Brake Disc Advice

[Gee88]

Folks

Looking for a quick view on something. Car (MGZS 2021) failed first MOT due to brake discs being visibly damaged, MOT done by halfords.

A month ago I had pads replaced, there are some minor scores on the discs as pads got low (maybe about 0.5m) but mechanic advised discs should be fine for MOT.

Car was then failed by Halfords. Key question, the actual brake test came out at 89% efficiency which is way higher than pass rate and in all honesty, they feel great when driving.

Wondering if anyone could give a view on this? I was trying to get an explanation but guy was sort of just saying it was his opinion and couldn't really correlate the visual observation with high score in the actual test.

Obviously will look to get discs changed when required but other mechanic said should be fine from an MOT perspective. Also heard some stories about halfords being pushy for repairs.

Just wondering if worth getting a second opinion here or challenging this? Just seems quite odd that the test scored so high but failed on a quick visual?

Thanks

Gee

[ARHarh]

Brakes will only fail a test if they don't work on the brake tester or if there is physical damage. Not sure scoring would class as fail though, they would have to be pretty bad. So if they are damaged it will fail which as the tester said is his opinion.

But if another mechanic said they will be fine, get him to double check and let him arrange another MOT for it.

You need to also bare in mind that brake pads and disks are easy to change and will allow the garage to make quick and easy money.

[E-bmw]

Damage & efficiency don't necessarily go 100% hand in hand.

I have several times had one but the other be fine.

TBH if I ever see a fail for either discs or pads, I do them all including fluid.

[Gee88]

Thanks for the replies folks. Bit to highlight is that no mechanic seems to be able to get rear discs for the car except through MG who are quoting like 400 quid.

Obviously if I need to get them then I will but just don't want to rush into it if the ones I have are good for a while.

[GreenV8S]

Gee88 said:

failed first MOT due to brake discs being visibly damaged

What is the nature of the damage?

If it's only surface scoring, and the discs are expensive, and they're above minimum thickness, you could consider getting them resurfaced.

Since your mechanic thinks they're still serviceable, it would imo be worth the small cost of another MOT attempt somewhere else before parting with a lot of cash. But of course they're going to need replacing eventually anyway.

[MustangGT]

Gee88 said:

Folks

Looking for a quick view on something. Car (MGZS 2021) failed first MOT due to brake discs being visibly damaged, MOT done by halfords.

A month ago I had pads replaced, there are some minor scores on the discs as pads got low (maybe about 0.5m) but mechanic advised discs should be fine for MOT.

Car was then failed by Halfords. Key question, the actual brake test came out at 89% efficiency which is way higher than pass rate and in all honesty, they feel great when driving.

Wondering if anyone could give a view on this? I was trying to get an explanation but guy was sort of just saying it was his opinion and couldn't really correlate the visual observation with high score in the actual test.

Obviously will look to get discs changed when required but other mechanic said should be fine from an MOT perspective. Also heard some stories about halfords being pushy for repairs.

Just wondering if worth getting a second opinion here or challenging this? Just seems quite odd that the test scored so high but failed on a quick visual?

Thanks

Gee

Put a photo up for us please.

[Maxdecel]

I'm reassured by a mate who is an authorised tester, failure can only arise from Judder or cracks, I asked because the rubbing path on the rear of mine are reduced 50% by corrosion. It's passed (another test station) twice since I asked, the efficiency was unaffected as I expected.

1.1.14. Brake discs and drums
A brake disc or drum must be significantly worn before you should reject it. Being worn below the manufacturer’s recommended limits is not a reason in itself.

https://www.gov.uk/guidance/mot-inspection-manual-...

Edited by Maxdecel on Thursday 15th May 18:18

[E-bmw]

Maxdecel said:

I'm reassured by a mate who is an authorised tester, failure can only arise from Judder or cracks, I asked because the rubbing path on the rear of mine are reduced 50% by corrosion. It's passed (another test station) twice since I asked, the efficiency was unaffected as I expected.

1.1.14. Brake discs and drums
A brake disc or drum must be significantly worn before you should reject it. Being worn below the manufacturer’s recommended limits is not a reason in itself.

https://www.gov.uk/guidance/mot-inspection-manual-...

The section that you pasted in above shows your mate is wrong.

Swept area damage CAN indeed be a failure.

[Maxdecel]

E-bmw said:

The section that you pasted in above shows your mate is wrong.

Swept area damage CAN indeed be a failure.

Not just him then, as I said it passed twice with the same discs & pads.

[GreenV8S]

Maxdecel said:

I asked because the rubbing path on the rear of mine are reduced 50% by corrosion

Your mate should have told you to fix the problem regardless of whether it's an MOT failure.

[Maxdecel]

GreenV8S said:

Your mate should have told you to fix the problem regardless of whether it's an MOT failure.

Not a problem whatsoever.

[E-bmw]

Maxdecel said:

E-bmw said:

The section that you pasted in above shows your mate is wrong.

Swept area damage CAN indeed be a failure.

Not just him then, as I said it passed twice with the same discs & pads.

That is a ridiculous statement to try to use as justification for a pass.

A car may have the same set of discs/pads for 10 years before they cause an MOT fail, by your logic above, each of the 9 previous passes was wrong.

[Matt_E_Mulsion]

A picture would help but normally discs have to be fairly bad to be an MOT failure especially when the efficiency is so good.

As for an MOT done at a Fast Fit Centre such as Halfords, well they are always looking to upsell especially on bread and butter items such as discs and pads, it is in their interest to fail items where all that constitutes 'worn' is merely the testers opinion...

Edited by Matt_E_Mulsion on Thursday 15th May 20:58

[Maxdecel]

E-bmw said:

That is a ridiculous statement to try to use as justification for a pass.

A car may have the same set of discs/pads for 10 years before they cause an MOT fail, by your logic above, each of the 9 previous passes was wrong.

It's not justification IT PASSED on balance & efficiency as I expected on both MOT's it's needed.
ie. It met/exceeded the requirements.