Brake Pedal Drop?

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4.0 V8 40v biturbo TFSI - 597 bhp (Performance)
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2Brains
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Brake Pedal Drop?

Post by 2Brains » Wed Nov 07, 2018 7:59 pm

Evening Gents,

Just back from being away with work for 2 weeks.

Picked up the motor and drove over 100 miles home.
However, on the way back I was pressing on the brakes (and successfully braking) before the pedal seemed to drop maybe an inch before coming up to pressure again and apply the brakes. Seemed to happen twice.

I’ve done some testing by braking slowly as well as some rapid hard braking and it all seemed fine.

Anyone got any ideas as to what could be the issue?

Appreciate any input - thanks.

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Anth
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Re: Brake Pedal Drop?

Post by Anth » Thu Nov 08, 2018 12:05 am

Maybe air? Although if it's not happened again think your good, take it in if its under warranty and get them to flush it from the calipers if you think it's not right . If it's not covered it's about £120 All in .
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MikeFish
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Re: Brake Pedal Drop?

Post by MikeFish » Thu Nov 08, 2018 12:53 am

Someone on here once had a discussion with one of the design engineers and they said the car had a means of controlling brake pedal travel and will adjust itself if it thinks there is too much pedal travel. Could have just been the car adjusting itself.
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Kal
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Re: Brake Pedal Drop?

Post by Kal » Thu Nov 08, 2018 10:13 am

Not sure if its the same issue but twice I've had an issue on the motorway where I have applied the brake and the pedal dropped about an inch and applied heavy break to the pads before coming back up. Quite unnerving when you don't expect it.

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Re: Brake Pedal Drop?

Post by Scotty C » Thu Nov 08, 2018 11:14 am

2Brains wrote:
Wed Nov 07, 2018 7:59 pm
Evening Gents,

Just back from being away with work for 2 weeks.

Picked up the motor and drove over 100 miles home.
However, on the way back I was pressing on the brakes (and successfully braking) before the pedal seemed to drop maybe an inch before coming up to pressure again and apply the brakes. Seemed to happen twice.

I’ve done some testing by braking slowly as well as some rapid hard braking and it all seemed fine.

Anyone got any ideas as to what could be the issue?

Appreciate any input - thanks.
Was it raining as I understand that the brake pads occasionally squeeze the disks to clean them when you are driving in the wet.

I had a similar problem twice about three months apart... I'd press the brake and it did not feel normal. In fact it felt like when you press it and the ignition is off. Quite unnerving when on the motorway. Dealer couldn't find anything wrong and fortunately it hasn't happened since.
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Re: Brake Pedal Drop?

Post by 2Brains » Thu Nov 08, 2018 2:14 pm

Thanks gents - as always much appreciated.

Yes, it was raining both times!

Hasn’t happened since but will keep an eye out for it and if it happens again - get it in under warranty.

Very unnerving! Makes you lose a bit of confidence!

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Re: Brake Pedal Drop?

Post by Yossarian » Thu Nov 08, 2018 2:25 pm

I had exactly the same last Sunday, road was wet, I was already lightly braking when the pedal dropped an inch, my instinct was lift off and reapply, so it all happened within a few seconds, and pedal was normal again and has remained normal ever since? Very strange experience in such a heavy fast car... i'd like to know my brakes will be working properly 100% of the time thanks :shock:

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Re: Brake Pedal Drop?

Post by 2Brains » Thu Nov 08, 2018 3:40 pm

Yossarian wrote:
Thu Nov 08, 2018 2:25 pm
I had exactly the same last Sunday, road was wet, I was already lightly braking when the pedal dropped an inch, my instinct was lift off and reapply, so it all happened within a few seconds, and pedal was normal again and has remained normal ever since? Very strange experience in such a heavy fast car... i'd like to know my brakes will be working properly 100% of the time thanks :shock:
That’s absolutely what I experienced.

I’ll speak to audi - see if they can shed any light!

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Re: Brake Pedal Drop?

Post by sasha320 » Fri Nov 09, 2018 1:19 am

I had the same when in very heavy rain last year.

I’m reluctant to put it down to the discs getting gemtly squeezed to keep them dry as I thought that happened imperceptibly and constantly as you drove when the windscreen wipers on.

So not sure what it was.
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Re: Brake Pedal Drop?

Post by GlynRS2 » Fri Nov 09, 2018 8:01 am

Maybe it is part of the driver alertness monitoring? Not satisfied that a "rest recomendation" alert on the dash made any difference, some development engineer decided that the best way to ensure the driver stayed alert is to randomly scare them shitless. :bash:
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Re: Brake Pedal Drop?

Post by MikeFish » Fri Nov 09, 2018 8:51 am

GlynRS2 wrote:
Fri Nov 09, 2018 8:01 am
Maybe it is part of the driver alertness monitoring? Not satisfied that a "rest recomendation" alert on the dash made any difference, some development engineer decided that the best way to ensure the driver stayed alert is to randomly scare them shitless. :bash:
You know you can turn the 2 hour warning off?

But the brake pedal is more likely to do with the automatic braking systems like active brake guard etc.
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Re: Brake Pedal Drop?

Post by Iain » Fri Nov 09, 2018 9:44 am

Has happened on both my 6's - last time being Tuesday - go to brake gently, having not touched the brakes for a good few miles, then pedal drops what feels like a long way and the brakes are applied rather hard!! - There was a discussion on this a while back - would appear to be normal, but disconcerting at best. Not least when your other half thinks you are slamming on the anchors for no reason!
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Re: Brake Pedal Drop?

Post by drbru » Fri Nov 09, 2018 10:20 am

I can't comment on the Rs6 because I don't have one.....yet!

However I have had this problem on my m5 and it turned out to be the brake cylinder which had failed

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Re: Brake Pedal Drop?

Post by bn8959 » Fri Nov 09, 2018 10:55 am

I opened a thread about this awhile ago, as experienced the exact same symptoms. Went to press brake pedal (gently) and it sunk down but the breaks were applied really hard!

I was thinking that i might have triggered an emergency brake response by the speed my foot switched from accelerator to brake (ie very quickly); and although I didn’t hit the brake hard, maybe it thought I was making an emergency reaction.

It’s only happen to me twice in a year and a half of ownership.
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Iain
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Re: Brake Pedal Drop?

Post by Iain » Fri Nov 09, 2018 11:01 am

bn8959 wrote:
Fri Nov 09, 2018 10:55 am
I opened a thread about this awhile ago, as experienced the exact same symptoms. Went to press brake pedal (gently) and it sunk down but the breaks were applied really hard!

I was thinking that i might have triggered an emergency brake response by the speed my foot switched from accelerator to brake (ie very quickly); and although I didn’t hit the brake hard, maybe it thought I was making an emergency reaction.

It’s only happen to me twice in a year and a half of ownership.
Exactly the same as I experienced, happened around 4 times with me; once when I was coming up on stationary traffic a bit too quick, the other times, just pressing it gently in normal driving.

I don't have ACC etc.
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2004 Lambo Gallarado Manual
3 x 997 C4S / C2s
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2006 RS4 Avant
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