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The idea with this bleeding procedure is to get the air pocket out of the flex and hard line,
the slave has to be the lowest point
starter removal is necessary to try this.
Disconnect the battery first
When I did my Engine replacement this year, I installed the GB hose and didn't have any trouble with the clutch at all, just bleeding by pressurizing the fluid reservoir with a Motive and then opening the slave bleed screw. Previously with the metal line, I was able to improve my pedal function by reverse bleeding the clutch slave. I hooked a line to one of the bleed nipples on the front left caliper and to the bleed nipple on the clutch slave, opened both, and gently pressed the brake pedal to force fluid from the caliper through the slave. I could see the bubbles in the brake fluid reservoir. Though I didn't do this, prefilling that connecting hose with fluid is probably not a bad idea, as without it you introduce a lot of air to the clutch slave (length of the hose) and then force it all back out. The GB hose is great, especially if you have to repeatedly remove the slave for various reasons after initial installation like I did.
You said that your slave cylinder is new, but your symptoms sound a lot like what I experienced when my slave cylinder was bad.
If none of the bleeding techniques are working, then it's probably not the bleeding that is the problem, but something else wrong with one of the components in the system.
thanks gentleman for ideas/experiences.
Bulvot , yes , all components are brand new.
A slave can only work or leak to the outside , there is only 1 seal on the plunger in it. With pressure it should work or leak.
The MC has 2 seals , making 2 chambers with a one way valve between. As mentioned , i guess that as long there is air , pedal pumping doesn't make enough pressure to close that valve , so no oil pumping effect …
curious to do the bleed with slave vertical this PM....
OK, we did it as proposed…. even pushing with my gearbox jack , so i could hold it in for minutes ( air bubbles going up ) and release it very slow. Did it 7 times , not 3....
result the same , no pedal at all.
Or should one be pushing the pedal also in those attempts bleeding ?
There was slack in the pushrod above , so no preload.
More and more i think a (new) bad MC …. in which the one way valve doesn't work.
OK take the C clip out of the master cylinder remove the piston and see if fluid flows out and drains the tank
you should have a helper to watch the master tank getting low or bubbles showing up.
if no flow the your line is not in a constant decline to the inlet port
i understand Stan, but what i do not understand : as i pressure bleed 1 liter oil ! from slave to reservoir ...to bottle , the front chamber must be approx full of oil. Pushing the pedal and the one way valve closing !!! must make at least a bit of pressure on the line/slave …. no ?
Could you confirm the functioning of that valve by pressing the pedal to the floor and seeing if you can pull a vacuum from the slave bleeder? Maybe that could even help fluid fill the slave when the pedal comes up. Unless someone else can think of a reason that the vacuum is a bad idea.
i finally have some action on the slave rod ! ( so the MC one way valve is working…. )
could be a combination of actions done, but last , with most result imho, was pressure bleed on reservoir and meanwhile old school pumping pedal , hold,bleed slave ...and repeat .
OK , now i can concentrate first on the slave rod length adjustment and see if the fork can go far enough backwards….to pull the clutch open : i have the single disc setup in a '82 lower bellhousing pan.
We already had to grind a bit on the interior so that the flywheel had some clearance .
As far as i see i will have to make the rod longer and expect to cut a opening in the back so that the fork tip can go further out...must measure .
Stroke of the MC is 35 mm which gives max 22 mm for the slave as they have diameters of 19 and 24 mm.
Stroke of the slave is 40 mm but should keep reserve ( WSM says 17 mm ) , as the rod comes more in the slave as the disc gets thinner with use . So i need a rod that pushes 23 mm in the slave when bolting it on. I will take 28 mm , don't see me driving with a complete worn disc.
PS 23 mm is a bit "just" as the MC "can " give 22 mm slave stroke and the plunger is not secured by a "real" circlips , one could push him out …. indeed, we see all those warnings to not push the pedal when the slave is unbolted.
i put a extra length part on the slave rod and cut a hole in the pan. The fork tip is protruding less than i thought , it's just level with the outside. So it was just the pan's 4 mm thickness what i need . Rewelding a plate on the outside will be enough.
Now that the clutch is working…. i was surprized by the clutch boost spring … one doesn't feel difference when taking away "play" and when really engage clutch… that's not it. I demounted quickly that spring and have now a "normal" pedal feel : soft taken "play" away and really feel the clutch releasing or coming up … That's perfect ! Even with the boost spring out , it remains a rather soft pedal …. i had stronger ones to push in....as with the pedal box in my rally BMW.
Eventually i can place a tension spring instead of the boost spring to make the pedal even more stiff….in a shaking rally car soft pedals are not ideal, better a firm push as with the gas pedal.
12-20-2019, 06:47 AM
