Brakes juddering after 5k miles

[Cad82]

Hi there, just want some advice or if you have come across this problem with other cars:
I have an Audi A6 avant 2014 reg and in the past 10 months have replaced the discs and pads 3 times. The first 2 sets were APEC discs and after 2 months starting to feel a judder when braking (approx 5-7k miles , I do a lot of miles) the technician at the garage took the last set off and said that the passenger side seemed abit blue to say it had heated up.
The set I have on at the minute are Audi discs and pads and just coming up to 7k miles .
starting to feel the judder Again slightly.
Surely can’t be the discs and pads .
Anyone have experience in what could of be the issue?

[tapkaJohnD]

Do you tend to brake, stop, and sit with your foot on the brake, rather than releasing and using the hand brake? This tends to leave a layer of brake material on the disc, under the pad, so that when you brake again the friction characteristic of pad to disk varies as the disc goes round, so you feel a judder.

Try re-bedding-in the brakes, progressive stops down to walking speed from successively faster, and repeat, until you are braking from the highest speed you would use. Don't stop or leave your foot on the brake. Then drive normally for a wjile to let them cool. The objective is to heat the brakes to the highest temp they will use, to condition new brake pads or in this case to wear off the brake pad deposit on the discs.
If this doesn't work, the doscs may be reground, or replaced, BUT CHANGE YOUR BRAKING STYLE!

See: http://www.stoptech.com/technical-support/technica...

John

[bearman68]

^^^^^ This.

[Cad82]

I do long journeys 80 miles per trip (160 round trip from home to work)
It’s an automatic car so I do tend sometimes not all the time sit with foot on brake. It does have a hill assist handbrake option but with these discs on I have not used this option. The previous 2 sets of discs I always had that on so came on when stopped at junction etc.
It just seems abit of a head scratcher as it seems to happen after a certain time (2 months 5k-7k) the mechanics are even scratching his head as he has had other makes/models with same issue and it seemed to be long journeys .
I’m not aggressive when it come to braking.
But surely there must be something else which is contributing to this issue?
Sliders and calipers have been cleaned when replaced apparently. Also the lateral run out as been ruled out too.

[tapkaJohnD]

Cad,
why so resistant to this suggestion? You are NOT aggressive in braking, DO sit with your foot on the brake, and the same problem has recurred after renewal after the same interval. It doesn't happen to other similar cars but they have different drivers. Why should there be "something else" to cause this problem? You garage can find nothing and maybe haven't thought of this. All your details fit as the cause.

Try the brake bedding in routine. It may work - see the link I included above.
John

[Cad82]

I appreciate your advice and thankful and will try the bedding in process.
I have only had the car 10 months and my previous car I had didn’t have no problem at all with the way I drove which has not changed.
I just feel that there is an underlying problem .

Any other suggestions are welcome

[GreenV8S]

tapkaJohnD said:

Try re-bedding-in the brakes, progressive stops down to walking speed from successively faster, and repeat, until you are braking from the highest speed you would use. Don't stop or leave your foot on the brake. Then drive normally for a wjile to let them cool. The objective is to heat the brakes to the highest temp they will use, to condition new brake pads or in this case to wear off the brake pad deposit on the discs.

Different brands and types of pads use different bedding-in procedures. Follow the manufacturer's procedure for the specific pads being fitted.

How hot do the brake discs get in normal driving?

[Trevor555]

My Audi TTRS developed a brake judder after only 4,000 miles.

No way could it be my grandad driving, not had the problem on any other cars with low mileage.

Someone on the TT forum got them done under warranty after an argument.

[Tony1963]

Grandad driving still involves braking, and a 1.5 ton car converts a lot of energy into heat under normal braking. Why is anyone surprised that depositing a raised area of brake pad material on the disc is a real thing?

At least nobody is claiming that their discs are warping!

