Brake disks corroded

Julie1979

Julie1979

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Can anyone help? I seem to need to replace the brake disks in every car I own. It always seems to be due to corroded disks. My cars are always bought new, the current one is an Audi A3 that needs rear disks replaced as they are corroded and lipped, it's an advisory on the MOT so they seem to have only just passed?

Could it be my driving style or the fact that I don't do a lot of miles, only 6-8,000 miles a year? I don't think I overuse the brakes but i'm obviously doing something wrong as that's the last 3 cars i've had that have needed corroded brake disks replaced.
 
if it is your rear pads, they are either sticking or you are leaving your handbrake on (cars beep these days so you would know if you had left it on).

Most braking is carried out by your front brakes. So it is unlikely to be how you drive.

After how long do they need replacing? 3 years? 5 years?
 
I don't think they should have much of a lip at 6-8000 miles, my (Honda) front's went to 74k@9yrs and rears about 54k@6yrs.

The corrosion can occur whilst the car is sitting around so lack of driving could be the cause of the corrosion building up.
 
Since asbestos was banned in friction material, brake pads are not as effective as they used to be so the brake discs have to be made of softer steel to provide the same amount of stop.

The result of this is that they wear faster and have to be replaced more often. Also, cars that are only used occasionally rather than every day will get a build up of rust on the discs when will be cleared away by the first application of the brakes (I notice this on my van for example, which I only use once every week or two), this causes them to wear down faster than a car that is used regularly.

In front engined, front wheel drive vehicles the rear brakes hardly do anything as there is no weight over them and the forwards weight transfer under braking reduces this further, which is why the rear brakes suffer disproportionately from corrosion and wear.

If you bought a mid-engined car you wouldn't notice this so much as the weight distribution is different (better) and the braking effort is more evenly distributed. Many people don't want to sacrifice the back seats and larger boot that a more usual front engined car will have though ;)
 
Have all the cars been Audis?

What age is the current car and does it sit for long periods without being used?

Googling the problem brings up You Tube videos of Audi discs being DIY ground to remove rust so it may be common.
Some Audis use ceramic discs that don't corrode.
 
Julie1979 said:
Could it be my driving style or the fact that I don't do a lot of miles, only 6-8,000 miles a year? I don't think I overuse the brakes but i'm obviously doing something wrong as that's the last 3 cars i've had that have needed corroded brake disks replaced.
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That's exactly it, brake discs are cast iron, and although it's very good with rust, if you're not using the brakes often then the disc surface isn't kept clean and the rust penetrates deeper and you evenually get some rather nasty looking discs. Th rears also don't get as much use as the fronts anyway which compounds problems.

Oh and some discs are better than others, a lot of ultra cheap ebay jobies are really poor quality material. Some OEM discs are aslo know for being made from chocolate too - Gen 7 Toyota Celica for example.
 
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I do the same amount of miles a year, I've never had a problem of them corroding quickly. Where do you park the vehicle overnight? If it's on grass/mud/loose stone driveway I have found that corrosion tends to be worse. I assume due to damp.
 
I think with all 3 cars, i've replaced rear disks at 4 years.

I'm not leaving the handbrake on so it's not that. It could be mud with the last 2 cars, A3 and Tigra as I live in the sticks so lots of tractor muck on the road. My journeys are on fairly long, quiet roads so don't really need to do a huge amount of braking so that could possibly be a cause also.

The brakes certainly work well as had to do an emergency stop from 60mph a few weeks ago due to deer on the road. I'll see what the garage say when I take it in for replacement brakes as the car passed the MOT with an advisory. Going to take it to another garage to get them replaced due to the MOT garage not bothering to carry out a small repair I asked them to do.
 
Not uncommon tbh, even at that low mileage - I say that as a garage owner. If a car is allowed to stand more than run, lack of heat through the discs means the damp hangs around longer and thus corrosion can affect them more than a frequently used car. I also think manufacturers have increased the 'minimum recommended thickness' ratings... the generous would say its a safety thing, the cynics would say its about selling more parts...I would say its a combination of both.

As it was only an advisory, I would get another garage to check them out anyway if you feel better about a 2nd opinion (y)
 
If it's an advisory, don't worry about it just yet but you could try braking a little harder than normal every so often to generate some heat and also wear through the areas of corrosion.

You could also (carefully and without allowing the park brake lever locking ratchet to engage by keeping your thumb on the button) apply the park brake while driving on dual carriageways or other fast roads for a few seconds to build up the heat and scrub the discs............. Use your common sense here and only do it on a straight road when safe to do so (remember the car will slow WITHOUT the stop lights illuminating) and don't do it hard enough to lock the wheels, don't do it if you have any misunderstanding of this text.

