clutch & slave cylinders!
Discussion
The Master cylinder is connected to your clutch pedal. when you depress the clutch pedal, it pushes a rod in the Master cylinder which forces the fluid down the pipe to the slave cylinder. The slave cylinder then 'obeys' the instruction (ie the fluid being pushed into it), because fluid can't compress, it pushes the piston in the slave cylinder out of its little housing, this pushes against the the fingers of the clutch plate, which disengages the drive from the engine to the gearbox.
The whole process above relies on the fact that clutch fluid does not compress. So even though the medium transmitting the presuure from the clutch pedal to the clutch plate is a fluid, becuase clutch fluid can't compressed the effect is like a steel bar linking the master to the Slave, but if air gets into the system, air can be compressed compressed, so that steel bar now turns into a squishy rubber bar, it doesent force the Slave cylinder out fully, so the clutch wont disengage properly and its hard to select gears.
Bleed the system by topping up the Master cylinder, get someone to press the clutch pedal while you slacken off the bleed nipple, and keep repeating till all the air is expelled.
PS I've written this at 1 in the morning it's taken me 45 mins, I'm at my Mum and Dads, just had a great evening big meal, numerous bottles of wine, etc etc - so what I've written could be absolute nonsense
The whole process above relies on the fact that clutch fluid does not compress. So even though the medium transmitting the presuure from the clutch pedal to the clutch plate is a fluid, becuase clutch fluid can't compressed the effect is like a steel bar linking the master to the Slave, but if air gets into the system, air can be compressed compressed, so that steel bar now turns into a squishy rubber bar, it doesent force the Slave cylinder out fully, so the clutch wont disengage properly and its hard to select gears.
Bleed the system by topping up the Master cylinder, get someone to press the clutch pedal while you slacken off the bleed nipple, and keep repeating till all the air is expelled.
PS I've written this at 1 in the morning it's taken me 45 mins, I'm at my Mum and Dads, just had a great evening big meal, numerous bottles of wine, etc etc - so what I've written could be absolute nonsense
Friggin hell, up at 6.00!! who said its peaceful in the country! Chickens making chicken noises, pigeons coo-cooing to each other right outside my bleedin window, cows mooing - give me nice quiet city life any day!!
Anyway...the bleed nipple is found on the drivers side of the engine. Up near the bulkhead you will see a Goodridge S/S type braided hose, you've probably seen it already and wondered "what the f*** is that?" well now you know, it's for bleeding the clutch. The master cylinder - just in case you don't know - is under that cover in the engine bay on the drivers side inner wing, remove 2 the self tappers and prise all the sealant away. When you replace it make sure you use sealant otherwise when it rains the car will leak!.
Handbook Reccomended clutch fluid is Dot 4, but if your flushing it all through, 5.1 is better.
Off to buy a shotgun now....
Anyway...the bleed nipple is found on the drivers side of the engine. Up near the bulkhead you will see a Goodridge S/S type braided hose, you've probably seen it already and wondered "what the f*** is that?" well now you know, it's for bleeding the clutch
. The master cylinder - just in case you don't know - is under that cover in the engine bay on the drivers side inner wing, remove 2 the self tappers and prise all the sealant away. When you replace it make sure you use sealant otherwise when it rains the car will leak!.Handbook Reccomended clutch fluid is Dot 4, but if your flushing it all through, 5.1 is better.
Off to buy a shotgun now....
Look out for difficulty getting gears in the morning. Gets better once the car has heated up.
Look out for brown bits in the fluid. All point to the seals on their way out.
Just about to pick mine up today cause I had the same problem. Its now got lovely new seals all round - and guess what - the suns shining.
Oh happy day !!
Look out for brown bits in the fluid. All point to the seals on their way out.
Just about to pick mine up today cause I had the same problem. Its now got lovely new seals all round - and guess what - the suns shining.
Oh happy day !!
mxi933 said:
Look out for difficulty getting gears in the morning. Gets better once the car has heated up.
Can I ask what if it works the other way around means? I.e. Difficulty in engaging/releasing gears when the engine is hot, after about 1-hour's use. Gear selection perfect when cold though.
Is this too a symptom of suspect seals?
cerbielee said:
Thanks for the info chaps! is there a set procedure for bleeding? and the stainless braided hose!"is that for bleeding the master or slave cylinder?"
