Another clutch travel query

[Downhill]

Hello all

Having put together the clutch system I could not get the the clutch to release. After many joyful hours of taking things apart and putting back together again ity became obvious that there was not enough travel on the slave cylinder.

Present setup is Girling 3/4 master cylinder 35mm stroke on Dax pedal box
Girling 3/4 slave cylinder on Lakewood centre pivot arm giving
25mm stroke.
Unfortunately at least 33mm stroke is needed to release the clutch

Having used the search it appears that others have had similiar problems but with unclear answers.
Would a 7/8 master give more travel but be unacceptably heavy? (current set is just about tolerable). Are there any other 3/4 slaves available to give more stroke?
A stalled cobra builder would be grateful for any suggestions.

Thanks
DH

[wilf]

You have only one possible solution - go up on master or down on slave cylinder bores.

I am assuming that the geometry at the pedal end is giving you a full "sweep" of the master cylinder, and that you have no lost motion mechanically at the slave end?

If the pedal becomes too heavy for you, your only solution is to fit a hydraulic booster (just like on the brakes). No biggy if you have the space. There is an article about that in the current Snake torque, and another recent thread here.

[skorpion]

Hi DH,

Knowledge is power so...it's not rocketscience....

http://users.telenet.be/cobra427/clutch.html

If you give me your constants/dimensions as shown in excel sheet, light yellow cells, I can calculate for you pedal force and whether it will work or not.

I had to reduce the fork length in order to get the stroke on the clutch.

Regards,
Andy

[TINKA]

If you decide to go the larger master route I have one for sale Cost £96 all I want is £35. Which ever way you go larger master or smaller slave the pedal weight will go up the same amount.

[Downhill]

Thanks all - I think I will have to go down to a smaller diameter slave . Andy - are you able to calculate what the stroke would be with say a 5/8 slave?

Va (slave to pivot) 175mm
Vb (pivot to thrust bearing) 75mm
angle 110

master 3/4 stroke 35mm

slave 5/8 stroke ?


DH

[Clarkson]

Originally Posted by TINKA

If you decide to go the larger master route I have one for sale Cost £96 all I want is £35. Which ever way you go larger master or smaller slave the pedal weight will go up the same amount.

What size is it Tinka maybe interested??

[Clarkson]

Originally Posted by d clarkson

What size is it Tinka maybe interested??

Tinka????

[TINKA]

Originally Posted by d clarkson

Tinka????

Sorry I forgot all about it i will have a look and post in about an hour

[Clarkson]

Thanks mate. Any pics??

[TINKA]

Originally Posted by d clarkson

Thanks mate. Any pics??

Dave having read another post think this is probably not what you want but it is a 1" master