S6C4 Hydraulic to Brake Booster conversion

[kotnelson]

I see the thread of conversion on other model but not with S6C4.
I have done the brake assist from Hydraulic to Vacuum assist sometimes ago, hope this info could be useful. Apologize if duplicate thread.



Part require

- Brake booster from A6C4
4A0611021E tandem master cylinder id 23,81mm (15/16")
Engine ACE,ABC,ACZ, AAH,AEJ
(While the stock was id 25,4mm (1"))
***Some of those brake booster already has 1 way valve, some not***

- 048145155FX vane type pump / power steering
ZF / AAR,AAN
Since the stock was not in good condition, I got replacement from Audi 100C4 AAR
which does not have the high pressure line to accumulator, cut me short not to mod
and plug the stock one.

- 1 way valve (I used one from local shop, with ball or Cylindrical valve, avoid flat rubber valve)

- Fuel hose 3/8" approx 1000 mm
- Clamp for fuel hose (to avoid damage to fuel hose if use other type clamp)
- 3 way brass pipe 1/2" and reduce to 3/8" (find the suitable set)

[kotnelson]

Remove this bar




Remove everything in this picture, except #26
#26 is return line from power steering.
Plug out, block, #14 and #15 (Red circle)

Install Brake booster, you need the old........

4A0611301E expansion tank lhd / AAN,ABH
4A0611301G expansion tank rhd / AAN


as the cap position.....

[kotnelson]

- Install vane type pump / power steering, connect feed line and high pressure line to steering.



- install brass pipe between ISV and IM





- run fuel hose to brake booster, if booster already has 1 way valve.
if not put 1 way valve in between this line.


- to have a better vacuum, you may add a reservier tank as this pic, another 1 way valve between IM to reservior must be added.

[kotnelson]

Brake bleeding.


Test
- Start the engine, idle for a minute. Press brake and feel the paddle.
- Idle for 1 minute and turn off
- Press brake and count, you should have about 2-3 time before it is very hard
- Keep pressing brake paddle, start engine. Brake paddle should move down
- Leak test, using soap solution or else, or use Boost test technique

Finish and off you go.

[popdemonic]

Parts added,it requires the clevis from A6/100 model.the hydro system clevis is different(smaller).

[popdemonic]

I forget another parts.you also need the o-ring between the mc and the booster for vacuum booster since after done the conversion.it became the closed system.

[caterpillar]

and the reason for doing like this; big trouble with the hydraulic brake asist or??? nice pics and idee .. but why?

[popdemonic]

Hydro system is cost a fortune.

[caterpillar]

Hydro system is cost a fortune.

thats correckt

[kotnelson]

I forget another parts.you also need the o-ring between the mc and the booster for vacuum booster since after done the conversion.it became the closed system.

Yes, if use the stock MC 1" with new vacuum booster.
Without new o-ring, you will have a vacuum leak.