MG4 Undertray dip/bulge

[Macadoodle]

The rear tray bolts to the back edge of the battery pack, so there isn't the ability to have an overhang.

That's the problem it doesn't. My pic is poor due to my 1954 era phone but if you look at the OP's first post pic you'll see the what I presume is the BMS casing sticking down into the airflow.
They did give the forward edge of the rear tray a lip but far too few fixings inboard on the BMS casing.
'Twas never going to work well.

 

[Deleted member 10041]

That's the problem it doesn't. My pic is poor due to my 1954 era phone but if you look at the OP's first post pic you'll see the what I presume is the BMS casing sticking down into the airflow.
They did give the forward edge of the rear tray a lip but far too few fixings inboard on the BMS casing.
'Twas never going to work well.

What he said, forward edge of rear tray, back edge of the front.
I'm giving myself a sore head here

 

[Ayoull]

That's the problem it doesn't. My pic is poor due to my 1954 era phone but if you look at the OP's first post pic you'll see the what I presume is the BMS casing sticking down into the airflow.
They did give the forward edge of the rear tray a lip but far too few fixings inboard on the BMS casing.
'Twas never going to work well.

I didn't have an undertray on mine and I can assure you it does bolt to the battery there are four mounting points on the back of the battery pack.

 

[Macadoodle]

What he said, forward edge of rear tray, back edge of the front.
I'm giving myself a sore head here

Aye, they need to be overlapped like roof tiles.

View attachment 14995

I didn't have an undertray on mine and I can assure you it does bolt to the battery there are four mounting points on the back of the battery pack.

Well, looks like standard and long range have a different set up. I have an external 70 x 10cm alloy casing with ribs that the central two hex head bolts holding the rear tray screw in to.
It's sitting lower than the battery pack, you can see it best in the OP's opening pic.

* Edit. I misremembered. Having refitted the undertray today, it does indeed pick up some fixings on the lugs that are part of the battery casting, that's where it fits fairly well and flush.
The whole issue with the middle bulge is caused by this infernal separate casting that bolts to the battery and sticks down around 10mm across a 70cm span.

I spotted a metre by 40mm flat aluminium bar in B & Q which I think might work well to address the issue.
3 slots or holes in said bar to align with the 3 middle fixings in the battery undertray immediately in front of the problem one will nicely bridge the gap, flattening the wavy tray and helping a continuous airflow.
Will post a pic once I get around to it

 

[turntoport]

Ma

Aye, they need to be overlapped like roof tiles.


Well, looks like standard and long range have a different set up. I have an external 70 x 10cm alloy casing with ribs that the central two hex head bolts holding the rear tray screw in to.
It's sitting lower than the battery pack, you can see it best in the OP's opening pic.

* Edit. I misremembered. Having refitted the undertray today, it does indeed pick up some fixings on the lugs that are part of the battery casting, that's where it fits fairly well and flush.
The whole issue with the middle bulge is caused by this infernal separate casting that bolts to the battery and sticks down around 10mm across a 70cm span.

I spotted a metre by 40mm flat aluminium bar in B & Q which I think might work well to address the issue.
3 slots or holes in said bar to align with the 3 middle fixings in the battery undertray immediately in front of the problem one will nicely bridge the gap, flattening the wavy tray and helping a continuous airflow.
Will post a pic once I get around to it

Macadoodle, did you get around to the 'stiffening/support strip' fix? I may well do exactly this myself.
[Have just had a response from MG via local dealer to the effect of: "the undertray performs as per the design intent, no action will be taken" - not quite verbatim, but nearly. If i can get the e-mail forwarded i'll re-post it. As a mechanical/aeronatics engineer myself, i'm none to happy at this level of manufacturer disregard of an issue which will (a) decrease the range of the vehicle, and (b) provide a nice scoop for all the road crap, crud, gunge and water, so neatly directing it into the motor/gearbox bay. One drive through an undertray-depth ford would see the rear undertray gone; i wonder if SAIC would take responsibility for that damage? (obviously not, lol !)]
atb - ttp

Ma

Macadoodle, did you get around to the 'stiffening/support strip' fix? I may well do exactly this myself.
[Have just had a response from MG via local dealer to the effect of: "the undertray performs as per the design intent, no action will be taken" - not quite verbatim, but nearly. If i can get the e-mail forwarded i'll re-post it. As a mechanical/aeronatics engineer myself, i'm none to happy at this level of manufacturer disregard of an issue which will (a) decrease the range of the vehicle, and (b) provide a nice scoop for all the road crap, crud, gunge and water, so neatly directing it into the motor/gearbox bay. One drive through an undertray-depth ford would see the rear undertray gone; i wonder if SAIC would take responsibility for that damage? (obviously not, lol !)]
atb - ttp

Apologies Macadoodle, didn't mean to call you 'Ma' (!)

