Warped discs or not ???

M

mickyh7

Guest
Again, I've got this on the A7 forum, but its very quiet on there so I hope this is ok.
Had my Discs and pads replaced about 1500 miles ago because they felt warped.
Huge pulsing under hard braking at speed. Now I've more than bedded the new discs in, the pulsing is back. Only when the discs are hot though?
Lovely and smooth when I first get in.
I'm baffled. Can anyone shed any light on this?
I read dont brake hard then leave the brake pedal pressed, but its an automatic, I leave it on Brake Assist.
I've tried multiple emergency stops it didn't work.
Anyone please ?
Thanks
 

45bvtc

The Older I Get The Better I Was
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Again, I've got this on the A7 forum, but its very quiet on there so I hope this is ok.
Had my Discs and pads replaced about 1500 miles ago because they felt warped.
Huge pulsing under hard braking at speed. Now I've more than bedded the new discs in, the pulsing is back. Only when the discs are hot though?
Lovely and smooth when I first get in.
I'm baffled. Can anyone shed any light on this?
I read dont brake hard then leave the brake pedal pressed, but its an automatic, I leave it on Brake Assist.
I've tried multiple emergency stops it didn't work.
Anyone please ?
Thanks

My sympathies, hope this helps:

Usual cause: friction material build up/deposit on the brake disc and more often than not on the inside face that you can't see.

Reason for: you are not braking sufficiently 'hard' enough to 'work' the pads/discs.

And while the outside face of the brake disc friction surface may look good this doesn't follow that the inside face will be.

Many 'sporting' cars today have brake discs, calipers, and pads way too large for road use and with modern-day traffic density we don't use 'em as we ought.

And, we just don't get the same problem with small diameter brake disc cars...

For more information go see:
http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths
 
M

mickyh7

Guest
My sympathies, hope this helps:

Usual cause: friction material build up/deposit on the brake disc and more often than not on the inside face that you can't see.

Reason for: you are not braking sufficiently 'hard' enough to 'work' the pads/discs.

And while the outside face of the brake disc friction surface may look good this doesn't follow that the inside face will be.

Many 'sporting' cars today have brake discs, calipers, and pads way too large for road use and with modern-day traffic density we don't use 'em as we ought.

And, we just don't get the same problem with small diameter brake disc cars...

For more information go see:
http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths
Thanks for that. But what do I do now?
I've tried repeated braking.
 

DaveM

Registered User
I had similar symptoms on a new car after 6k miles, Audi offered to replace them for £800 as not a warranty item. Mechanic did the hard brake test but didn’t help. In the end I did nothing and after a long run to Scotland and back, the vibration disappeared on its own, which suggests friction material buildup probably due to the car sitting unused for long periods?

Just out of interest, do you put anything on your alloys as a protector that might get onto the disc?

Advice on here suggested it’s unlikely to be warped discs, if you can stand it I’d just live with it and see.

https://www.audi-sport.net/xf/threads/front-disc-replacement-after-only-6000-miles.377290/
 
M

mickyh7

Guest
Thanks some useful information there.
I may put some ceramic pads on. But I'll leave it for now. I did 6 emergency stops on the way to work this morning. Stunning braking power, no pulsing at all when cold ?
 

45bvtc

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Thanks for that. But what do I do now?
I've tried repeated braking.

I think first you need to seriously undertake a brake pad/brake disc bedding-in procedure as I'm sure you've friction pad deposits on your brake discs - remembering you're not 'seeing' the inside face of the disc and for sure that'll be far worse than the outside face which no doubt 'looks' perfect...

A few years back, 2014, we did the Audi Silverstone Experience day that starts with a briefing; and the first thing out of the instructor said to us - following welcome and good morning, etc., was that "you guys just don't brake hard enough!"

So, here's EBC's Bedding-in Procedure for EBC REDstuff - and to be fair is the same for any and ALL other brake pads:


"The purpose of the brake pad and/or brake disc bedding-in procedure is to gradually increase the temperature in the components without thermal shock and to mate the brake pad and disc friction surfaces, generating a uniform transfer layer: and here's how it should be undertake:

• Perform some TEN brake applications slowing MEDIUM-HARD from 60mph to 10mph

• Allow 15-20 seconds MAX between each brake application

• DO NOT brake to a stop as friction deposits are likely to 'bond' to the brake disc and you'll believe you have a warped brake-disc

• When completed, drive the vehicle for at least 5 minutes with little or no braking allowing the brake discs and pads to adequately cool"


Failing this - of which I've little or no doubt will work - I'd suggest having the brake discs re-surfaced using a Pro-Cut and a set of Ferodo Eco-Friction Green brake pads - just had this done on my SQ5 (380mm diameter discs) and the braking is perfect at all speeds:

Pro cut SQ5 brake disc.JPG
 
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45bvtc

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Gooders

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I have this issue on my b8, have discs and pads done and still have the snag. Would dry or worn guild pins be the issue?


Sent from my iPhone using Tapatalk
 

45bvtc

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I have this issue on my b8, have discs and pads done and still have the snag. Would dry or worn guild pins be the issue?


