no clutch pressure
08-17-2006, 06:43 PM
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no clutch pressure
i recently purchased a 1989 audi 80 with a 2.0 and maual transmission, i had to replace the slave cylinder for the clutch, but i still have no resistance in the clutch pedal, it just pops to the floor and pops back up when i pull up on the pedal, the car runs great, i just can't drive it, can someone please offer some assistance and/ or guidance? i've never worked on this type of hydraulic clutch and i'm getting frustrated. please help!!!!
08-18-2006, 04:36 AM
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BTDT recently...(LONG)
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
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
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