What can cause juddering/uneven braking?

berisen

berisen

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Recently i've been starting to feel a juddering feeling when braking. Mostly in low speeds, like in town and such. The feeling when braking is as if there is uneven braking action on the disc. It feels like the braking increases on a part of the rotation and then "normal" braking again and so on, also noticed this when had new tires fitted and the car jacked up.

Can this be caused by a warped disc? Cant remember me driving in such a way that would make them that hot so that would be strange. The only thing that has happened during the winter is that the brake pads got stuck a few times after driving in wet conditions or washing it and then parked it for a few days but that should have been braked away by now i think. Had it out for a real braking session some days ago but no difference since then really.

I got a small noticeable lip on the front discs but nothing bad really. The pads looks alright as well from what i can tell.

YSOGwkW.jpg

Any ideas? New discs/pads needed?
 
Warped disc


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If it only happens when braking, it is quite likely a warped disc. Mine used to have a slight judder/little shake through the steering wheel whenever I braked from a higher speed. Changed the discs and pads at the front and it had disappeared.
 
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Seen it with the disc cracked down the middle aswel were vents are only needs to be airline crack


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I had exactly this, changed the discs now its perfect
 
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Definitely warped disc. Make sure the hub is spotlessly clean when you or your mechanic fits the new ones.
 
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Does tend to sound like warped disc(s) as said already. Also, pads should not really start sticking simply because they get wet or the car is parked-up for a few days. Personally, I would investigate whether this "pad sticking" is the cause of excess heat and thus disc warping. Is that an ATE calliper? If so, these have a combined slider/calliper retention bolt on which brake dust gets baked on over time in the form of hard, black carbonised deposits. This causes "sticking" after activity like prolonged periods of braking down a steep hill etc. I find the best way to clean it off is with wire wool. I would also check whether the piston is moving freely in the calliper.
 
Retroman said:
Does tend to sound like warped disc(s) as said already. Also, pads should not really start sticking simply because they get wet or the car is parked-up for a few days. Personally, I would investigate whether this "pad sticking" is the cause of excess heat and thus disc warping. Is that an ATE calliper? If so, these have a combined slider/calliper retention bolt on which brake dust gets baked on over time in the form of hard, black carbonised deposits. This causes "sticking" after activity like prolonged periods of braking down a steep hill etc. I find the best way to clean it off is with wire wool. I would also check whether the piston is moving freely in the calliper.
Click to expand...
Thank you all. Sounds like this was an easy guess. Happy to hear that someone else had the same issue :)

I don't know really if this is an ATE caliper, have not done any research until now when i started to notice this behaviour but i can try and look it up.
I think i'm going to try and change them on my own, just need to get me one of them "piston pressing tools". Is there any special disc/pads i should aim at?

Found these at a local shop for around £130/pair. Any good? They also got pads from ATE for £120/pair.

bromsskiva-fram-levparvis-prisst.jpg

Image
 
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If you look on Euro car parts you will see the same ATE parts at a much cheaper price, especially if you use the discount code service30. ECP also sell a "grease" that is for lubricating the pad locating points called Pagid Ceratec. I have always used copper grease before but apparently it can affect the ABS

I changed the front discs and pads on our TT last Friday. You do not need a special tool to push the front piston back other than a G clamp or a squeezy type clamp with plastic jaws.
Audi recommend replacing the calliper mounting bracket bolts when changing the discs. They are about £18 for 4 bolts.
 
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prt57 said:
If you look on Euro car parts you will see the same ATE parts at a much cheaper price, especially if you use the discount code service30.
Click to expand...
They doesn't seem to sell to Sweden unfortunately but there might be other similar sites around.

Are there any better or worse options if i compare between the most common ones?
Bosch, Brembo, Zimmermann, ATE, Valeo, TRX,Ridex, Ferodo.. there is a lot out there to choose from :D
 
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Our original Audi pads on the TT had an ATE logo on the back.
Thinking of the discs, some like Brembo do not have an anti rust coating on so the hubs rust very quickly. Check this out on your preferred option before buying.
 
prt57 said:
Our original Audi pads on the TT had an ATE logo on the back.
Thinking of the discs, some like Brembo do not have an anti rust coating on so the hubs rust very quickly. Check this out on your preferred option before buying.
Click to expand...
Ok thanks. Seems like Brembo (and the others) often has a coated alternative as well for a little extra, easy choice in that case.

Do i need to match pads and discs in any way?
 
I can tell by that style of disc pad in the picture above (i.e. the three prongs on the back of one pad that clip into the piston) that you have ATE callipers. I have the same on the front of my A3 but at 312mm. There is no need to fit either ATE discs or pads - any decent make will do - I fitted Pagid discs and pads on mine last year. You have mentioned Brembo which is a good make. It is not essential to match the discs and pads from the same maker - I would just suggest avoiding cheap, budget brake pads.
 
