VFR Hydraulic Clutch Conversion Info and Questions-*PICS*

I'll give the info,then my situation,and lastly my questions.

The Honda VFR slave cylinder(the one on the engine),pushes a rod to release or free wheel the clutch.I measured an overall throw of the slave cylinder at 14mm or roughly .50in.Any movement passed that will result in the piston dropping out of the housing.The rod opening in the slave cylinder piston measured at 8mm.It could probably be machined to accept a larger rod size and can be bushed down to a smaller rod size.One important note on these slave cylinders.They have a fairly strong spring inside pushing the piston out.This is to make sure there is no slack between the slave piston and the clutch push rod.There is zero play.Knowing how strong this spring is,I think that it could cause clutch slippage on some motorcycles with softer or weak clutch springs.I haven't been inside one of these units,so I can say what it would take to put in a softer spring.Another note,if to soft of a spring is used in the slave cylinder,the master cylinder will pull the piston all the way in,loosing contact with the clutch push rod,when the clutch hand lever is released.

Here are some physical dimensions.

Widest spaced bolt holes,center to center,as best as I could measure.


There is a slight step where the slave cylinder slides into the case cover.This also shows the max travel of the piston.


Outside diameter of the mounting area.


Pic of me holding the piston in as far as it will go.


I have never had my hands on a VFR slave cylinder before.I couldn't find dimensions anywhere,so I ordered one just to see how my luck is holding up.My luck isn't holding up so well.My sprocket cover holds the clutch actuator on my bikes,GS500.A VFR master cylinder is way to large and my actuator is to close to the edge of the cover.Therefore,it can not be machined to accept the VFR slave cylinder.Also,my cover has a slight bow cast into it.











My questions.Is there a smaller slave cylinder from a production bike.I prefer something from a production bike that way I can order repair parts from a dealer or another one from ebay if I break down.

This unit will be listed in the for sale area if anyone is interested.

Funny you posted this since I'm experimenting with a clutch slave on my CB350. I even have the same part as you. I've researched other ones and it seems the aftermarket ones such as Oberon, are smaller in diameter and the piston is housed above the mount. Don't bother with looking for a smaller Honda unit, they tend to use the same one throughout the model lineup to save production costs. I doubt the tension of the slave piston spring is greater than the clutch springs.

DrJ said:

Funny you posted this since I'm experimenting with a clutch slave on my CB350. I even have the same part as you. I've researched other ones and it seems the aftermarket ones such as Oberon, are smaller in diameter and the piston is housed above the mount. Don't bother with looking for a smaller Honda unit, they tend to use the same one throughout the model lineup to save production costs. I doubt the tension of the slave piston spring is greater than the clutch springs.

Click to expand...

Thanks for the info.

check my tread in the tracker section. It's top 10 somewhere, called cb550f 1976 back from the dead. I made a clutch conversion on my 550f and i think you could get some info out of it.

edit: here ya go -> http://www.dotheton.com/forum/index.php?topic=26406.10

Bert Jan said:

check my tread in the tracker section. It's top 10 somewhere, called cb550f 1976 back from the dead. I made a clutch conversion on my 550f and i think you could get some info out of it.

edit: here ya go -> http://www.dotheton.com/forum/index.php?topic=26406.10

Click to expand...

I saw that thread.Isn't that a puller type clutch slave cylinder?

Nah. It's a pusher. I have one here that I wanted to stick on something else.

Anyone looked at one of these little puller units? http://www.ebay.com/itm/Magura-Hydraulic-Clutch-Kit-HONDA-CRF250R-2004-2009-/290638955981?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item43ab6e85cd

or this:
http://www.ebay.com/itm/Black-HYDRAULIC-CLUTCH-LEVER-MASTER-CYLINDER-PIT-BIKE-/160688289820?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item2569c4b81c

They are a cheap copy of the excellent Magura system. They also don't work on my project but might work on yours. I figured that at less than 30 bucks it was a cheap gamble I mean R&D investment.

Those $30 units have been discussed on here before.I did a google search on this site using "hydraulic clutch" as my search term.It only brought back 30 hits,IIRC,so it shouldn't be hard to find.

Another option could be this unit:


It is out of Germany I believe and is designed for the Kawasaki Z1/KZ900/KZ1000.
It bolts right into where the worm gear was on the sprocket cover.
I found it at www.americanclassix.com under "improvement parts".

Not cheap, but it could work on other bikes as well.
I would expect that a lot of those worm gear clutch actuators are very similar to the Kawasaki...

To expensive and I wanna stick with production parts, in the event I break down while traveling.