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How Can I Work Out Master Or Slave Clutch Cylinder Fault?


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#1 4V8s

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Posted 01 January 2021 - 07:43 PM

Hi all,

 

my mini has suddenly lost clutch pressure. If I pump the pedal rapidly say a dozen times I can build up enough pressure to change gears but it doesnt last long.

 

So I am guessing one of the cylinders is gone.

 

Is there a way to test which one is faulty? Or should I just replace both anyway?

 

thanks

 

 

 

 

 

 

 

 



#2 imack

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Posted 01 January 2021 - 07:51 PM

Remove the metal pipe from the master cylinder and screw an appropriate bleed nipple in place of it.
Carefully bleed from this nipple, do up nipple and apply pressure to clutch pedal.
Solid pedal feel and not pedal creep when keeping gentle pressure on it = master cylinder ok. (you'll have a little play between the pedal clevis pin and push rod)

#3 nicklouse

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Posted 01 January 2021 - 07:55 PM

Look for a damp clevis pin on the pedal box.



#4 Spider

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Posted 01 January 2021 - 08:11 PM

Pull back the boot on the slave and have a look in there.

 

Usually though, when one goes, the other isn't far behind. Replace them both now and then you only need bleed them through once. Be a good idea to replace the hose while you are at it.



#5 cal844

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Posted 01 January 2021 - 08:13 PM

Pull back the boot on the slave and have a look in there.

Usually though, when one goes, the other isn't far behind. Replace them both now and then you only need bleed them through once. Be a good idea to replace the hose while you are at it.


I agree with this

#6 bpirie1000

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Posted 01 January 2021 - 08:28 PM

Check the fluid condition as well...

#7 MiniMadRacer

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Posted 02 January 2021 - 08:36 AM

Yes due to brake fluid being hydroscopic - think thats the right word - it absorbs water and causes rust in the components, so as said if ones gone the other wont be far behind, so change both, and make sure you change fluid at least every two years to combat the water absorption of the fluid..same principle applies to the brakes and its fluid.. water in it kills those rear wheel cylinders



#8 4V8s

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Posted 02 January 2021 - 02:51 PM

Great, thanks all top tips.

 

I think you're right, for what they cost I may as well replace both and the pipe but I will do a couple of simple checks first as suggested for the signs of damp as I think the slave is easier to change than the master? although I remember doing on on my previous mini back in 1998 and i seem to remember it was a fiddly job

 

thanks



#9 MiniMadRacer

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Posted 02 January 2021 - 07:03 PM

Only pain doing the master cylinder is the clevis pin removal at the pedal end.. if its not new.. when replacing the master cylinder buy a new clevis pin too as they wear.... and soak the nuts under the bonnet for days before trying to undo them.. if you break one its a pedal box out job... so gently does it...



#10 bpirie1000

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Posted 05 January 2021 - 02:25 PM

Be ready to learn new swear words you did not even know that existed.

Never mind coming your own mouth...




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