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MG Midget and Sprite Technical - Clutch won't disengage

I have decided to start a new thread as I have drifted way off the original topic. The story so far is here:

https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&mode=thread&access=&subject=97&source=T&thread=202602111301411357243

To recap, this is a complete 1275 clutch system on a 948 engine. Roller release bearing which has never given any trouble in 11 years of use. Slave cylinder has a new seal and doesn't leak. Master cylinder is new, only fitted yesterday. I am unable to get the clutch to disengage. I have been experimenting with an adjustable pushrod, and I have just tried an old pushrod which has been shortened even more. But now the slave piston is right at the end of the cylinder. Every time I fit the pushrod I check that I have about 2 mm of free play. Then when I press the pedal a few times the free play disappears. Before fitting the new clutch plate I always consistently had 1-2 mm of play. This never changed. Now all that is different is that I have a new clutch driven plate, and a new master cylinder. The behaviour with the new master cylinder is exactly the same as it was with the old one, after fitting the clutch plate. The slave cylinder seems to be filling up with fluid every time the pedal is pressed, and not going back to where it was before.

I am running out of ideas with this.
Les Rose

Oh dear. The new MC came from MGB Hive but it's a TRW one. I just read the relevant thread and residual pressure is mentioned. That seems to be what I am getting.
Les Rose

Les,
I had a similar problem with the clutch dragging. Like yours the clutch has a roller release bearing (but from Peter May as Alan's weren't available at the time).

It was the slave cylinder.

Usual suspects' slave cylinders partially cured the problem but it would recur when the engine was hot and they failed regularly.

A NOS Lockheed from Paul Hunt finally cured the problem. I believe his supply has exhausted but he may have found an equivalent supplier.
https://powertrackbrakes.co.uk/

I wonder if the new ones are made to metric equivalent dimensions where the difference my just be enough to affect their performance or more likely quality control is absent.
Jeremy MkIII

I haven't studied the 1275 ones, but there is certainly an issue with aftermarket MGB slaves, which give rise to insufficient stroke no matter how well bled. They lack the wide plastic support under the seal, with the spring having an end cap of only 15mm-ishin a 1.25" slave. The seal has a deeper but thinner outer lip. I think what happens is the combination of reduced support and thinner lip allows the seal to deflect and air to bypass it into the cylinder.

Now I confess to not fully reconciling this explanation to the pressure changes as the clutch is operated, but what I do know is that retrieving the spring and support from the old slave and fitting that and an original format seal into the new cylinder solves the problem. Consistently.

I don't have the required operating stroke for the 1275 to hand, but we have one in the workshop at present so I will get the team to do some measurements and report back. I know with the B the figure should be 11mm and that anything less than 10 will cause problems disengaging.

Note that when you fit a new plate disengagement is always closer to the floor because the spring steel to which the linings are riveted is slightly wavy and holds the linings apart a bit when unloaded (presumably to cushion take-up) whereas in worn plates the waviness is usually gone. So it could be that your setup had an underlying issue of not enough stroke that didn't show up until the new plate with the unloaded lining separation was fitted.

Re the pushrod length, the system is quite tolerant to length, unlike those in which an external spring fully retracts the piston and seal after each application (examples: Mini, Jaguar).
Without the return spring (Midget, MGB) the piston goes back only as far as the clutch pushes it, so it self adjusts. If the pushrod is too long it will bottom out in the slave, if too short the piston can protrude or even pop out. So anything between these two extremes should work and allow the piston to sit where the clutch arm pushes it back to.

I have found that some designs of roller bearing have excessive weight which causes the bearing to "nod", pushing the piston back further and so losing the first bit of stroke in making up for that. (Alan specifically addressed the weight issue in his units)
Paul Walbran

Paul
My roller release bearings are a tad under 250gm. Posture in the yoke is assisted if new spring clips are used when fitting.
I have a bearing, manufacturer unknown, that weighs 400gm.

Alan Anstead

I am considering changing to silicone fluid. I already have Goodridge hoses fitted, and as these are PTFE lined will I still need to change them? The Goodridge site is not helpful.
Les Rose

Think it's a question of you 'pays your money so makes your own choice'!
It used to be a straight 'No' when I was considering it but as I was renewing all the braking and clutch systems that didn't matter.
Now it seems permissible if you ensure a thorough flush to get rid of any contaminants and old hydroscopic fluid.
I have Goodridge stainless steel brake hoses and it's worked ok with them - so far🤞
Jeremy MkIII

Have you put the clutch plate in the right way around ?

