Unbelievable MK4 VW Polo Dune brake discs fail mot


Registered User
Hi folks I wonder if any of you out there are MOT testers? If so, could any of you tell me the minimum thickness on the vented front discs on a MK4 Polo 1.4 tdi 3 cylinder.
I nearly fell over when my wife's car failed the mot with the discs being 19mm thick. The wear on each side was approx. o.7mm of wear with a very small bevelled lip. The discs start at only 21mm thick & failed on 19mm WTF like, you'd have to change the discs every time you nipped to Tesco at that rate. I know a fair bit about cars & have always worked on & serviced my own. The mot was Free with the wife's insurance, so I warned her of money making scams. I questioned the tester of at least 70yrs of age & said how can less than a mm off each side of the disc make them dangerous? He stammered & stuttered & said there's rust on there too. Of course there's freakin rust, I do go out in the rain like. Now were talking fine surface rust here not a chunky lip, he hadn't even put a micrometre on them either. Anyway I took the car away with the promise of changing the discs. 3 separate mot centres I visited & all 3 laughed their freakin heads off. They said I had at least another 4 years out of them & were shocked to hear my missus car failed on that.
My rant is over, but if anyone can give me the minimum thickness I'd be much obliged.
Ps, old discs back on & I'l keep the new ones for the next 4 years eh! he he!


Registered User
Hmmm on an mot you don't take the wheels of and cannot fail on thickness.

As a tester despite knowing the thickness of a disc I have to be impartial and give the benefit of the doubt.
VOSA (now DVSA) changed the rules about 2 years ago to stop things like this happening. Dare I ask it have you gone to **** fit?

Also, the minimum thickness VW would recommend replacement at would be 19mm. You do not have to change them although I would highly recommend to do so.

As far as the MOT goes they cannot fail unless the VISUAL condition deems them unsafe ie: excessive corrosion, or cracks etc. And the corrosion would have to be across in my opinion atleast 60% of the disc surface weather this be the inside or outside surface.

I understand this question was asked 4-5months ago but still atleast you know the truth about what it should be.

Sounds like they are trying to rip you off!