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Coaxial hydraulic clutch release


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I'm in the process of fitting a coaxial clutch release and new gearbox. Tonight I was attempting to bleed the system but couldn't get any pedal. With limited technical knowledge, one thing that seems obvious to me is that the piston in the master cylinder is not releasing back against the pedal. I noticed that there was no clutch pedal return spring fitted and I'll get one of them but that is not my problem. Is it possible that the cylinder seals have seized?. I did have sylicone fluid but now have to use DOT4 and I know I should fit new seals in any event. I have to fit a pedal stop with this clutch release system but if I have a dodgy master cylinder, I notice that Cambridge Motorsport sell a master cylinder to match the fluid needed by this system therefore I assume not then requiring the pedal stop.

Any advice or experiences anyone can pass on would be appreciated. I'm pulling my hair out, what hasn't dropped out already that is!.

 

Thanks

Wyn

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Hi David,

 

Racetorations, they did the gearbox for me too. If I have to change the master cylinder, then I would prefer one that means I could do without a pedal stop if possible.

 

Wyn

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Take out the clevis pin on the pedal, try and jam the pedal it so its at the top of its travel, as you dont have a return spring, make sure the pushrod is fully pulled out of the master cylinder, and adjust the clevis so that there is some free play. There should be a bit of free travel on the push rod before when the pedal is then pushed, this makes sure that the master cylinder can fill the chamber from the reservoir.

You could disconnect, or loosen the pipe down near the clutch and see if fluid runs out, if the reservoir is full, also make sure that the the bleed pipe comes out of the top of the slave cylinder.

If you open the bleed nipple, the fluid should really run out on its own.

Hope this helps

 

Regards John

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Thanks John,

 

I have now ordered a new master cylinder (smaller than standard) to suit the coaxial. Fluid seemed to be running through ok. No slave cylinder attached to the bellhousing with this clutch but bleed nipple still there. Hopefully, when I have the replacement cylinder all will be ok, we will see.

 

Regards

Wyn

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Wyn

 

Racetorations fitted a coaxial system to my 6 earlier this year and yes its got a pedal stop on it; there is a smaller master cylinder (I think 6mm if memory serves) and it uses DOT 4 fluid

 

Cheers

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Wyn,

 

I would suggest that a pedal stop is vital to ensure no chance could ever exist whereby you pop the bearing out of the cylinder.

 

I cannot imagine anything worst than having to take the gearbox out to simply reinsert the bearing.

 

It won't be difficult to fit a stop.

 

At it's most basic, find out where the best spot on the bulkhead is to ensure the bolt head lines up with the clutch pedal, drill a hole, run nut down long bolt and then insert long bolt through hole into engine bay add another nut and secure to correct length by adjusting the nuts.

 

It will all make sense when you do it.

 

Alternatively, use a rivnut in the hole or weld a nut on in the correct place.

 

Turning to the bleeding, or lack of it, I assume that the bleed pipe is the upper one so that the fluid enters the bearing lower down and any air is pushed out of the top of the cylinder.

 

Good luck.

 

Regards

 

David

Edited by david ferry
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I hope to receive my master cylinder today (6.25), I have the pedal stop already in place, just needs adjusting after bleeding. You are quite right, I would be totally pi...d off if I had to take the box out to replace the bearing.

 

Thanks everyone, I will post an update during the week.

 

Wyn

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  • 11 years later...

there was a bloke on CT a few yers ago ed yan of thee,s things,

it was always going wrong, 3 times box was oot in as many years.

his was leaking seals if memory serves me right.

Butt, saying that, there loadsa moderns with em on,

So summat must ev been amiss wid his, maybe  what folk on here are sugesting, a stop,!!

 

M

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17 hours ago, GT6M said:

there was a bloke on CT a few yers ago ed yan of thee,s things,

it was always going wrong, 3 times box was oot in as many years.

his was leaking seals if memory serves me right.

Butt, saying that, there loadsa moderns with em on,

So summat must ev been amiss wid his, maybe  what folk on here are sugesting, a stop,!!

 

M

Without a pedal stop they will go to far and sometimes eject the rod altogether. Adjustment is critical.

Stuart.

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  • 2 months later...

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