Pipework for Clutch

Ian Anderson

Lifetime Supporter
My car uses a Renault turbo box and related slave cylinder.

I have heard that the 3/16 brake type pipe is not large enough to allow the flow of fluid causing the clutch to release more slowly than the pedal may move / cause extra slip on take off.

Is this the case?

If so what diameter pipe should I run for the clutch?

Thanks
Ian
 

Alex Hirsbrunner

Lifetime Supporter
Ian,

I've never heard of this, but one thing you might want to do is take a look at the actual size of the drilled ports that the hydraulic lines attach to (clutch slave and master sides). If they are already smaller than the ID of the 3/16" tubing, then larger tubing may not help much.

Regards,

Al
 
There are threads on this subject....consensus is to use 1/4 " tubing...whether it helps I don't know...but easy
enough to do during the build phase.

MikeD
 
Ian
Definetely go for the 1/4" tubing..I have had the experience of helping a friend with his setup which used 3/16" tubing and although I suggested the 1/4" tube he went ahead anyway. What he got was a clutch that released OK but would engage slowly after the pedal was lifted, and this was in the warm weather. The 1/4" line cured this immediately, but the change was a little more difficult to make as the car was further along by then. I hope this helps
Cheers
Phil
 

Ian Anderson

Lifetime Supporter
Al, Mike and Phil

Thanks for the comments - it makes sense to me as it seems the Renault slave is a very big bore and you then need to move a larger volume of fluid to get the movement.

I will try the 1/4 inch route or perhaps a smaller slave unit?

Can the slave be changed for a smaller bore unit - I know others have sleeved theirs? How small a pre coud I go to without compromising and potential snagging of the push rod on the bore at max travel?

Thanks
Ian
 
[ QUOTE ]
Can the slave be changed for a smaller bore unit - I know others have sleeved theirs? How small a pre coud I go to without compromising and potential snagging of the push rod on the bore at max travel?

[/ QUOTE ]

Ian,
Talk to Frank Catt. He fitted a large clutch slave cylinder to my car to reduce pedal travel.
Didn't half push up the pedal pressure though!
But we're supposed to be hairy chested! /ubbthreads/images/graemlins/1poke.gif
 
Ian
Changing the diameter of your slave cylinder will change the effort at the pedal, and the travel at the slave cylinder. A smaller slave cylinder will push further than a larger one, but require more pedal effort on your part, A Larger slave will travel less distance but require less pedal effort, also it may not move enough to release the clutch. Measure the travel at your pedal pushrod, and if you know the diam of your master cyl. you can calculate the area( PI X rad. squared) then multiply by your pushrod travel...this will give you the cubic volume of fluid being displaced by the master cyl. Apply this to your slave cylinder in reverse and you will get the travel being applied to the clutch release mechanism. Of course this is on a bled system with no air. Also be sure to allow for any free play at either end as a small amount can make a big difference. I hope all of this helps!
Cheers
Phil
 
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