 

[Macadoodle]

Apologies Macadoodle, didn't mean to call you 'Ma' (!)

Been called worse No I haven't got around to doing the aluminium strip thing as yet, still experimenting with the breather problem so the undertrays are permanently lying in the garage.
I did find a piece of thin ally plate about 10 cm x 5 cm and tried that on the middle bulge that's the worst one of all, flattened it pretty nicely.
The penny pinching and denial from MG is beyond belief, great way to build brand loyalty.
So short sighted of them. I doubt I'd buy another.

 

[SydneyPat]

Howdy all. I attended the Sydney Fully Charged show today, where the MG4 has made its Australian debut. Two cars were on display, and I am sure you will all be pleased to know they both exhibited exactly this type of undertray bulge. Both vehicles were right-hand drive, and I don't know when they were built. Not due on sale here till the second half of 2023, but no sign, at least based on these two cars, that a factory fix is in place at this point

 

[Norfunk]

This is the response to the undertray bulge from my dealer 'the tray is designed like that because of the motor within the bay'! I've forwarded his response onto MG customer services to see what their official response is, as I'm concerned this will greatly reduce the longevity of the car.

 

[mst33594]

This is the response to the undertray bulge from my dealer 'the tray is designed like that because of the motor within the bay'! I've forwarded his response onto MG customer services to see what their official response is, as I'm concerned this will greatly reduce the longevity of the car.

On collection a few weeks ago I pointed out a slightly bulging undertray. Dealer acknowledged it was not right. They phoned me today to talk me through a potential fix as well as telling me they’ve ordered the kit to fix the noisy passenger quarter light. Dealer said the noisy window is a known problem so After I’d told them I had an issue they went ahead and ordered the kit without having to hear the window noise. I’m pleased with the dealers proactivity and attitude. Glyn Hopkins Bedford.

 

[jamesc83]

On collection a few weeks ago I pointed out a slightly bulging undertray. Dealer acknowledged it was not right. They phoned me today to talk me through a potential fix as well as telling me they’ve ordered the kit to fix the noisy passenger quarter light. Dealer said the noisy window is a known problem so After I’d told them I had an issue they went ahead and ordered the kit without having to hear the window noise. I’m pleased with the dealers proactivity and attitude. Glyn Hopkins Bedford.

What was the potential fix for the bulge?

 

[mst33594]

What was the potential fix for the bulge?

They said something like…. As the gap is quite small, which it is, they will remove the tray to re fix the fasteners in a sequence to close the gap and use if needed a heat gun to shape the tray. May or may not be an official MG fix ?? Or not
So long as it’s sorted I’ll take it.

 

[Macadoodle]

This is the response to the undertray bulge from my dealer 'the tray is designed like that because of the motor within the bay'!

So it's air cooled ? Makes you wonder why they bothered with the water cooling then. The utter nonsense some dealers spout

 

[tsedge]

So it's air cooled ? Makes you wonder why they bothered with the water cooling then. The utter nonsense some dealers spout

I agree but also it is because MG have left them to fend for themselves, there should be much more comprehensive training to transition from ICE maintenance to EVs.

 

[Deleted member 10041]

I agree but also it is because MG have left them to fend for themselves, there should be much more comprehensive training to transition from ICE maintenance to EVs.

Agree but some dealers seem to default to lying.
The decent ones actually admitt they don't know but say the will try and find out

 

[siteguru]

They said something like…. As the gap is quite small, which it is, they will remove the tray to re fix the fasteners in a sequence to close the gap and use if needed a heat gun to shape the tray.

That's essentially what my dealer did to make mine a lot better - plus slotting a couple of the fixing holes. (One of the key problems is the pitch of the holes is not quite right).

 

[Nearly There]

My first post on the forum.... I'm excited to be collecting my black Trophy next week.

I had the dealer take a photo of the undertray today. He sent this saying "as you can see, all is well"

It looks minor compared to other photo's I've seen on this thread. My inclination is to accept the vehicle, but somehow document the "bulge issue" and ask to be kept informed of any official response from MG. Can anyone suggest how to go about this?

 

[siteguru]

I've seen worse, I've seen better. That would easily flatten out with a bit of hole elongation and a hair dryer.

 

[Ian Key]

Ask your dealer to note that there is a slight bulge then if anything happens you are covered

 

[siteguru]

This is mine:

 

[Deleted member 10041]

My first post on the forum.... I'm excited to be collecting my black Trophy next week.

I had the dealer take a photo of the undertray today. He sent this saying "as you can see, all is well"

It looks minor compared to other photo's I've seen on this thread. My inclination is to accept the vehicle, but somehow document the "bulge issue" and ask to be kept informed of any official response from MG. Can anyone suggest how to go about this?

View attachment 16168

Definitely not all is well!! Dealer BS, as has been said there is a lot worse out there though.

Makes me laugh "all is well"