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Engine Bay Brake and Clutch lines.


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1 hour ago, mhossack said:

PS I missed off load on load

Can this be done on your own.

I assume when all buttoned up I should be able to move the piston 15mm by hand before it tries to engage the clutch.

Thank you,

Mick.

No it is when the system is full and the pedal full down 

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Thank you ntc.

I am sorry I still do not fully understand your answer.

It sounds to me you need 2 people, which will not be a problem.

You fully depress the clutch pedal and then you measure what, will you still be able to move the clutch slave cylinder rod, or the cross shaft lever, sorry for my stupidity.

Mick.  

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Hi ntc.

I think I now understand, you need to measure the distance between the pedal fully depressed and fully released, about 15mm, and then when fully released you need a small about of travel on the pushrod to make sure the clutch is fully disengaged, or in old fashion words, not slipping.

Thankyou,

Mick. 

 

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45 minutes ago, mhossack said:

Hi ntc.

I think I now understand, you need to measure the distance between the pedal fully depressed and fully released, about 15mm, and then when fully released you need a small about of travel on the pushrod to make sure the clutch is fully disengaged, or in old fashion words, not slipping.

Thankyou,

Mick. 

 

You measure the distance the slave pushes at the fork 

Edited by ntc
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Hi I am still in trouble.

I thought I had completed my full clutch hydraulic install, only to find the clutch lever arm would only move 8mm not enough to engage the gears. The slave cylinder is in the correct position. 

I fear my 2 cylinders may be not compatible, it would seem I may have unequal fluid volume, so the master cylinder is unable to displace enough fluid to operate my clutch lever arm fully.

Parts used a refurbished AP Lockheed clutch slave cylinder 99364C Q-310 and a NOS Girling clutch master cylinder .70 64676310 (154932) from T D Fitchett.

I am also not that technically mined.

Thank you,

Mick. 

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That slave cylinder has a bore of 7/16" (0.875")and that Master one of 0.7", so for every inch that the master piston moves, the slave will move 0.8".   So your theory of a mismatch may have truth.     

 The orginal Master had a 0.75" bore, which would increase slave travel to 0.85".       

But I frar that this probably isn't your problem!

JOhn

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Oops!

The volume changes as the square of the radius - not linearly. 

A 0.75 master and a 0.875 slave has a travel ratio of 1 0.73

a 0.7 master and 0.875 slave has a travel ratio of 1 : 0.64

The third post down on this old thread suggests the slave may actually have been refurbished to be 1"  in which case the ratio  would be even worse with a 0.7 master, at only 1 : 0.49

 

 

 

Edited by RobH
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Hi RobH 

I have spoken tonight with a friend who I showed your post and understands your reply, I do not, and told me it is correct.

Is it possible as you know what I have fitted, which one I need to change and for what, more information if required. 

No chance you mix with the London group, not to far away from you.

Thank you very much,

Mick.

 

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Sorry Mick - I think we have caused confusion by discussing the technicalities.

I don't have a '6 so can't speak from experience but from what I have read the system was originally designed with a 0.75" master cylinder.  That was later changed to 0.7" to lighten the pedal force at the expense of having to push it a down bit further, and of making the slave travel a bit more critical when the clutch plate gets worn.  The master and slave cylinders you have are the right ones and are known to work as per the old thread I linked to.  Maybe the mention of a 7/8" slave was a red herring as 1" seems to be the one commonly available and used. 

That means what you have now ought to be OK but you do need to make sure there is no lost motion in the linkage as Neil (NTC) said above. No worn clevis pin and no elongated holes.  (That goes also for the bits in the bell-housing which move the release bearing.)

Make sure the slave piston is fully back in the cylinder when the clutch is not operated. (That may even need a different length rod ?)  There is a circlip at the end of the cylinder to stop the piston coming out and which will restrict the available travel if it is starting from half way up the bore. 

 

 

 

 

 

 

 

 

 

 

 

Edited by RobH
typo
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24 minutes ago, mhossack said:

Hi ntc

Thanks I will look at all mechanical wear, but my problem really started after changing both cylinders, although it was only the slave that had to be changed.

Mick

You need to also check for restrictions in the line and I am not a fan of the braided hose 

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Hi ntc.

Sorry if 2 posts are confusing, the only reason was, because marki (Mark) started a new post asking for a recommendation for a new clutch master cylinder I told him about the NOS Girling clutch master cylinder .70 64676310 (154932) from T D Fitchett.

As we know people are so helpful, they reply so quickly hence the 2 post on the same subject. 

The next day when I fitted my clutch cylinders I had the problem I am now asking about.

I wanted to insure Mark knew to check what I had recommend would work on his car.

Mick.

Edited by mhossack
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