Upside down slave cylinder and 9.5mm throw

[mhossack]

Hi Les

You wrote: (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 am a little mystified, your cars underside looks like it has just left the factory, surely this must be the restorers problem not yours.

You also wrote: (I was told the push rod was in the top hole because the clutch dragged in the centre hole.) This does not make sense to me, the push rod should be in the correct hole, and only moves the lever, how can this affect the clutch.

I have just renewed all my TR6 clutch hydraulics, and when the clutch slave cylinder is in the correct position and the push rod, I would expect it to be air in the system.

I have now read on you may have a faulty clutch slave cylinder.

If you have an original clutch slave cylinder I would have it rebuilt by Past Parts, I would avoid aftermarket parts.

Richard Crewe-Read (Colchester Essex rcreweread@gmail.com) a very helpful man, has some rebuilt original clutch slave cylinders refurbished by Past Parts, a little expensive compared to aftermarket clutch slave cylinders, but you get what you pay for, Richard supplied mine. I had a completely seized aftermarket clutch slave cylinder, some of it would be my fault, using the car very little.

You also wrote: (The required 16mm throw) This is a best guess only, and may or may not operate your clutch I do not know.

Triumph engineers did not guess this measurement, unfortunately no one on this forum has been able to unearth this dimension, lost in the mist of time I expect.

I deal in hydraulic facts only.

If you can give me the clutch master cylinder travel (throw), which unfortunately no one could when I asked this question, people were obsessed with the mythical clutch slave cylinder travel, together with the bore of both the cylinders I will use a clutch calculator and give you the correct clutch slave cylinder travel (throw), a hydraulic fact not a theory.

All the best with your problem.

Mick

[Mike C]

The cylinder should be mounted like this. Clevis pin in the centre hole.

[elclem1]

Have you checked the operation of the master? Is it a new one? Have the seals inside been changed ? I have found in the past even the new masters can pass the oil over the seals and you don’t get the full amount of oil operating the slave piston. So you may have fluid loss over the seals over the plunger in the master and therefore less oil to move the slave pistol and therefore reduced travel ? 

I also noticed that you have a braided pipe to the slave is this expanding when you operate the system under pressure? Try the original pvc one. 

Clem

[Les Pettitt]

Hi Mick,

My restorer went into liquidation the week before my car was returned so I'm on my own with this problem

Richard Crewe-Read has kindly contacted me so I will get a recon slave cylinder from him.

The slave piston is now jammed in the bore (well I can't push it back by hand while under the car even when the bleed nipple is undone) so I will await a new slave cylinder before doing any more tests. I have no idea why the slave cyclinder would suddenly jam. It is coated with thick dark grease inside the bore.

If I still have problems when all is back together I'll measure master cylinder throw and get back to you.

Hi Clem,

Good point, the master cylinder is a new one. Despite an awful lot of pumping the clutch pedal yeasterday trying to bleed the system there is no trace of any fluid passing the seals in the master cylinder. I'll check the braided pipe when the system is back together.

Hi Mike,

Thanks for the picture. That looks as though the slave cyclinder mounting bracket goes on the gearbox side of the bellhousing. As you will have seen mine is mounted on the engine side and then a 20mm longer than normal push rod was used to compensate.

Just for my own peace of mind could someone please post a photo of their slave cylinder and the mounting bracket similar to the photo I attached to my first post on this topic.

 

Many thanks

Les

[Nigel A]

My gearbox is being rebuilt at the moment so took this photo to make sure it went back the same way as been working for 30000 miles

Nigel

[Les Pettitt]

Briliant Nigel, thank you so much. That is so helpful.

So my mounting bracket is on the correct engine side of the bellhousing.

It just seems a bit strange that my restorer used a push rod 20mm longer than the correct one.

With the correct push rod in place I calculate the piston will be quite close to the end of the bore (8 mm) when the clutch pedal is fully depressed but maybe that was the intention.

That assumes the slave cylinder fitted to my car is for a TR and the replacement will have similar dimensions.

Thanks again

Les

 

[John L]

The master cylinder push rod I know are different to L/H cars, I'm sure there was a topic on here a short while ago.

Also check how much free travel/movement in the master cylinder rod to pedal hole.

One way to check, perhaps, if you have the right push rod is with the pedal at rest with its return spring attached, is the height of the pedal equal to the height of the brake pedal, if its much lower, you may have the wrong pushrod, this would give the wrong amount of travel for the master cylinder.

John

[Les Pettitt]

Hi John,

I am limited to what I can test at the moment as the old piston is jammed. The clutch pedal appears to be in the correct position and the clevis pin on the master cylinder seems a good fit. I'll report back when I have the new slave cylinder.

Thanks for all your suggestions

Regards

Les

[Tim D.]

