MG4 Undertray dip/bulge

[NickHeynes]

Not sarcasm I think, just a valid comment on the quality of the undertrays.

Oh I see, Well if it takes belt and braces so be it . As long as it works .

 

[FrancisM]

Oh I see, Well if it takes belt and braces so be it . As long as it works .

Maybe the original tray was so warped they couldn't flatten it, or was starting to crack. And replacements have been known to warp after being fitted.

 

[LenEV2016]

Maybe the original tray was so warped they couldn't flatten it, or was starting to crack. And replacements have been known to warp after being fitted.

Poorly designed, too flimsy and definitely a big batch with the holes not fully lining up with the bolts. The fix is a bodge job but at least it cures it and stops it catching all the road crap on manky roads

 

[NLMGSAN]

It was sarcasm for sure.
If it is done under warranty then MG UK themselves do not even trust the new undertray....

 

[Shocky]

Mine was present when I picked it up from the dealer

I checked mine soon after taking delivery, no obvious bulge. But now after only 600kms two bulge areas have developed. So I guess I'll get the brace fix at the 3 month/1000kms complimentary check.
Does anyway know if this has been rectified in latest build models or are there still reports in 24 builds?

 

[crc32]

I checked mine soon after taking delivery, no obvious bulge. But now after only 600kms two bulge areas have developed. So I guess I'll get the brace fix at the 3 month/1000kms complimentary check.
Does anyway know if this has been rectified in latest build models or are there still reports in 24 builds?

I just discovered the bulge on my Jan 24 build.

 

[Coulomb]

Mine has a bulge, and is also a Jan '24 build.

 

[Les burrows]

You have a point Siteguru but as anyone seen this down under fix i don’t recall seeing any pictures.
Les


No no it’s a new tray I can assure you of that.
Les

My wife’s car MG4 SE final after two and a half years has the bulging rear under tray looking as it should, a brand new replacement tray was fitted a year ago which made little or no improvement and at last yesterday my dealer Chorley MG manage to fit the reinforcing bar that MG as issued as a recall for the problem and yes it’s now looking good.
Here below is a picture after the replacement new tray was fitted with a picture of the part number label attached to it.



And this is how it looks after the modification is fitted under the recall.


Now I don’t understand why but no other work was carried out at this visit but it appears the battery was disconnected to fit this mod as when I got back in the car all trip meters where at zero and I recall when I took the car in the GOM was reading 74% battery with 101 miles but after driving home around 10 miles GOM reads 67% with 219 miles that would be fantastic on a MG4 SE LFP 50kw battery it a great same but I’m sure it will sort itself out once driven a few more miles it never shows that even it summer.


So a shout out to Chorley MG who got there in the end.
Les

 

[AndyL61]

My wife’s car MG4 SE final after two and a half years has the bulging rear under tray looking as it should, a brand new replacement tray was fitted a year ago which made little or no improvement and at last yesterday my dealer Chorley MG manage to fit the reinforcing bar that MG as issued as a recall for the problem and yes it’s now looking good.
Here below is a picture after the replacement new tray was fitted with a picture of the part number label attached to it.View attachment 34210

View attachment 34211

And this is how it looks after the modification is fitted under the recall.
View attachment 34212

Now I don’t understand why but no other work was carried out at this visit but it appears the battery was disconnected to fit this mod as when I got back in the car all trip meters where at zero and I recall when I took the car in the GOM was reading 74% battery with 101 miles but after driving home around 10 miles GOM reads 67% with 219 miles that would be fantastic on a MG4 SE LFP 50kw battery it a great same but I’m sure it will sort itself out once driven a few more miles it never shows that even it summer.
View attachment 34213

So a shout out to Chorley MG who got there in the end.
Les

My personal opinion of this "solution" is that it's a bodge job and a proper solution would have been a redesigned undertray. I still can't believe that they haven't issued a new undertray. Oh well I suppose after over 2 years it's the best we are going to get.

