Clutch Hydraulics

[BDN712V]

After rebuilding the master and slave cylinders, AND bleeding several times, the performance of the clutch is variable to say the least! Occasionally it is fine, but the rest of the time it behaves as though there is air in the system. If I put the clutch in / out EXTREMELY slowly it behaves better than if driven normally. The level of fluid has remained constant, and my only thought is that air is somehow leaking INTO the system (not sure how...)<br>
<br>
Does anyone have any thoughts as to how to cure it / what the problem is!<br>
<br>
Cheers,<br>
Tim

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[alun n]

Sounds like expansion of the flexipipe; when you ease the clutch in its insufficiently violent to cause the flexi to initiate expansion?

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[BDN712V]

Looked for swelling when the clutch was depressed, but if it is this, why does it change over time? Surely it will get worse and worse (been there before...).<br>
<br>
When I pump the clutch air bubbles rise in the master cylinder reservoir, despite having bled several times and removed all the air (I thought).<br>
<br>
??? somewhat puzzled ???<br>
<br>
Tim

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[Carl]

Does the clutch get worse after you've been driving for a while ? Maybe heat from the engine softens the pipe. I use the pipe from a Midget 1500 which is the hard, red plastic type. You can also get them made up in braided stainless steel. Might be worth the change.

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[Jon Tilson]

point to a failed recuperating seal...the little one at the end of the spring loaded pluger at the end of the piston. Ive had a few of these fail fairly soon after doing rebuilds.....<br>
check the end of the master cylinder bore...the surface there must be smooth..<br>
To check the integrity of the flexi pipe...take off the slave and make sure the piston cant come out the end, then pump it and it should go rock solid....like as hard as a brake pedal.<br>
<br>
If it doesnt then it should be obvious why. Lots of previous threads on this too...<br>
<br>
Jonners

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[BDN712V]

Will give it a go tomorrow afternoon - have another load of seals and a spare master cylinder (minus spring).<br>
<br>
Tim

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[BDN712V]

Hydraulics seem to be sorted. It was that little seal that had failed, but htere was also a score that I'd somehwo missed. Think it must have been caused by the spring when it broke.<br>
<br>
BUT (there's always a but...) after bleeding once again, there doesn't seem to be enough travel in the slave cylinder piston, so putting it into gear with the clutch down and there's a crunch and it goes off without having to let it up. <br>
<br>
WHY???!<br>
<br>
Tim

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[Richard the old one]

You have not stated what model you are working on.<br>
<br>
I only have experience with the 1500cc and a problem I have come across is the clutch fulcrum pin falling out and this causes the problem you are indicating. I did not find the problem until I had to replace the clutch as I found that the clutch would operate if I pushed the slave cylinder fully forward before I tightened up the locking nut and bolt. <br>
<br>


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[BDN712V]

1500HL.<br>
<br>
So if it's the fulcrum pin I would need to separate the engine and gearbox to get at it...<br>
<br>
Oh.<br>
<br>
Anything else I could do to be certain it is this?<br>
<br>
Tim

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[Jon Tilson]

the other cause may well be a lot less pleasant. This engine is very prone to thrust washer wear. Can u feel any play at the front pulley? I recently was sold a Spit and the owner had suspected the clucth fulcrum pin....but it was the thrust washers. Hope not cos the cheapest cure is a new engine...<br>
The isnt much scope for moving the slave cylinder in...only a few mm....will it pump up solid if you restrict the slave piston?<br>
<br>
Jon<br>
<br>


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[BDN712V]

There was NO play in the front pulley when I replaced the oil pump recently - big ends are a different matter! I have all the bits to build up an engine (except a flywheel to suit a midget) but not time... yet.<br>
<br>
Took master and slave cylinders off with the pipe to test integrity after rebuilding, and there were no problems. So it looks like the fulcrum pin unless anyone can suggest any different ailments.<br>
<br>
What's the easiest way of sorting it?<br>
<br>
Cheers,<br>
Tim

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[Jon Tilson]

be able to see the end of the fulcrum pin in the bell housing with some sort of mirror arrangement. It is about 1/4 inch diameter and has a domed end. You may see it from below but I forget wots in the way on a Dolly. If its gone then u may be able to insert a long bolt from the top. If u take off the complete slave mounting, 2 bolts the rod and clucth bearing lever should be visible enough to see if the pin is there and help insert a bolt if required.<br>
I'm afraid I have had a "broken" diaphram on a Midget once that did exactly this too....new clutch cover solved it. That car had been standing a while and the cover was only about 10k miles old too...hence I did everything else first. There was no apparent damage either to the diaphram. I wonder what might have happend if I'd just started it in gear and driven it...maybe the diaphram would have released and sorted itself out... <br>
<br>
Jon<br>


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[BDN712V]

...am ordering a pin, but should I get a clutch cover in case? Don't want to spend the money really!<br>
<br>
The diaphragm spring shouldn't suddenly die, should it?? Admittedly when the return spring inside themaster cylinder broke, the clutch did stay in, and I would have expected it to pop back out again....<br>
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Any further thoughts before I do the deed and order some more new shiny bits for the car??!<br>
<br>
Very greatful,<br>
Tim

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[Richard the old one]

If you are going to obtain a replacement pin I recommend you fit a PART Number %%WORD9%'13 pin as this will not drop out if fitted from above as it has a lip /enlarged end. The original pin was part number 129410 and I have had two of these drop out over the years on two different cars. <br>
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I have been told that an old inlet or exhaust valve is just the right size.<br>
<br>
I also believe that you should be able to replace the pin without removing the bell housing from the engine provided you remove the clutch slave cylinder housing as this will give you some access to move the arm around.<br>
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Please update us as to what you find and how the work goes.<br>
<br>
Richard

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[BDN712V]

Unfortunately the pin is in place (at least top an bottom), so I'm thinking that it sounds like the diaphragm spring of the clutch cover. Which isn't the cheapest part to replace!<br>
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BUMMER!<br>
<br>
Any other suggestions or knowledge of cheap suppliers?<br>
<br>
Cheers,<br>
TIM

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