# Tesla Model S drive unit oil pump change



## brian_ (Feb 7, 2017)

While it's really about the transaxle, rather than the motor itself, this news item might be of interest:
Car and Driver:* Tesla Model S Breaks 400-Mile Range Barrier*
_The Model S Long Range Plus was rated at 402 miles of range by the EPA after Tesla made some judicious changes to the EV._


> The rear motor and transmission now use an electric oil pump instead of a mechanical one, to optimize lubrication and reduce friction. Plus, the company has improved the gearbox of the front AC motors.


I don't know what issue has been fixed in the front drive unit, but the change to an electric gear oil pump could be very handy for DIY builders wanting to use the drive unit in a reverse rotation mode; it could also help low-speed cooling in the large drive units which depend on oil flow for motor cooling. It's not clear if this applies to all drive units (small front, small rear, large rear), or if the new electric pump could be retrofitted to an older drive unit.


----------



## Duncan (Dec 8, 2008)

Interesting - and makes perfect sense

The problem with a mechanical oil pump is that it pumps proportionally to rpm

So if it has enough flow at low rpms it has too much flow and too high a pressure at high rpms
So if its big enough for sustained low speed use it will eat an unnecessary amount of power at high rpm


----------

