BMW i3 Motor Movement During Extreme Stresses Of Autocross Race

SEP 4 2016 BY MICHAEL BEINENSON 20

We are often used to seeing vehicle engines (motors) by simply opening the hood and taking a peek. Well for Tesla, BMW i3 and few others, that is not an easy endeavor. Tesla keeps their motor(s) on the axle and the only real way to see one is to go to a Tesla showroom and see the chassis display. BMW i8 for example requires two people to open the hood.

BMW i3's Electric Motor

BMW i3’s Electric Motor

The BMW i3’s motor and if equipped with a range extender motor (REx) can be accessed through the trunk by removing a few hex screws. What we find inside is single assembly of the motor and the axle, effectively making the motor (and REx engine) move along with axle in both acceleration and deceleration.

There have been plenty motor footage with the cover removed, but none this extreme. The video (below) you see was shot during a BMW CCA Peachtree Chapter Autocross and shows both front and back movement, as well as, to my surprise lateral movements of the motor.

At 1:07 mark you can clearly see the great stresses the motor experiences and it is no wonder BMW issued a bolt replacement for the i3 motor for early models as the engine would simply detach from the frame after passing over a bump or a bridge joint. Don’t be alarmed about your i3, you were probably contacted by your local BMW store to perform the work if it was required.

The video clearly illustrates the technical challenges BMW team had to overcome in order to fit such a compact motor in a very small space. Enjoy!

Categories: BMW, Racing

Tags: ,

Leave a Reply

20 Comments on "BMW i3 Motor Movement During Extreme Stresses Of Autocross Race"

newest oldest most voted

Did you ever try to gun an old V8? It moves a lot as well.

I brake torched , gunned, raced , etc; Never seen An Engine and “drive shaft” Bounce around like that, Unless it had BAD/Broken engine mounts … Trust me I’ve Built Cars from scratch , I never had that Bouncing Engine thing happen..This Is Terrible engineering..& Dangerous ..That shaft carrying on like that, can go right through the floor if something snaps …It looks very Iffy…

It does what it’s designed to do. There is a lot of torque here, and its handled as it should, if anything the engineering is great. A gas engine moves _alot_ as well in the engine room Usually you restrict it in a race car because it give a slight ‘bendy’ feeling when accelerating hard. On the other hand, in a car not primarily aimed at racing, you usually have more elastic fittings as it smoothes out the ride. The bmw is not primarily intended to be a race car in this setting. And yes. I actually have built card as well…

Well Jimijon,

Your source of fear is probably that your “old age” memories are in reference to engines, but here we are in the “new age” watching an electric motor in action. So there’s no mechanical throttle linkage, no mounted exhaust, fuel lines, etc .. (typical “old age” problems for excessively loose/broken motor mounts)… nothing that’s going to get stressed by the “excessive” movement other than the mounting apparatus itself.

I would expect a smoother ride (vs “traditional” engine mounting) under such harsh acceleration/deceleration afforded by the increased flexibility of the “modern” drivetrain mount in the i3.

IOW, … I suspect what you’re looking at is actually the ultimate motor mount, … only made possible by utilizing an electric drivetrain.

WOW ! Great Video ! It re-Enforces all my beliefs ! Bolts Breaking ? W T F.&..They kept it so Hush Hush.,The 1st I’ve heard of it, & I am Sure there is More to come..All that engine bounce ??? Unheard of ! I’ve never seen anything even close like it, in my 50yrs around cars ! This car must have been Designed & Built in Disneyland?? Because it is for sure Mickey Mouse material…Can they get away with that?

You really are clueless…

So Are You Much more than I .,Because you probably own one of these Lemons! SOUR GRAPES LOL…Crap happens , Next time “Do your Research” !

Keeping it secret? They have had this bolt update out of many months now. Mine is due for it, and I haven’t even bothered to bring it in. I race mine harder than just about anyone. Full throttle starts at almost every intersection. Mashing the throttle every opportunity I have because it is just so fun. I know dozens of people with i3’s, no one in our group had any failure remotely similar. And autocross extreme throttle transitions is also much more extreme than the average i3 is going to encounter on the street. This is old new anyways. “Hush Hush” You realize this video is a year old? Where have you been?

More like 2 years. No 2015 or 2016 should be affected.

He has been under a rock clearly.

Not new news!

Welcome to 2016!

BMW should announce a “Recall” on this issue ., if they have not already..They usually discretely send them to the owners..

A technical service bulletin is in effect.
And it is for broken bolts from to much torque off the line.

It is actually to prevent sudden wheel spin when a wheel gets airborn or loses traction suddenly. This is because the drivetrain shock was so great when the wheel suddenly regained traction. If you don’t have a wheel suddenly losing traction, then there is no effect on the torque with the new programming.

The torque was reduced off the line in the update they did. Not just for wheel hop. BMWi should have used a better bolt choice from the onset.

This is where having a transmission (even a simple 2-speed one) would help a lot. With a single speed transmission the motor has to deliver a lot of torque at low speeds, which is stressing the fittings.

On the other hand, an electric motor produces far less vibration than an ICE, so perhaps beefing up the fittings would be an option.

It would be interesting to see how other EVs behave in such conditions.

If the Camera were mounted to the motor, would this have been called ‘body roll’?

Exactly. If you look closely, there is zero movement of the engine with respect to the suspension. People forget that an electric motor is not separate and coupled to the axle with a transmission. It looks like it is moving when in reality, it is just the suspension at work.

Whatever that is NOT holding on to the motor needs to be beefed up!
I’ve only seen THAT much movement of an engine when the engine mountings are totally bolloxed!
When the top mounting rubbers of Austin Minis got really bad, it would allow the engine to kick backwards when the clutch was dropped and the carb choke would shear off when it hit the bulkhead!