Disappointed with Oberon slave cylinder - further possible solutions

[cuoccimix]

After much hesitation, I purchased and installed an Oberon slave cylinder for my '98 5th gen. It costed over 200 euros including purchase, shipping, customs fees and installation. I was expecting a decent improvement, but as soon as i picked up the bike from the workshop, the disappointment was almost total.
The load required to operate the clutch has decreased by 10% - 15% in my opinion. Not more. Pretty much a negligible gain. The only advantage is that the lever is smoother, but that probably comes from the fact that the old slave was 25 years and 75,000 km old. The effort to pull the clutch is almost the same.

I am so disappointed that I would be tempted to take it apart and resell it, but it would not be worth it.
The most irritating thing is that the point of engagement has remained almost the same, a sign that the leverage ratio has not changed much.

In my opinion it could have been increased slightly (there is still a lot of travel) but evidently in the design phase the leverage ratio was not increased further to avoid problems.
Surely my rhizarthrosis is quite demanding, but ultimately a bigger slave is useful only in combination with other interventions (clutch springs, clutch lever, master cylinder, physiotherapy, etc.).
Not that it's useless, but I don't agree with the people that review it as a definitive solution. Probably it's a decent gain for their needs, but not for me. Just my 2 cents.

Question: Is it possible to install another master cylinder or another lever to increase the leverage? Assuming of course that disengagement is not made impossible at that point.

[Mohawk]

Whats wrong with the stock one ? It s quite a light clutch in stock trim IMO. I fitted shorter levers & it still feels lite. 

[Presson]

IMHO that is a bit insensitive Mohawk. The op asked for advice about a cost effective potential solution to a problem they experience. That you find the stock clutch feel fine is irrelevant. I'm sorry cuoccoimix that I do not have an answer for you. Perhaps others will know more. My only uninformed thought revolves around clutch springs but I have no idea if that has any merit.

[cuoccimix]

1 hour ago, Mohawk said:

Whats wrong with the stock one ? It s quite a light clutch in stock trim IMO. I fitted shorter levers & it still feels lite. 

 

As said, i have a problem on my left hand. So i needed something to ease the effort a bit. Also i have noted that 00-01 5th gens have a slightly lighter clutch. 

I'm even thinking to replace the whole clutch basket and plates with a 00-01 one, if possible. It seems they are smoother and also more resistant (i have slipping problems in 6th gear). 

[Mohawk]

Well excuse me. I thought this was a bike forum 🤷‍♀️ Either way if not happy with the product return it as not fit for purpose. If they advertise Oberon as 50% effort reduction & you didn't get that then fair enough. It's not like any VFR has a clutch like an old Ducati FFS.  

[Mohawk]

I just noted your hand issue, so understand the reason for the requirement now. The only solution would be a change of Master Cylinder or change to a semi automatic system where the actual lever is just a control for an electro hydraulic actuator. Not seen one but it could be rigged up, its a short throw fairly light pressure system. Hope you find a working solution. 

[cuoccimix]

6 minutes ago, Mohawk said:

I just noted your hand issue, so understand the reason for the requirement now. The only solution would be a change of Master Cylinder or change to a semi automatic system where the actual lever is just a control for an electro hydraulic actuator. Not seen one but it could be rigged up, its a short throw fairly light pressure system. Hope you find a working solution. 

 

What could be an adaptable master cylinder? I would prefer something that doesn't alter the look of the bike, possibly from other old Hondas.
Something that allows me to take advantage of almost all the travel of the lever, without compromising its functioning.

[Presson]

Just to clarify. Are you looking for:

A. A lighter clutch with the same amount of handlebar lever travel as standard.

B. Less handlebar lever travel for clutch actuation/disengagement.

C. Both.

If A or B, which is the priority?

 

[cuoccimix]

52 minutes ago, Presson said:

Just to clarify. Are you looking for:

A. A lighter clutch with the same amount of handlebar lever travel as standard.

B. Less handlebar lever travel for clutch actuation/disengagement.

C. Both.

If A or B, which is the priority?

