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Upside down slave cylinder and 9.5mm throw


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Hi All,

After restoration, I found my clutch engages the instant the clutch pedal is raised from the floor and the rebuilt gearbox is stiff, especially in 1st and 2nd. This makes the car tiring and unpleasant to drive.

I was told the push rod was in the top hole because the clutch dragged in the centre hole. I can also see that the clutch slave cylinder is upside down and I measured the throw of the push rod at 9.5mm instead of the required 16mm.

Has anyone else had an upside down slave cylinder and did it cause reduced throw, presumably from incomplete bleeding? I am just surprised that it can make such a difference.

Is there anything else in my set up that looks wrong?

I know the engine to gearbox bolts are all the wrong way round as they point forwards instead of backwards but I can't believe that will make any difference.

Grateful for your experiences.

Regards

Les

Clutch slave upside down.JPG

Push rod in top hole.JPG

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29 minutes ago, JochemsTR said:

Les, turn the slave so the bleed nipple is on top. Re-do bleeding and put the rod in the middle hole. Post your results incl. throw. Than we can debate again.

But as you have it, is not as it intended to be.

Jochem

+1 Bruce

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Hi All,

Hoping to crawl under the car tomorrow and rotate slave cylinder and bleed. I'll also move the push rod to the centre hole. I no longer find it easy or comfortable to lay on the floor and work under the car but this has now come to the top of the list and has to be done as the car is so uncomfortable to drive. I'll let you know how I get on, I just hope it cures all the problems. A new master cylinder has been fitted and I don't think I have much play in the clevis pins. The irony is I had 40 years without any clutch problems except a couple of broken taper pins in 1978-80.

Regards

Les

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Before you bleed it, with the pin removed from the operating arm, push the rod all the way back into the cylinder, and tie it there, then bleed, its a way to get all the air out of the cylinder.

Then reconnect the rod to the middle hole.

John

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1 hour ago, John L said:

Before you bleed it, with the pin removed from the operating arm, push the rod all the way back into the cylinder, and tie it there, then bleed, its a way to get all the air out of the cylinder.

Then reconnect the rod to the middle hole.

John

Should be no need to do that 

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Help! I have turned the slave cylinder the right way up but it is now defying the laws of physics.

I have been bleeding it with my wife working the clutch pedal and I get fluid out the bleed nipple with no air bubbles, but when I close the bleed nipple and press the clutch there is absolutely no movement at all of the push rod and there doesn't appear to be any fluid leaking anywhere.

I will try John's suggestion and tie the push rod back.

Anyone else got any ideas?

I have never had any problems bleeding brakes in the past so don't understand why this is proving so difficult.

Grateful for any further advice.

 

Regards

Les

 

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John's idea is correct but bleeding the clutch can indeed be a little tricky.

I use a vacuum pump. This is more convenient as the 2 person option is.

Secondly, when bled, do not worry straight away. Press the pedal, hold it with a block of wood for about 24 hours.

Jochem

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There is a spring inside the slave, so you may need a bit more of a push.  You could try and slacken the slave mounting bolts a bit, could be causing the piston to be nipped inside possibly?

If you take off the rubber boot of the slave, how far out is the piston inside.

Could you give us the part number you ordered and from where?

John

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Hi John,

Ok many thanks I'll try that.

The slave cylinder was fitted by the company that restored my car but it is not new. The rubber dust cap is worn and the push rod looks corroded and has been painted silver. I doubt it came from my car originally so is of unknown origin.

I'll go and measure where the piston is and report back.

Thanks for your help.

Les

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Les,  At this stage I think its worth taking it off and on the bench you may be able to tap the piston back in, and then use some cleaning solution to see what the bore of the cylinder is like, but looks as if you may need a new one....

John

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Ok thanks for the thought Neil.

Well John the mystery deepens. I removed the push rod and it looked longer than I remember.

I had an original British Leyland 138572 still in its original packet and yes, the one fitted to my car is 2cm longer than it should be (see below.

I am now thinking the wrong slave cylinder may have been fitted to my car and I would feel a lot happier with a new one.

Thanks for all your guidance and help

Les

 

Push rods.JPG

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Slightly off piste..

Having just changed the clutch fluid , bleed nipple on top, push rod in centre hole,.

The clutch is very heavy, more so than it has been.

I used DOT 4 Brake and Clutch Fluid. last changed about 4000 miles ago and a pressurised bleeder.

Was the old fluid just past its best ?

 

Phil

 

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Les, with the longer rod and the top hole it should disengage the clutch and more.

If you press the pedal down now with the rod in the middle, how far out is the piston in the slave, has it reached the end?

I'm sure my slave is mounted on the gearbox side not the engine, this maybe because of the stroke of the slave.

How much free play do you have in the push rod on the master cylinder, before the pedal does something, this will reduce the available movement at the slave.

John

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Hi All,

A stupid question maybe, but I'm getting paranoid about my slave cylinder. The bracket it bolts to 136353 is described as 'bracket slave cylinder to gearbox'.

Should this bracket be bolted to the engine side or the gearbox side of the bellhousing? Mine is on the engine side (see original pictures).

I am just thinking that if I put in a push rod that is 20mm shorter, the piston will come very close to the end of the slave cylinder.

If the piston is down the bore by 44mm now it will only be 24mm down the bore with a shorter push rod and if it moves by 16mm then the piston comes within 8mm of the end of the bore. Does that sound right?

Regards

Les

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Hi John,

Our posts crossed.  I couldn't get the piston to move at all even after repeated bleeding. I can't push it back either. I don't get any resistance at the pedal.

It would be great if you could confirm whether your slave cylinder bracket is on the engine or gearbox side.

If mine is wrong I'm surprised some the eagle eyed forumites didn't spot it on my origianl post.

Regards

Les

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You say a new master cylinder has been fitted.   Some of us have discovered that our repro master cyls come with a pushrod that is wrong length, too short.  Wasted hours and hours of my time cos I was looking at the slave.  You might be unlucky also. Search this forum for details.  Good luck. 

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