clutch hyd question

[steveo3002]

pedal spring pings up a bare pedal after its past midway

both parts are springy to press in your hands , takes both hands to push the rods in theyre fairly strong

22mm slaves dont seem to exist anymore guess it was superceeded early on , plenty of corrados , passats use these parts its not like its super rare

am i right here...so if the slave has more fluid inside (23.8 vs22) when the clutch springs push the slave home more fluid would be returning to the master ?..if anything shoving it back into place faster?

 

[T5 TDI]

Not something I have ever thought about but yes if the piston displaces more fluid on the return stroke it needs to get back to the reservoir. I'm not sure about faster but that supply hose (not the hydraulic hose) could slow down the return if it is collapsed inside or kinked)

I'm sure you must have tried it without the cap on already by now but it's another thing worth checking in case of wrong cap or blocked hole in the cap. (A bit unlikely but you might as well eliminate it.)

 

[steveo3002]

pretty sure its not the supply hose , its like 7-8mm bore

if its the 23.8 vs 22 then all the others must be suffering the same

 

[T5 TDI]

pretty sure its not the supply hose , its like 7-8mm bore

It might not be if it has collapsed inside.. Since your original problem was only a soft pedal it does seem unlikely it's something like that but I think I would stick some old bit of petrol pipe on it as a temporary test. Sometimes just disturbing something finishes it off.

 

[T5 TDI]

Where did the master cylinder come from? It shows up as 'No longer available' from VW. If it's aftermarket, is it a known good replacement? I mean do you know if others have had any problems using it as a good alternative?

 

[steveo3002]

yeah its an aftermarket from a place ive trusted , theres dozens of different brands available , where do i stop ?

if its not leaking , bleeds up , spring works what else can i do

 

[T5 TDI]

It's a bad one, I feel your pain. If they are not completely crackered you could try putting them back part at a time but maybe the new pipework isn't compatible.. I would definitely eliminate that return pipe being blocked/collapsed because it does sound like the fluid is not being able to return quickly enough for some reason.

 

[steveo3002]

orig bits are done for but i have other used ones i can swap on ...will lash a bit of fuel line or something on to eliminate it

maybe a internal hole hasnt been drilled right size?

 

[T5 TDI]

It's possible but never had that happen maybe some swarf inside but that would be pretty rare too. My old boss when I was 15 used to say if you get weird things happening with clutch or brake hydraulics always look to the master cylinder first. With clutches that used to be creeping or failing to stop the gearbox, your one is a really odd one..

 

[RichardM]

Have you tried bleeding it and just cracking the banjo blots off with some paper towel around them to catch the brake fluid - using them as a bleed nipple?
My old bike brakes used to be a right PITA to initially bleed, used to slacken each banjo in turn to get the trapped air out. Eventually resorted to bleeding the system off the bike as it was the quickest way.

 

[steveo3002]

Have you tried bleeding it and just cracking the banjo blots off with some paper towel around them to catch the brake fluid - using them as a bleed nipple?
My old bike brakes used to be a right PITA to initially bleed, used to slacken each banjo in turn to get the trapped air out. Eventually resorted to bleeding the system off the bike as it was the quickest way.

i tried alsorts at first , but im pretty sure if the master is hard with the slave blocked then theres no air ...correct me if im wrong ?

 

[steveo3002]

might order another over center spring ...seem to recall my other golf was almost violent action with no cable on , maybe its weak ?

 

[steveo3002]

Travel is in inverse proportion to the diameter squared.

whats that in english pls

 

[Gareth_16V]

Means a bigger master cylinder will push more fluid out for the same pedal movement. So yes, an extra 2mm diameter would affect it - you'd get a heavier pedal.
This isn't an application with a clutch delay valve, is it? **EDIT - '91 G60 so guessing not.

As you've replaced the slave, which on those I think is an external (i.e. not concentric slave like an 02M), does the linkage between slave and clutch return easily?

 

[steveo3002]

its a different size slave im asking about ..yes it all moves freely/no valve

 

[mike 109444]

Is the clutch lever arm free to move as in if slave removed and you use a length of tube on lever arm can you operate arm and more so does it return freely as it would be that, that returns the slave and pedal to it's home position with force.
Another option is above is ok would be to manually or with pedal operate clutch lever Then wedge the lever into its forward position. Now try bleeding the slave. Reason I was recommended this many years ago was that unlike brakes that have a hard stop (pad meets disc or shoe meets drum) the clutch has the sprung diaphragm working against the bleeding action. Now once you have bleed the air, slowly release the arm/wedge and allow the returning slave to push fluid back up to m/c.
Not sure how feasable some of the above is as it takes quite a bit of fource on the lever and you maybe strapped for room!

 

[mike 109444]

Also could it be that the slave is returning fine but the clutch lever is sluggish !
You might need to get someone to operate the pedel and watch how the lever follows/pushes the slave back.