I didn't on one build and the clutch didn't work ?

Sorry for asking the dumb question, but you seem to have covered all the other bases
Malc Gilliver

Les
I have silicone brake fluid in all three of my cars: the most recent since 2004. I have Goodridge hoses on all three.
Alan Anstead

Yes Malc, I said in the previous thread that the clutch plate was in the right way round.

Jeremy, it's not so much whether I can use silicone with Goodridge hoses, rather that having used DOT 4 will I need to change them before using silicone? I think as they are PTFE lined they will be fine. At £30 each I don't want to change them if it's not necessary.
Les Rose

Les, appreciate that and that's why I said it was permissible (to change from hydroscopic to silicone) so long as you gave the system a thorough flush.
If you're considering using Automec fluid, you can send them a message and ask if it's safe to change. The link is at the bottom right of their webpages.
Jeremy MkIII

Just be aware---as I wasn't

On top of polly bush manufacturers completely stuffing up a perfectly good colouring system for grades of polly bushes to suit their own naming/advertising-

NOW we have brake fluid manufacturers stuffing up brake fluid grades---I've noticed recently Dot3 and Dot4 fully synthetic brake fluid being advertised---How dumb is that---WHY stuff up a system that everyone has got used to----now we'll go in to buy dot4 and tip it in and it'll all turn to crap" mixing it with real dot4.
The world's stuffed-
William Revit

Automec confirmed that PTFE lined hoses will be fine with silicone if fully flushed and dried. So I am about to rep[lace all the seals.
Les Rose

I suppose I should rename this thread (if I could), as progress has been made. The clutch is now disengaged, but won't engage. The rather poor quality photo shows that there is a lot of pushrod showing, as you might expect. But let me get you up to date.

It has been an utter nightmare. First of all, I bought a pressure bleeder, not the Gunson one as my local shop didn't have it, but one that works on the same principle. On testing the device I could not stop it from leaking at the MC end. The rubber seals were just not up to it. After trying various O-rings etc it seemed to be OK, so I filled the system with DOT 4 and tried bleeding the rear brakes. While I was so engaged, the bleeder (an appropriate term) leaked again and pumped fluid all over the pedal box and bulkhead. Three days were spent on scraping off the affected paint and repainting everything.

At this point I decided to change to silicone. New seals were ordered and everything flushed with meths. I thought I should replace the seals in the new TRW MC as they had been exposed very briefly to DOT 4, but on dismantling it I found that the piston seals are not standard. The pistons look like aluminium and the groove for the seal is narrower. The pressure seals I could of course replace.

500 ml of Automec DOT 5 arrived and before using it I had another go at rectifying the leaking bleeder. The main problem seemed to be that the rubber seal in the screw cap supplied was much too thick and stopped it from tightening fully. On testing it seemed to be OK. So back to bleeding the rears. But the damn thing leaked again and pumped £30 worth of DOT 5 onto the garage floor and into the footwell.

Further work was indicated to stop the leak. This required a rubber washer (cut from old inner tube), a steel washer to compress it, and a good wrapping of PTFE tape. It still leaked, but only very slightly so was manageable. Meanwhile more DOT 5 arrived and the bleeding seemed to go OK.

That's where I am now. The slave pushrod length is about 50 mm measured from the eye, which is a lot shorter than standard. On assembly the slave piston was well back and I could easily insert the clevis pin, but now the slave is full of fluid which won't return to the MC. The pedal feels reasonably OK but softer than before. I have about 2 mm of free play at the MC pushrod.

Would lengthening the slave pushrod help? It is adjustable. But I'm worried that the cylinder, which doesn't have a circlip, has its piston very near the end, and with fluid pressure in it as seems to be the case right now, if I remove the pushrod there will be a deluge of fluid again.

The brakes feel OK but the pedal is softer than I expected. I have bled everything twice.


Les Rose

I don't know why the clutch seemed to be disengaged, because now after trying various lengths of the adjustable pushrod it's back to refusing to disengage again. I think I will have to get the engine and gearbox out and see what's going on. On top of all this the slave has been on and off so many times that one of the holes in the gearbox has stripped. This is not much fun at all at my age.
Les Rose

I think I was misled by the diff allowing the opposite rear wheel to rotate when the car was in gear and the clutch pedal released. I am now wondering whether the release fork is bent.
Les Rose

As per my earlier post I have measured the pushrod stroke of a properly operating 1275 clutch: 11mm. Sorry it took so long, car was on stands and buried behind others while its wheels were getting stripped and painted.

