Costly Brake Replacement

[Lovemyev]

Stoob, I'm a retired technician & from the pictures those discs look fine. The grooving on one or two of them looks ok. Not bad enough to need replacing. The one caveat is that the grooves may not be showing up properly on the photo but I suspect they are fine. If you need new pads they will settle down ok. Have a chat with your dealer about this or go to another dealer for a second opinion.

I totally agree, if you are going to replace them discs at that stage, then it is likely that every 2 year old EV would need them replacing .
Good business for the dealer charging almost a grand on top of servicing an EV.
Looking for work IMHO.
I try to remember to drop my regen to the lowest setting one day a week to try and reduce rust build up forming.
Winter / road smuts etc is the main cause, and lack of use.

 

[MG Clive]

By the way @Stoob, don't worry about the rusty bits you're seeing on the discs, that doesn't affect the use or efficiency of the brakes, so they won't need replacing because of that.

 

[Stoob]

Stoob, I'm a retired technician & from the pictures those discs look fine. The grooving on one or two of them looks ok. Not bad enough to need replacing. The one caveat is that the grooves may not be showing up properly on the photo but I suspect they are fine. If you need new pads they will settle down ok. Have a chat with your dealer about this or go to another dealer for a second opinion.

Thank you. The groves can be felt with the fingertip on one disc but they’re not deep. I might look for another dealer. Or take them to another mechanic altogether.

Discs look fine.
Would be interesting to know the thickness but I'd be 99.9% sure they are OK.

Disc thickness on the front between 9.35 and 9.4 mm. At the back, 10mm+.

 

[Stoob]

By the way @Stoob, don't worry about the rusty bits you're seeing on the discs, that doesn't affect the use or efficiency of the brakes, so they won't need replacing because of that.

I was actually wondering whether that was what was bothering the mechanics. Didn’t see how they’d interfere but…what do I know?

 

[Alb]

Disc thickness on the front between 9.35 and 9.4 mm. At the back, 10mm+.

Doesn't sound right for the fronts, minimum is 23mm IIRC.
Rears would have been 10mm when new so are pretty much unworn.

 

[Stoob]

Well, there seem to be two discs on the front. Can't really see; separated but together? both - i.e. the pair of discs and the gap between them - measure 26.36 mm. Previously, I measured only the outside, visible disc on the front wheels. Is that right? The two discs on the front are bound together, apparently one unit with a gap between them, but I can't really get in there to see properly. If necessary, I could turn the wheel, I suppose.

 

[MG Clive]

Yes that is correct @Stoob, the measurement should be for both discs together, this type of discs are known as 'vented discs', and it's as you've described, it's basically 2 single discs fixed together with an air gap in between to aid brake cooling.

 

[OriginalBigAl]

It appears that all the evidence points to them " trying it on " if they were serious they would have put it in writing? which would put themselves in a better position legally.

 

[Stoob]

It appears that all the evidence points to them " trying it on " if they were serious they would have put it in writing? which would put themselves in a better position legally.

In fact they included this in their report. (I’ve shown only the references to the brakes). It’s a bit puzzling because it’s the second they sent. The first does not have the strike throughs. What’s shocking is that you can buy a pair for under £100.

 

[Lovemyev]

Until third party parts became available and a much lower price point, the dealer had total monopoly on what they wanted to charge for the MG replacement discs and pads.
The third party items are WAY less expensive than the dealer supplied parts of course.
The problem here is of course, that to retain the warranty, genuine MG parts have to be installed and they know this !.
unless you can circumnavigate around this issue ( if you get my drift ).

 

[Gadget Geek]

I'm wondering, if brakes aren't covered in the warranty, will using 3rd party pads and discs affect the warranty of the parts which are covered?

 

[BOB353]

I'm wondering, if brakes aren't covered in the warranty, will using 3rd party pads and discs affect the warranty of the parts which are covered?

I think brakes are part of the wear and tear like tyres. But they should last longer than 2 years.

 

[Data]

Usually brakes are not covered under warranty in the same way as other parts of the car. It's normally a 3 or 6 month warranty on friction parts of the brakes depending on brand of car.

I would add, while there definitely are some dealers who actively seek work from their customers, and it is debatable as to whether it needs doing, these dealers are in fact in the very small minority of dealerships. I have worked at dealerships at differing times of my life & overwhelmingly they do a very good job, care about their customers & try to minimise costs where they can. I and many other tech friends get a bit cross when we hear the generic term 'stealership' used. In fact from the many cases I looked at in my career this was almost never true. Often customers don't understand a reason something is quite expensive or has to be done. And to be fair, some dealers don't always explain everything very well. This causes customers to go away with the wrong impression. This situation isn't uncommon but normally isn't about the garage 'just making money'!

I do think that this thread about brake discs needing replacing needs looking at though because to me the discs look fine. So based upon what we know the owner needs to dig deeper. There could be other reasons also as to why the discs are recommended to be replaced. This may be because there is warpage on one or more of them...we just don't know so we cannot base an opinion on what we know here. A chat with the dealer might reveal something the owner has not understood or realised. No disrespect to the owner intended but that is often the number one cause of issues like this. I know some of you will jump on me for saying this but ask any good tech & they will tell you the same.

 

[JohnV6]

A fair comment they could be warped but you would think if all 4 were the driver would feel it via the steering.

As you say based just on photos we can't tell that.

 

[decrep]

But what would cause them to warp. My understanding is excessive heat?
Running out of regen going down a steep mountain perhaps?
But for normal EV driving it shouldn't happen, the friction brakes just don't do enough work.

 

[Data]

But what would cause them to warp. My understanding is excessive heat?
Running out of regen going down a steep mountain perhaps?
But for normal EV driving it shouldn't happen, the friction brakes just don't do enough work.

Yes, it's not likely in this case. But we don't know for sure.. As you say, heat is usually the cause, but not always. It's most often caused by drivers slowing from speed or downhill running , bringing the car to a stop & keeping their foot pressed on the brake pedal. This causes a localised hotspot on the discs causing them to warp. Some drivers of EV's & ice cars, do this all the time. Mostly manufacturers take account of this & try to eliminate this risk by providing good disc ventilation. You can see this in the front brakes in the form of vented front discs. It's really just the front discs that tend to warp from being heated like this as it's the front discs that deal with most of the braking load.
The other reason for warped discs is faulty disc manufacture. It does happen where the metals used to produce some discs is of the wrong grade & mix. That can make them more likely to warp. Several car manufacturers have had that issue over the years.

 

[OriginalBigAl]

A warped disc would usually be felt through the steering , and certainly through the brake pedal action . The warping would knock the pads back in the caliper and the first bit of pedal movement would be really slack as the pads have to travel more to make up the distance to to disc , the pedal would firm up but knock and vibrate as though ABS had activated. ( with varying degrees of severity ).
Also in the OP s case the inspection was likely visual and very doubtful if any run out gauge was used.

 

[saluja]

My 2020 ZS EV was serviced yesterday and they advised that the front and rear break discs will need replacing in 5 months or so. Mystified as they recently MOT’d it 2 months ago but did not make that advisory then. Also, the price is HUGE! Around a £1000!
Questions: is this normal (Car only done 18,000 miles, first 12,000 in Edinburgh)? Should I shop around for cost? Or to get a second opinion? Is it sane to ignore?

As an EV there should be very low brake wear but even ice car shouldn’t need discs replacing let alone all four. Kwikfit do good brake check. Report includes photos of all the discs with relevant thicknesses to check with car spec etc.