A6 judder when brakes applied at high speed

Moanin

Hi,

As per title - 2011 A6 vibration felt when braking at high speed & warp disc effect felt when braking at low speed.

Mechanic has replaced all 4 x brake discs and pads (Brembo).

I was charged for a guide sleeve kit also but problem has risen its head once more a month after the job was done.

Could anybody shed some light as to what this maybe before I send it back once more to mechanic?

Could it be worn bushes? Caliper need replacing?

Thanks

Eoinbmw

Sounds like a sticking caliper!

Moanin

Eoinbmw wrote: »

Sounds like a sticking caliper!

Thanks can calipers be reconditioned?

New calipers for this are pretty expensive

Eoinbmw

Moanin wrote: »

Thanks can calipers be reconditioned?

New calipers for this are pretty expensive

They can be or Usually an exchange

punisher5112

Tracking and imbalance on wheels wouldn't help either

Moanin

punisher5112 wrote: »

Tracking and imbalance on wheels wouldn't help either

Thanks they both have been checked and are fine.

2ndcoming

<unhelpful, removed by moderator>

Moanin

On last service mechanic said caliper was sticking so he used this'guide sleeve kit' on calipers but this obviously didn't work.

I'll book it in tomorrow to see when he can look at it....

Ardent

Warped discs?

Edit: sorry didn't read OP fully.

muckwarrior

Out of interest, how does a sticking caliper cause a warped disc effect?

Tropheus

I had this problem on my '03 Allroad. Admittedly, it didn't come back as quickly as a month, but did a few months after replacing the front disks and pads. I did the disks myself and didn't clean the hubs sufficiently. A coating builds up between the disk and the hub and needs to be cleaned down well when fitting new disks otherwise there's a risk of the disks being slightly off line thus causing the juddering on breaking. The Allroad is seemingly very sensitive to this and you're talking about fractions of mms.

Another thing to check is control arms. If there is any play at all, that could cause vibration on breaking.

Moanin

Tropheus wrote: »

I had this problem on my '03 Allroad. Admittedly, it didn't come back as quickly as a month, but did a few months after replacing the front disks and pads. I did the disks myself and didn't clean the hubs sufficiently. A coating builds up between the disk and the hub and needs to be cleaned down well when fitting new disks otherwise there's a risk of the disks being slightly off line thus causing the juddering on breaking. The Allroad is seemingly very sensitive to this and you're talking about fractions of mms.

Another thing to check is control arms. If there is any play at all, that could cause vibration on breaking.

Thanks. Control arms on both sides were replaced about 4 months ago (OEM quality)

greasepalm

6 months ago we had issues with a v40 shudder at high speed and changed discs and pads,months later it was back again with a shudder again and second set fitted and still had issues as the drivers side on outside part of disc showed not all part of pad was using the wide surface area of disc.Get a felt black tipped pen draw lines from inside to outside of discs to see whats happening.Mine still showed after a test run parts of lines still showed.Sent back under warranty and they swore blindly discs and pads were ok and it was a faulty caliper kit and i argued it was not tight or excessively loose.

Different make of discs and pads fitted problem sorted.
Sometimes a faulty flexy pipe might not releasing fluid and would ask does piston push back easy when pipe is clamped and valve open as can see what condition caliper is in .I have had a few in with tight to go back pistons and had to pump piston out to clean the piston which is manky,remove seal and clean the groove under it,wash the rubber seal under warm water and thumb nail dry and install with some rubber grease.Everything should glide in smoothly when lubed and 2 thumbs to push piston in.

Moanin

greasepalm wrote: »

6 months ago we had issues with a v40 shudder at high speed and changed discs and pads,months later it was back again with a shudder again and second set fitted and still had issues as the drivers side on outside part of disc showed not all part of pad was using the wide surface area of disc.Get a felt black tipped pen draw lines from inside to outside of discs to see whats happening.Mine still showed after a test run parts of lines still showed.Sent back under warranty and they swore blindly discs and pads were ok and it was a faulty caliper kit and i argued it was not tight or excessively loose.

Different make of discs and pads fitted problem sorted.
Sometimes a faulty flexy pipe might not releasing fluid and would ask does piston push back easy when pipe is clamped and valve open as can see what condition caliper is in .I have had a few in with tight to go back pistons and had to pump piston out to clean the piston which is manky,remove seal and clean the groove under it,wash the rubber seal under warm water and thumb nail dry and install with some rubber grease.Everything should glide in smoothly when lubed and 2 thumbs to push piston in.

Thanks I'll mention that to mechanics'. It's booked in for next Thursday

Moanin

*UPDATE*

My mechanic replaced front discs once more (FOC) as ones replaced previously (Brembo) had warped again.

He replaced with a different brand (not sure which)

Harcrid

Interestingly I had to take a set of Brembo discs off my BMW F10 after about 2 months due to something similar. Ended going with OEM parts which are much more expensive, which I knew but I though a reputable brand like Brembo would have been good enough. Obviously not.