Anyone fitted an electric brake vac pump to the S3 , BAM [yet ?]

AGB-S3 · Nov 27, 2019

Asked this a while back ,

Anyone fitted an electric brake vac pump to the S3 , BAM . ? ive run out of brakes too often,when swapping from full open to hard on brakes , only to find the servo has lost vac and taking its time to pump down ,
Running with hard pads , tootsie pressure is woefully inadequate ..

and as JackStu says , ''only accidents happen in real time''

The A3 looks to have the ideal thing, where is it mounted ?, where powered from ?

Tnx-G

badger5 · Nov 28, 2019

how can you loose brake vacuum? never ever come across this....

<tuffty/> · Nov 28, 2019

AGB-S3 said:
The A3 looks to have the ideal thing, where is it mounted ?, where powered from ?

What A3 are you on about?

<tuffty/>

AGB-S3 · Nov 28, 2019

Its not so much, how you loose vac assistance , its when

Under normal use , never a problem or zipping round the back roads
or even over at the iom ..probably not show at track day ,

Could have a leak or servo is worn out - how to test servo ?

Q with the engine off , how long , should the vac hold with the peddle hard down ?

but , if the intake has been under pressure
for some time ... there is a issue

Test conditions -
mid range gear , 4 , full throttle , up hill , 3000 to 7000 rpm max then
instantaneous, drop throttle apply brakes
result , at
T=0 hard brake peddle , very little brakes ,
T=1 some travel
T= + 2 seconds full peddle travel + brakes start to apply fully ,

How many one-way valves are there , between manifold and servo ?

this pump shows with google search ...AUDI 1J0612181C

myth · Nov 28, 2019

There is only 1 one-way valve between the manifold and servo. Check if it holds vacuum: shut off engine without applying brake, wait 10-20 minutes then remove the hose that goes to the servo. If you hear air rushing in, it's okay. If there is atmospheric pressure, then the valve is broken.

hendo#1 · Nov 28, 2019

I had this exact same problem. Pretty frightening when it happens to you.

I replaced the pipe from the inlet to the brake booster with a new genuine item complete with check valve.

Problem sorted. The old one had a minor split behind the heat shielding.

AGB-S3 · Nov 29, 2019

Yes, at 100 mph , that's ~ 150 feet per second, )

Not sure If I have a conventional 'leak' in the system, the brakes function 'normally' , inlet vac looks good etc , however , I don't think the system retains VAC for very long , when the engine is stopped .. that would put the issue , at the one-way valve and/or the servo

Q Is the Servo VAC valve available , as separate item .or is it part of the pipe assy ? .part number ?

Tnx-G

NB- old thread- I can see ref to ''two'' check valves and delay as well -- Im not convinced the concept is sound , asking for vac from a positive pressure system , even my xr-4x4i had a fully pumped braking system , that was a lot older than this . one of those vac pumps looks very appealing at the moment ,

https://www.audi-sport.net/xf/threads/brake-vacuum-problem.329008/

badger5 · Nov 29, 2019

AGB-S3 said:
Its not so much, how you loose vac assistance , its when

Under normal use , never a problem or zipping round the back roads
or even over at the iom ..probably not show at track day ,

Could have a leak or servo is worn out - how to test servo ?

Q with the engine off , how long , should the vac hold with the peddle hard down ?

but , if the intake has been under pressure
for some time ... there is a issue

Test conditions -
mid range gear , 4 , full throttle , up hill , 3000 to 7000 rpm max then
instantaneous, drop throttle apply brakes
result , at
T=0 hard brake peddle , very little brakes ,
T=1 some travel
T= + 2 seconds full peddle travel + brakes start to apply fully ,

How many one-way valves are there , between manifold and servo ?

this pump shows with google search ...AUDI 1J0612181C

check the connections from inlet manifold to servo..
not uncommon for the plastic pipe to split, hidden behind heat wrap.. and you will loose vacuum.
Fix the leak, dont waste your time finding a solution to a problem that does'nt exist dude

AGB-S3 · Nov 29, 2019

Well yes . only problem is , it works quite normally , for 99.99 % of the time , and the manifold vac is ok

The leak has to be on the other side of the valve , or the valve which is either the valve or the brake servo K-nacked

any links to part numbers for the pipe and valve assy ? can see lots on ebay , but , that may be
false economy -

Tnx-G

AGB-S3 · Nov 30, 2019

8L6612041G

This have the VALVE as part of the assy ?

correct part number ?

AGB-S3 · Dec 7, 2019

New pipe [T to servo] , on, and found some arze had used pvc pipe to make the connection , which , when covered in oil and muck , looked just like the other pipes, which are rubber , and yes the pvc pipe leaks ever so slightly .. so the leak was on the servo side of the second valve

At the moment , system is holding vac with engine off ...wonderful

Q what is connected to the other end of the T in the VAC pipe , runs off to the other side of the engine bay ?

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Anyone fitted an electric brake vac pump to the S3 , BAM [yet ?]

AGB-S3

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badger5

www.badger5.co.uk

<tuffty/>

Badger 5 Edition...Its all about the flow...

AGB-S3

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myth

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hendo#1

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AGB-S3

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badger5

www.badger5.co.uk

AGB-S3

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AGB-S3

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