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 Clutch won't release properly - hydraulics?
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EdinburghJoe
V4 Beginner

United Kingdom
71 Posts

Posted - 15 Jul 2019 :  18:45:11 Show Profile Reply with Quote
Hi all,

First drive in a couple of weeks - I got to the end of the road and couldn't engage 1st without a crunch. I pumped the clutch a few times and it was good enough to get home without any more problems.

I peeled back the rubber cover so I could see the slave pushrod (where it goes into the clutch housing) and it only started to move when the clutch pedal was about half way through its travel.

I suspected the hydraulics, so I used an easybleed to bleed the system. Once I'd done this I noticed a pool of brake fluid on the mat under the pedals! The clutch itself was just as before - no difference.

So I think my questions are:

1) should the slave pushrod start moving pretty much at the same time as the clutch pedal is pushed?
2) does pool of fluid suggest I need a new set of seals on the master (assuming the actual cylinder itself isn't scored - I had that problem earlier this year on the brakes and had to get it re-sleeved)?

If the answer to both is 'Yes' then I'd hope a new set of seals could cure the problem!

I replaced the clutch at the end of last year (with the generous help of Andy Deans). We set the 'free play' correctly and it has been really smooth and quiet ever since, but in retrospect it has always seemed to require the pedal to be pushed right in to release properly, and it bites very quickly as the pedal is released. I wander if this problem has been a while in the making, and just 'gone critical' now.

Thanks for any pointers,

Joe

Woody
V4 Guru

United Kingdom
2447 Posts

Posted - 16 Jul 2019 :  20:49:30 Show Profile Reply with Quote
The fact you have fluid leaking into the cabin suggests the rubbers have failed. You may just get by with re-rubbering the M/C' They don't like being stood for any length of time. Worth doing the slave cylinder at the same time.
I know I will have to do both on the Troll, but haven't tested them yet.
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andydeans3
V4 Guru

United Kingdom
1215 Posts

Posted - 16 Jul 2019 :  20:59:22 Show Profile Reply with Quote
Joe
The actuating arm should certainly move as soon as you touch the pedal.

Malbrad has both master and slave brake cylinders, though they are not cheap.
You could of course just change the seals, but there's no way of knowing what the wear is like in the two cylinders.

As Woody says, I'd replace both. (either complete cylinders, or seals).
If one has gone, the other is probably on its' way.

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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RhysN
V4 Fanatic

United Kingdom
286 Posts

Posted - 17 Jul 2019 :  06:35:29 Show Profile Send RhysN an AOL message Reply with Quote
Just in case, have you started with the simple possibility first? Check over the line between the master and slave. Sometimes under pressure all you are doing is swelling the flex part.
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EdinburghJoe
V4 Beginner

United Kingdom
71 Posts

Posted - 17 Jul 2019 :  10:19:10 Show Profile Reply with Quote
Thanks for the replies,

From a diagnostic point of view I think the piece of information from Andy is key: if the actuator arm should start to move as soon as the clutch pedal gets pressed and mine doesn't then that points strongly to the hydraulics.

I did wander about the flexible pipe as suggested by Rhys. It looks pretty new so I wouldn't suspect it straight away, but how could I tell? Would I see it bulge by eye when the clutch is pressed? Or feel it by hand? Or some other way?

I've ordered master and slave seal kits from John-Saab, so I'll assess the condition of the cylinders themselves when I've got them stripped.

On the subject of which - are they easy to remove from the car? The master looks easy enough, and as for the slave do you just undo the bolt at the back? It does look tricky to get to though, but I'm hoping taking the battery out will help. Any other tips?

Thanks all,

Joe
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andydeans3
V4 Guru

United Kingdom
1215 Posts

Posted - 17 Jul 2019 :  14:30:54 Show Profile Reply with Quote
Joe.
The clutch Master is a bit fiddly, but not necessarily difficult.
Same the slave cylinder. Pay attention as to whether there are any washers/shims behind the slave cylinder.

When you fit it all together again, it can be fiddly getting that screw back into the back of the slave cylinder. Took myself and John N, an age, when we did on my car. At one point we thought we were going to have take the whole caboodle (engine and box), out again, but we got it in the end.
Bleeding can also be fun, because the bleed screw on the slave is below the master. but I think you said that you have an Ezi Bleed kit, that certainly makes things easier.
Some people fit it all up, and bleed it on the bench before fitting, I believe.

If you need a hand, just shout, and I'll come over from the darkest East Neuk of Fife....

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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EdinburghJoe
V4 Beginner

United Kingdom
71 Posts

Posted - 27 Jul 2019 :  21:19:49 Show Profile Reply with Quote
Finally got to look at this a couple of days ago. I stripped the master cylinder and flushed it with meths to get it all clean. The cylinder itself had a small circular scratch about half way down. I ran a pencil over it to guage the precise depth, and it would have sat exactly where the metal head of the piston would lie. Since the seal sits just a little further in than that I thought it would probably be OK.

I used the set of seals bought from from John Saab. I had a couple of puzzles:
1) Haynes says that there should be a convex/concave washer, but the replacement was flat. I couldnt see why it needed to be shaped anyway, so I just used the flat one.
2) the flared end of the bottom seal on mine was pointing down towards the open end of the cylinder. I didnt think that was right, and Haynes was no help, so I put the replacement with the flared end pointing up towards the closed end of the cylinder.

Got it all back together OK, bleeding was easy with the Easybleed, snd it seems to work. The slave cylinder operates after very little free movement of the pedal, and the bite is safely clear of the floor.

I didnt do the slave, but I have the seals ready and might try that if nothing more pressing goes wrong and I have some time on my hands!

Meant to say, I checked the hydraulic cable by holding it tight while someone pumped the pedal for me- there was no bulging.

Thanks all for the advice,

joe.
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RhysN
V4 Fanatic

United Kingdom
286 Posts

Posted - 30 Jul 2019 :  07:13:45 Show Profile Send RhysN an AOL message Reply with Quote
Good result.
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Derek
V4 Guru

United Kingdom
1879 Posts

Posted - 30 Jul 2019 :  12:43:19 Show Profile Reply with Quote
If the washer you are talking about is the one that retains the pushrod and held in place by a circlip, the washer is shaped to match the shaped end of the pushrod. If you put it on the wrong way round it sets the piston in the wrong position, in further, and the piston can cover the fluid return hole to the reservoir. If it is a different washer or MC, please ignore.
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EdinburghJoe
V4 Beginner

United Kingdom
71 Posts

Posted - 05 Aug 2019 :  14:38:05 Show Profile Reply with Quote
Hi Derek,
the washer I meant was between the far end of the piston and the seal. I think its job is to cover the small holes in the piston end.

The original wasnt curved either, so it does seem fine to be flat.

Joe
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Derek
V4 Guru

United Kingdom
1879 Posts

Posted - 06 Aug 2019 :  12:07:55 Show Profile Reply with Quote
The illustration on John's eBay appears to show a non-flat washer, but if you say yours is flat and John's replacement is also flat I'm not sure if either is correct.
https://www.ebay.co.uk/p/Clutch-Master-Cylinder-Kit-Lockheed-SAAB-95-96-99/691763932

I would be tempted to bleed the MC by cracking the connection where the pipe is attached to the top of the pot. That will be messy but might remove the air trapped in the pot. I've seen mention of air being trapped in the inverted U bend of the pipe.
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