Clutch master Cylinder R and R ?s

[bljones]

The clutch master in my 86 Syncro has started piddling on my left shoe while driving, so it looks like it is time to replace it. the MC, not the shoe. (well, maybe the shoe as well) Got the part, got the time, now I am scratching my head. My Bentley has a lovely exploded diagram of how it all fits together, but little advice on how to get to the elusive bugger. The only advice Bentley offers is the cryptic "remove instrument panel." "Instrument panel"? do they mean the gauge cluster? the dashboard? I pulled the guage cluster, which gives me a lovely panoramic view of the the brake MC, but the clutch MC still seems hidden. Anyone done this before, and have any tips to offer? Thanks.
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[?Waldo?]

You don't have to pull anything other than the instrument cluster cover (which you already did.

Pull back the carpet from around the pedals and fold it towards the center isle. Look at the steering column and behind it you will see the clutch master cyl. Spread towels around the floor there. Also get a small tray to catch fluid. Pull the hose off the cyl. and let it drain in the tray. Undo the metal line and the two mounting bolts (they're obvious to the naked eye). Remove the cyl. Installation is the reverse, but make sure the metal rod is properly placed in the rubber boot of the new cyl. Also be sure to remove all the little plastic plugs from the new cyl. When done, fill the reservoir. Pump it, and pump it some more. You'll see bubbles moving from the hose into the reservoir, you might have a pedal that's good enough. If not, then go for the slave cyl and bleed as you would a brake system.

Andrew

[Christopher Schimke]

Here's a decent article on the job:

http://www.vanthology.com/1Layout/Technical/Clutch1.html
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[bljones]

Thanks for the tips, gents. Got the old MC out and the new MC in in less than 45 minutes. Then i screwed the pooch by snapping the bleed nipple off the slave.

Anybody have any ideas on bleeding the system without a bleed nipple???
_________________
OG JHC
Author of Original Rant #1
"It stingd itself to dead... now that is control on you"

2%

[tom power]

Hate to tell you, but you should always replace the slave when doing this job. Slave usually goes out real soon after the master.

[?Waldo?]

I don't know how many times I've seen this posted and just do not agree. I've replaced many brake and clutch master cylinders without replacing the slave and have NEVER had a slave fail any time soon after. I replaced the clutch master cylinder in one of my vanagons 3years ago without replacing the slave and it still works fine.

I suppose that it's possible that the master cylinder could fail by not pushing enough of the fluid and so only partially move the slave. Over time that reduced range of motion could result in some corrosion forming in the cylinder outside the range of motion. With the full range returned by the MC replacement, the corrosion could damage the seal in the slave as the seal would then travel over the corrosion. But a MC failing to leakage outside the cylinder is not a failure mode that reduces the travel of the slave.

IF the MC replacement were to cause the slave to fail, then replace it then. There is no way that the function/dysfunction of the slave can impact the MC, so you wouldn't be damaging the MC by using the old slave until it failed.

Save your $70.

If really concerned about it, then buy the slave, but stick it in the back cabinet for the next few years until the slave fails. Put 7mm, 12mm and 13mm wrenches along with a bottle of brake fluid, with it, so you can swap it out roadside...

Andrew

PS On a similar note, the failure mode of the slave is ALWAYS to leaking. If it isn't leaking, the problem isn't with the slave, but with some other part of the system.

[Bambus]

agreed, mostly. Clutch Master failure seems to be much lower on the fact sheet than slave failure, which in my vans (Florida: high moisture) is bi-yearly.
new clutch master leading to failure of old slave seems anecdotal at best. Slaves fail regularly, just replace for a 2-year+ fix, or rebuild for a yearlong fix (in my experience)

bleeding a slave with snapped bleed-screw: possible, though it's gonna take a crawl under and an assistant. Usual pedal routine, but bleed with the steel brakeline threaded junction instead of the bleeder. This won't by any means be a complete bleed, as the air rises to the top of the cylinder where the bleeder is. Try it, but a new slave is the really the only correct fix.

Get the old slave out and try to extract the snapped bleeder-- if you get the broken bleeder out with the threads clean, buy a slave repair kit and a new bleeder screw-- rebuild the slave and keep it under your seat for a another day. And keep the right wrenches under the seat as well!

[Christopher Schimke]

[ryecatcher]

Resurrecting this one to ask this:
I've got the ol' brake fluid piddling on my shoe problem. I traced the leak to the Master Clutch Cylinder, to the (pardon me if this is not correct terminology) union nut pressure fitting.
It squirts out a little there when pressurized. I've tried tightening it, and it helps, but I'm afraid to over-tighten. My question is: Do I need to just replace the MCC, or will some kind of sealant like loctite (sp?) make it seal and hold?
This is on an '82 air-cooled.

Not my pic, but this is where it's leaking, at the lower bolt where the metal line goes in to the MCC:

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[MarkWard]

It is a metric double flare fitting and should seal without sealer. Something is wrong if it is not sealing. It is not the sort of thing that will loosen up with time. At this point, you have a few options, tighten some more and hope is does not pull, or remove it and really inspect the line and where it seats in the cylinder. I can't tell you how tight though. That is a feel thing.
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[insyncro]

Late vans have flex line at the cylinders to allow for tiny movement.
If the hardline has even the slightest pressure on it from not being perfectly centered in the connection, it will weep.

[insyncro]

Ask any plumber...cranking on connections is not going to fix the problem.

[Jeff's Old Volks Home]