Audi S2 3B

[ristokru]

Hello,

i have a S2 sedan replica. Audi 80 body and 3B technics on it.
I have a question about brakes system. If i but pedal to the floor and then suddenly brake,then the brakes are off. They will brake but without power.
If i drive normally then brakes are good.

What may be the issue? Brake silinder?

Thanks!

[Error404]

Hydraulic or vacuum booster?
If you have vacuum it sounds like the check valve is not working.

[ristokru]

http://kuldnebors.ee/search/soidukid...b_page_size=25

I dont know can you see it from engine picture?

[Error404]

Can't quite see, looks like vacuum booster to me.

[ristokru]

Yes,its vacuum booster.

[Error404]

So make sure that the check valve is OK, otherwise the booster will not hold vacuum and you have no assist until engine builds vacuum. It is a good idea to use 2 check valves in series on a turbo motor, so you don't boost the servo & damage it.

[RichLV]

So make sure that the check valve is OK, otherwise the booster will not hold vacuum and you have no assist until engine builds vacuum. It is a good idea to use 2 check valves in series on a turbo motor, so you don't boost the servo & damage it.

How do you fit 2 valves? I wanted to do this too, but haven't found valves which can be placed in series.

[Error404]

Just cut the vacuum pipe to the booster and add another valve in series.
I used 191 611 933 from the VW bus

[RichLV]

Just cut the vacuum pipe to the booster and add another valve in series.
I used 191 611 933 from the VW bus

What kind of booster do you have?

[ristokru]

How can i check is the valve ok?
And is this stronger:
http://www.ebay.co.uk/itm/331470792631

[LHD_Kid]

How can i check is the valve ok?
And is this stronger:
http://www.ebay.co.uk/itm/331470792631

It is a pain to fit the forge one as the pipe diameter is larger. Just fit 2 good OEM ones

[Error404]

OEM is perfectly good enough, probably better in fact.

[ristokru]

How can i check is the valve broken or maybe booster?

[LHD_Kid]

How can i check is the valve broken or maybe booster?

Remove the valve - noting which way it was mounted.

Suck and blow through it, flow should only be possible in the direction away from the vacuum servo.