[Polome]

A few years ago my son claimed a similar juddering whilst braking. A new set of discs/pads made no difference. I went out in the car with him so he could show me the symptoms....he was braking so hard he was activating the abs! That was his fault. Could it be the abs triggering early or a fault in that system? Good luck

[Tony1963]

Another possible cause is not cleaning all surfaces. Encore mounting the new discs. After a few thousand miles of the disc settling in, a small gap forms and gives the disc wriggle room.

[bearman68]

Tony1963 said:

Another possible cause is not cleaning all surfaces. Encore mounting the new discs. After a few thousand miles of the disc settling in, a small gap forms and gives the disc wriggle room.

In my experience this gives a long brake pedal travel, rather than juddering brakes, but maybe others have different experience.

[GreenV8S]

Tony1963 said:

Another possible cause is not cleaning all surfaces. Encore mounting the new discs. After a few thousand miles of the disc settling in, a small gap forms and gives the disc wriggle room.

The disc is normally clamped between the hub and the wheel. When you say the disc has 'wriggle room', do you mean the wheel has come loose?

[stevieturbo]

Tony1963 said:

Grandad driving still involves braking, and a 1.5 ton car converts a lot of energy into heat under normal braking. Why is anyone surprised that depositing a raised area of brake pad material on the disc is a real thing?

At least nobody is claiming that their discs are warping!

One single article on the internet about pad deposits...with very little by the way of supporting evidence...and suddenly everyone dismisses warped discs !!

Discs can and do warp. Pad deposits, corrosion or whatever may be another possibility, but it certainly isnt the biggest cause of bumpy brakes.

[tapkaJohnD]

stevieturbo said:

One single article on the internet about pad deposits...with very little by the way of supporting evidence...and suddenly everyone dismisses warped discs !!

That's a bit like saying that the 1905 article "Ist die Trägheit eines Körpers von seinem Energieinhalt Abhänging?" (Annalen der Physik 18, 639–641) was only one paper. But it won Einstein the Nobel Prize for Physics.

Maybe you should look up Carrol Smith. No Nobellist, he, but a highly respected race engineer.
John

[bearman68]

stevieturbo said:

One single article on the internet about pad deposits...with very little by the way of supporting evidence...and suddenly everyone dismisses warped discs !!

Discs can and do warp. Pad deposits, corrosion or whatever may be another possibility, but it certainly isnt the biggest cause of bumpy brakes.

I've 'clocked' brakes - as a standard fitment measure I measure the throw of error in a disc when I'm fitting it. Any thing less than 0.1mm is OK, and many discs get down to 0.03mm.
'Warped' discs usually show less than 0.03mm, (sometimes less than 0.01mm) so clearly the mechanism for the vibration in the steering wheel is not cold dimensional accuracy on the disc.
Once I attempted to clean a friction surface of a disc with a grinder. It was a disaster - the steering wheel was all over the place under braking - so the difference in friction on the disc was causing this issue.
From these bits on info, I find it very easy to see frictional differences on the face of the disc causing 'warped' discs as it's usually described. In fact, close inspection will normally show differences in surface finish on the disc.
Given my experiences above, I would find it hard to agree with your statement that frictional differences are a minor concern.

[Tony1963]

GreenV8S said:

The disc is normally clamped between the hub and the wheel. When you say the disc has 'wriggle room', do you mean the wheel has come loose?

If the mounting surfaces are not cleaned adequately, after time the debris can shift/dissolve/flatten, therefore leaving the disc slightly loose.

Just a wipe with a clean rag is usually enough, but, even (especially?) at main dealerships the fitter just can't be bothered.

[E-bmw]

bearman68 said:

Once I attempted to clean a friction surface of a disc with a grinder. It was a disaster - the steering wheel was all over the place under braking - so the difference in friction on the disc was causing this issue.

So you deduced that the abrasions to the disc surface causing a different level of friction must be the issue rather than maybe, just maybe the metal you had taken off........ Right!

[Tony1963]

Once someone starts behaving like a troll, even a crap one, I ignore a thread. Life is better.

[GreenV8S]

Tony1963 said:

therefore leaving the disc slightly loose.

And therefore also leaving the wheel slightly loose? If that's happening, brake judder is the least of your problems.