Slave cylinder for hydraulic clutch conversion.

[Tony saccParticipant @tonysacc93877]

I made this slave cylinder to convert the cable operated clutch to hydraulic.  Body is 6061, Piston is stainless, seal is a hydraulic ram seal.  Due to limited room behind the cover i couldn’t fit a circlip and a dust seal, so I machined up an aluminium cover that serves a dual purpose.  To fit, I had to bore out the cover a little where the original screw actuator fitted, and drill the M5 threads out with a 6mm drill.

Bore is 22mm, piston only has to move a mm or two.  I designed it to fit behind the side cover to make it as unobtrusive as possible.

[OldironParticipant @oldiron]

Good job. Fitted well.  But I did wonder what it was for until I got to the last picture.

[Clive FosterParticipant @clivefoster55965]

Lovely job.

One query tho’. I’d always understood that you needed square section sealing rings that twist slightly as the piston moves and relax when pressure is released pulling the piston back enough to ensure there is mechanical clearance in the system. The twisting action doesn’t interfere with the main sliding movement of the piston but the defined, small, pullback allows the system to self adjust to consistent minimal free play.

I made useful beer money over the years sorting motorcycle brake systems where corrosion behind the seals had inhibited piston return so the brakes were, to greater or lesser extent, always on.

Clive

[noel shelleyParticipant @noelshelley55608]

Very neat ! Clives comment is interesting, but clutch slaves usually had a cup seal because of the need for greater travel.  If it works thats all that matters. Noel.

[Phil LinghamParticipant @phillingham79132]

Nice job!

To re-iterate what Noel said my Ducati clutch slave cylinder uses a cup seal. For some reason every now and then the seal would fail and of course the Ducati item cost a Kings ransom but an equivalent part from a local bearing supplier done the job just as well for a fraction of the cost.

[Grindstone CowboyParticipant @grindstonecowboy]

Only seen square section seals on disc-brake calipers. Drum brakes and clutches have all been cup seals on those I have experienced.

Rob

[Dave HalfordParticipant @davehalford22513]

Clutches have a big ole spring to return the piston so cup seals work.

Brakes have no mechanical return apart from a little bit of disc runout. The seal is square on the 3 sides that face the cylinder groove. The piston face side of the seal has a slight taper which grips the piston and distorts on the way out. When pressure is released the seal returning to normal pulls the piston back in to the cylinder.

[Clive FosterParticipant @clivefoster55965]

Thanks for the education on seal shapes for hydraulic clutches. The ones on both my motorcycles are square with cup seals at the lever ends.

Clive

[Tony saccParticipant @tonysacc93877]

Disk brake calipers us square seals, well on this bike they do.  I chose the cup seal because that’s all I could get.  The clutch has springs behind it, so they push the actuating rod back against the slave cylinder piston.

 

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