Author Topic: Brake pressure.  (Read 280 times)

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Offline GlenT

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Brake pressure.
« on: December 07, 2017, 11:37:32 am »
Hi guy's,
I have been itching to get my WR out and use it this summer. However, there is some odd behaviour from the brakes.
Last time I drove it (over a year ago) the pedal was slightly soft with the engine running. Now with the engine running the pedal is easily depressed all the way to the floor.
After switching the engine off I get 11 pumps of the pedal where it goes to the floor then I feel the pressure take up as per we should expect.
But if I leave the pedal for 5 or so seconds then try again, it will go to the floor.
At first I thought it was the accumulator, but I replaced this a number of years ago (probably only 1000kms) with an OEM one and also had the master cylinder bored out and a stainless steel sleeve inserted. This was done as the seals had perished and the master cylinder bore was pitted. Since the car is driven very rarely this re sleeving seemed prudent.
I'm going to start with a complete brake fluid bleed out but I'm not holding any hopes for a significant improvement with that. But it has to be done regardless due to the age of the fluid.
Anyone had a similar experience?
Cheers,   Glen

Offline RobClubley

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Re: Brake pressure.
« Reply #1 on: December 07, 2017, 11:44:19 am »
The brakes on mine feel pretty spongy at first but work when the pedal is pressed harder. Is that normal for these cars?
They've been bled 3 times now. New pads, discs and lines.

Offline GlenT

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Re: Brake pressure.
« Reply #2 on: December 07, 2017, 11:56:46 am »
Hi Rob,
Both of my WR's had this slightly soft feeling until you pushed quite hard, then they would deliver the goods.
I think people get used to the sometimes over assisted brakes on late model cars.
The quattro's seemed to understate their own ability, yet performed well when you asked a lot from them.
I've had a couple of people comment on how spongy the brakes felt around town. I failed a WoF once as the testing guy thought there was something wrong. I put him straight.
Also, I took my current WR on a track day at Ruapuna a few years back where I consistently out braked my friends WRX STI RA lap after lap. Evidence they stand up well when pushed.
I currently have EBC green pads and rotors installed.

Offline colingrant

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Re: Brake pressure.
« Reply #3 on: December 07, 2017, 12:57:45 pm »
I had a very similar thing. Pedal would go to the floor after starting and afer a few pumps to the floor you would feel a dull thud and suddenly brakes would be normal ready for driving and they would stay ok till next time. As there is no connection between your foot and the brakes when working correctly only booster oil pressure, I decided it was the booster so I took it off the road to rebuild it That was 4 years ago . I got involved with a 39 Chevy..................Yeah I hear ya...........and have only just started looking at the quat again. I paid the price too. The fuel pump is dead so I hacksawed it open and found it seized with thick brown varnish. Couldn't believe it.  Replaced all the filters and got a fuel distributor rebuild kit and I'm on that at the moment. Could be fun. Watch this space.

Offline John Stone

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Re: Brake pressure.
« Reply #4 on: December 07, 2017, 01:48:51 pm »
Have look her Glen - the Isham Research site hosted by the late Phil Payne is now linked to Audifans....make a cuppa and begin reading


audifans.com/mirror/www.isham-research.co.uk/quattro/brake
86 WR
04 A3
05 V50T5

Offline Lee

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Re: Brake pressure.
« Reply #5 on: December 07, 2017, 02:37:19 pm »
Just to add to this...I assume you all know Rob at Euroline in Auckland has a large box of accumulators and stuff collected over the years.
Might be useful ..... I hope he hasn't thrown it all out..

Offline GlenT

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Re: Brake pressure.
« Reply #6 on: December 07, 2017, 03:59:39 pm »
Have look her Glen - the Isham Research site hosted by the late Phil Payne is now linked to Audifans....make a cuppa and begin reading


audifans.com/mirror/www.isham-research.co.uk/quattro/brake
Thanks Colin,
I've read most of this over the years. Really sad to hear of Phil's passing a while ago, he was a guru.
I have read of other people having a similar but not the same issue. It could be any of the main components at this point.
Normally there is some indicator as to which component it could likely be, but this is plain weird.
I may just have to start with the easier items, such as remove and inspect the master cylinder and go back from there.
If I could try a known good accumulator after that it would help.

Offline GlenT

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Re: Brake pressure.
« Reply #7 on: December 07, 2017, 04:03:26 pm »
Just to add to this...I assume you all know Rob at Euroline in Auckland has a large box of accumulators and stuff collected over the years.
Might be useful ..... I hope he hasn't thrown it all out..
I'll keep that in mind. Thanks.
Mind you, if it is the accumulator I'd rather just buy new if they're still available.
Last one I bought was NZ$400 from Archibalds.

Offline GlenT

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Re: Brake pressure.
« Reply #8 on: December 14, 2017, 01:49:22 pm »
Took the master cylinder and proportioning valve into a local brake service center here in Dunedin, they couriered it to a firm in Auckland over night. 
After stripping they found the master cylinder bore was scored and will need re-sleeving.
Good thing is, something was found. Better than having to dig deeper.
So they'll re-sleeve the MC and re kit both items then I'll assemble, flush out the calipers and lines (fingers crossed). :)