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  • The final cut of the 9th episode of the Tesla Motors Club Podcast, featuring Balazs Biro, of the prominent Hungarian EV channel Villanyautósok, is now available. You can watch it now on YouTube or listen to it on all major podcast networks.

Rear Drive Unit full tear down explanation video

Understanding the Tesla Model S Performance Motor - YouTube

45min long. EV auto repair school teacher's teardown. Talks about the "ceramic" bearings, lubrication and coolant compartments/channels.

Quite amazing we don't see common cross contamination issue between coolant and oil given the complexity (which I'd imagine would be catastrophic for the gear/bearing train). Must benefit from the far lower temperature than ICE engines where the seals and sealing materials usually degrade.

Motivated to gather more knowledge before last round of boxing match with SC on my13 MS85's 3rd DU's (1025276-00-Q) droning/humming (I think not milling) noise between 30-35mph. Getting the typical HQ mandated SC run around these days for older cars even though my DU is still under warranty for a 3 more months. Already a few rounds of run around on this AND the well known MCU eMMC failure (Thanks to NHTSA for forcing Tesla's hand)
 
FYI, here is model 3's DU design. Much simpler and more reliable. Looks like Tesla learned from the Model S motor failure points and evolved to same design as everyone else.

Tesla Model 3 Motor Tear Down - ALL EV - YouTube

Here are the major design changes

- Motor rotor+stator is now cooled by the gear oil (Same as Prius and other EVs, probably benefits from the perm magnet design). This eliminates complex coolant channel in the motor like S/X. In addition, no need to be concerned about keeping gear oil out of the motor. Gear oil is cool by external heat exchanger with coolant. No more complex coolant routing channels through multiple (including moving) components and potential leaky seals. Basically, its more reliable to use gear oil to remove the motor's heat and coolant to remove the gear oil heat. Both are proven technology.

- Gear oil now has an externally changeable filter.

- Inverter coolant now has casted heat exchanger compartment with reliable separation between electronics and coolant. This eliminates all those failure prone sealed surfaces in S/X to separate coolant from inverter electronics.

Summary : Looks like Model 3 motor+gear cooling architecture evolved to same design as other EVs after learning all the failure points on S/X. S/X's drive unit is likely failure prone before (most owners had multiple DUs already) AND after the 8 year warranty. Since DU is integrated motor+gear+inverter and Tesla don't provide design or repair info to 3rd party. Lower cost component level repair options is not going to exist despite DU being easy to remove+install+disassemble. Unfortunately, every DU failure out of warranty will be $10k bill from Tesla for complete integrated DU exchange :(
 
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Understanding the Tesla Model S Performance Motor - YouTube

45min long. EV auto repair school teacher's teardown. Talks about the "ceramic" bearings, lubrication and coolant compartments/channels.

Quite amazing we don't see common cross contamination issue between coolant and oil given the complexity (which I'd imagine would be catastrophic for the gear/bearing train). Must benefit from the far lower temperature than ICE engines where the seals and sealing materials usually degrade.

Motivated to gather more knowledge before last round of boxing match with SC on my13 MS85's 3rd DU's (1025276-00-Q) droning/humming (I think not milling) noise between 30-35mph. Getting the typical HQ mandated SC run around these days for older cars even though my DU is still under warranty for a 3 more months. Already a few rounds of run around on this AND the well known MCU eMMC failure (Thanks to NHTSA for forcing Tesla's hand)
Great video from Washington state university! Go cougs!
 

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