Sent from my iPhone using Tapatalk

I doubt that, not on both calipers at the same time anyway. Most common issue is light-braking causing friction deposit in the inside and outside faces of the brake disc due to our typical driving patterns. Difficult to hard-brake these days, needs driver effort to undertake regularly. :racer:
 
M

mickyh7

Guest
You would think then, all cars with big discs would suffer. Unless everyone drives like they were on a track day !
On my car, at the weekend, the vibration was so bad it was uncomfortable for the passenger!
I've been trying to clean the discs on the way to work. Now I need to get onto the Motorway to see if its worked.
Nothing but trouble on my first Audi so far !
 

45bvtc

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You would think then, all cars with big discs would suffer. Unless everyone drives like they were on a track day !
On my car, at the weekend, the vibration was so bad it was uncomfortable for the passenger!
I've been trying to clean the discs on the way to work. Now I need to get onto the Motorway to see if its worked.
Nothing but trouble on my first Audi so far !

Occasional hard braking - where safe to do so - does get rid of the friction deposits on the brake discs; most problematic in my experience is the inside face of the brake disc, darn, and you'll not see that unless you remove the disc. You can, however, run a finger around part of the inner face and compare surface texture.
 
M

mickyh7

Guest
Bit of a result today.
I've had the car to my local (read Old Bloke) Mechanic.
Immediately he said "If its only the pedal pulsing, and not the steering as well, its your rear discs"
He. Is 100% certain the front Brembo's are fine. Been clocked, well in spec.
New rear discs and pads going on tomorrow morning.
Cheap as chips compared to the fronts!
I'll leave some feedback. Fingers crossed!
 
M

mickyh7

Guest
Hmmm. No different at all.
I've had the Front Calipers off this morning but all looks well.
I'm going to try and get some Ferodo Green Eco Pads today, as I noticed my newish front Brembo Discs have been fitted with Padgett Pads? I can only find bad things about Padgett parts on the internet!
I WILL get to the bottom of this !
 

B5NUT

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VCDS Map User
Do you mean pagid? If so then they are not bad pads, there only real down side is they create a lot of brake dust.
 
M

mickyh7

Guest
Yes, sorry, Pagid. And yes lots of dust !
After working the Caliper pistons in and out this morning the brakes have been much better. So, I'm thinking now that at least one of them is/was ?? sticking when hot.
I thought my local mechanic would have picked this up ?
I'm doing a long drive tomorrow, if it hasn't improved, I'll get some reconditioned Calipers fitted and be done with it!
 

45bvtc

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Yes, sorry, Pagid. And yes lots of dust !
After working the Caliper pistons in and out this morning the brakes have been much better. So, I'm thinking now that at least one of them is/was ?? sticking when hot.
I thought my local mechanic would have picked this up ?
I'm doing a long drive tomorrow, if it hasn't improved, I'll get some reconditioned Calipers fitted and be done with it!

Any news?
 
M

mickyh7

Guest
Yes, I've ordered new discs and pads and I'll fit them myself tomorrow. I now have doubts about where the Brembo Discs came from. I now suspect they may not have been brand new, but were fitted as new! Maybe returned parts? I have no evidence, so I'm snookered here, but something does not ring true about this whole thing. Because they have been on the car around 3 months they offered to skim them at £50 per side. I've sourced new Mintex discs and pads at £130 (50% discount). From Europarts.
I'll obviously find a new Garage for any future jobs that are beyond my competence.
 

45bvtc

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Yes, I've ordered new discs and pads and I'll fit them myself tomorrow. I now have doubts about where the Brembo Discs came from. I now suspect they may not have been brand new, but were fitted as new! Maybe returned parts? I have no evidence, so I'm snookered here, but something does not ring true about this whole thing. Because they have been on the car around 3 months they offered to skim them at £50 per side. I've sourced new Mintex discs and pads at £130 (50% discount). From Europarts.
I'll obviously find a new Garage for any future jobs that are beyond my competence.

That sounds the best way forward, always best to have the best brakes possible. I'll be very interested to see the 'inside' faces of your front brake discs, usually the 'problem' face. Make sure to bed-in the pads and discs - see #6 above. Good luck...
 
M

mickyh7

Guest
That sounds the best way forward, always best to have the best brakes possible. I'll be very interested to see the 'inside' faces of your front brake discs, usually the 'problem' face. Make sure to bed-in the pads and discs - see #6 above. Good luck...
Thank you for your help.
I'll post back in a few hundred miles.
This has really ****** me off. (The thought that someone's ripped me off). Brakes as well ! Unbelievable really ?
 
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M

mickyh7

Guest
Well drove down to Bristol today from Leeds.
What a different car.
Silky smooth brakes, no silly stuff today, just bedding them in gently.
A joy to drive now.
Brembo's going in the skip at work tomorrow! I need to walk away from them.
They looked perfect though !
Big thank you to all who helped with comments. It is appreciated.
Mick.
 

45bvtc

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Well drove down to Bristol today from Leeds.
What a different car.
Silky smooth brakes, no silly stuff today, just bedding them in gently.
A joy to drive now.
Brembo's going in the skip at work tomorrow! I need to walk away from them.
They looked perfect though !
Big thank you to all who helped with comments. It is appreciated.
Mick.
:yahoo:
 
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