Disapointed With 15mph Reverse Speed Limit

[Woodrick]

Except that the limit is in place to keep the gears from turning at high speeds because the gear driven oil pump doesn't work in reverse. Vehicle speed doesn't really matter if that is the case, it's the wheel speed. Plus I assume Tesla measures vehicle speed by wheel speed not GPS. Certainly wheel slip and traction control is done with wheel speed not vehicle speed.

But isn't the gearbox different on the Cybertruck?
And if it was limited at 15 mph on the other Teslas wouldn't that equate to maybe 30 mph on the Cybertruck if it is axle and gears are moving much slower than on the Model Y with smaller wheels?

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[BannedByTMC]

There are videos of it being limited to 15mph in reverse.

"The only race in which the Raptor R claims an easy victory is in reverse. It seems Tesla limits the Cybertuck reverse speed to 15 miles per hour, "

https://insideevs.com/news/700268/tesla-cybertruck-dirt-race-ford-f-150-raptor-pavement/

 

[Rutrow]

... because the gear driven oil pump doesn't work in reverse.

If that's true it's the worst engineering fail of all time. Gears should never turn without adequate lubrication. Not even if it's limited to 15 MPH. Starting an IC Engine for the second before oil pressure builds gives engineers the chills. I can't imagine Tesla's engineering team thinking that backing out of your driveway for even a few dozen feet, much less up a long, sloped San Franciscan alleyway without oil circulating would be acceptable. ?

 

[BannedByTMC]

Its not as if the oil on the gears and bearings evaporates, there should be enough residual for low speed reverse, and millions of Teslas on the road prove this. In most normal driving it's not an issue but off road is one use case where higher reverse speeds can be important.

 

[CyberGus]

If that's true it's the worst engineering fail of all time. Gears should never turn without adequate lubrication. Not even if it's limited to 15 MPH. Starting an IC Engine for the second before oil pressure builds gives engineers the chills. I can't imagine Tesla's engineering team thinking that backing out of your driveway for even a few dozen feet, much less up a long, sloped San Franciscan alleyway without oil circulating would be acceptable. ?

Gears don’t suddenly run dry. Most gearboxes lack active lubrication.

 

[CyberGus]

I’ve driven for years under the soft glow of the “check oil” light ?

 

[Rutrow]

Gears don’t suddenly run dry. Most gearboxes lack active lubrication.

Exactly!

They immerse parts of themselves and begin flinging lubrication right away, WHICHEVER direction they turn.

 

[BannedByTMC]

I expect there is still some splash lubrication going on, (hence my desire for a temporary override of the speed limit), but Tesla obviously felt a pressurized system provided more protection.

 

[BannedByTMC]

Here is a good look at the oiling system of the small Tesla drive unit. It's upside down in the video. Should start at the 4:07 mark:

 

[android04]

Here is a good look at the oiling system of the small Tesla drive unit. It's upside down in the video. Should start at the 4:07 mark:

The older Model S and X used mechanical oiling, but that is no longer the case. Starting with Model 3, Tesla started using an electronic oil pump and oil filter. Model Y and newer Model S/X have the same electronic oil pump. Cybertruck should have the same. Either the 15 MPH limit carried over from the older drive units and Tesla never thought to update it, or there's another reason for it on the newer drive units.

 

[BannedByTMC]

Interesting, an electronic pump should not be affected by reverse at all.

 

[Woodrick]

Interesting, an electronic pump should not be affected by reverse at all.

Not, but the flow direction and gear direction may conflict.

 

[BannedByTMC]

Not, but the flow direction and gear direction may conflict.

Yes the drip lubrication gets pulled into the drive gear/driven gear interface in forward but pushed away in reverse but I'd still think there would be enough lube to allow higher than 15mph limit. Maybe there is but they don't want to take the chance of allowing it in case some people overdo it. On the other hand it looks to me as if the bottom of the drive gear is close to the same level as the oil pickup and would still get some oil on it as it rotates.

 

[Woodrick]

Yes the drip lubrication gets pulled into the drive gear/driven gear interface in forward but pushed away in reverse but I'd still think there would be enough lube to allow higher than 15mph limit. Maybe there is but they don't want to take the chance of allowing it in case some people overdo it. On the other hand it looks to me as if the bottom of the drive gear is close to the same level as the oil pickup and would still get some oil on it as it rotates.

You mean as if someone was drag racing a Ford in reverse?

 

[BannedByTMC]

You mean as if someone was drag racing a Ford in reverse?

This was one thing I had hoped would not carry over from the other models. I wonder if there is a way to over ride it temporarily? The reason being is I've been in situations off road in mud when high tire speed in reverse kept me from being stuck in a hole or mud pit.

This is the reason I'd like to have the option, they could put a time limit in place.

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