 

 

Travel is not important. I just need a lighter action on the lever. A lighter clutch needs a wider range of leverage though. So i need something with a long travel (more leverage) but still able to disengage the clutch safely. 

I have read that 14 mm (the size of the 5th gen master cylinder) is already the smaller one among Honda master cylinders... 

[Presson]

Found an article about slip/assist clutch (not a slipper clutch) which might be of interest. However, while it says that it enables a lighter clutch action, no actual stats are provided and I've no idea whether anyone makes a product that would fit a VFR.

 

http://www.motorcycle.com/features/is-slippper-clutch-same-thing-as-slip-assist.html

 

Playing around with master cylinder size may just affect lever travel in practice which brings us back to springs but you said there was already a problem with slipping. I'm stumped on this one

[SEBSPEED]

From one human to another, fix your body before you fix your bike. It's more important. 

 

Next, adapt your bike to you. Adjust your body position and controls to make them as ergonomic as possible. This may require exercise to strengthen yourself, and making minor modifications like trimming locator tabs so controls can be repositioned on the bars.

 

The last step may be changing parts like the handlebars, seat, and clutch components to close the gap between the way the bike is now, and your physical requirements. 

 

Which model # Oberon slave did you buy? There are 2 versions for the VFR - the later model unit has a smaller piston and would offer a stiffer pull.

 

Is your clutch master cylinder clean and leak-free?

 

Has the system been properly bled to be air-free?

 

Have you changed the clutch line to stainless, or still the original rubber hose? The original hose will be quite broken down by now, and expands under pressure, robbing force that should be directly transferred to the slave piston from the master piston. Upgrading this part to stainless will not reduce the force by a large amount, but the more efficient fluid transfer will be noticeable and can reduce the amount of work required by your hand. 

 

You have a new slave cylinder installed now, so there's no point in asking if your oem slave is/was in good order. However, it's worth noting that the age of seals and corrosion inside the slave can affect its performance. 

 

The clutch engagement/disengagement zone is quite small. It does not take much movement to cause slipping and disengagement, s omaking sure your system is working properly and efficiently makes a big difference. 

 

I am using a Brembo RCS master cylinder, ss line, and larger model Oberon slave to combat the 99lb springs I had to install to prevent clutch slipping after isntalling a supercharger and greatly increasing the bike's power. Even with the massively heavier springs, my clutch pull feels lighter than stock. Not feather light, but lighter for sure. The Brembo is not an aesthetic match for the oem masters... so I installed another one on the brake side 😉

 

Good luck with finding a solution that keeps you riding!

[cuoccimix]

5 hours ago, SEBSPEED said:

From one human to another, fix your body before you fix your bike. It's more important. 

 

Next, adapt your bike to you. Adjust your body position and controls to make them as ergonomic as possible. This may require exercise to strengthen yourself, and making minor modifications like trimming locator tabs so controls can be repositioned on the bars.

 

The last step may be changing parts like the handlebars, seat, and clutch components to close the gap between the way the bike is now, and your physical requirements. 

 

Which model # Oberon slave did you buy? There are 2 versions for the VFR - the later model unit has a smaller piston and would offer a stiffer pull.

 

Is your clutch master cylinder clean and leak-free?

 

Has the system been properly bled to be air-free?

 

Have you changed the clutch line to stainless, or still the original rubber hose? The original hose will be quite broken down by now, and expands under pressure, robbing force that should be directly transferred to the slave piston from the master piston. Upgrading this part to stainless will not reduce the force by a large amount, but the more efficient fluid transfer will be noticeable and can reduce the amount of work required by your hand. 

 

You have a new slave cylinder installed now, so there's no point in asking if your oem slave is/was in good order. However, it's worth noting that the age of seals and corrosion inside the slave can affect its performance. 

 

The clutch engagement/disengagement zone is quite small. It does not take much movement to cause slipping and disengagement, s omaking sure your system is working properly and efficiently makes a big difference. 

