everything about Tesla without having a reason for that, probably not even owning a Tesla.

We must admit that build quality is not always solid, and many cars deliver with misaligned body panels, badly installed components, and other issues. Most of them get sorted out post-delivery. It's possible to have a poorly-assembled car and still enjoy it without issues for years. Still, poor build quality indicates bigger manufacturing issues that could cause problems down the road. One example is the dreaded rear motor failure that many Model 3 and Model Y owners have complained about.

This is an intriguing issue, considering that Tesla has been making drive units for quite some time. You'd expect to have sorted out problems by now. Still, we can't dismiss Tesla's resolution to optimize costs. Sometimes, a bad engineering decision can lead to costly repairs. That's why car recalls are not unusual. Tesla has not issued a drive unit recall yet, but we know it changed the design of its rear drive unit several times.

A teardown by Ingineerix revealed that Tesla is now installing the fourth generation of the rear drive unit in the Model Y built at Giga Texas. This should fix the problems reported with the previous units, or so we hope. At first sight, Tesla has made the new unit more efficient, easier to manufacture, and potentially cheaper. It also installed a new inverter that is more compact and efficient while baking in more safety features. Instead of temperature sensors, Tesla uses infrared sensors to measure the temperature in various inverter parts.

The first obvious thing is that the new drive unit has a new oil filter cartridge that is not user replaceable. This might indicate that it should last the car's lifetime, cleaning the cooling fluid of small debris from the unit. Opening the motor reveals the new hairpin stator that Tesla discussed during Investor Day on March 1. Besides being more efficient, the hairpin stator is much simpler to manufacture because everything can be automated. It's the opposite with fine copper wires, which must be manually wound in previous stators.

We're sure this would have been a teardown that Sandy Munro would have loved to do, but the timing wasn't right. The fourth-generation drive unit appears identical on the outside to the older units, so they can be used as replacements without problems. This indicates that the Tesla Model 3 might get the new motors soon.