Brake disc backing plate

Rockbox

Active Member
Apr 6, 2018
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Hi,
My disc backing plates on the front are rattling a bit.

I'm I correct in saying that it's wheel off caliper off brake disc off then is it a case of just unbolting the plate.

Thanks.
 
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RUM4MO

Active Member
Jun 4, 2008
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From my experience of working on a 2015 VW Polo, yes, though be prepared for at least screw/bolt to be partially covered by the wheel hub. Typically the threaded portion of the bolt is clean as is the threaded hole, but corrosion will have attacked the bolt head and backing plate, so after the initial "bond" has been broken, the bolts should be free to unscrew by hand.

Maybe buy in some new bolts in case you damage the head of some removing them, they are a common part across Skoda/VW/SEAT/Audi, I went to a Skoda dealer to get some as they were easier to reach, they had none for sale but found the Audi dealership round the corner had over a 100 in stock!
 

Mr Pig

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Jun 17, 2015
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I'm I correct in saying that it's wheel off caliper off brake disc off then is it a case of just unbolting the plate.
Yip, that's it. Held on by three small bolts. If it is rattling just now the plate will come completely loose quite soon. If you take the wheel off you'll be able to break the last bit free and pull of the plate. Then you can run without it until it's convenient to replace it.

Buy new bolts but the old ones will probably come out just fine.
 

martin j.

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Feb 11, 2007
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Fife
The back plates on my Leon rusted and broke away around the bolt holes, removed the wheel and then snapped off the damaged back plate, all bolts were tight, did at some point when both sides had been ‘removed’ did I bother dismantling brakes to remove the small broken sections, didn’t fit new ones, ok I maybe get more brake dust on the wheels but not sure, not an MOT requirement.
 
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Mr Pig

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Jun 17, 2015
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Didn’t fit new ones, ok I maybe get more brake dust on the wheels but not sure, not an MOT requirement.
I certainly don't think there is much harm in running without them for a while, maybe forever, but I like them to be there.

Probably the most important function they have to to protect the brake lines from the heat of the brakes but in practice I doubt they make a huge difference. They will also catch and grease or oil coming from the engine bay. And of course their primary function, to catch small stones between them selves and the disk making an awful noise about nothing! ;0)
 

Rockbox

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Apr 6, 2018
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Knackered IMG_20230514_150424.jpg
 
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RUM4MO

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Jun 4, 2008
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I'm guessing that these knackered ones are aluminium alloy?

If so, maybe a good reason to buy steel aftermarket replacements.

I originally was quite happy when I bought my slightly used 2011 Audi S4 in 2013, to see that it had unpainted alloy discs back plates - after starting to read many tales of back plates coming loose/free and seeing that most of them are alloy, I'm not quite so happy about having alloy ones now!

Rapidly dissolving aluminium alloy heat shields that you can repair with bits of tin plate is almost acceptable, the same thing happening with brake back plates/covers, is not so ideal.
 

BigJase88

Jase
Apr 20, 2008
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Reaction between 2 dis-similar metals. They always go at the contact point to the bolts / hub.

They are crap tbh
 

SuperV8

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May 30, 2019
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I'm guessing that these knackered ones are aluminium alloy?

If so, maybe a good reason to buy steel aftermarket replacements.

I originally was quite happy when I bought my slightly used 2011 Audi S4 in 2013, to see that it had unpainted alloy discs back plates - after starting to read many tales of back plates coming loose/free and seeing that most of them are alloy, I'm not quite so happy about having alloy ones now!

Rapidly dissolving aluminium alloy heat shields that you can repair with bits of tin plate is almost acceptable, the same thing happening with brake back plates/covers, is not so ideal.
I checked mine (original alloy type) when I did my front wheel bearings and they were perfect - at around 100k miles and 6 years old.

As long as you have no contact between the steel bolts and allot covers you'll be fine.

Thinking out loud! my 184 has alloy front knuckles - where as the 150 and lower have iron knuckles!
I think (hypothesise) the incidence of corroded alloy dust shields will be higher on these lower power versions with an iron knuckle due to the higher chance of a galvanic corrosion.

I've seen some wheel cleaners really eat into these dust shields - both steel and alloy ones.
 

RUM4MO

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Jun 4, 2008
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Ah, fair comment, my S4 will also have alloy suspension parts, so as long as the fixing bolts used have that effective green barrier coating, there should not be an issue.
 
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BigJase88

Jase
Apr 20, 2008
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Some nylon washers may be a worthwhile upgrade to keep them from contact with each other. One between hub and backing plate and one between backing plate and bolt. Not sure if they would take the heat though 🤔
 

RUM4MO

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Jun 4, 2008
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There are probably more suitable engineering materials for doing that, it would/should suit DIYers, but not professionals where time = money, for some DIYers, a bit more money can mean saving money!

Edit:- my 2011 S4 that has alloy uprights etc is fitted with unpainted alloy brake covers, many of the alloy brake covers that I've seen pictures of, look a lot like they have a coating/paint on them, so maybe VW Group are taking steps to minimise this being an issue on cars that have ferrous uprights. VW Group used to at least always supply "green" coated/dipped bolts for use where aluminium alloys existed near ferrous components, these brake cover bolts are certainly coated with something, not the translucent green coating of the past, but a darker coating, although that might just be a typical corrosion protection and not protection against dissimilar metals being in contact.
 
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