MG4 Reduction Gearbox Broken (first in the World???)

[Macadoodle]

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Good lord, that's a pretty spectacular failure ! The motor output support bearing has busted through what looks like a pretty thin casing
Diff ring gear has escaped through the bottom too. Catastrophic failure due to inadequate lubrication would seem to be a distinct possibility considering this units history to date.
Unless there's been a serious miscalculation in the design of the casing and the thrust load from the motor just popped that bearing through the side. Worrying

 

[Chequers]

No crash, catastrophic fault motor

As a retired Engineer and looking at the colour of that bearing, it's basically lack of lubrication that has overheated and expanded the bearing which has split the "very" thin alloy housing.
I cannot see how that alloy casting as thin as it is can stand up to the forces generated and to the differences in expansion of dissimilar metals with the heat that is generated.

 

[capitan capete]

Shit made in china... And poor service quality

 

[Macadoodle]

As a retired Engineer and looking at the colour of that bearing, it's basically lack of lubrication that has overheated and expanded the bearing which has split the "very" thin alloy housing.
I cannot see how that alloy casting as thin as it is can stand up to the forces generated and to the differences in expansion of dissimilar metals with the heat that is generated.

Always thought that 900ml was a fairly small quantity of oil, never mind the 600ml these units will settle to with the leak in full flow.
I wonder if the extreme temp of summer in Spain is thinning this lube to the point of complete failure of the boundary lubrication needed to keep the components separated.

The side casing does look far too thin, the helical gearset will be producing axial thrust, the designers couldn't get a simple breather right so I could easily believe they've miscalculated that too.

If this becomes a common failure it's going to cost SAIC millions worldwide, think I'll give the x power a miss for now, that might explode through the boot floor

 

[capitan capete]

Good morning, I am using a translator and it may not be perfect.

I mainly suspect that the main problem has been. a lack of lubrication due to an oil leak in a transmission joint when the car had approximately two thousand miles, when reporting this oil leak to the service they did not give it importance and the car after driving approximately fourteen thousand miles, had a Service check and they didn't check the oil or where it was coming from.

Shortly after leaving official service, the engine would pick up a piece of loose metal and destroy the entire assembly.

I just spoke to the place where I bought it so that they report this incident to the person most responsible for mg to obtain a solution and make a unit change possible since the car has multiple faults, I personally do not understand how it can have so many problems

 

[tsedge]

Yes, no oil will lead to a broken gearbox, seems very clear cut what has happened here.

 

[Macadoodle]

The transmissions have vertical movement that does not look good...

I ask the service if they have verified the transmissions and they say they are fine.

Was it the driveshafts that had vertical movement before the 'big bang' occurred ?

 

[capitan capete]

Yes correct

 

[Macadoodle]

Bearing failure on the differential then. Gears no longer aligned, broken teeth, jam, bang.

Think I'll be changing the oil on mine every 20k miles for as long as I have it, it's no better than owning a fossil burner

 

[tsedge]

Bearing failure on the differential then. Gears no longer aligned, broken teeth, jam, bang.

Think I'll be changing the oil on mine every 20k miles for as long as I have it, it's no better than owning a fossil burner

Well it is a lot less oil, but I get your point! ?

 

[Macadoodle]

Well it is a lot less oil, but I get your point! ?

Although if you use the official oil 1litre is more expensive than 5 litres of synth engine oil.
Mine has ran on synthetic ATF for the last 6000 miles, tenner a litre, still smooth as butter.
Make of that what you will but don't tell MG.

 

[capitan capete]

Yes , before the fault no os posible load videos

 

[bowfer]

Jeez that casing does look thin…
I’ve seen thicker on low power motorbikes.

 

[Deleted member 10041]

Jeez that casing does look thin…
I’ve seen thicker on low power motorbikes.

Built to a budget

 

[ianwlk]

Interesting to know if the power delivery characteristics of EVs put greater stress on bearings than ICE cars

 

[Kithmo]

Yes, no oil will lead to a broken gearbox, seems very clear cut what has happened here.

I remember a gear oil additive in the 70s, Molyslip IIRC, that let you run the car with no gear oil in it for many miles before it failed.

 

[tsedge]

I remember a gear oil additive in the 70s, Molyslip IIRC, that let you run the car with no gear oil in it for many miles before it failed.

They still make it.

 

[Macadoodle]

Molybdenum disulfide is a pretty effective extreme pressure additive, I poured some into a couple of ICE lumps in the past and it noticeably quietened the normal valve train and cam chatter.
I believe the RAF used it in aircraft during WW2 as it would allow an engine to run for some time after losing its oil if a .50 calibre went through the block ( or metric equivalent )

Not sure it would have helped the MG here though, that looks sadder than any machine gun peppered Merlin ?

 

[Kithmo]

Molybdenum disulfide is a pretty effective extreme pressure additive, I poured some into a couple of ICE lumps in the past and it noticeably quietened the normal valve train and cam chatter.
I believe the RAF used it in aircraft during WW2 as it would allow an engine to run for some time after losing its oil if a .50 calibre went through the block ( or metric equivalent )

Not sure it would have helped the MG here though, that looks sadder than any machine gun peppered Merlin ?

It certainly helped my Cortina to survive losing most of my engine oil after my aftermarket oil gauge feed pipe got dragged off in deep snow. ?

 

[coff33]

Any updates on this? were you able to get a replacement car?