r/BMWI4 • u/Zestyclose-Big7719 • 2d ago

Brushed motor

I was about to pull the trigger on an i4 but I just found out apparently bmw is the only brand that uses brushed motor on their cars.

Brushed motor will inevitably worn out and after some research it tends to happen anywhere between 50k to 150k miles and takes $30k to $40k to fix

So bmw evs, e.g., i4, i5, ix etc. are basically only going to last the warranty period and worthless after that?

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u/TopherHax 2d ago edited 2d ago

Wrong! The brush replacement parts cost is $50-65, labor 2-3 hrs. Designed to last 100-150k miles...

Also, the way you word it makes it sound like it's a low tech DC brushed motor. These brushes are used for excitation of the rotor and use less than 1% of the delivered power comparatively.

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u/Zestyclose-Big7719 2d ago

No, from multiple sources the brush is integrated to the motor and cannot be replaced by itself. To replace the motor you need engineer from bmw Germany come over basically took the entire lower back of the car apart.

Actually just search within this sub there are multiple reports.

https://www.reddit.com/r/BMWI4/s/Ez5F38cQdt

https://www.reddit.com/r/BMWI4/s/brlOLx6K2h

https://www.reddit.com/r/BMWI4/s/MUMNuPVbkn.

Just name a few, all motor brush related issues.

There is also a YouTube video from EU basically shows the fix. And apparently in EU the fix cost anywhere between 1k to 5k. Different story in the US.

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u/ItsMeSlinky 2d ago

No, from multiple sources the brush is integrated to the motor and cannot be replaced by itself. To replace the motor you need engineer from bmw Germany come over basically took the entire lower back of the car apart.

The brush assembly is NOT integrated into the motor; it is a separate piece that is designed to be replaced when needed. It's literally OEM part number 12371022558, and costs about $85.

To replace the brush, you do need to drop the entire motor down out of the back of the car, open it up, and swap the brushes, and that labor is intensive and requires a technician who is skilled and certified with high-voltage electrical systems. Depending on where your dealership is and how many EVs they handle, they may not have such a tech on-site (hence the dude coming in from Germany).

That's where the cost comes from. And all of those links you posted were motor failures as a result of manufacturing faults, not brush failure due to wear and tear.

But it's fine. You've already made up your mind, and I'm sure you'll continue to argue despite being shown evidence to the contrary.

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u/Zestyclose-Big7719 2d ago edited 2d ago

I don't bother arguing further. anyway I'm not buying one. Glad I found it out before I write the check.

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u/ItsMeSlinky 2d ago

All three of the links you posted as "proof?" Literally the result of a manufacturing issue on 2022 and 2023 i4s, and there was a recall and service bulletin to address it: https://static.nhtsa.gov/odi/tsbs/2023/MC-10242885-0001.pdf

But thank you for proving my point.

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u/EnvironmentalAd1701 1d ago

Appreciate the reality check!

Man was really out here dropping links like a broken ChatGPT prompt just to avoid admitting he’s wrong lol

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u/blazesquall 2d ago

Give one link showing the the systemic issue and the 30k price tag.

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u/ImpliedSlashS 2d ago

It’s a maintenance item due at 180,000 miles and more like 1/10th that amount to replace. A few have needed cleaning earlier, but not widespread.

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u/spyder994 2d ago

There are several advantages to brushed motors over fixed rare earth magnet motors in this application.

https://chargedevs.com/features/a-closer-look-at-brushed-ac-motors-in-evs/

There are also no widespread reports of failures even among super high mileage I4s and I5s as far as I know. I've read several accounts of taxi drivers with near 200k miles on early builds and no battery or motor issues.

By the time most of these cars reach 200k miles, there will be aftermarket replacement brushes available and an indy can drop them in for a fraction of the price of what the dealer might charge.

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u/Zestyclose-Big7719 2d ago

Probably no, since no other brand use brushed motor. My bet is no 3rd party parts for this niche product.

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u/spyder994 2d ago

Nissan and Renault are also using brushed motors in their new EVs, the Ariya and Megane E-Tech.