And jesus jensena! how the hell did you get up at 6am???
i was still
I bought one of those Eazibleed kits. Much easier to use. Make sure you suck out the old fluid - no point in bleeding the old stuff out. Let the air out of the tyre you are going to use. Down to about 5 PSI. If you dont there will be too much pressure and you wont get a seal with the kit. Connect up. Screw the Easzibleed lid to the Reservoir and slowly open up the bleed nipple. The kit forces new fluid through the system. Job done!And jesus jensena! how the hell did you get up at 6am???
i was stillThe problems with the slave cylinder are:
Crap seals: They absorb the clutch fluid and degrade with time, this causes them to soften and expand.
Fluid over heat: Possibly aided by the rubbish seals, the fluid ends up with lots of moisture in it, when it then gets hot (sat over the exhaust and being deep within the bell housing) the moisture boils and creates gas, this gas then compresses and gives you a spongy pedal.
Seal Failure: Combined with the heat and the seals being rubbish in general when they get really hot they can shift and or fail altogether.
They do warn you first, as you've seen. They'll play up when the cars hot, there'll be bits of black "stuff" in the master cylinder. If you do have this seriously think about getting a seal kit fitted.
When that is done, make sure you ask the guy fitting the seals to check the slave cylinder bores, the tolerance on the parts is pretty rubbish. The pistons can run out of alignment and cause damage to the bores. However ensure that it is damaged in the areas that the seals work as like I found on mine it was scored but not in the areas that mattered so it was good to reuse. Also the lead-in of some of the machined surfaces and also the oil in/out drillings are not very good. These need to be taken back with a fine file and 1200 grit paper to ensure that you don't "nick" the seals when refitting.
Also ensure that the holes are fitted in the 12 and 6 o'clock positions.
Finally, make sure you get 4 new slave cylinder retaining screws, these are a bugger to get out and it's easier just to drill the heads off and replace them, use a small amount of Loctite thread lock when refitting or they will rattle loose and you'll have to take it all apart again.
Hope that helps.
Crap seals: They absorb the clutch fluid and degrade with time, this causes them to soften and expand.
Fluid over heat: Possibly aided by the rubbish seals, the fluid ends up with lots of moisture in it, when it then gets hot (sat over the exhaust and being deep within the bell housing) the moisture boils and creates gas, this gas then compresses and gives you a spongy pedal.
Seal Failure: Combined with the heat and the seals being rubbish in general when they get really hot they can shift and or fail altogether.
They do warn you first, as you've seen. They'll play up when the cars hot, there'll be bits of black "stuff" in the master cylinder. If you do have this seriously think about getting a seal kit fitted.
When that is done, make sure you ask the guy fitting the seals to check the slave cylinder bores, the tolerance on the parts is pretty rubbish. The pistons can run out of alignment and cause damage to the bores. However ensure that it is damaged in the areas that the seals work as like I found on mine it was scored but not in the areas that mattered so it was good to reuse. Also the lead-in of some of the machined surfaces and also the oil in/out drillings are not very good. These need to be taken back with a fine file and 1200 grit paper to ensure that you don't "nick" the seals when refitting.
Also ensure that the holes are fitted in the 12 and 6 o'clock positions.
Finally, make sure you get 4 new slave cylinder retaining screws, these are a bugger to get out and it's easier just to drill the heads off and replace them, use a small amount of Loctite thread lock when refitting or they will rattle loose and you'll have to take it all apart again.
Hope that helps.
Thanks for all the info chaps! not having any difficaulty selecting gears (hot or cold) just had a new clutch fitted and noticed that after a good run out and getting stuck in traffic that the bite point seemed a little higher! but its still the same after it cooled down??? just thought putting better fluid in would be beneficial!
jayzee said:
Can I ask what if it works the other way around means?
I.e. Difficulty in engaging/releasing gears when the engine is hot, after about 1-hour's use. Gear selection perfect when cold though.
Is this too a symptom of suspect seals?
Thats probably down to the clutch expanding when it gets hot. Your clutch pedal may need adjusting.I.e. Difficulty in engaging/releasing gears when the engine is hot, after about 1-hour's use. Gear selection perfect when cold though.
Is this too a symptom of suspect seals?
Edited by cerbymad on Monday 9th July 17:36
Edited by cerbymad on Monday 9th July 17:37
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