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Brake judder

Posted: Sun Mar 31, 2019 11:36 pm
by holsy10
Hi folks

Recently started getting brake judder when braking and after a bit of digging around on here came to the conclusion brake discs had warped. When to garage and it would seem as though the discs where lined up properly as the 2 screws had snapped off that lines everything up.

By any chance does anyone know that screw size?

I know it’s counter sunk screw but unsure on size.


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Re: Brake judder

Posted: Mon Apr 01, 2019 5:20 pm
by iduff
https://audi.7zap.com/en/usa/audi+rs4+q ... 615055/#17

Says for the 380mm rotors the screw is M6 x 16 countersunk. Guessing it's common across rotor sizes.

You might also consider that your judder is uneven deposits on your rotors. One possible inexpensive solution is to do the brake-bedding rigamarole again, you know, the five or so repeated almost-stops from like 80mph, then after letting them cool off, a few more from a lesser speed. This method doesn't always work, but as it's so expensive <sarcasm>, might be worth the vast investment.

Re: Brake judder

Posted: Mon Apr 01, 2019 6:24 pm
by James1984
It shouldn’t matter if the screws are present or not once the wheels are mounted

Re: Brake judder

Posted: Mon Apr 01, 2019 8:38 pm
by holsy10
Iduff

Cheers for the response. My first job was to try bed brakes in again but hasent worked unfortunately. There’s a company near me that rekon they might be able to skin the discs as they’re quite new for only £50. They said they have done a few of RS4’s failing that new discs :(


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Re: Brake judder

Posted: Mon Apr 01, 2019 8:40 pm
by holsy10
James

I was hoping this is the case. Tbh since I have all the brakes & wheels lined up correctly I haven’t checked to see if it had moved. I just thought while Im getting it done might aswell fit new screws.


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Re: Brake judder

Posted: Tue Apr 02, 2019 2:50 pm
by iduff
holsy, James is correct, the lug bolts do all you need, except when changing wheels. The small screws simply hold the disc hats in the correct place to allow you to get the lug bolts into the holes in the hubs. Good on you to get it all correct, though.

Re: Brake judder

Posted: Tue Apr 02, 2019 7:21 pm
by James1984
Screwfix have the screws, £3 for 50

Re: Brake judder

Posted: Tue Apr 02, 2019 9:27 pm
by Covkiller
This has been done to death. Look it up and read more.
In short disks don't warp.
Clean your disks, clean you callipers, drill your holes out and jet wash the hell out of them.
Then your brakes won't judder.

Re: Brake judder

Posted: Wed Apr 03, 2019 8:58 am
by MrHilario
Covkiller wrote:
Tue Apr 02, 2019 9:27 pm
This has been done to death. Look it up and read more.
In short disks don't warp.
Clean your disks, clean you callipers, drill your holes out and jet wash the hell out of them.
Then your brakes won't judder.
This.

I've had judder many times, and it goes away after some cleaning without changing disks or pads.

Re: Brake judder

Posted: Wed Apr 03, 2019 9:58 pm
by holsy10
Cheers for the reply’s. I did look around on here but didn’t find one that answered my question which was about screw size.

Also I’m only going by what a specialist has told me. I’m a car lover but not technically minded and always get a garage todo the work so if someone has told me this is the problem I’m not one to argue. Once I get car back from having the alloys done i will spend the weekend cleaning and jet washing to see if this gets rid of the problem.


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Re: Brake judder

Posted: Wed Apr 03, 2019 11:00 pm
by iduff
@holsy, see my earlier reply, pretty sure the screws are M6 x 16 countersunk.
iduff wrote:
Mon Apr 01, 2019 5:20 pm
https://audi.7zap.com/en/usa/audi+rs4+q ... 615055/#17

Says for the 380mm rotors the screw is M6 x 16 countersunk. Guessing it's common across rotor sizes.

You might also consider that your judder is uneven deposits on your rotors. One possible inexpensive solution is to do the brake-bedding rigamarole again, you know, the five or so repeated almost-stops from like 80mph, then after letting them cool off, a few more from a lesser speed. This method doesn't always work, but as it's so expensive <sarcasm>, might be worth the vast investment.

Re: Brake judder

Posted: Thu Apr 04, 2019 7:58 am
by holsy10
Yes iduff I see that thank you.

I was just replying to someone who said this has been done to death. The discs problem has yes but I couldn’t find screw size anywhere until you told me cheers bud.


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Re: Brake judder

Posted: Fri Apr 05, 2019 4:42 pm
by KernowPete
As Cov said, discs do not warp. This is a myth, one I even saw recently perpetuated in EVO mag sad to say. Brake judder is actually caused by one of two things, or a combination of both. One is the interface between the disc and the hub not being totally flush and clean and hence the disc not running true. The other more common one is build up of foreign material on the disc face and in the holes, usually transfer of brake pad material caused by riding the brakes when everything is hot. This creates minute high spots on the disc face which, even though only a fraction of a millimetre thick, can produce truly horrible judder.

Re: Brake judder

Posted: Fri Apr 05, 2019 5:51 pm
by holsy10
Thanks for the reply’s guys.

I think wheels off and a good clean up is in order over the holidays.


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Re: Brake judder

Posted: Mon May 13, 2019 12:23 pm
by Covkiller
Any update?