A new problem deserves a new thread and I will try to keep it concise! After a sticky clutch pedal problem lately, I drained the clutch fluid and attempted to refill and bleed it. It seemed impossible to get any kind of return pressure on the pedal no matter how careful I was with the bleeding or how much fluid I wasted. The pedal just flipped from fully up to fully down i.e. just working off the spring pressure in the pedal assembly.

All along I have been able to get rock hard pressure on the downstroke of the pedal and the system is properly bled AFAIK. But the upstroke of the pedal simply draws fluid out of the master cylinder and does not pull the slave cylinder rod back in. Once I had bled it perfectly, tightened the nipples and given it two or three up and down strokes of the pedal, it blew the slave cylinder piston out, wedging it hard against the clutch release lever, and thereby wrecking the bore of the slave cylinder. To all intents and purposes, it's as if I've got a 'ratchet' system that only works one way!

The downstroke pressurises the slave cylinder perfectly, giving either an outward push of the piston, or a nice clear bleed of fluid from the nipple if it's open. But the upstroke of the pedal does nothing but draw fluid from the master reservoir. The rod does not withdraw back into the slave cylinder, although with the pedal up, it can then be pushed in at least. I replaced both the cylinders and it's exactly the same.

All I can think of is that it's the pipework at fault? Some kind of debris in there that is working like a one-way valve? I really really need help on this as it's driving me crazy. Bleeding a clutch shouldn't need two replacement cylinders, two litres of brake fluid and two days' labour!

 

Should I try taking the plumbing off the car all in one piece and trying to clean it out under pressure?

 

You have to remove the slave cylinder from the gearbox. Lift it as high as possible and put it in a clamp, then bleed the cylinder. This is described in the servicemanual, it is necessary to relieve all the air from the system.

You also need a brake bleeder with a one-way valve if don't have any assistance.

 

Sounds like the slave cylinder flexy pipe has collapsed internally causing the problem... with what you have said in this post.

Russ.

 

have you adjusted the pedal rod by any chance?

 

hmhaga - did all that. I had it clamped in right up to the end and lifted high, just as everyone says. There was no more air that I could find, and with the slave clamped, the nipple shut tight and the pedal at the top, you could not press it down at all - it was rock solid. I did have assistance so no problems there.

thedrill - thanks for your help on this one Russ. I've had the whole plumbing run off the car, blasted it out both ways with brake cleaner and blown air through it with a bike pump. Seems to flow OK so I'm about to stick it back on the car now and see what happens. If it doesn't work, I'll either get a replacement plumbing run from a scrappy or just get a Goodridge steel braided hose made up. Anyone know the thread on the end where it goes into the master cylinder?

scoobyboy - already done. First lengthened it and it made no difference, then put it back and it made no difference. There is just nothing at all pushing back at the pedal even with the system bled. Which brings me onto my last point:

Why exactly SHOULD there be any return pressure on the pedal, even when it's bled? Let's assume that between the master and slave you've got a perfect hydraulic system with no air in it...push the master in and the slave pushes out; pull the master back and the slave pulls back in as well. There is no connection between the slave rod and the clutch release lever really and the lever exerts no pressure on the slave rod. All there is at that end is a weak spring inside the slave cylinder, pushing it gently outwards. At the master cylinder end, you've got a slightly stronger spring behind the piston, pushing it outwards. So the net force I suppose is slightly in favour of returning the pedal upwards. Then on the pedal itself there is a single spring that basically keeps the pedal on the floor or at the top....so someone explain to me - why exactly should the pedal EVER come back? There's no reason for it to, that I can see.

 

It might have something to do with the 1000kg diaphragm spring on the clutch cover. That pushes back the slave rod until the pedal is past the point at which the helper spring becomes a lifter spring and keeps the pedal firmly at the top of the travel.

 

At last! I'm sure I've been asking and asking this for a week now, with no real definite answer - it seemed bloody odd to me that the clutch release lever exerted no pressure on the slave cylinder rod.

So basically, this whole time the hydraulic system was perfectly fine and it's definitely a problem with the diaphragm spring in the clutch assembly. So the big question is then: is there any way of fixing this without having to actually get into the gearbox?