Pushrod stroke is the key diagnostic gateway. If your pushrod is moving less than 11mm, the problem is in the hydraulics. If you have 11mm then the problem is in the bellhousing. 10mm can be just enough if the plate isn't new.

On a self adjusting arrangement like the Midget, changing the pushrod length has zero effect, unless it is lengthened so much that with the piston bottomed out in the slave the release bearing is permanently displacing the diaphragm pressure pad. That would reduce the required stroke. For a while. Until the release bearing failed, due to being continually loaded.

Paul Walbran

Les
Picture of a correct 1275 yoke. They often bend at the narrowest point before the clevis. Sometimes they can bend a lot.

Alan Anstead

Yes they can bend a lot !

richard b

Les--just had a rememberance that I'd put out of my mind because it caused me to go bald. Years ago with our elan the clutch stiff at times and was slipping so out she came and new clutch, bolted it all back together and still the same---turned out to be the flex hose going to the slave cyl had deteriorated internally and was working like a valve, sometimes hard to push the pedal and mostly holding the pressure on the clutch enough to make it slip, it'd bleed up ok and fluid appeared to flow but with pressuure on it'd block the flow---If you're running a rubber flex hose--just maybee an issue-???

willy
William Revit

I seem to think/recall a bent fork was dismissed way back in the first thread on all this.

Several of us were keen on this answer at the time, but it was discounted.

Or was that somebody else's cluch disengagement problem?

I've lost track.

It's a good reason imo for not starting multiple threads. Stick to one, so the history and logic can be followed.

Only start anew, when you reach fwb or breather/oil sucking lengths. 🤣🤣...

And even then, under protest. 🤪







anamnesis

Good thought Willy, but my slave is fed by a cunifer pipe.

I don't recall dismissing the bent fork suggestion, but anyway I have the lump out of the car now and the pivot bush is totally worn out. I'd be surprised if that amount of slop would stop it from disengaging, but let's see. The bronze bush is available so it's on order. The fork is not bent at all. I did take the opportunity to check that the plate was the right way round, and it is.

I can now of course assemble the gearbox to the engine and check mechanically that I can disengage the clutch. I was trying to cut corners before by only taking the engine out. The sunshine was beckoning me to get the job done quickly! Well I have got a lot of repainting done, and changed to silicone fluid so that I won't have paint stripped all over again.
Les Rose

I am losing the will to live. Engine is back in, clutch bled and it still won't disengage. It is exactly where it was five weeks ago. This is after replacing the master cylinder, all of the rubber seals everywhere, the release lever bush and pivot, and changing to silicone fluid. The system has been bled with a pressure bleeder, and I have had the car jacked up as far as I can on the offside in case air was getting trapped. No air is coming out now. I have fitted the Peter May remote bleed kit, and can't see any leaks from this. The pedal feels OK, although a little softer as expected with silicone fluid. The slave pushrod is exactly 2 11/16" measured from the eye. The master pushrod has about 2 mm of free play. At rest the release bearing has about 2 mm of clearance from the pressure pad.

I feel I have been working on this pretty much full time for over a month. I have had the engine out twice and it looks as if a third time is on the cards. What more can I do? I didn't replace the pressure plate because it was working perfectly well before, the only problem being a worn driven plate. This is not a matter of the clutch simply dragging, it is showing no sign at all of disengaging. I didn't test it out of the car as I am no longer strong enough to operate the lever.

The sun is out, the hard top is off, and at this rate I am going to miss the shows I am booked into. This is the worst problem I have had in 55 years of Sprite ownership. Sorry for the rant.
Les Rose

Time to 'fess up...
Years ago, following a rebuild, clutch would not disengage. The inspection rubber on the gearbox was removed in situ as my assistant peered in and l operated the clutch pedal...turns out " someone" had put the clutch fork in the wrong way round. How we laughed.
Dave
David Cox

I knew somebody else who did that David! Good idea to look inside. I have an endoscope, and an assistant (sadly not glamorous) is arriving shortly.
Les Rose

I can see with the endoscope that the clutch is being compressed by the release bearing, but it's impossible to judge by how much. The engine is out again now and tomorrow my assistant is coming over again, with a big implement to try operating the lever.
Les Rose

You are probably all wondering how I am getting on with this, or not as the case may be! With the engine and gearbox out, I have taken advice from AH Club members and I am trying to simulate exactly what happens when the engine is in the car. A new pressure plate arrived yesterday, so everything has been replaced that can be. I have the slave installed on the gearbox and connected to the master. Rather than wait for another long piece of hydraulic pipe to arrive, I uncoiled the existing one on the car, and with a short length of hose was able to connect it up. I had to tip the engine/gearbox over quite a way, about 30 degrees, to get all the air out of the slave, but the pedal feels fine now. With the help of a glamorous assistant and a length of wood to hold down the pedal, I have measured the pushrod travel at 10mm. I suspect this is a bit short. There is no significant wear in any of the linkages.

