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Discussion Starter · #1 ·
Hi all, so my neighbour has a Vauxhall Insignia and asked me to check his discs for as he was unsure if they need replacing, I took a look with the view of putting my micrometre on and couldn't find a spot to get them on. I thought, 'I know, I'll sign up to Insignia forum and ask there - they will be as helpfull and knowleable as Ford Forumers are :)

Anyway, below is my attempt to get help, please tell me what you think (oh, 'ave a look at his time on that forum and post count).

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How to check Front Brake Disc Thickness

Darfyddi:

I have searched the forum for this and found great info on how to change the discs and what diameter comes with various Insignias but I can't figure out the easiest way to measure the thickness of the existing ones.

On my Mondy, I can get my Ext. Micrometre through the wheel and over the discs but on my neighbour's Insignia the dust shield on the back of the discs come over the outer rim a little way and completely around the entire disc (on my old Mondy the dust shield only covers about half of it or so). The Insignia he has is a 64 plate Vauxhall Insignia Elite Nav CDTI E, please can someone tell me where I can get the micrometre on the discs please or do I have to take the wheels and callipers off?

Many thanks in advance for your help.
D.

RBH:
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why do you want to check thickness???

Darfyddi:

Go on.... you asked this for some reason... is there a wear warning system for if the discs need changing or something?

RBH:

not as far as i know. experience tells us when the discs need replaced due to wear or corrosion.

Darfyddi:

Many thanks, I shall let him know not to worry - experience will tell him. cheers for such quick responses, will put his mind at ease.

RBH:

Unless they're really thin - you can tell by a lip at the top edge, or very badly scored/uneven wear then they should be fine.

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Now, am I being pedantic or should we not care about the disc thickness anymore? Is this maybe a Vauxhall owner thing? I did phone Brandish Vauxhall and got a similar thing from them too - 'we don't measure them, just look - if they look worn then we measure them'. oh, and they charge £57 for their wisdom. In the end I found Kwikfit do a free brake inspection and I will go with my neighbour to make sure they don't get him buying a new engine at the same time as a 'free' check :)

I am so glad I still have my Mondy, not only for free brake and suspension check at Allen Ford (presuming that still happens) but for the great help and advice we get here.

Cheers for reading, What are your views of the advice given to the question I asked originally on the forum? LOL.
 

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Yeah discs should have a minimum thickness. The wheel will probably need to come

of if access is limited.

As a rough guide 2mm for 25(ish)mm thick disc. 23mm minimum, if the discs below

20mm to start then 2mm maybe too much.
 

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TrevorB BMW320 M Sport 2020 M Sport Pro Pack. Tech Pack (Head Up Display)
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Hi Alan, what a disgraceful arrogant response you had from RBH on the Vaux Forum.

Thats the sort of response I see on a certain snobbish BMW forum (I am NOT a member of any BMW forum bye the way)

On a BMW forum a guy asked for wheel nut torque figures - the reply he got was "what do you want to know that for, take it to the dealer if you want a wheel(s) to be taken off and on"(To**er)

Every manufacturer will have a minimum thickness statement

Purple is right with his figures but to be 100% theoretically correct you need Vauxhalls figure.

For example a MK2 Focus ST225 has new OEM front disc thickness at 25mm. Official minimum thickness is 23mm.

An easy way to check is to measure the "lipping" on the disc. If say the lip is 1mm each side of a disc, in this example it would be down to manufacturers minimum recommended thickness.

Of course, if the brakes have been looked at before, the lipping could have been chipped or filed away by a said mechanic

I dont do Vauxhall so unable to tell you how to check disc thickness with your micrometer
 

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Hi

I have often seen minimum thickness quoted on eBay adverts for replacement discs, this is the number usually stamped on rim of disc.

Now this has mostly been for Ford items although I have occasionally looked for alternative larger discs that may have been adapted to Fords.

Perhaps Vauxhall find this unnecessary as they only employ Technicians with calibrated eyeballs.

Peter
 

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Just had a quick google of this, not a euphemism, and it would seem the Poxhalls go with a 3mm wear. Insignias look to be 30mm thickness when new and a 27mm minimum thickness.

It's reassuring to know that Poxhall drivers/dealers are so highly attuned that they can measure 1.5mm accurately by eye and probably through the wheel
 
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Thanks for posting the above, it's given me an excellent idea to make shed loads of cash.

I'm going to raid the local scrapyards, buy up all the worn vauxhall discs....................

And here's the 'money maker'..................

I'll grind off the raised lip around the edge of the discs, then sell them for top dollar as 'as new condition' :)
 

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Discussion Starter · #7 ·
LOL, I thought it might raise a giggle - or confirm I was being a muppet. I know my mk3 Mondy is 24mm max, 22mm min. The Insignia are 30mm as you say, 27mm is good to know but that dust cover is a pain and I am not willing to spend the time to take 2 wheels and 2 calipers off just to get the disc away from the dust cover. I'll keep an eye on Kwikfit to see how they do it.

In the mean time though I shall thank myself luck that I am a Mondy muppet :banana:
 

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Hi

Reading through the 77 point service check on the Omega, the Brake inspection is with wheels off. Perhaps with whee out of the way there is a point where a measurement can be taken.

Peter
 
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