Vehicles that park on grass and mud do suffer more than vehicles that park on a hard surface, I can only imagine it's a moisture thing...... I've lost count of the number of motor homes I've looked at after their owners have complained of the inner friction face of the disc being corroded.

You said you did an emergency stop, even with full brake force applied the pressure at the rear brakes is likely to be less than 40% of that applied to the front brakes unless the car is fully laden.
 
Yv said:
Not uncommon tbh, even at that low mileage - I say that as a garage owner. If a car is allowed to stand more than run, lack of heat through the discs means the damp hangs around longer and thus corrosion can affect them more than a frequently used car. I also think manufacturers have increased the 'minimum recommended thickness' ratings... the generous would say its a safety thing, the cynics would say its about selling more parts...I would say its a combination of both.

As it was only an advisory, I would get another garage to check them out anyway if you feel better about a 2nd opinion (y)
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I've had rear discs replaced at two years under warranty on a couple of cars and now as I deliver parts for a living I see loads of discs being fitted, it is in actual fact though down to your driving Miss Daisy!,:D you need to drive harder/faster to make the rears work more, more heat will prevent rust and keep the faces clean.
 
mj4456 said:
it is in actual fact though down to your driving Miss Daisy!,:D you need to drive harder/faster to make the rears work more, more heat will prevent rust and keep the faces clean.
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And of course that won't wear out the front pads and discs faster ... :nuts:
 
Yves Geza said:
And of course that won't wear out the front pads and discs faster ... :nuts:
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But his advice gets garages buying more discs and pads and therefore keeps him employed ......... :clap: :D

With modern vehicles, the theory of drive harder doesn't always work as the stability assist or load apportioning strategies will put the optimum brake force to the wheel that needs it most. I'd be surprised if the Op's A3 hasn't got a stability assist function.
 
Yves Geza said:
And of course that won't wear out the front pads and discs faster ... :nuts:
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digitalfailure said:
But his advice gets garages buying more discs and pads and therefore keeps him employed ......... :clap: :D

With modern vehicles, the theory of drive harder doesn't always work as the stability assist or load apportioning strategies will put the optimum brake force to the wheel that needs it most. I'd be surprised if the Op's A3 hasn't got a stability assist function.
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yes Jonathan, shut up! :LOL:


Seriously though, longer journeys would actually be more beneficial than harder ones. As Brian says, the handbrake technique is a well known one but ONLY if you are confident you can do it properly, please don't even think about doing it if you are even slightly doubtful. :puke:
 
I had an 07 plate civic that went through disc and pads every 12000k miles. So that was approx every 4 months. Having said that it was the worst car I have every had.just pleased I didn't heave to pay for the upkeep of it.
 
I don't use my brakes much either. I have to make a conscious effort to use them a bit more every week or so to make sure they are cleaned up. It is worse in the winter as they get salt and crud on them more. I have a steep hill nearby which I descend in a higher gear with the brakes on most of the way down now. Usually keeps them ok. It can take quite a few good stops to clear off anything other than basic surface rust.

Garages often want to replace things way before they actually need to be done. If they say brakes are worn then ask them what is the thickness of the pads and disks as a percentage of the original and how many mm are they off the wear limit. They usually back down at this point as they realise you're not going to be fobbed off with 'worn'.
 
If you are doing 6-8000 miles a year, I cant see corrosion being a major contributor to the need for replacement. I would wager that it's relatively minor.

If the car has passed it's MOT then the brakes are functioning properly. The advisory sounds very vague as I'd expect wear percentages to be quoted for discs and pads separately.

This sounds like a bad case of trying to over-sell replacement brake parts.

Who did the MOT - franchised dealer, fast-fit chain (e.g. Kwik-Fit) or local independent ?
 
The guy that does my mots is clearly looking for business, was told that my discs were warped as there was "a hell of a rumble off the brake pedal" I showed him my invoice for the new discs dated a week before the test and suggested he might be causing the abs to kick in. I've had advisories on suspension bushes front os in 08, 09 no advisory in 10 as a cheap replacement bulb had melted and he'd thought he'd secured a job then this year the advisory is back!! I trust my mechanic more than this numpty and he advises me when parts need replacing.

Seriously if it's an advisory and your own mechanic is happy with it I wouldn't bother doing anything.

I'd stop using the mot station if he wasn't so cheap!! £36 for an mot!!
 
Defiance said:
If the car has passed it's MOT then the brakes are functioning properly. The advisory sounds very vague as I'd expect wear percentages to be quoted for discs and pads separately.

This sounds like a bad case of trying to over-sell replacement brake parts.
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They haven't advised on almost worn out brake linings, they've advised as to the condition of the brake disc surfaces.