It’s interesting you have a longer push rod.  I rebuilt a one owner triumph 2500tc saloon last year which has the same setup as the TR6. It had a longer pushrod and the slave cylinder spaced closer to the rear of the car with some washers as spacers on the mounting bolts and the pushrod was connected to the upper hole in the clutch fork.  I immediately thought that the clutch fork pin had broken and had visions of a gearbox removal :-(. Anyhow I checked the clutch fork lever position and it was vertical suggesting to me that the pin was fine. I returned the clutch slave and pushrod back to standard setup and all worked well. In the end I figured that at some point in the life of the car the clutch pin had sheared. A garage had modified the pushrod, added washers and moved the lever to the top pin to correct for the broken pin. Later down the line the gearbox was removed to sort the clutch (I have a receipt for this work from the past) and because this garage didn’t know that the clutch slave actuation had been modified they put it back as is (e.g. incorrectly). Just shows how errors can be compounded in old cars. 
tim

[ntc]

16 hours ago, mhossack said:

Hi Les

You wrote: (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 am a little mystified, your cars underside looks like it has just left the factory, surely this must be the restorers problem not yours.

You also wrote: (I was told the push rod was in the top hole because the clutch dragged in the centre hole.) This does not make sense to me, the push rod should be in the correct hole, and only moves the lever, how can this affect the clutch.

I have just renewed all my TR6 clutch hydraulics, and when the clutch slave cylinder is in the correct position and the push rod, I would expect it to be air in the system.

I have now read on you may have a faulty clutch slave cylinder.

If you have an original clutch slave cylinder I would have it rebuilt by Past Parts, I would avoid aftermarket parts.

Richard Crewe-Read (Colchester Essex rcreweread@gmail.com) a very helpful man, has some rebuilt original clutch slave cylinders refurbished by Past Parts, a little expensive compared to aftermarket clutch slave cylinders, but you get what you pay for, Richard supplied mine. I had a completely seized aftermarket clutch slave cylinder, some of it would be my fault, using the car very little.

You also wrote: (The required 16mm throw) This is a best guess only, and may or may not operate your clutch I do not know.

Triumph engineers did not guess this measurement, unfortunately no one on this forum has been able to unearth this dimension, lost in the mist of time I expect.

I deal in hydraulic facts only.

If you can give me the clutch master cylinder travel (throw), which unfortunately no one could when I asked this question, people were obsessed with the mythical clutch slave cylinder travel, together with the bore of both the cylinders I will use a clutch calculator and give you the correct clutch slave cylinder travel (throw), a hydraulic fact not a theory.

All the best with your problem.

Mick

I will give you facts it was me I was asked many years ago to find the correct movement and I had four original cp cars in the garage they all was between 14/16 mm

[Les Pettitt]

Hi Tim,

I must admit I used the top hole trick when my taper pin broke in 1978 and 1980. Worked for a few miles.

I am waiting for a restored Lockheed slave cyclinder (thank you Rich) and will then use my new standard length push rod and see how it goes.

My clutch fork lever is vertical and I am supposed to have both taper pin and roll pin fitted, so hopefully all will work ok.

Regards

Les

[michaelfinnis]

Straying off the question a bit, but just curious-the clutch fork has three holes, manual says the push rod must be fitted to the middle hole, so what are the other holes for? Same part used in other other applications maybe?

Mike.

[Tim D.]

I know for the saloon and stag the middle hole is also used. 

Tim

[jurgensbrother2]

Hi Les, I don't know if this is relevant but my tr6 was in the same place as yours 2 weeks before you. You might of ended up with my slave cylinder as mine was a left hooker and only a couple of years old and the pushrod is a different length. I ended up with a load of parts that I know never were on my car. Had to change a lot of parts. 

[mhossack]

ntc

I found your sentence below on the 19th September, Clutch problem thread rude, I let it go because I don’t come on the forum for a Row, but as you are at it again I will this time.

(Good luck with your theory but the slave will only move so far and at that the master is doing it’s job and the measurement is what I have found correct over many years of experience) hard to understand your English.

Unlike you mine is not a theory as you quoted, mine is a hydraulic fact, shame you don’t understand basic hydraulics. I don’t care if you measured 100 cars of the production line. Triumph never measured in millimetres and the movement would be at most a few thousands of an inch difference between cars, if you were capable of producing a clutch calculator and inputting the figures you would get the correct dimension like Triumph engineers did.

My clutch master cylinder has a bore of 0.7 and a travel of 30mm with a clutch slave cylinder bore of 0.998 this gives a clutch slave cylinder travel of 14.76mm a hydraulic fact not some wild guess of between 14/16mm as you quoted, I added a screen shoot of the calculations, not my fault you did not understand them.

Please create your own clutch calculator and show me I am wrong, I will not provide the formula required I am sure you know it

Also you are the only person so far to have a bad word about Past Parts.