There has been a bit of discussion about which way round to fit the driven plate. The factory workshop manual (see photo) says the long side of the boss goes towards the flywheel. When I do that the boss is quite tight to the inner edge of the flywheel. In fact it's hardly necessary to use the alignment tool. In this configuration the clutch partially disengages. It's possible to turn the gearbox over, but the clutch is dragging a lot and it would be impossible to drive like that. I tried turning the driven plate the other way, which some people say is correct and the manual is wrong. This would be with the long side of the boss towards the gearbox. In this configuration there is no sign of disengagement.

So possibly I don't have enough pushrod travel. Adjusting that is a waste of time as the travel depends totally on volume of fluid displaced, not the pushrod length. Or I have the wrong release fork. There is >1mm of free play at the master, so nothing to add there. What baffles me is that this all worked perfectly 11 years ago when installed, and all I have done was to change the driven plate.


Les Rose

Les,

Good to hear you report back, I was wondering how you were getting on, not great that you haven't resolved the issue though. As you say the only thing that's changed is the driven plate, have you checked that to see if it's in spec. Maybe it's too thick or the wavy plate separator is too wide. To measure the thickness you'll need to compress the friction surfaces together to compress the wavy spring plate to get a correct overall thickness measurement. Wavy spring plate width maybe compare to the old one. Did you check the slave internals to see if yours had a poorly supported seal as IIRC Paul Walbran mentioned earlier in the thread.
David Billington

Thanks Dave, but I don't know what the correct spec is for the plate. Measuring it sounds tricky. I replaced the slave seal just before embarking on the present odyssey. From what Paul Walbran says I am marginal on travel at 10mm. I don't know how to get more.
Les Rose

Well I have got the clutch to disengage properly, but only by fitting the old driven plate, and by putting it the opposite way round from what the manual says. I am wondering if the slipping was more to do with the pressure plate than the driven plate. The photo shows both plates, new on the left old on the right. You may be able to see that the new one is quite a lot thicker, and the gap with the wavy separator is a lot wider. The old plate is not heavily worn, and I was surprised that this amount of wear would cause the slipping that I was getting.

So ideally I want another 1-2mm of pushrod travel, and a thinner driven plate.


Les Rose

Is the friction plate not marked 'flywheel side' or similar?

I do remember, about 40 years ago, a friend of mine fitted a new clutch to his 1275 Sprite. He couldn't get it to disengage. When he removed the engine and checked it, the friction plate had actually been assembled incorrectly, so when fitting it correctly as marked, it was fouling on the centre hole of the flywheel when the pedal was depressed.

I'll see if I can take a photo of one of my spare friction plates to compare to yours.
Dave O'Neill 2

The flatter side (uppermost in photo) should face the flywheel and it should be marked ‘flywheel side’.




Dave O'Neill 2

A search for the driven plate thickness got an AI answer of 7.2mm to 8mm which sounds about right, I was thinking 5/16". The friction faces need to be pressed together such as with soft jaws in a vice when making the measurement.
David Billington

With these clutches I have found that over-thick linings result in the thrust pad (in the centre of the diaphragm) coming into contact with the driven plate before the latter is fully released. Any further movement then pushes the driven plate onto the flywheel. Unusual, but can happen.

To check, seeing as everything is out, put some bearing blue on the front face of the pad (the one facing the plate) and then after operating the pedal through its stroke have a look for any sign of blue on the driven plate.

One thought about the 10mm. We have found on a significant number of occasions that insufficient stroke was down to too much carpet/underlay on the bulkhead restricting pedal stroke, and this doesn't show up until a new plate is fitted. Reason being that the wavy plate separator has more spring in it when new and so the linings spread more as the clutch is disengaged, meaning the pressure plate has to retract more than it did with the old plate in order for the plate to be properly free.

