Battery based electric vehicles of today and tomorrow.

[Grumpycat]

Why are wheel-mounted motors a bad idea?

”unstrung unsprung mass” is the buzzword. The more your wheels weigh the harder they hit bumps. Also the road impacts must be borne by the hub centric motor. A driveshaft is a cheap simple means of reducing unstrung unsprung mass, increasing reliability, improving ride.

The hot setup these days is to mount rear brakes inboard, between differential and halfshaft to wheel.

Edit: darn predictive speller.

 

[MossRoad]

Why are wheel-mounted motors a bad idea?

Don't know if its a bad idea or not, but there's sprung and un-sprung weight. I learned about this when I ran my street bike hard and wanted to improve performance AND handling.

Anything that rides above the suspension is sprung weight (it rides on the springs).
Anything that rides below the suspension is un-sprung weight (it doesn't ride on the springs).

The way I understand it is that you want the suspension to be able to keep your tires in contact with the road as much as possible. The heavier the un-sprung weight (tires, rims, rotors, brake components, wheel motors, etc.), the harder the suspension has to work to keep that weight pushed down against the road.

Make sense?

 

[MossRoad]

”unstrung mass” is the buzzword. The more your wheels weigh the harder they hit bumps. Also the road impacts must be borne by the hub centric motor. A driveshaft is a cheap simple means of reducing unstrung mass, increasing reliability, improving ride.

The hot setup these days is to mount rear brakes inboard, between differential and halfshaft to wheel.

I think it's un-sprung, not unstrung, but you have the thought process correct.

 

[goeduck]

Will there be Old EV Car Shows? Oohing and aweing at those electric motors . This sure will change that slice of Americana, there is nothing really like looking under the hood at an Old Car Show to many of us. Oh well, there is still paint and upholstery.

 

[MossRoad]

Will there be Old EV Car Shows? ....

Apparently, yes!

 

[goeduck]

Apparently, yes!

Oh man, look at those Batteries!! Oh well, there is still paint and upholstery !!

 

[airbiscuit]

 

[Grumpycat]

Will there be Old EV Car Shows? Oohing and aweing at those electric motors . This sure will change that slice of Americana, there is nothing really like looking under the hood at an Old Car Show to many of us. Oh well, there is still paint and upholstery.

This is what I have under my Tesla Model S hood ("frunk" in Teslaology):

 

[SylvainG]

Oh! I should do that when I receive mine LOL

 

[txdon]

Don't know if its a bad idea or not, but there's sprung and un-sprung weight. I learned about this when I ran my street bike hard and wanted to improve performance AND handling.

Anything that rides above the suspension is sprung weight (it rides on the springs).
Anything that rides below the suspension is un-sprung weight (it doesn't ride on the springs).

The way I understand it is that you want the suspension to be able to keep your tires in contact with the road as much as possible. The heavier the un-sprung weight (tires, rims, rotors, brake components, wheel motors, etc.), the harder the suspension has to work to keep that weight pushed down against the road.

Make sense?

Yes Thanks.

Here is an article that goes into detail on the extra unsprung mass of the wheel mounted motors in an EV.

"Lotus found that the impact of increased unsprung mass, though noticeable to a trained driver, was really not all that significant."

StackPath