The op stated that the test station don't do repairs, so they're not selling replacement parts either :)
 
I had a Kia Sorento purchased with 78 miles only on the clock ,It was pre registered. it had only done 800 miles and the front discs had distorted badly causing terrible steering wheel shake, a sure sign of warped discs. Apparently there was a bad batch in manufacture although no recall, on a Kia web site group like this one, several other members had suffered exactly the same problem at around the same milage with the same age car.

Realspeed
 
Yv said:
...at the time of the test.... doesn't mean they will be the next day or next week ;)
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absolutely right, although the point of having an advisory option in the MOT is to advise is potential failure is ahead and in this case the advisory is very vague ;)
 
digitalfailure said:
They haven't advised on almost worn out brake linings, they've advised as to the condition of the brake disc surfaces.

The op stated that the test station don't do repairs, so they're not selling replacement parts either :)
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They advised they were lipped and therefore it would be best practice to advise on disc and pad wear.

She said the test centre couldn't be bothered to do a small repairs, not that they didnt do repairs. Council depots are the only people I've ever come across who do MOTs but not customer paid repairs.
 
Julie1979 said:
Can anyone help? I seem to need to replace the brake disks in every car I own. It always seems to be due to corroded disks. My cars are always bought new, the current one is an Audi A3 that needs rear disks replaced as they are corroded and lipped, it's an advisory on the MOT so they seem to have only just passed?

Could it be my driving style or the fact that I don't do a lot of miles, only 6-8,000 miles a year? I don't think I overuse the brakes but i'm obviously doing something wrong as that's the last 3 cars i've had that have needed corroded brake disks replaced.
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The MOT station isn't the Audi main agent is it by any chance?
 
Defiance said:
They advised they were lipped and therefore it would be best practice to advise on disc and pad wear.

She said the test centre couldn't be bothered to do a small repairs, not that they didnt do repairs. Council depots are the only people I've ever come across who do MOTs but not customer paid repairs.
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If you supply the parts, many will do the work for you.
 
I work for a car parts company and can maybe shed a bit of light on this, if the carbon content of the discs are lower than OEM spec then the disc will wear out quicker as friction material is now harder than when asbestos was allowed to be used.

Also because of rising raw material prices in the far east some manufacturers are not using the "right" mix resulting in lower quality product that corrodes and wears quicker.

Many OEM brands and propriety brand suppliers source from China, we buy our discs from the same source as some very well known names...
 
Brembo sell higher carbon content discs, very competitive prices too.
Try searching nextdaybrakes
 
I guess you have taken the cars to the same garrage all the time?

I had to use another garrage once for a tyre and after they handed me a sheet, your brakes are worn, fluid levels needed a top up and listed all 4 tyres needed replacing even though they had just replaced one of them due to a puncture. All the tyres were at 3-4mm and aparently they recomend they be replaced at 3mm.

Anyway the car had been serviced 3 weeks prior so I went back to the garrage who agreed the brakes were worn but only by 30% so still had plenty of life in them fluid levels were fine oil level had dropped slightly but I had done 4000 miles in that 3 weeks and it uses about 1l every 10000 miles and the washer fluid needed refilling but it wasnt empty. A lot of garrages take the urine and try to get you to spend money when you dont need to by scaring the bejesus out of you saying your brakes are on their way out or your engine is running dry.
 
depends what you mean by corrosion? is it the outer edge that looks worse for wear like this:

mini-disc%2008.jpg


the rusting round the edge is normal, the pad will keep the disc clear, hence the shiney metal, the lip will be felt this is were the pad rubs into the disc, if you have groves then you have uneven wear so either bad/goosed pads or warped discs,

the lip at a push can be ground down, you can also buy some very good aftermarket pads and discs from the likes of mintex etc.
 
Thanks for all the info.

It was first time in this garage. Not an Audi dealer but one that advertises as an Audi repair and servicing specialist. The previous brakes were all replaced using other garages, all independent. I would normally use an independent garage to carry out work but the last 2 garages we have used haven't put the cars pack together right, resulting in my husbands engine bay being sprayed with oil and my car sounding like it had exploded when a hose flew off on the way home from the garage.

Once the snow clears i'll ask my dad to get the wheels off and have a look. The advisory is as vague as i've described it. It was a very strange situation in the garage, they weren't pushing me at all to book it back in for the repair or the MOT advisories. All they did was confirm what was wrong with my car, which even with my limited knowledge of car engines was exactly what I told them was wrong. I think the fact it was the day of the storm hasn't helped, they were practically throwing the car back at me.

I have several long, quiet straights on my main routes for driving so I can try the handbrake trick in future.
 
Have you got the exact wording of the MOT advisory? also you say you brought the car new and do about 6-8k a year but you haven't said how old the car is.