And weirdly, my clutch has been working for the last few weeks since I replaced the release lever spring and I am CERTAIN that the release lever was waggling around free then; there was definitely no spring pressure on it from within the clutch. So how did that happen?

When I looked closer at it this time, it was clear that the release lever's pivot shaft had partially worked its way out, helped by the fact that the plug in the side of the gearbox was missing. Is it possible to fix this problem by just waggling the pivot shaft around and trying to locate it?

 

Hmmmm. I think you are missing the point here.

In the first instance, the clutch system wasn't properly bled, this you have fixed. However, the whole cluch system ONLY works when fully installed in the car. The diaphragh spring IS the clamping force that clamps the clutch together when engaged. It exerts a force of around 1000kg, if it was broken your car would have no drive.

You need to do the following.

1. Remove the starter, push the pivot pin back in, put in a new plug.
2. Refit the clutch hydraulic system, properly bled.
3. Refit the starter, and make sure to fit the tension spring to the top of the fork.

Presto, your clutch will work.

 

Thanks for the help on this btw... but there's something that still just doesn't make sense here and usually I can get my head around pretty much anything.

My understanding of the system WHEN PROPERLY WORKING is below, please correct me if I am wrong on anything, I really want to learn this or I'm going to lose my mind:

1. The clutch is normally engaged.
2. By pressing the pedal, pressure is transferred from the master cylinder to the slave and pushes the rod outwards.
3. The rod pushes on the release lever, helped by the spring.
4. The release lever pulls the release bearing backwards, against the clutch plate's spring pressure, to disengage the flywheel and clutch plate.
5. By lifting the pedal, you allow the pressure transmitted through the release lever to push the slave cylinder rod back in and thus the clutch re-engages.

I still can't see how the system can work without any backward force being exerted on the slave cylinder rod by the release lever. Sorry if I'm being thick, but I really can't understand that at all!

Apart from pushing the pivot pin back in and plugging it (and it had definitely been loose like that for at least 2 or 3 weeks whilst driving around), I have done everything else on your list. The system as it is now, in its fully bled and fitted state, is no different to the dozens of other times I've fully bled it over the last week. Push the pedal down and it stays on the floor and the slave rod pops out. Pull the pedal up and the slave rod stays put but can be pushed back in manually. I thought it was pressure from the release lever on the slave rod that is what you feel when the clutch pedal pushes back at you in normal driving? Am I wrong about that? Just by pushing the pivot pin in and and plugging it, will the release arm suddenly start pushing back on the slave rod?

I had it fully installed in the car, with the pivot shaft in far enough to give a good back and forth action on the release arm. But there was no way it was going to work at all. All that happened was that yoiu press the clutch once and the slave rod gets into position against the release lever. Pull the pedal up and press it down again and the rod pushes the release lever further. Push it a third time and the rod wedges so hard against the release lever that it jams and the slave piston busts open, pissing brake fluid everywhere. There is nothing to make the slave cylinder rod return at all, thus the system simply cannot work?!

Unless there is something special that will happen when I push the pivot shaft back in further?

 

the clutch pressure plate spring pushes back against the slave cylinder..

are you sure the release bearing is engaged in the pressure plate?

My pedal did exactly the same recently when I fitted my new engine.. the release bearing had not engaged.. removed the slave cylinder and pushed the release fork until it engaged in the pressure plate and it worked perfectly again.

Why did you remove the pivot pin? I thought you just bleed the clutch?

Simon

 

If the clutch fork is properly fitted, and the slave cylinder is fitted in place it is not possible for the slave rod to pop out.
Sounds like the two fingers of the fork are not behind the release bearing. You need to pull the pivot pin, position the release bearing in the correct orientation, hook the fork behind it and refit the pin. IT IS A PULL CLUTCH so it will not "just work", it has to be assembled properly! When it is properly assembled, the clutch itself is what returns the clutch fork, pretty much as you decscribe.

Do a search for a DIY clutch change thread for a detailed description and or pictures, there should be a few examples about.

 

No Simon, I'm not really sure that the release bearing IS engaged. Problem is, having never meddled with it before it was knackered, and having always been used to cable operated clutches before, I don't know what's right and what's wrong...

