RS4 BRAKE JUDDER

[RS4RS6]

Evening, there seems to be a lot of posts on brake judder, I’m getting quite a bit now and am trying to understand why, details below.

B7 RS4 2006 goes in for service at Audi dealer and has slight judder on front, front discs and pads fitted, judder goes away. 2000 miles later the judder comes through the steering wheel on braking again, car goes back and the dealer changed under warranty. judder goes away, 1000 miles later the judder comes back on braking. Car goes back to Audi for review, this time I am told its the suspension bushes on the front causing the judder as the brakes are perfectly true running. Cost to replace £1200, I opt for my local garage to change these parts, bill is £650, a little different! Judder is still there under braking following the replacement using OEM parts. The car is booked to go back to Audi this Wednesday for another check over. Does anyone know the tolerance that the discs should be running within when rotated, or run out? Any help/advice would be appreciated.

[Terry1948]

Could it be that you have a problem with the calipers some of the pots sticking perhaps and the discs and bushes have never been the problem. Do you use it Dailey. I have noticed since using mine every day mine have improved.

[MikeFish]

Isn't this a classic case of brake pad residue building up on the discs after a bit of light brake usage?

[grizz]

Did they check the front hubs for runout , I've had a few and they needed new wheel bearings and flanges .

[adsgreen]

Isn't this a classic case of brake pad residue building up on the discs after a bit of light brake usage?

It could be.

Key question is how hard the OP pushes their brakes.

[Tile Diver]

Are you following Audi's outrageous bedding in procedure for your new discs and pads?

[MikeFish]

Are you following Audi's outrageous bedding in procedure for your new discs and pads?

Unfortunately, I don't own a private race track to allow me to safely bed my brakes in, in accordance with the recommendations, and now I have residue.
Didn't suffer last time around though.

[RS4RS6]

I used the car every day, well until last week when I bought a 2008 RS6. Audi checked the run out on the discs and said they were perfect, however I checked them the weekend at my works and they are running 0.15mm out, I wondered what the tolerance is on run out.

They 100% said that the judder was down to the bushes, so I had them replaced but its still there.

Bedding in of the brakes, took their advice and all was ok for a while but then you could just feel a slight wobble in the steering, it got worse very quickly.

[klauster]

I have gone through this scenario myself, it's a combination of factors which basically boils down to 2 things, the RS4 brakes are not a great design and you need to change the way you use them, I changed one little thing and it has prevented this happening again.... Use your handbrake when stationery, when cleaning your car clean the holes in the brake disks

Unfortunately you will either need to skim your disks or replace them

[RS4RS6]

what I dont understand is that I have covered 40,000 miles in this car with other brake changes being ok, this one with this particular garage has been a nightmare. Once the brakes are changed under warranty then I will use the handbrake as you suggest to see how this helps. Probably wont get long to try it as I will be selling it as I have the 6 now.

[adsgreen]

I have gone through this scenario myself, it's a combination of factors which basically boils down to 2 things, the RS4 brakes are not a great design and you need to change the way you use them, I changed one little thing and it has prevented this happening again.... Use your handbrake when stationery, when cleaning your car clean the holes in the brake disks

Unfortunately you will either need to skim your disks or replace them

To be fair, it's not the RS4 brakes being a bad design. The are actually over designed for normal road use and it's just that they simply dont get used enough thats the problem.
You only need a tiny amount of pressure/contact to slow the car comfortably under normal day to day conditions and this is what can lead to breake residue build up.
Being firm to hard on the brakes and as you say not using the handbrake when still is good advice for any performance car with over spec'd brakes. The new M3 IIRC has a specific mention of this in the owners manual (something like "use the brakes in the spirit to which the car is deisgned").

What manufacturers could do is dynamically change the brake balance based on the cars speed and brake pressure. So under normal conditions you might as well turn off the rear brakes so the extra effort is required by the front wheels. That way they get used more and shouldn't suffer quite so easily.

