MG4 X Power Vibe/Hum 65 to 75mph

[Deleted member 11291]

No chance with reel to reel or 8 tracks either then? Or am I really showing my age ?

 

[Macadoodle]

I believe the x power just uses one of the standard perm mag motors on the front, no fancy decoupling mechanism in the reduction box.
If the motor is idle but still being spun by the cars forward motion, the magnets will still be causing electrons to flow in the field coils 'cogging' I believe is the term.
I have a few rc cars and aircraft with brushless perm mag motors and they all display this tendency if you spin the prop or wheels.
Wonder if this is the x powers' issue ? Good old MG cost cutting strikes again alas ?

 

[Bricktop X PWR]

I believe the x power just uses one of the standard perm mag motors on the front, no fancy decoupling mechanism in the reduction box.
If the motor is idle but still being spun by the cars forward motion, the magnets will still be causing electrons to flow in the field coils 'cogging' I believe is the term.
I have a few rc cars and aircraft with brushless perm mag motors and they all display this tendency if you spin the prop or wheels.
Wonder if this is the x powers' issue ? Good old MG cost cutting strikes again alas ?

Thanks Macadoodle.
At last, something that makes sense to me.(at least?)
I did wonder what was going on but couldn't get my head round it as I don't know enough about it.
I have always thought it was some sort of resonance coming from the front motor.
I didn't think it was anything unbalanced in the drive train as surely balancing components should be basic engineering.

I don't do much motorway work, but if I do, I travel at 75mph as the vibes almost disappear at this speed in my car.
And although this country (Wales) is getting more oppressive every year, I don't expect a ticket anytime soon. (You watch what happens now I've said that ???)

The hum/vibe in my personal case, is such a small part of the overall positive ownership experience, that I will not be rejecting the car.

 

[Lampymic]

I believe the x power just uses one of the standard perm mag motors on the front, no fancy decoupling mechanism in the reduction box.
If the motor is idle but still being spun by the cars forward motion, the magnets will still be causing electrons to flow in the field coils 'cogging' I believe is the term.
I have a few rc cars and aircraft with brushless perm mag motors and they all display this tendency if you spin the prop or wheels.
Wonder if this is the x powers' issue ? Good old MG cost cutting strikes again alas ?

This is sort of what I’m thinking.
I’ve felt something similar but it’s when driving an electric train through a neutral section and it’s trying to regen under deceleration but with nowhere for the power to go.
Going to be a challenge to explain that though although they did fix the trains with a software update!

 

[Macadoodle]

Watched a munro live vid on the youtube where they estimated a $100 cost to Hyundai for fitting a decoupler in the front motor assembly.
They also reckoned it made the drivetrain 6 to 8 % more efficient, equivalent to saving $600 in several kWh of battery capacity they didn't need to install ( for the same range )

If the same physics are playing out in the MG and it's dumping 6 % of its power through front motor losses, it's a pretty poor design decision IMO.
Odd that the resonance or whatever it is is mostly noticeable at a specific speed but that's possibly the resonant frequency of the front assembly, just like a tuning fork vibrates at a specific frequency.

I guarantee you every owner of this car would have gladly paid a little more to have no vibes and 15 miles more range. This is a company who released their standard models with the inability to contain their gear oil inside the gear casing so no great surprise I guess.

Still want an x power though

 

[siteguru]

If those losses are being generated anyway, why not use them as low level regen back into the battery?

 

[Bricktop X PWR]

If those losses are being generated anyway, why not use them as low level regen back into the battery?

Yes, I thought that when I was waffling earlier!
Surely when the front motor is being turned (when not in use) could be like a permanent re-gen?
If that's generating power I suppose the rear is working harder thus negating any benefit?
I've put on my energy consumption screen, I'm in normal mode (rear motor only) and when I'm decelerating I will see if both motors are used for re gen.
Just leaving Saundersfoot. Very nice ?

Yes, I thought that when I was waffling earlier!
Surely when the front motor is being turned (when not in use) could be like a permanent re-gen?
If that's generating power I suppose the rear is working harder thus negating any benefit?
I've put on my energy consumption screen, I'm in normal mode (rear motor only) and when I'm decelerating I will see if both motors are used for re gen.
Just leaving Saundersfoot. Very nice ?

OK, so regen is done by rear motor only regardless of whether you are in Sport or not.

Surely MG have missed a trick there ?

Although both motors would probably be "too harsh" a re-gen?

 

[Chikyu]

This vibration is also present in the Chinese version of the MG4 X-Pwoer. We have ruled out a problem with the front tires, and the vibrations can be easily felt on the steering wheel when traveling at 110km/h. Disappears below 100km/h.

 

[Bricktop X PWR]

This vibration is also present in the Chinese version of the MG4 X-Pwoer. We have ruled out a problem with the front tires, and the vibrations can be easily felt on the steering wheel when traveling at 110km/h. Disappears below 100km/h.

Thanks Chikyu
I knew I had seen you comment somewhere before.
I take it nothing has been done about it by SAIC/MG where you are?

 

[Chikyu]

Thanks Chikyu
I knew I had seen you comment somewhere before.
I take it nothing has been done about it by SAIC/MG where you are?