Which way should I push the release fork? Forwards or backwards? And will I know once it's properly engaged because it will then be exerting spring pressure back against the slave rod?

I didn't remove the pivot pin at all. When I started delving around down there I noticed that the release arm was wobbling about all over the shop and then saw the pivot shaft was sticking out the side of the gearbox by about a cm. The plug was missing. I pushed the shaft back in but it doesn't go all the way - only in by a few mm - which makes me think perhaps it needs to be turned to locate it at the opposite end or something? Bearing in mind I've not taken the starter motor off yet...is that as simple as it looks by the way?

 

So Paul, what you're saying is that because the rod has popped out twice it must mean that the clutch fork is NOT properly fitted. Whilst waggling the release lever back and forth, it does feel like there's some kind of light mass there, and a few clicky noises, but nothing that feels like a positive connection to the clutch - it's more like a wooden spoon stirring a bowl of porridge LOL. Which is weird because before I starting working on it, the clutch WAS working, and I've definitely not had the pivot shaft out, because the starter is still in the way and it would be physically impossible. The strategy that you describe to realign everything - is this possible without separating the gearbox from the engine, i.e. just by removing the starter motor and the boot of the release lever? Or is it definitely a gearbox off job?

 

If the pivot was partially out, there may have been enough play to cause the fork to slip off one "ear" of the release bearing. Remove the rubber boot from the clutch fork and you should be able to see a little more clearly.

Paul

 

Could be. That might explain why the clutch still worked OK but just felt reluctant to return - before I somehow totally knackered it that is.

I took the rubber boot off but I can't get my head and my lamp round the right way to properly see inside. I've got workshop manual pictures of the assembly, but is there anywhere where I can find a good close-up photo of the 'box showing the release lever coming through from the top right, the pivot shaft going through and the bearing/release lever connection? If it is hanging on by only one of the bearing tabs, IS it possible to fix from outside the gearbox?

 

Just another quick point; I'm about to replace the whole hydraulic plumbing assembly with a single short run of Goodridge steel-braided clutch hose with a banjo on one end to fit the slave and a male concave fitting at the other to fit the master. I really had this in mind simply to rule out the plumbing as a problem area. I often get two problems happening at once that confuse the diagnosis of a fault, and taking the definite clutch fault out of the equation for a minute, it still seems weird to me that the hydraulic system still acts 'one way' when disconnected from the clutch. Surely it should be a kind of see saw effect or like when you connect two syringes with a piece of rubber pipe - press one end and the other pops out, and vice versa. At the moment, the pedal/master/plumbing/slave system doesn't work like this. You press the master end and the slave pops out instantly. Press the slave end and the master doesn't move, then if you let go of the slave it pops back out again. That's not right, surely?

Am I wasting my time replacing the run of hydraulic plumbing? Is this kind of operation, independent of the clutch itself, correct? Is the net overall force of the small springs in the pedal and the cylinders biased towards keeping the pedal down and the slave rod pushed out?

 

If the pivot shaft has fallen out, and you cant get it fully home again, i think it can only be the release bearing engagement on the pi$$, or as Paul says, its dropped off one of the tabs.

Whatever hydraulic/actuation issues you may or may not have, you wont get engagement back without taking the box off, and putting the plate/bearing/fork asembly together correctly.

Seems to me that should be the first thing to do now.

 

Sounds sensible. Get the clutch engagament sorted first, then the hydraulics. Well, the pivot shaft's never been out yet, only protruding a little, so I'll take the plunge tonight and pull it out to see if I can get everything manouvered around without having to take the gearbox off. If it comes to it, which is easier - pulling the engine off the gearbox, or vice versa? I.e. which one stays put? And IS it possible at all to realign everything just by waggling the release lever and pivot shaft around? Or should I save myself the grief and try and get a garage to come along and take it off my hands? Is the starter motor hole any help in realigning everything?

 

If the release bearing is not engaged on the tabs, no amount of wiggling will sort it out, you will have to take it off.

Some people prefer to take the engine out, but the gearbox is quicker. If you are lying on your back under the car its just heavy and awkward.

