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First 10% of brake pedal feels soft after total fluid loss

spudboy6

Active Member
Feb 4, 2014
697
91
Swindon
Good evening all.

I’m having some issues with my brake system but i can’t decide if it’s all in my mind or not , In the workshop at the moment i have a mk1 Audi TT on hand with only 30.000 miles on the clock to compare this to and it feels similar but I’m sure my pedal is worse than the TT and used to be solid before a small incident over the weekend

Main concern - when engine running and driving down the road the first 10-20% of brake pedal travel feels like it does nothing , you know when your driving and press the pedal but the car feels like it’s speeding up (similar sensation of lack of control ) but brakes are great after this first bit of travel is cleared

Engine off pedal is rock solid no issues

So you ask what happened to start this all off ?

Over the weekend I had a braided brake pipe split on me , the crimp let go and when I came to push the pedal I had nothing and then pumped all my brake fluid out onto the road and the system went dry guessing by how much was up the road .

New brake pipes made and changed both fronts

System has been bled several times now over the weekend with a pressure bleeder including the master cylinder (2 nipples ) and the clutch and run the ABS

Does this sounds like I’ve rolled my master cylinder seals ? I obviously hit the pedal in panic hard

My brakes used to feel rock solid when driving I don’t ever remember having some free play in the travel before it started to bite , I appreciate its hard for me to explain exactly what’s happening over the internet .
Pedal is solid when engine off so looks like I have no air in the system but could be trapped somewhere like master cylinder

Imagine you’re coming to a stop you push the pedal and the first let’s say 20mm maybe a bit more of travel feels like it’s doing nothing .

I’ve been driving it all week and brakes are great once your past the first 20mm but this bit of “spongy pedal “ doesn’t feel right to me but I’m not sure if it’s all in my head and I’m just out looking for problems after what happened .

Standard system , Brembo calipers up front

If you’ve made it this far it really grateful and thanks for reading !




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mty12345

Active Member
Jun 17, 2011
3,196
208
bristol
Obviously it's hard to say mate, i guess it's possible that you have damaged the seals, but if you have a nice firm pedal without the engine on then i'd doubt it. More likely it's just your mind playing tricks on you. I've done it plenty of times over the years where i have fitted a caliper or something, pressure bled it, all seems good, then I take it for a test drive and worry that the pedal seems softer than before. After bleeding a couple more times without finding any air bubbles, I finally decide that it's just my imagination because i'm kind of 'looking for a problem' if you know what i mean.
 

Sparkie

Angling Adict.
Sep 25, 2009
2,208
548
Middlesex
It’s pretty common to have this.
My last fluid change think it took 3 or 4 attempts to bleed as you’ve described before I got the proper feel.
It’s not in your mind.
I’ve been there and you start to question if you’re just imagining and maybe it was similar before.
No.
Your brain is sensing something different and it is.

Sadly he only thing to do is bleed it again.
It will become firm as you expect.
Plenty of us have had this and have discussed it before on a FB group. TeamcupraR


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Andrewwright

Turbo lover
Aug 16, 2016
1,562
219
Peterborough
The Leon 1.8t I just got rid of had this 10/20% before anything happened feeling...now this TDI with tiny disks on has 50% more stopping power than the 1.8t with its 312mm disks.

Get them checked...I could outbreak you and that 20% you needed leaves you in the back of me and an unhappy insurance company.

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Compo1

Active Member
Jul 19, 2010
219
49
Did you bleed the ABS system via VCDS ? As that is the most likely place the air will get trapped after fluid loss.
 

spudboy6

Active Member
Feb 4, 2014
697
91
Swindon
Hi all thanks got the reply’s

Yes abs has been bled with vcds twice.

I’m on 323mm with 4pot brembos

To be honest on the way home this evening it felt okay ,

I’m going to do a full re-bleed again this week and will let you know if the feel improves or not but as it stands Barajas feel good. Maybe I got fluid on the discs and it’s only just burnt off ?


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spudboy6

Active Member
Feb 4, 2014
697
91
Swindon
So I’ve been driving round for a few days , throwing in a few hard stops to get the ABS working and getting some heat in them , Still not satisfied so i decided to bleed them again .

Pressure bleeder set up , elevated the rear calipers to get the bleed screw as high as possible so they don’t trap any air ,

Using the pressure bleeder and pumping the pedal halfway just to make sure there’s no air trapped.

Done the brembos inside and outside nipples.

Done master both nipples

Done the clutch.

Initial drive home they feel much much better. I’ll keep this updated and see how they feel over a longer drive .


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Sparkie

Angling Adict.
Sep 25, 2009
2,208
548
Middlesex
Result


Badger5 Custom Map + TIP,
3”Custom exhaust, FMIC, Bosh 550’s, BC Coilovers, ARB’s +loads more.
 

spudboy6

Active Member
Feb 4, 2014
697
91
Swindon
Still feel great ,
Going to re-bleed them this week with my race fluid I usually run as I’m going to the Nurburgring on Friday. used standard dot4 in them until I got my pedal back as it’s expensive to waste .
 

Sparkie

Angling Adict.
Sep 25, 2009
2,208
548
Middlesex
Still feel great ,
Going to re-bleed them this week with my race fluid I usually run as I’m going to the Nurburgring on Friday. used standard dot4 in them until I got my pedal back as it’s expensive to waste .
I’d buy an extra small bottle as it may take a couple of bleeds next time too.


Badger5 Custom Map + TIP,
3”Custom exhaust, FMIC, Bosh 550’s, BC Coilovers, ARB’s +loads more.
 
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