The discs and pads I fitted to the TT were Pagid. If I had waited an extra day I could have bought ATE for only £20 more.
As mentioned above, avoid cheap and nasty. The Pagid discs have the anti rust coating
 
Thanks for all the help guys. New brembo discs/pads ordered. Looking forward to it :D

Is it the same procedure changing the stuff compared to A3?


Can i follow this guide on my S3 as well?
 
the brake systems are the same for all cars (some minor changes), just prepare yourself some wire brush to clean the rust, some grease to lubricate the sliders on calipers, if you don't mind some quids more is good also to replace slider pins and rubbers (you need to grease the pins if sealing surface of your rubbers is NOT waved), degrease the discs, clean and put thin layer of grease on hub. tip: in order to remove caliper bracket turn the wheels to get easier access, use wd-40 to get to them easier. Ah be sure to not put any grease on discs or front (breaking) part of pads. Makes are irrelevant (got pagid, bosch, brembo, and ferodo on mine, all good) if not performance or unknown.
 
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Looks like I'm a bit late to the party :)

@berisen have you currently or at some point in the past had refurbished wheels and not cleaned the paint off the mounting face? If so, that is quite often the root cause of brake judder. Contamination on surface of hub, disk or wheel will cause the disk to deform over time and result in uneven braking. A cheap fix is to resurface the disks, but that will likely be a temporary measure as the root cause would not have been addressed.

Anyway, I had this issue before and bought new disks, resurfaced said new disks, upgraded to BBK and kept getting the judder until I went to see someone who knows what they are talking about. See my post about this here - http://www.audi-sport.net/xf/thread...-money-pit-project.256146/page-3#post-2727595
 
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leshkin said:
Looks like I'm a bit late to the party :)

@berisen have you currently or at some point in the past had refurbished wheels and not cleaned the paint off the mounting face? If so, that is quite often the root cause of brake judder. Contamination on surface of hub, disk or wheel will cause the disk to deform over time and result in uneven braking. A cheap fix is to resurface the disks, but that will likely be a temporary measure as the root cause would not have been addressed.

Anyway, I had this issue before and bought new disks, resurfaced said new disks, upgraded to BBK and kept getting the judder until I went to see someone who knows what they are talking about. See my post about this here - http://www.audi-sport.net/xf/thread...-money-pit-project.256146/page-3#post-2727595
Click to expand...
I actually got the same tip from a company here around specialised in braking systems so i will definitely make sure that the surface of the hub is absolutely clean before mounting the new discs. I had no idea that it was down to microns but apparently it's a common misunderstanding that it is caused by warped discs instead of poor cleaning when installing the discs.

I had no problem for like 5-6000km after buying the car but recently its become clearly noticeable that something is not right.

I hope my problems will go away like yours did with a good installation of the new discs once they arrive :)
 
What is commonly referred to as "warped disks" is usually caused by this contamination. Most people change disks and pads and this solves the immediate symptom, while the underlying root cause remains and in most cases just comes back again in a few thousand km/miles.
 
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leshkin said:
What is commonly referred to as "warped disks" is usually caused by this contamination. Most people change disks and pads and this solves the immediate symptom, while the underlying root cause remains and in most cases just comes back again in a few thousand km/miles.
Click to expand...
Since you get good results, what did you use for cleaning the hubs and make the surface as good as possible? :)

I bought these two for cleaning, do you think thats enough for getting a clean surface? First the steel one (bottom one) and then the other one for finishing.

103698024-origpic-166903.jpg


103699654-origpic-057063.jpg
 
I went to a brake specialist, who did it for me. The wheels have been on for a while like that, so needed to be filed down to make them sit flush again as they deformed around the contamination slightly. Cleaning the surface using a wire brush like that is great before it becomes an issue, once it happens, I'm not sure it will be as effective.
 
Ok, i will have a look at the hubs when i get the brakes that i ordered and try to make them as clean as possible and hopefully thats enough :)

Thanks!
 
So i just had the new rotors and pads fitted and everything looks great so far :)

Just one question, is there two different types of springs on the callipers depending on hear of make or something?

I got these on mine:
https://www.ecstuning.com/b-genuine...parts/s3-anti-rattle-spring-pair/8p0615269kt/
(See image in the first post or here YSOGwkW.jpg )

But the ones that was delivered with my Brembo-brakes was a thinner spring version. Like this:
s-l500.jpg

I kept the anti-rattle version of the spring since it seems a lot tougher and i want the S3-logo but is there any practical difference between these two?
 
probably this brakes are used also in other audis like in normal 3.2 or e.g. a4 so spring instead of being emblem-ed s3 is normal, the spring you change when it's actually not working or rusted, if your is fine just stay with it, but need to clean from brake dust before refitting.
 
Ok thanks. It was a little difficult getting them both on and off, hopefully they are fitted correctly now. A normal spring is easier but the larger one seems better.
 
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