Topic: hydraulic clutch / not completely disengaging - FIXED

[evan77]

Hey guys,
I am putting this in the high performance forum because it is a mod that varies from stock equipment. If it is misplaced I apologize in advance.

Anyways here is the hydraulic clutch setup that I fabbed up. I used a master / slave cylinder from a late 90’s VFR.




I milled out the center portion of the factory clutch cover for more clearance. I wanted the slave cylinder to be tucked in as far as possible.


Here is the oil seal and carrier that bolts to the back of the factory clutch cover.


I ran a stainless steel hard-line from slave cylinder up to a mount near the steering stem. I have bled the system and no air remains. My concern is that when I pull the lever I get a good positive feel but with the bike in gear it seems that there is way to much resistance when I try and push it. I can get it to move but it just doesn’t seem as though I am getting proper disengagement. I have figured out all the technical mechanics of the setup (i.e. push rod length. etc.) so theoretically it should work. I do not have oil in the bike as I have had the cover off for some time working on this system. Could this have something to do with it. I just don’t want to put oil in it if I am missing something here and need to pull it all back apart.

Thanks for any tips and info.
-Evan

[scottly]

How far does the hand lever move before you feel resistance? If it is excessive, maybe try a slightly longer push-rod?

[Dyrden]

Hope you sort it out.  Really good looking set up!

[Retro Rocket]

Hope you sort it out.  Really good looking set up!

Yeah, thats a tidy looking set up Evan, keep us posted on your progress please.
Cycle X has a hydraulic clutch set up, maybe send Ken an email and see what he thinks.I know their unit sits out further than yours, are you sure it has enough travel.?

[evan77]

Hey guys.
Thanks for the props.
Here is a section I drew that should explain what is actually going on.


The pushrod is the correct length and there is no room for any adjustment there. I think the issue lies with the master cylinder itself. It seems as though its piston does not have enough travel to displace enough fluid to move the slave piston far enough. I have removed the clutch cover to inspect the piston travel. Starting with the clutch lever all the way out and pulling it in completely it only seems to move the slave piston about an 1/8". This does not seem like enough and I am a little puzzled as the master and slave were designed to work together. I am going to make a spacer tonight to push the master cylinder pushrod a little further and hope that takes care of it. I will post results.

Thanks again!
-Evan

[mick7504]

That's excellent and a credit to you for a very neat and compact setup.

Over many years, a lot of guys have fitted V8's into their 4x4's (mainly Toyotas) and it's almost 100% guaranteed that they will have clutch disengaging issues with the original hydraulics operating in a different environment.

Generally, a slight increase in master cylinder bore size or a decrease in slave cylinder bore size will overcome this.

Keep up the good work.

Mick

[scottly]

I checked the travel of the clutch lifter on my bike at about 1/16", so 1/8" should be more than adequate.

[Tintop]

very interesting, tagging along.

[Ricky_Racer]

Yep! Me too!    RR

[scottly]

Evan, the drag you are feeling might be normal. I think I would fill it up with oil and road test it. Just my 2 cents. Nice work, BTW.

[MRieck]

I have seen disengagement problem with slave cylinders when the engine is hot. The brake fluid expands, pushes on the piston and cause the clutch to slip. Most of the time the master was overfilled or the vent blocked. I'd put oil in it and run it.....you can work on the clutch with the bike on the side stand and not have to worry about losing oil.

[mick7504]

Is there any flex in the custom cover when the clutch is applied?

[Bodi]

In theory the slave cylinder is self adjusting, only retracting with the clutch spring pressure so the full travel should be available for declutching. This means your pushrod length, as long as it's in the ballpark, shouldn't matter. The stock clutch release ramp thingy doesn't have much travel, I've never measured it but 1/8" should be enough with a self-adjusting hydraulic unit. Note that a "dry" clutch pack may be stuck together a bit, or if you disassembled the clutch you may not have the disks in with their "cups" matched. This causes bad disengagement.
As far as oil goes, I believe none of the SOHC4 engines have the clutch below oil level so you can remove the cover without a flood. The 750 is dry sump anyway, the others keep their oil in the sump. You can set the dipstick beside the engine at its correct position and angle to confirm the full level is below the clutch cover.

[evan77]

Hi guys.

I know it has been a great long time but just wanted to provide an update. As Bodi eluded to, the issue was a dry clutch pack and the friction disks had stuck together. Broke them loose and that did the trick. Both clutch operation and shifting are seamless. Thanks again for all the compliments. Most importantly, thank you for all the tips and suggestions. It really is a great group of people here!

All the best.
-Evan

[Retro Rocket]

Excellent...

[Jerry Rxman Griffin aka MuthaF'er]

Great setup. Something you could do for others?

[evan77]

Great setup. Something you could do for others?

Hi Jerry,
Thank you for the compliment. Potentially if there is enough interest. I recently moved from Ohio to California and did not bring my entire shop with me. I have plans to bring my CNC machine out but needed to get situated first. It is in the works.

I will keep those interested, posted.

Thanks again,
Evan

[jaguar]

Very cool set up.  Would be interested in knowing about a "kit" if it is ever developed.