[Es2] [audi20v] Re: 91 CQ - Brake fluid low - Clutch?

[Peter Schulz]

Recently replaced BOTH the clutch and slave in trying to resolve a 
low pedal issue.
Replaced the slave first, of course issue ended up being the master, 
which by the way had no external leakage.

You can replace the master without jacking up the car, but it is 
easier to access the slave to bleed it later...

To R&R the master ...
You may want to put some penetrant ( Pb Blaster, Kroil, etc on the 
flare nut fitting on the engine side of the Clutch Master cylinder a 
day or two before starting the R&R)

from the interior - remove the kick panel or shelf on the driver's 
side. Put down some cardboard/plastic to protect the rug from grease 
and brake fluid.
remove the circlip holding the pin on the clevis at the end of the 
clutch master.

from the engine compartment:
Use a turkey baster or other means to reduce the level of brake fluid 
in the reservoir BELOW the level where the supply line to the clutch 
master enters ( rubber hose exiting the Brake fluid reservoir close 
to the firewall)

clamp off the hose close to the reservoir using a pair of radiator or 
hose pliers ( before removing to keep the brake fluid trapped in the hose)
remove the two 10 mm nuts holding the cruise control mechanism to the 
bracket and swing it out of the way ( may have to disconnect a vacuum 
hose)...remove the 10mm nut holding the bracket with 4 connectors on 
it ( two are the knock sensors)

You should now have limited access to the rigid line off the back of 
the clutch master...using a 12mm? flare nut wrench, loosen and remove 
the line ( removing and reinstalling this took by far the most time, 
access limited me to only having 1/8 to 1/4 turn reach for the 
wrench. be patient and take your time)  Before completely removing 
put a small cup underneath the line to catch the fluid, if any comes out.

Back to the interior...remove the two allen bolts holding the clutch 
master to the pedal assembly.  carefully pull the master down and 
towards you, the rubber boot on the firewall should come along with 
the rubber hose and clutch master.  Over a container to catch any 
residual brake fluid, remove the rubber hose and connect it to the 
new clutch master, do the same with the firewall rubber boot. Measure 
the distance on the old Master from the nut to the clevis and 
replicate the position on the new master.

Installation is reverse of removal.

Note, you want to "reverse bleed" the clutch master and slave...that 
means you want to PUSH brake fluid into the bleeder on the clutch 
master. Access the slave bleeder screw, either from above or through 
the driver's wheel well pretty much stinks.  I ended up loosening it 
through the wheel well with a 6 pt deep socket, then accessed it from 
above with a 11mm flare nut wrench I cut in half to make it a stubby wrench.

Some folks use a hose from the drivers brake caliper bleeder to the 
clutch slave bleeder and by pumping the brake, force fluid under 
pressure from the brake caliper into the slave...the fluid then 
travels through the slave up to the Master and then ultimately into 
the reservoir.  Instead of doing this, I used my motive pressure 
brake bleeder, remove the hose with the Brake fluid reservoir cap and 
replaced it with a section of clear vinyl hose from a hardware store, 
put about half a liter of fluid into it, pressurized it to about 
15psi, opened the clutch slave bleeder and let it run...while 
watching the brake reservoir fill.  Be patient and careful when doing 
this, can be messy and the brake fluid can eat paint.

Biggest lesson learned, if you EVER have to take the engine of the 
car ( transplant etc), you may want to consider replacing the master 
and slave then, because you will never that kind of access again

..Fat wallet syndrome be damned..

HTH

-Peter




At 01:46 PM 8/6/2006, you wrote:
>Well, I just noticed fluid leaking out of the rear rubber boot on the end
>of the clutch master cylinder.
>
>Any one replaced one of these?
>
>-B
>
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-Peter Schulz
Chelmsford Ma, USA
http://www.naaclub.org/

1991 200 20v Q Avant Titan Grey
1991 200 20v Q Avant Indigo Mica
1991 90 20v Q Red

1990 CQ silver (awaiting S2 engine transplant)
1991 CQ silver  (potentially replacing the 1990 for  the transplant)
1990 CQ red ( to part or not)