My friend gave SAIC feedback half a year ago, but there was no progress or reply. The X-Power sold in the UK also has this problem, and I think maybe SAIC won't be able to solve it in a short time.

 

[tsedge]

I believe the x power just uses one of the standard perm mag motors on the front, no fancy decoupling mechanism in the reduction box.
If the motor is idle but still being spun by the cars forward motion, the magnets will still be causing electrons to flow in the field coils 'cogging' I believe is the term.
I have a few rc cars and aircraft with brushless perm mag motors and they all display this tendency if you spin the prop or wheels.
Wonder if this is the x powers' issue ? Good old MG cost cutting strikes again alas ?

What's your evidence for this belief? Be good to have it confirmed one way or another if this is a design problem.

 

[DrAndyPerry]

I've noticed this too. I seem to spend a lot of time between 65 and 70 on my commute.
I'd describe is as sounding like you are overtaking a lorry.
You can feel it in the steering wheel as well as hear it, very low frequency and low volume.
As others have stated it happens in 4wd mode as well as 2wd mode, coasting, accelerating and regenning. To me, that means it seems unlikely that it's motor electrics related. I'd have expected it not to be present under hard acceleration in 4wd if it was a motor coupling / decoupling issue.... but I'm no motor expert.

My car is booked in on the 19th for someone to have a look at it.

AJP

 

[fnegroni]

Has anyone with this issue replaced their tyres yet? Maybe to winter or all season or UHP?

 

[Bricktop X PWR]

Has anyone with this issue replaced their tyres yet? Maybe to winter or all season or UHP?

I think Chikyu has with the Chinese version of Xpower. (or his friend)
Double checking the wheel balance and a tyre change made no difference.
It's in amongst all the threads somewhere?

I am taking off my front and rear undertrays at the weekend,
The rear one is quite flexible (haven't checked the front but imagine its the same) and "could???" be oscillating in the air under the car?
Just to rule out another thing.

The more I dwell on it, the more frustrated I become. How was the car signed off by the test drive team?
Was there a test drive team?
Surely tens of 1000s of miles were completed test driving the car? and yet it's us, The G.B.P.T.D. "Great British Public Test Drivers" doing the bloody testing!!?

P.S. I still love my car.

I've noticed this too. I seem to spend a lot of time between 65 and 70 on my commute.
I'd describe is as sounding like you are overtaking a lorry.
You can feel it in the steering wheel as well as hear it, very low frequency and low volume.
As others have stated it happens in 4wd mode as well as 2wd mode, coasting, accelerating and regenning. To me, that means it seems unlikely that it's motor electrics related. I'd have expected it not to be present under hard acceleration in 4wd if it was a motor coupling / decoupling issue.... but I'm no motor expert.

My car is booked in on the 19th for someone to have a look at it.

AJP

Hi Andy
I did say somewhere that if you spend a lot of time in the vibe zone (65-73/74 in my car) this could become quite waring, quite quickly.
Does anyone know how to "@MG" so that they see the issues we are having.
I don't do twitter or Facebook so have no idea.

 

[fnegroni]

I think Chikyu has with the Chinese version of Xpower. (or his friend)
Double checking the wheel balance and a tyre change made no difference.
It's in amongst all the threads somewhere?

I am taking off my front and rear undertrays at the weekend,
The rear one is quite flexible (haven't checked the front but imagine its the same) and "could???" be oscillating in the air under the car?
Just to rule out another thing.

The more I dwell on it, the more frustrated I become. How was the car signed off by the test drive team?
Was there a test drive team?
Surely tens of 1000s of miles were completed test driving the car? and yet it's us, The G.B.P.T.D. "Great British Public Test Drivers" doing the bloody testing!!?

P.S. I still love my car.

Maybe they tested it and decided it wasn’t an issue. It’s just a characteristic.
Like ICE engines and their turbo lag or irregular idling or silly mixture for fuel economy etc…
I’m not denying it could be better and it’s probably quite annoying but I also know this is possibly what the budget allowed.

 

[DrAndyPerry]

The vibe zone sounds more exciting than it actually is!!!

 

[Deleted member 11291]

The vibe zone sounds more exciting than it actually is!!!

Spoiler alert……..

 

[Bricktop X PWR]

Maybe they tested it and decided it wasn’t an issue. It’s just a characteristic.
Like ICE engines and their turbo lag or irregular idling or silly mixture for fuel economy etc…
I’m not denying it could be better and it’s probably quite annoying but I also know this is possibly what the budget allowed.

You see for me, it is there but not really an issue as I drive around it by taking A and B roads where possible ( I'm rural don't cha know??)
But as Dr Andy said, it's where he is, most of the time, so it could become annoying in very short order.
I will be very surprised, when/if we get an answer MG concluded that it wasn't an issue. (And disappointed)

 

[JonnyG]

I have a long trip this weekend up the A1 and then back down, so will report back, but on my 15 mile trip home on the M1 from picking up the new car I could hardly detect it at all and I was purposely trying to find it at 65-75. There was a slight feeling in the steering, but no noise, and the feeling was like the tyres were running on a different type of road surface for a while.

 

[Macadoodle]

What's your evidence for this belief?

The belief the front motor doesn't decouple or that current is induced when moving magnets near coils ?