For what it's worth I'm always pretty hard on the brakes (nothing stupid though), never cleaned the holes in the discs and mine have 30k on pads and rotors. No wobble or judder and still stopping perfectly (touch wood). Interestingly I've just check the holes on my rotors and whilst there is a tiny amount of build up all the holes that I could see were not blocked fully or even close to half. My belief is that if you regularly get the brakes hot into their optimum operating range and use the firmly then the holes seem to keep themselves clear. I suspect it's light braking thatallows them to build up and cause problems.

[klauster]

I have gone through this scenario myself, it's a combination of factors which basically boils down to 2 things, the RS4 brakes are not a great design and you need to change the way you use them, I changed one little thing and it has prevented this happening again.... Use your handbrake when stationery, when cleaning your car clean the holes in the brake disks

Unfortunately you will either need to skim your disks or replace them

To be fair, it's not the RS4 brakes being a bad design. The are actually over designed for normal road use and it's just that they simply dont get used enough thats the problem.
You only need a tiny amount of pressure/contact to slow the car comfortably under normal day to day conditions and this is what can lead to breake residue build up.
Being firm to hard on the brakes and as you say not using the handbrake when still is good advice for any performance car with over spec'd brakes. The new M3 IIRC has a specific mention of this in the owners manual (something like "use the brakes in the spirit to which the car is deisgned").

What manufacturers could do is dynamically change the brake balance based on the cars speed and brake pressure. So under normal conditions you might as well turn off the rear brakes so the extra effort is required by the front wheels. That way they get used more and shouldn't suffer quite so easily.

For what it's worth I'm always pretty hard on the brakes (nothing stupid though), never cleaned the holes in the discs and mine have 30k on pads and rotors. No wobble or judder and still stopping perfectly (touch wood). Interestingly I've just check the holes on my rotors and whilst there is a tiny amount of build up all the holes that I could see were not blocked fully or even close to half. My belief is that if you regularly get the brakes hot into their optimum operating range and use the firmly then the holes seem to keep themselves clear. I suspect it's light braking thatallows them to build up and cause problems.

I have been using them harder too and found them to behave themselves for a lot longer than before

[P_G]

The other part to what you have said ads is that whilst the brakes are immense for the car and most of the driving public's use, they are like Nick has pointed out not the best design. They have been designed like most things on a mass market production car to a budget which is why they are pinned rather than vented discs and on all subsequent RS models the cross drill holes are bigger to stop clogging with what are in fairness, also a result of quite soft OEM Pagids. Added to this is that some of the Brembo discs were made of Chinese steel which in itself is soft, porous and more susceptible to pad deposition than European spec steel.

I like Nick and several others had issues even when I felt like I was almost abusing the discs and found a change to harder EBC Yellowstuff pads, harder braking, leaving the car in gear and handbrake off when parked up and handbrake on at lights rather than standing on the brake pedal virtually eliminated all my issues with pad deposition because it is not just cross drilled hole cloggng but surface deposition that was often the killer for me.

I know there is a common crticism of the RS3 brakes squeeling and I have experienced this myself in set conditions but again this is glazing of the discs by the pads fitted and the way the brakes are used on semi auto cars to keep it stantionary when the discs and pads aren't up to temperature. As with the RS4 I see there are now harder compound pads available that eliminate this.

[guffy]

My new discs also developed a slight judder after 2000 miles. Bedding in improved the situation, but it comes back, so i have to keep bedding them in. Also avoid sitting on the brakes.

The judder disappears under hard braking, so it's safe to say that they're not warped, or that the bushes need replacing.

I've never had a car with this issue before, it is really annoying.

[ASH555]

I have posted on this subject last week, I have had the hubs pointed out as a possible root cause for 3 sets in 26k and needing another now, on a ramp the nearside front wheel has a pronounced wobble, and the offside a slight wobble, I now need to get the hubs checked for run off....

I always give the brakes a good running, do not sit with my foot on the brakes and do not park up using the handbrake (leave in gear)