Query on when to change brake discs

[lost-in-translation]

Hi all, this one is hopefully fairly easy. Essentially I have a vehicle which to my mind, went quite under utilised for the last year (covid and all) yet when I took it for a service, there was what appeared a steep decline in its brake conditions.

Make Hyundai
Model I30
Year 2018
Mileage 16,021 (12,736 on service 14 months prior)

So for some backround

Essentially, on my most recent service (start of this year) it was flagged the front discs were 95% worn, at 23.5mm. This was clarified as meaning worn towards their recommendation of 23.4mm as a minimum. Under their rating system, this was flagged Red. For wider context, Front pads are 40% worn, rear discs 20% worn, rear pads they ommited to give a number, as they instead recommended a service to fix binding).

the service before this (14 months) had everything green, including the front discs which were 95% worn this time round. It transpires the difference between the two was 2mm for about 3.3k miles. Not sure how good or bad that is, or why the margin between green and red is so slim..

The actual question at hand

Can someone educate me in terms of legality on the brake disc wear, but also the safety aspect here. I'm not simply trying to be cheap here, but they did want to charge about £350 quid to replace them, and in my mind it had barely any mileage. 16k over 3 years isn't a lot. I got it at about 8 months after its registration, so to my expectation, everything is factory fitted. Being told the brake discs are basically done when the pads are only at 40% wear makes no sense to me. Hyundai aren't being particularly helpful either, when I ask them if this is expected wear, and what the sizing in mm is out of the factory, they pointedly ignore the question. I get the impression their email is being handled by one individual as well, hence its maybe not their fault about the poor response I'm getting. I don't know what's going on with their staffing right now.
I got Hyundai because it seemed a decent brand, with a good reputation. But I'm not impressed at the idea brake discs need replaced every 16k miles. Perhaps this is the reality now with metal discs, My previously car was a 2004 Vauxhall Astra which I had for about 8 years. I replaced the pads about 3 times, and the discs never. I see a lot of people mention the removal of asbestos has reduce the lifespan, I'm not sure if a 2004 Astra would have had that.(incidentally I got an i30 for comfort, its not the case I'm accelerating and braking hard here.)


From someone that isn't after a quick service fee:
Is the amount of wear here actually a problem?
Are there legal limits I should also be aware of?
How soon should these be replaced?
Is this an expected level of wear for a modern car?
Bonus points if someone can tell me what the stock width of these ought to be, I haven't had any luck getting that info

I haven't had cause to use it much recently, but I will make a few long trips in the coming months as lockdown eases, and if this is in fact a tangible risk I'll have to bite the bullet and replace them.
Any guidance for a noob is appreciated. Cheers.

 

[Mottie]

I doubt very much if they are 95% worn after that sort of mileage. Front pads at 40% worn is not even half worn! The average car would normally go through two sets of pads to one set of discs so based on the pad wear alone, the discs are nowhere near to needing replacement.

There’s no 'legal limits' for brake disc thickness, only manufacturers recommendations and for the mot, the minimum pad thickness is 1.5mm.

Decent quality parts will cost around the £100 for discs and pads and I think the last one I did (while I was doing a service), I charged around £160 fitted - its no more than an hours labour to fit them.

Get a second opinion if you want but personally, I wouldn’t worry about it.

 

[Burnerman]

After a bit of braking your discs should be nicely polished (on both sides - but the inside is more difficult to see.)
At 18k miles there shouldn't be much of a wear lip on the outer edge of the disc either and the pads hardly worn - but Hyundai do give the rear pads some work as they aren't very large. The handbrake is usually drum inside the disc on these.
As the vehicle has a 7 year warranty, this is the way that Kia/Hyundai try to recover some of the lost revenue - I've seen this many times.
If you do go for replacements, ask an independent garage to fit you Blueprint parts.
John

 

[johnny2007]

They're trying to rob you.

 

[norseman]

There's too much of this going on & it's not just main stealers.
18 months ago I had a complete set of tyres fitted to our daily & the guy who processed my payment informed me that the front discs were worn to the point of needing urgent replacement. What the chancer didn't know was that having recently bought the car I'd had a full service & inspection carried out by my local trusted garage.
Not only have (they) blown any chance of future custom from our family but possibly anyone else who happens to ask my opinion.
I won't mention the outfit on an open forum ... lets just say it's the same title as used in international motor racing

 

[DIYspanner]

We have an 2009 i20 from new which went to the main dealer for service while in warranty. In its last warranty year they quoted around £350 for news pads all round. I did it all a wee bit cheaper.

 

[cdbe]

Just ignore the brakes till the wear indicator comes on, that's what it's for. You then have at least 1,000 miles to get the pads changed. While you're waiting, go onto carparts4less with your registration number and price up replacement discs and pads, expect no more than 2 hours labour to fit them (thought it will probably take them about 20 minutes) and work out what you think is a fair price.