 

[ReintjeWA]

Now I don’t understand why but no other work was carried out at this visit but it appears the battery was disconnected to fit this mod as when I got back in the car all trip meters where at zero and I recall when I took the car in the GOM was reading 74% battery with 101 miles but after driving home around 10 miles GOM reads 67% with 219 miles that would be fantastic on a MG4 SE LFP 50kw battery it a great same but I’m sure it will sort itself out once driven a few more miles it never shows that even it summer.
View attachment 34213

So a shout out to Chorley MG who got there in the end.
Les

Not sure how long the drive is from the dealership but your total accumulated time has reset 38 minutes before you took that photo.

When the total time reaches 100 hours it resets (because it can’t show you 100) and that also resets the GOM. Thus the GOM reverts back to WLTP range or even more optimistic figures. It should settle after a while when the GOM gets used to real life driving again.

 

[siteguru]

For info, it should only be the Accumulated Total trip that resets due to time ... the other 2 should retain their values. (The chances of the other 2 reaching 100 hours is slim to none. But yes - the GOM uses the Accumulated Total for range estimation). When software updates are applied all 3 trips reset.

 

[Otterks]

Picked up my mg4 ER on 11th Jan, thanks to this forum knew about the undertray and had a note put on the acceptance form regarding the repair, when I tried to get hold of the dealer a few days later to book in despite the promised return phone call (never happened) and sending an email (no reply) it took another email direct to mg to get a response from the dealer and get the bracket fixed to the undertray. The completed fix has improved the sag which was in 2 places but is not perfect or what I would expect from a brand new car. Am i being to picky or should I go back to the dealer and get them to replace the whole tray and fit the bracket, TBH it has been so much hassle and the wife is getting edgy about the car.

 

[ReintjeWA]

. The completed fix has improved the sag which was in 2 places but is not perfect or what I would expect from a brand new car. Am i being to picky or should I go back to the dealer and get them to replace the whole tray and fit the bracket.

I’m not too impressed with that, it looks like the bar was loosely added, I would expect the tray to be flattened by the bar/bolts, that would surely still give you wind noise.

Mine is going in a few weeks for this fix, I’ll take pictures when I get it back and show what mine looks like. Which hopefully will look better than that

 

[siteguru]

It helps if they try and adjust the undertray to be as flat as possible before they fit the bracket.

 

[NLMGSAN]

And, from what I see here the bar is smaller then it was in the beginning when the fix came out?

 

[Les burrows]

Picked up my mg4 ER on 11th Jan, thanks to this forum knew about the undertray and had a note put on the acceptance form regarding the repair, when I tried to get hold of the dealer a few days later to book in despite the promised return phone call (never happened) and sending an email (no reply) it took another email direct to mg to get a response from the dealer and get the bracket fixed to the undertray. The completed fix has improved the sag which was in 2 places but is not perfect or what I would expect from a brand new car. Am i being to picky or should I go back to the dealer and get them to replace the whole tray and fit the bracket, TBH it has been so much hassle and the wife is getting edgy about the car.

Hi all that can be said is if you're not happy take it back and complain; you have every right to. Our car had a brand new tray fitted around a year ago and that made no real difference but it is looking far better now with the bar fitted. I don’t know but maybe Siteguru above in post #994 has a good point in what he as written. Perhaps loosening the tray all round then fitting the bracket, tightening that first. and then tightening the rest of the bolts fully might work; he as a good point.
I can’t believe new cars are still coming from the factory with this issue to be honest.
Les

 

[Anon70]

If you think it is just MG under trays that have issues this is an interesting watch from timestamp 4:00. So lulls you into a false sense of all good for 2 years then the tray falls off

 

[Kevin Smith]

I've seen in other threads talk of vibration from it and mine has basically come to pieces and I'm hoping Mg will be fixing it.

 

[Leebeejeebee]

I asked about this in December when I took mine in for service - they said it's fine. I said I was concerned that it would be scooping in air which would then have nowhere to go and create drag - they said it wouldn't create any drag and refused to fix it. Surely this is just physics?

 

[siteguru]

Given that there's a well-known fix for this, which is available under warranty, I really don't understand why some dealers are so intransigent.

Direct link to PDF of MG's Technical Bulletin about this issue. (Hosted on my website. HTTP link rather than HTTPS, so your browser may flag a warning). You could do worse than print this out and show it to your dealer - after all you have raised a customer concern about this.