The fresh wavy bit always results in a new plate needing more stroke, so probably an underlying issue just turned critical because of it.
Paul Walbran

Chasing down lost motion, remind me if you have already checked the pedal bush and linkage and measured the piston stroke at the master cylinder end? Is there more travel to be had there? Pivot holes can wear to an oval.

Likewise, is the hydraulic hose good and definitely not expanding under pessure?

AdrianR

Dave O'N, the driven plate is not marked. While I was on the phone to another Sprite expert, he unwrapped a brand new driven plate he happened to have and that wasn't marked either. I remember that they always used to be, but no longer it seems. Over 55 years I have always fitted them with the long side of the boss towards the gearbox, which is the reverse of what the manual says.

Dave B, my steam driven vernier says the compressed thickness is 7.9 mm. On the high side of normal range?

Adrian, the pivots at the master end are good and I can see no significant lost movement. The hydraulic hose is brand new, actually a braided one that came with the remote bleed kit.

Paul, I will try your test with bearing blue. Regarding pedal travel, I do have some stick-on sound deadening on the bulkhead, and will try removing a patch of it. It has been there for 20 years and has probably been bashed thinner by now. I will remove the carpet as well although again it's old and thin.

I am encouraged that I actually know what's wrong now, thanks in large part to you guys and your excellent advice. Finding a solution still eludes me.
Les Rose

Success! Firstly, Paul's marking blue test didn't show anything. But after removing a patch of sound deadening, and the carpet, I got another 2 mm of slave movement, which seems to be enough. It will put the bite point a long way down, but that will improve as the plate compresses and wears.

In summary, this was caused by a combination of slightly short pedal movement, and a plate that was at the upper limit of thickness. I think it was worth replacing the pressure plate, in view of the slipping that I was getting with a not disastrously worn driven plate. Replacing the master cylinder turned out to be completely unnecessary, but what's done is done. I am very glad to have changed to silicone fluid, as the engine bay paintwork remains pristine.

Heartfelt thanks to all you chaps for such sage advice. I have learned a few things. I hope I am not speaking too soon, as the unit is still not back in the car!
Les Rose

Les,

Good to hear you've got it resolved and hopefully the reassembly goes smoothly and you've got your transport back.

Probably no need now but you could have measured the uncompressed thickness of the driven plate to see how wide the wavy plate is, maybe too late as likely fitted.

I presume by vernier you're referring to a Vernier caliper. It annoys me when I see people referring to a 'vernier' when they're using a dial or digital caliper which don't have Vernier scales. I don't have one myself, only having a dial caliper and a few digital calipers. I do have micrometers with Vernier scales and angle protractors with Vernier scales. https://en.wikipedia.org/wiki/Vernier_scale
David Billington

Good result Les, always a such a relief to crack a thorny and persistent problem.
Paul Walbran

Yes Dave, it's a very ancient analogue Vernier caliper that was my dad's, and probably dates from 1930s. Only reads to 0.1 mm.
Les Rose

Just when I thought I was winning, I can't stop the clutch slave from leaking. I have replaced the fitting on the end of the pipe, which was a pain as I had to cut the pipe, file it smooth, put the fitting over it and then flare it again - all while under the car. It's hard to see whether it's the adapter on the slave that's leaking or the fitting on the pipe. It looks as if the fitting screws into the adapter, but stops before it fully seals. Again there is nothing different about this, it has all worked perfectly for 11 years, but now it leaks. This is a 1275 slave, but I don't use the flex hose, just the 948 coiled metal pipe. Maybe I should change to the flex hose?
Les Rose

If I change to the flex hose, what sort of fitting will I need to connect it to the existing metal pipe?
Les Rose

Sometimes it pays to use Hydraulic Seal on threads. I use Draper hydraulic sealant.

Alan Anstead

Thanks Alan, but the Draper one is out of stock everywhere. Others are available, but as usual I have to wait for it to arrive. How fondly I remember those days when you could walk into a shop and buy things. I have a tube of Fernox, which is really for water. I wonder if that would work? What about Hylomar Red?
Les Rose

That sort of thread sealant shouldn't be required on a fitting where the sealing surfaces make a metal to metal contact and the thread is only there to apply the pressure to create the seal at those surfaces, it may mask other issues.
David Billington

Les
You are having a torrid time!
I use the 1275 cylinder with an adapter connecting to the 948 coiled clutch pipe. I like you have never had a problem. My adapter fits to the slave with a copper washer and then the pipe screws in the other end of the adapter.
The later clutch hose does effectively the same thing but is retained by a bracket welded to the chassis rail. I guess you could just leave the hose without the bracket but it would flop about.
Are you sure the adapter is still ok?
Bob Beaumont

Ah, I think I have lost the copper washer. I use the same same setup as you Bob, but have not had it apart for 11 years so forgot about it. I am just off to the garage to find one.
Les Rose

This of course is the "other issue" to which you allude Dave! Needless to say I don't have a copper washer the right size, although I did contemplate a fibre one which I do have. Actually I can almost certainly make one on the lathe from some scrap copper sheet.

