Capacity of hydraulic clutch system?

G

Gary McCormick

True Classic
Just replaced clutch master with new one from (again) and am going to try reverse bleeding through the slave cylinder. Have emptied the reservoir in preparation for this task.

Am wondering approximate capacity of the system, but Haynes doesn’t list it.

Any input will be appreciated.

Regards,
Gary McCormick
‘79X
Carlisle, PA
 
Buy a quart. You will need it, perhaps even two.

The actual capacity is well under a pint, the real issue is bleeding the damn system which often takes multiple tries and lots of wasted fluid.
 
Gary McCormick said:
Just replaced clutch master with new one from (again) and am going to try reverse bleeding through the slave cylinder. Have emptied the reservoir in preparation for this task.

Am wondering approximate capacity of the system, but Haynes doesn’t list it.

Any input will be appreciated.

Regards,
Gary McCormick
‘79X
Carlisle, PA
Click to expand...

The owner's manual for my '86 Bertone says on p109 that the clutch system takes 2/5 of a pint, or .180 liters. If you are wondering, it says the brake system takes 1 pint or .400 liters.
 
Generally it takes multiple pints by the operator to complete the job. The assistant may also desire having a few...

A single malt to consummate the completion is generally the desired outcome.
 
TA DA

Just took X for short jaunt around the neighborhood, and clutch APPEARS to be working fine (I shouldn’t say that because it is bound to come back to bite me).

Reverse bleeding through the slave cylinder, by myself, took about 15 minutes or so (steps 3, 4 and 5 below), after I got everything ready to go (see steps 1 and 2 below).

1. Sucked clutch reservoir dry with turkey baster.
2. Screwed a M8x125 male by 5/16” OD male hose barb fitting into slave bleed port; pushed one end of a couple feet of 5/16” clear tubing onto the hose barb end of fitting and pushed the other end of tubing onto a new plastic condiment bottle containing 2/5 pint of brake/clutch fluid.
3. Held condiment bottle vertically above slave, pushed clutch pedal down with broom handle, and softly squeezed bottle to start fluid flow by gravity.
4. After column of fluid stopped flowing (system was apparently full), I unscrewed aforementioned fitting and quickly screwed in a SB8125 Speed Bleeder.
5. I connected one end of a couple of feet of 1/4” clear tubing to Speed Bleeder and other end to jar partially filled with brake/clutch fluid. I backed Speed Bleeder out 1/4 turn per mfr. instructions and pumped clutch pedal a few times with broom handle. Only a few small air bubbles emerged, then bubbles stopped, so I tightened Speed Bleeder.
That was IT!!!!!

Hope I don’t jinx myself by posting this.

Regards,
Gary McCormick
‘79X
Carlisle, PA
 
Man you are going to be sorreeeeeey

I have had a similar experience but it is the exception and not the rule. Others have spent days. Days.
 
My home grown method has never failed me.

1 Put a box wrench on the slave nipple and turn the valve until it is almost open. Position it so that it can swing the rest of the way open when you are ready.
2 Place a long clear clean fuel line on the nipple of the slave cylinder.
3 Drape the line up out of the engine bay, over the roof, and across the window so you can see it from inside.
4 Have your assistant hold the other end over the open resorvoir.
5 Attach a piece of rope to the pedal to pull the pedal up after being depressed
6 Open the valve and start pumping while you watch the line. Fluid with bubbles will be visible in the line. The fluid will go back into the resorvoir, the bubbles will vent to the atmosphere.
7. Pause to add fluid as needed to avoid running the resorvoir to empty.
8 Pump until there are no more bubbles coming thru the line
9 Close the valve, drain the line, close the resorvoir.
10 Enjoy.

Works for clutch and brakes ( each caliper). Recycles the fluid. If it's nasty in the clear line then send it to a bottle instead of the resorvoir until it runs clean. I've never needed to add more than a few ounces from a new container of fluid.
 
Gary McCormick said:
3. Held condiment bottle vertically above slave, pushed clutch pedal down with broom handle, and softly squeezed bottle to start fluid flow by gravity.
Click to expand...
Gary, I'm curious. Did you keep the pedal pressed to the floor the entire time, or pump it up and down while the condiment bottle was attached? I've never had much luck with 'reverse' bleeding, but I've never tried keeping the pedal down the whole time either. So would like to clarify your technique. Also want to hear more feedback after quite a bit of driving. Thanks
 
Dr.Jeff said:
Gary, I'm curious. Did you keep the pedal pressed to the floor the entire time, or pump it up and down while the condiment bottle was attached? I've never had much luck with 'reverse' bleeding, but I've never tried keeping the pedal down the whole time either. So would like to clarify your technique. Also want to hear more feedback after quite a bit of driving. Thanks
Click to expand...
I did keep pedal down the entire time.
 
Rod Midkiff said:
I am very puzzled that peddle down got any fluid into the Master resecure???
Click to expand...
Unsure if “resecure” was spell checks word for “reservoir” , but if that is intent of query, I completely sucked reservoir empty with turkey baster in prep steps.

When plastic condiment bottle was empty (there was still some brake/clutch fluid in the 1/4” tubing), the MC reservoir was full.
 
The clutch master cylinder is only difficult to bleed until you see the following two pictures:
P_20190727_191244.jpg
P_20190727_191510.jpg
 
You kind of lost me. I understood the method you used, but are you saying something more than that with the pics?

Ooops, never mind. I just looked at them again before posting. You are referring to the angles of parts and fluid/air. The air will rise upward from the fitting (master's outlet) to the nipple (mater's inlet). I think the pressure generated by the squeeze bottle is the key to making it move retrograde.

Depressing the pedal down while filling is the part that seemed surprising. But it worked, and not pressing it down does not work for me. So enough said, worth trying. By the way, others have mentioned that another method of pressurizing the fluid is to use a clean oil squirt/pump can...like one of these:
312j1hvi3oL._SX425_.jpg
 
Well, I guess those pictures weren't as clear as I thought. The problem with the clutch master cylinder is that a big air bubble persists in the top of the cylinder if you bleed toward the slave cylinder. The fluid just keeps moving past the bubble without clearing it. I've heard of people using quarts of brake fluid trying to get a firm pedal. But looking at the pictures you can see that the bubble will never clear that way.

However, if you bleed toward the reservoir like Gary (the op) did, the bubble flows out quickly to the reservoir. It doesn't matter if you use vacuum at the reservoir or positive pressure at the slave cylinder as long as the fluid is moving in the reverse direction toward the reservoir to clear the bubble. I've never depressed the clutch pedal and it still seems to clear the bubble almost instantly so I don't think that matters unless the pedal is pushed past the reservoir outlet in which case the system becomes blocked to reverse flow.

My preferred method is to fill the system pulling vacuum at the slave using a vacuum bleeder until I can't get any more air out. I pull off the line to the vacuum bleeder and leave it in a container of new brake fluid. I switch to an homemade attachment that is basically a bathtub stopper on the end of a vinyl hose. The bathtub stopper fits over the mouth of the reservoir so I can pull a couple of psi at the reservoir to clear the bubble. Done.
 
Last edited:
Cratecruncher said:
if you bleed toward the reservoir like Gary (the op) did
Click to expand...
Ha, I completely misunderstood. When I saw the pictures I thought you were the OP and the reference was to the specific method you (he) did. My fault for not looking closer at who was posting, and assuming you were the OP...sorry for my confusion.

And thanks for clearing up your point with the pictures. I see what you are saying now.
 
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