Sorry Les I did not start it.

Mick.

Edited November 13, 2021 by mhossack
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[ntc]

So you ended up with the same measurement not a lot more to say then

[mhossack]

No ntc

I did not end up with your guess I have the correct hydraulic dimension fact.

[Tim D.]

Guys...

Could this be a disagreement about theory and practice? A common disagreement in engineering. Mick is correct mathematically and ntc is correct by measurement. These things don't always agree with one another. Theory will come up with a single figure as it is all dimensions that can be measured. But observation/measurement will include any deformation of seals and pipes for example which will inevitably reduce the movement of the slave. Add into that imperfect bleeding of the system, slight compressibility of the fluid, play in the linkages and what was certainty of theory becomes uncertainty of reality. 

I am a scientist as a day job and it is something we are forever having to wrestle with. The key thing is to understand each other and the limitations of each others observations/calculations. 

Tim

[ntc]

Indeed there are many variations the under bonnet temperatures can make all bets off 

[mhossack]

Tim D

Nice to hear from a scientist, as you will know Triumph engineers would have made engineering drawings and come up with calculations that made the clutch operate, unfortunately it would seem these drawings have been lost, Triumph engineers would have worked to a few thousands of an inch.

I supplied a snip of a clutch calculator which ntc went on to ridicule as theory, I have never been rude, as you can read I first ignored it but did not a second time, ntc does not understand basic hydraulics, I never said 14/16mm would not work I just did not know, but supplied a factual figure using the clutch cylinders Triumph fitted to the car that would work.

I do not come on the forum for a row so I will not reply, life is to short, plus none of this help Les who has had a very hard time with his TR ownership and only wants to sort out his clutch problem.

Mick.

[Tim D.]

Thanks Mick, I think I used your calculator when I installed my 0.625” master cylinder to reduce pedal pressure for my sister when we drove the RBRR last month.  Actually works well if you use an adjustable push rod for the master cylinder and don’t mind a slightly longer pedal throw. 

[keith1948]

Hello Les (Fellow CVTR)

The slave cylinder on my 4A is a different set up to yours but looking at the parts for TR6 slave cylinders there seems to be a spring inside the cylinder. If this is broken then could explain why it is stuck. Also should not be thick black grease inside the cylinder. I had a broken spring in a master cylinder once causing it to jam.

I would agree with others that it is the centre hole it is attached to and the bleed screw should point up and it is mounted correctly.

Take the cylinder off the car and strip it down to see what might be the problem would be my course of action. There seems to be some differences for the length of the pushrod but I am not familiar with the 6 system. The one I have on my 4A has an adjustable pushrod and the Haynes manual is wrong stating a gap of 0.010 inch when it should be 0.1 inch (1/10th inch). If the bore is ok then you might be able to rebuild it with new seals etc. I use an eezibleed kit to bleed brakes and clutch system. It is much easier than having an assistant pressing the pedal and less likely to draw air in if they release the pedal too soon.

And I know how you feel about crawling about under the car.

Good luck. I would offer to help but I am suffering with toothache at the moment.

Keith

Edited November 14, 2021 by keith1948
typo

[JohnC]

Replied and realised I hadn't read the whole thread. I'm outa here!

Edited November 15, 2021 by JohnC
Deleted

[Les Pettitt]

Hi Jurgensbrother,

That doesn't surpise me as I eventually managed to get back some parts after  a lot of pestering but some were clearly not mine and from a lhd car.

Hi Keith,

I have a refurbished Lockheed 993640 on its way to me (thanks Rich). I have no faith in the slave cylinder currently fitted but will examine it and compare it the Lockheed one.

I will also use the correct pushrod which I have had on the shelf for 30 years or more and is still in its British Leyland bag.

With the correct slave cylinder and correct push rod I think I have a fighting chance of the clutch working properly.

I have in reserve a variable length push rod but hope I don't have to use it.

I still have the original slave cylinder which came with the car and that is also Lockheed 993640 which I will now get refurbished and keep as a spare. I am hoping a new cylinder will cure all my woes including incredibly stiff gearbox.

I also have an eezibleed kit and it has always worked well but it was only after trying that without success and using my wife I discovered the piston is completely jammed.

I'll report back later in the week.

Thanks everyone

Regards

Les

[mhossack]

Hi Les

Good to hear your clutch problem is moving on, with the correct push rod there is very little use for an adjustable push rod, it could be 12inchs long, but it will still only move the distance of the displacement of fluid from the clutch master cylinder to the clutch slave cylinder, taking into account for the clutch master cylinder pushrod travel.

I will post a picture of my adjustable clutch master cylinder pushrod I made, until I was told it was next to useless.

Mick.

Edited November 15, 2021 by mhossack
Missing word