The adapter looks OK, I can't see a fault in the mating surfaces or any cracks.
Les Rose

I recently made a neighbour a new billet copper washer for the sump plug on his Volvo as the old one was looking a bit sorry for itself and he didn't have any the right size. I had some 1" or 25mm copper bar which was the right size for the OD so about 10 minutes of drilling, boring and parting and a quick anneal and job done.
David Billington

I don't have any suitable bar stock so had to flatten some plumbing pipe and turn it on the lathe. Too thin, but looking in the adapter I can see it's making good contact. But it still leaks. Not just a weep, quite a squirt. The hydraulic sealant has arrived but I'm not confident it will cope with such a leak. Difficult to see exactly where it's coming from. Definitely not the piston seal or the bleed nipple. It's either the adapter to cylinder joint, or the flared pipe to adapter joint. I have checked the latter with bearing blue and it looks OK.
Les Rose

Les
I used an Automec brake pipe kit when I rebuilt the Frog. For the clutch, as I needed a non standard pipe to link the 3/4 MC to the 1" clutch slave I got Automec to make me a custom pipe up (all metal). It worked well. They still make custom pipes.
Bill B

The copper washer didn't work, and neither did the sealant. Been on the phone to AH Spares and they are rummaging through their stock for a slave that will accept my 3/8 UNF male connection. Can't remember where I got the one I have, it was over 11 years ago. I think there's an invisible crack in the adapter or the cylinder.
Les Rose

My experience with anaerobic thread sealant is that it's best to leave it overnight before applying pressure so that it has time to fully cure regardless of what the literature said about making an instant low pressure seal. That was for systems using propane/butane gas at pressure up to 3 bar and on tapered threads intended to be gas tight. I did also take the advice of a couple of professional gas installers who advised using gas grade PTFE tape and anaerobic sealant as belt and braces.

Can you view the area where it's leaking, maybe with your endoscope.
David Billington

Now I am up a gumtree. In 2015 I bought slave GSY113 and adapter 21K8564. The adapter has male end 7/16" UNF, and female end 3/8" UNF. It is actually for an MGA. These came from Sussex Classic Car Parts, now closed down. See photo 1. They are available from other suppliers. So I asked MGOC Spares to check that these would fit together. They say that they don't. Looking at other suppliers, they all offer the same adapter judging by the identical photos (photo 2). The female end does look too big. It looks like I will have to make an adapter, and I will have to buy the necessary taps and dies. Should it be steel or brass?





Les Rose

Hi Les

Have you tried Past Parts for the adapter?
Bob Beaumont

I ordered a new slave and adapter from MGOC. Arrived today. The slave is correct but adapter is wrong. As usual I have been barking up the wrong tree. I don't need an adapter, I only need a 7/16" tube nut for 3/16" tube. I didn't know such a thing was obtainable, but it is and I have ordered it.
Les Rose

The 7/16" tube nut arrived today. Very difficult to fit. I flared the pipe again, having made sure that it was as square as possible at the end. All back together, and guess what, it still leaked. Yesterday I bought a pack of copper washers and today I glued one in the slave using hydraulic sealant. I held it in place over lunchtime with a 7/16th bolt. Back together again and, lo and behold, there is no leak. Bled the system and it works. The bite point is a long way down, but that should get better as the plate beds in.

So I now have a new pressure plate, new driven plate, new master and slave cylinders, new seals everywhere, and conversion to silicone fluid. I am exhausted. But the sun is out!
Les Rose

Interesting the 1275 clutch standard uses 1/4” copper tube not 3/16” ? More fluid to move ?
richard b

Richard

I had wondered the same.

Obviously with a larger bore slave cylinder, there would be more fluid moving in a given time, which maybe gave a heavier pedal and also a slower return.
Dave O'Neill 2

I hadn't thought of that, but it makes sense. However the pedal pressure is much lighter than some of the 9-spring clutches I have used.
Les Rose

This thread was discussed between 14/04/2026 and 24/05/2026

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