I work for VW which is sister company to Audi so a lot of parts are carried over between models. I tend to find on a Golf's which are pretty much identical to an Audi A3 underneath, that the rear brakes do tend to get a bit corroded and pitted surface on the disc due to them only doing about 30% of the overall braking for the car which means under normal braking then don't apply much pressure to clean any rust of from a vehicle standing around for long periods without use. I also find the pads stick a bit in the sliders after a couple of years so tend to advise a strip,clean and regrease of moving surfaces of the rear brakes every couple of years as the pads can get so stuck tehy don't budge under normal braking very well.
Also check all the handbrake mechanism is moving freely as sometimes the cables get water in and hold the handbrake mechanism on slightly and wear the pads out quickly on one side.

Hope this helps.
 
rssmrry said:
I'd stop using the mot station if he wasn't so cheap!! £36 for an mot!!
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Had mine done a week ago ... garage collected from home, did the MOT and returned back to home ... £49 - well pleased!
 
I'm not too sure that driving style is a major factor in the wear rate of rear discs. I have a '96 LR Discovery with about 105,000 miles on the clock and it still has its original discs all round. They're not showing any signs of adverse wear or ridge build-up. I've changed the pads several times and refurbished the calipers twice - due to the amount of mud and grit that gets in there during off-roading.

My '58 plate Vx Insignia has 55,000 miles on the clock and had to have new rear discs and pads at 54k. I drive both vehicles "enthusiastically" on the road so if driving style was a big factor I'd expect to have to replace the Discovey's discs before now - it takes much more braking effort to stop 2tonnes of LR than the piddlingly light Insignificant.
 
It's mainly the fact that my last 3 cars have needed brake disks replaced within the first 4 years that made me think it was something I was doing or not doing.
 
Bristolian said:
I'm not too sure that driving style is a major factor in the wear rate of rear discs. I have a '96 LR Discovery with about 105,000 miles on the clock and it still has its original discs all round. They're not showing any signs of adverse wear or ridge build-up. I've changed the pads several times and refurbished the calipers twice - due to the amount of mud and grit that gets in there during off-roading.

My '58 plate Vx Insignia has 55,000 miles on the clock and had to have new rear discs and pads at 54k. I drive both vehicles "enthusiastically" on the road so if driving style was a big factor I'd expect to have to replace the Discovey's discs before now - it takes much more braking effort to stop 2tonnes of LR than the piddlingly light Insignificant.
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When we service a car [we dont do MOT's we dont have room for a bay, plus using an independent means generally speaking, a fail is a fail, not us trying to get work - it sounds mad, a fail or advisory should mean the same thing where ever you go, but threads like this only go to prove the suspicions people have] and the brakes are getting low but not yet at the point where replacement is advised, customers will often ask "so how long/how many miles are left on them?" - we can't tell them, you cannot give a definitve answer to that question, simply because driving style does affect brake wear. Yes, we possibly notice it more in London where brakes get heavier use than most areas, but it's still something you cannot say simply because you are not sitting in the seat next to them watching their style. Do they tend generally to be early, gentle brakers, or last minute, throw your passengers around brakers? Are they good at predicting what is happening around them and can lift off early and use gears to slow down more or would you be amazed that they don't have daily accidents because they seem to have no awareness at all? Is the car a manual or auto? Automatic drivers nearly always rely on brakes over every other option to slow.... and so on.
So yes, driving style can affect brake wear hugely, as can the type of driving [a lot of round town, or miles and miles on a motorway, or like your landrover, lots of off-road with all manner of crap flying around] so as Rob [Defiance] mentioned earlier, we always advise on current brake wear as a percentage, and a comparison ot the manufactures min recommended tolerances, rather than trying to predict how much longer they have left in them and offer a free check in 3 to 6 mths if they want it, especially on those cars that had a 2 year service schedule, because otherwise, you can guarantee the next time they came in, would be 2 yrs later and instead of a set of pads, it was was pads and discs all round :bonk:
 
The main issue with the MOT scheme is that for the large part it's open to interpretation by the tester, as with every government scheme the number of grey areas is astounding. What one tester advises on might not be advised by another. I've seen testers issue advisory notices for brakes work to around 50% where other testers don't bother until they are 25%. As Yv said, you just don't know the driving style.
 
edit.
post removed as can't be bothered
 
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already edited my post within about 1 minute of posting it.
can't be bothered trying to defend the motor trade from the ignorance of armchair experts :shrug:
 
Tirpitz said:
already edited my post within about 1 minute of posting it.
can't be bothered trying to defend the motor trade from the ignorance of armchair experts :shrug:
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Except that a number of people in this thread work in the motor trade...
 
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