Taking the starter motor off (dead easy) will perhaps let you feel a bit more whats going on with the pivot shaft. There is a M6 tapped hole in the end of the shaft you can screw a bolt in which will help as well if you are 'waggling'

 

no if the releae bearing is over the lay shaft and in the release fork, if you remove the slave cylinder (two bolts) you can engage it by pushing the fork towards the bulk head, assuming all is lined up and correct.. no need to remove engine or gearbox to do that.. But if you have not messed with that then it is unlikely to have become unengaged from it as you really need a screwdriver to either ping the tabs through or remove the release circlip depending on which type it has fitted.. most likely the release fork has jumped out of the release bearing.. get a torch and look throug hthe inspection holes.

Simon

 

Starter motor's now off. I'll have a go at waggling the shaft and see what I can do. So question no.1 - am I going to wreck it by fully withdrawing the pivot shaft? And no.2 - how long should it take to remove the gearbox, fix the problem (or possibly change the clutch) and put it all back together again? I'd do it myself but I dread knackering things even further, and at the moment, the car's stuck in my garage, there's not much room to work and it's not up on ramps. In other words, if I end up ringing someone local to take it away and fix it, how much labour are we talking about? 4 or 5 hours? Is it a DIY job really? Removing the entire clutch hydraulic system is about the most complicated task I've done so far but I've done other jobs like replacing gearbox switches, fitting an oil catch tank, changing all the filters, plugs and fuel pump etc...

 

You do not need to remove the box to get the fork back into the release bearing. About 50% of the time I refit an engine, the release bearing remains on the clutch and we put the fork in the bearing after the engine is in place.

Before anything is done, remove the fork boot and look inside with a torch to see what is happening.

 

OK latest update:
Can't see much inside the starter motor hole, apart from the edge of the clutch assembly which I was expecting.

By rotating the pivot shaft and keeping the pressure on it, it suddenly pushed home nice and solid - presumably it's notched on the other end or something?

Release lever could be toggled FULLY back and forth in its opening at first. Couldn't see much down the release lever hole on the 'front' of the release lever, it just seems to be a load of complex bits. On the 'rear' side of the release lever, at first I could clearly see the release bearing sliding back and forth along the input shaft (is this the right word?), and the lever would go to a fully upright position, tight up against the front of the lever opening. After a bit of waggling and some clicky noises from within, I got it so it stopped half way and would only move backwards towards the slave cylinder and not any further forward.

There seems to be no spring pressure on the lever at rest, but am I right in thinking that the front half of the lever travel that I had before - where it went vertical and I could see the bearing - was what SHOULDN'T have been possible? In which case, everything's now in place (please!!!), and only the slave rod will now be strong enough to push the lever any further, disengaging the clutch? The end could be in sight!!!

 

Sounds like you have made progress. Do make sure the clutch fork has both fingers engaged in the release bearing.

When properly fitted, there should be around 8mm of movement of the release bearing in the clutch cover, it should be free play, but is the bearing sliding into the "locked" position.

 

YES!!! All done. Or at least I think it is, I've just taken it for a run and it's fine. AFAIK both the fingers of the lever are engaged - at least, the pivot shaft is rock solid and locked in, and the lever can only move back and forth in one plane - no more 'stirring porridge' effect. I can't tell how much the release bearing is moving but the clutch now engages and disengages cleanly so it must be ok.

All it needed in the end was another quick bleed and it was spot on. Thanks to everyone who helped out!

 

Glad you got it sorted, I presume you are using my old units?

P.S The leads arrived quick and are fitted..cheers.

 

That's right, they're doing sterling service on my wagon now. Glad that my old leads are working out for you.

 

Nice one. thank **** you did not take my advice and take the box off. I could not see how you could do it but quite happy to be proven wrong. Moral of the story is listen to Zen performance who has done loads and not me who has done a couple

 

LOL luckily getting the box off was well beyond me, but I'm a cheapskate and I was willing to try and do whatever I could myself to avoid having to pay someone else to fix it!

Sooooo glad to have it back on the road again and not have to rely on my wife giving me lifts to work.