Hi All,

I've had an issue with the clutch that came up this morning. It was fine yesterday afternoon!

So:
Pedal takes up really low - about 1cm from the bottom and isn't disengaging fully
Fluid level is high and no sign of leaks
We tried bleeding the slave cylinder and bubbles kept coming through the line
The master, slave and rubber line are all ancient, possibly original and I've never touched any of it since I've had the car

Does this point to any particular part being worn out, or should I start taking things off and seeing if there is something obvious?

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Tim
Pull the clutch arm out , may have broken the ball off the end of the arm
check that the hydraulics are working , eg the clutch arm is actually moving

if bubbles keep coming through then there's air getting in somewhere, simple as that. The seal in the master or slave cylinder has failed, if air goes in, fluid is usually coming out

Lift the boot on the slave cylinder, if there's fluid under the boot, then the seal there is gone.

Put your hand up under the dash where the clutch pedal goes up to the master cylinder, you might find that fluid is leaking down there... it creates a lovely corrosive puddle in that cutout in the crossmember

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did I tell you that I won a trophy?

Thanks guys. I'm assuming there shouldn't be mustard under the seal then? I'll be taking that out next, hopefully a new seal kit will sort it out, a new rubber hose is probably a good idea too.


Strange that the fluid level hadn't dropped?

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Tim,
My bet is you have an aftermarket slave cylinder, these don't have a seal spreader in them (unless AP brand) like Lockheed did and they suck air if not in constant use. Or yours is missing.
It sits on the end of the internal spring.
You can't buy this spreader from suppliers but I have machined some from HDPE.
SMS sent.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks for the help! The problem has turned out to be a combination of three things, with the third one being the main cause for yesterday's issue...

1 - Clutch slave cylinder was slowly leaking rusty sludge. The bore and seals look OK and a spreader was present (all made in England). There was a rusty ring on the seal but nothing obviously wrong.


2 - Clutch master cylinder was also leaking a small amount of rusty sludge. As above the seals and bore look OK. There was not a large puddle in the floorpan like when my brake master seals died..


3 - Clutch master cylinder clevis pin was missing . This is why there was a completely free/loose pedal till just near the floor. I assume it's in the floorpan somewhere but I haven't looked yet. The only upside is it made removing the master incredibly easy!

Plan is:
New slave seals
New master seals
New rubber hose
New clevis pin

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go for a new pin on the end of the slave cylinder pushrod too

I'd even look at a new arm

_________________
did I tell you that I won a trophy?

Thanks Simon, I will check that out too.

The R-Clip curse has struck again! I don't know why this one was so big though? No wonder then that it fell off. The seals are branded PBR Australia, so someone has obviously been in here in the past..

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That R clip is massive Tim! I used to use them but have reverted to split pins after hearing a few horror stories about R clips getting dislodged by the action of the pedal against the pedal box. Inconvenient for clutch but potentially disastrous for braking...

I just use good quality clevis pins (with a small hole for split pin not like the cheap ones that have a huge hole bored in them) and a nice short split pin slightly opened out. Squeeze the split pin with some vice grips to pop it in the clevis pin then release the grip and it will stay in place long enough for you to turn it around and spread the ends with a sharp screwdriver. Job done.

I reckon your clutch will be good as new after those few little jobs on your list.

When I changed the brake master last year it had a split pin, and I replaced it with a split pin as I had heard that they could fall out, and you definitely don't want that happening with the brakes! I don't think I even looked at the clutch at that time. I removed the carpet on the weekend and found there was a rusty imprint in the shape of the R-clip on the underlay so it must have been on the floor for some time before the clevis fell out.

I have ordered all the parts now to rebuild both cylinders and all the wear items. The clutch pedal will be back as good as new.

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Next question, I don't remember the master cylinder having a gasket under it when I removed it. Is this necessary? I have got a new gasket in the order today and it's a couple of mm thick.

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It's not necessary, but will look after your paint. I leave them out

If the rest of the system is worn then that extra little bit taken up by the gasket will lose you some pedal travel - though shouldn't be an issue for you.

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did I tell you that I won a trophy?

Thanks Simon, I will go without the gasket

Slave all done


Master done

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Tim looking good. Might want to check the hole for the clevis pin on the bottom of the master cylinder pushrod - it looks a bit flogged out (ovalized). Would be best to address now if you can, as losing even a mm or two there will make for a slack pedal. If you have any other MCs pick the best pushrod to use?

true! another (more work but can have good results) option is to weld and redrill the holes or take the pedal out and redrill the pedal and pushrod to the same size and use an oversize pin which is what I did with mine

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did I tell you that I won a trophy?