TheSamba.com :: View topic - Having trouble bleeding hydraulic clutch.

Thu Jul 30, 2020 3:39 am

I'm using a Subaru transmission and clutch master and slave on a beetle pan and pedals. I can get the slave to go back and fourth with the pedal but it only contacts the fork when pedal is at the floor and has a gap when I let it up. If I open the slave bleeder it draws a bunch of vacuum. I can't vacuum bleed the system with the master hooked up it just holds vacuum but without the master it it vacuum bleeds everything. Maybe the Subaru master can't be below the slave. What would be a good master option to put with the stock VW pedals and not cut the tunnel ?

Thu Jul 30, 2020 6:15 am

Can you vac bleed through the slave? If not then there's something wrong at the master, either the push rod is too long and is closing the fill port from the reservoir, or the master is faulty. Or the master bore is too small for the slave

Thu Jul 30, 2020 6:36 am

66brm wrote: Can you vac bleed through the slave? If not then there's something wrong at the master, either the push rod is too long and is closing the fill port from the reservoir, or the master is faulty. Or the master bore is too small for the slave
Everything is off the original Subaru donor car. I can vacuum bleed everything except when master is connected even if master is not connected to brake pedal. I'm buying all new parts and starting over so I can eliminate the bad master possibility.

Thu Jul 30, 2020 10:02 am

The best way I have found to bleed clutchs is to remove the slave, leave the hose connected to the master. Then, push/pull the rod. Pull fluid in, push it back.
Do it a few times.. Done..

Thu Jul 30, 2020 10:56 am

Back in my motorcycle mechanicing days I made up a reverse bleeder. I bought a high quality , short and squat oil squirt can. I added about 18" to 24" of clear plastic hose the right size to be a good fit on the bleeder valve nipple and fit tight on the squirt can's nozzle. Fill the oil can with brake fluid and pump brake fluid until the hose is full then put the hose on the bleeder nipple. Then put a full 360* loop about 12" diameter in the hose with the top of the loop 12" above the bleeder valve. Then open the valve and start slowly pumping brake fluid into the system. If any bubbles of air end up coming out of the squirt can they will stay at the top of the loop.

Keep pumping until the MC is nearly full. Tighten the bleeder and test the lever or pedal. Should be very firm if not perfect. Sometimes you do have to do a few strokes of normal bleeding to get a few trapped bubbles out of the slave or caliiper.

Sometimes due to plumbing layouts you get trapped air that can't be moved by bleeding. Motorcycle rear brake master cyls are often subject to this. The solution is to loosen the banjo bolt at the top of the master cyl after pumping the pedal a few times and then holding the pedal down as the banjo is loosened. Tighten the banjo and repeat until no more air comes out. Then clean up the blasted mess !!!

Thu Jul 30, 2020 12:37 pm

Vacuum or pressure bleeding helps. Many factory clutch slave systems use a residual pressure valve on the MC to fix this issue.

Ray

Thu Jul 30, 2020 6:50 pm

I was actually wondering about a Residual Valve because the master is lower.
I bought a new master, slave, and hose and now the vacuum bleeder draws fluid from the master like it should. I did a quick bleed and it should work now. I need to reinforce my master bracket then I'll know for sure. The clutch did release and engage though.

Thu Jul 30, 2020 7:38 pm

shermer-high wrote: I was actually wondering about a Residual Valve because the master is lower.
I bought a new master, slave, and hose and now the vacuum bleeder draws fluid from the master like it should. I did a quick bleed and it should work now. I need to reinforce my master bracket then I'll know for sure. The clutch did release and engage though.
I read your original post and that thought crossed my mind. However, my buggy seems fine with the Wilwood master cylinder on the floor and the CNC Machine slave cylinder mounted up on the transaxle. My first master cylinder (not Wilwood) proved to be defective but once replaced the clutch was easy to bleed and seems to be holding up fine while I build the rest of the buggy. It still releases the clutch when pressed with the same pedal feel as when first bled. I don't remember reading about any other Bug hydraulic clutch setups with a residual valve while sorting out my setup.

Fri Jul 31, 2020 4:09 am

I wanted to use Subaru parts as much as possible it just makes it easier to replace them when they go bad. I always use factory parts whenever I can my brother just had to use Wilwood calipers on his Cadillac because he could only get one side and they hit the rim not to mention the price difference.
I thought about a residual valve for brakes also because I've never had enough back brake with disc front drum rear. I've driven it that way since 2001 it stops fine but when checking brake bias it's to much front brakes.