Mottie will probably tell you that there's a huge difference between what car servicing places and MOT inspectors think is acceptable for brakes.

 

[Mottie]

Mottie will probably tell you that there's a huge difference between what car servicing places and MOT inspectors think is acceptable for brakes.

Certainly is although MOT standards are absolute limits/about to fail.

 

[lost-in-translation]

Cheers guys, glad its not just me that thinks this seems unreasonable then. Appreciate the feedback.
Also on the note of MOT's, the garage I always take my car too (non chain) mentioned mot tends to only glance over discs, there main focus is the pads. He also said much the same as you lot when I asked him about the discs. That the dealership's simply try to scare people who don't know much about car maintenance, into replacing everything. The dealership have tried to sell me an aircon clean every service as well, stating there's a build up of bacteria and I'd start to notice smells. 2 years and I still have no issue there... I digress though..

Hyundai got back after chasing them on social media, saying they were waiting on a response from the factory as to what the original MM was for the discs. I suppose I'll use that to decide at what point they should be replaced (id assume not prior to 50% wear at the least), but they certainly wont be getting replaced till the actual pads are done.
I cant help but feel they are stringing this out so I wont know how little they have actually worn. Its been several months of emailing them to even get this far.

 

[Astra99]

Your I30 is the equivalent of the Kia Cee'd which I had for three years. As you have between two and three years warranty left it is always worth having the car serviced at the main agents. However, brake pads and discs are regarded as consumable items, so, to maintain the (rest of the) manufacturer's warranty, there is no need to have that work done by the dealers. You can go and buy the bits from Euro Car Parts (or similar) and do it yourself!

After my Cee'd's second service, the Kia dealer reported "front pads worn" and offered to replace them for (IIRC) £120. I did the job myself for about £35.

 

[cdbe]

The only thing I would say in "defence" of main dealers is that if the car is on one of the long life service schedules with 20,000 mile intervals they could argue that they are trying to save you the bother of issues between services, but an expensive way of motoring!

 

[Londoner2]

My front n rear discs/pads were well worn, bought both sets on ebay for £160 (mintex) and had them fitted at £150 (front n rear).

 

[lost-in-translation]

After 3 months they finally gave me an answer from the factory. The I30 rolls out of the factory with 25mm on the brake discs. Anything below 23.4 they (hyundai) regard as needing changed.
So yeh, 1.6mm is what they think is appropriate wear. Either a testament of poor quality, or an admission they want to fleece me. Had to chase them constantly before they would tell me. Deeply unimpressed.

Just wanted to give some closure in case anyone has simialr "failings" on their service plans. I should have asked for factory fitting specs day 1.

 

[Avocet]

0.8mm off each face off the disc, doesn't seem like much of a wear allowance? Try searching online for "Hyundai I30 front disc minimum thickness". 25mm sounds about right for a "new" thickness on a ventilated front disc, but I'd have thought they might have let you lose maybe 1mm off each side?

16,000 miles sounds incredibly low for the lifetime of a pair of front discs. Before Covid, I used to do "big miles" in various company cars. That would have equated to about 2 sets of discs per year for me! I don't think, on any car, I've ever had less than 30,000 miles out of a set of discs! Do you do a lot of track days in it?

With the car having done so little mileage, is there a possibility that something has seized? A sticking caliper, perhaps, causing the pads to be permanently dragging against the disc face(s)? I'm not familiar with the I30, but I can't think of any other car where the original pads outlived the original discs? Presumably, at that mileage, it is on its original discs and pads? Maybe worth seeing if you can ask on a model-specific forum and see what other I30 drivers say?

Regarding legality, the law won't specify a minimum thickness, but it will say something like: "...shall, at all times, be maintained so as to ensure effective operation of the braking system..." (blah blah). What this means, in effect, is that if you had a serious enough accident for an accident investigation to be needed, and they found the discs below manufacturer's minimum recommended thickness, you'd be on a bit of a sticky wicket.

If it were me, and it really is on its original discs & pads, I think I'd probably go back to Hyundai customer services and say something along the lines of: "really, guys?! I mean... REALLY? You're telling me that your discs only last 16,000 miles, and your pads are good for more than twice that"?!

It's true, by the way, that modern pad materials are much harder, and that disc wear is consequently accelerated, but I think there has to be something wrong when a 40% worn pad eats its way through a genuine, factory-fitted disc!

 

[Mottie]

The minimum thickness are set by the manufacturer. You have to have it maintained according to spec to enjoy the 7 year guarantee. Wear and tear is not included in that guarantee. They have to find some ways to get something back for offering a 7 year guarantee. Brakes are just one of those ways.