 

I am using a Brembo RCS master cylinder, ss line, and larger model Oberon slave to combat the 99lb springs I had to install to prevent clutch slipping after isntalling a supercharger and greatly increasing the bike's power. Even with the massively heavier springs, my clutch pull feels lighter than stock. Not feather light, but lighter for sure. The Brembo is not an aesthetic match for the oem masters... so I installed another one on the brake side 😉

 

Good luck with finding a solution that keeps you riding!

 

Thank you for the wise and balanced suggestions. Yeah, i have thought to various solutions for driving position. But i discarded them all for various reasons. Variobars are damn expensive. ABM kits are practical but aesthetically horrible from my point of view (i hate tubular handlebars on VFR). Spacers/risers under the original clipons are almost useless. I did not trim the locator tabs because more "open" clipons would paradoxically make the position heavier on the front. 

As only viable option, i was thinking to get clipons with different shape from another bike, i.e. VF 1000 F or something other to allow a further back position. 

Currently i'm using an heavily padded left glove. No problem (almost) on the right hand, no problem in braking.  

 

About the clutch, master cylinder was  serviced one year ago with new gaskets and everything. Still has some squeaking noise though - not very sure if the workshop did a good job, also because i replaced clutch plates 2 years ago (with spring spacers that i will remove) and now they slip again in 6th gear. So there is still some work to do. Braided line is also a good advice. Sure there are still lot of things to do, but the basic fact is that the Oberon slave alone is not resolutive, and with a negligible difference other things being equal. Mine is CLU-3038 specific for my bike. 

 

Radial master would be nice, but it would alter the originality of the bike (yes , i'm a bit conservative about that...supercharger is cool though 😉  ). And more €€€ on the way. 

First thing to do will be to fix the slipping problem, so i will remove the useless preloader spacers installed on the original clutch springs. And then....well, i will try with more cortisone and more hyaluronic acid! 

[Dangeruss]

The title of your post caught my attention as I just received an Oberon slave cylinder for may 5th gen. I bought new seals to rebuild the stock one, but when I got it apart I didn't like the condition of the piston so I went aftermarket. I measured both cylinders and the area of the Oberon piston is 13% larger, so your assessment of the effort decrease is bang on. They are constrained by the housing size as far as making it much larger in diameter. I do not know of any master cylinders that would work, maybe try looking on Ebay and see if you can read the diameter off the pictures posted by sellers. 

I found this page for calculating the ratios between 2 components; https://www.kfz-tech.de/Engl/Formelsammlung/HydrUebersetzung.htm

The VFR is stock with a ½" (12.7mm) master and 35.75 (measured) slave. The oberon slave is 38mm. You can get an idea of what is available on potential donor bikes by looking at the Brembo spares offered here: https://www.oppracing.com/category/40-clutch-master-cylinders/

I have changed bars to eliminate numbness on my Yamaha RZ350 and used Convertibars https://convertibars.3dcartstores.com, which I was very happy with and am planning to buy for my VFR. They are not cheap, but if it makes riding enjoyable again it is money well spent.

I have recently had hip surgery and am looking forward to riding in comfort again this year, being in pain due to the riding position really takes away from the enjoyment of it, I wish you the best in your pursuit of riding comfort. Please share your results.

[ShipFixer]

I see all of the Oberon size discussion occurred in the year before I bought my VFR back :lol:

 

I have the 36mm Oberon installed in my 6th gen now and like it.  But may try the 38mm now that I know that's a thing.

[SEBSPEED]

17 hours ago, cuoccimix said:

 

Thank you for the wise and balanced suggestions. Yeah, i have thought to various solutions for driving position. But i discarded them all for various reasons. Variobars are damn expensive. ABM kits are practical but aesthetically horrible from my point of view (i hate tubular handlebars on VFR). Spacers/risers under the original clipons are almost useless. I did not trim the locator tabs because more "open" clipons would paradoxically make the position heavier on the front. 

As only viable option, i was thinking to get clipons with different shape from another bike, i.e. VF 1000 F or something other to allow a further back position. 

Currently i'm using an heavily padded left glove. No problem (almost) on the right hand, no problem in braking.  

 

Re: locator tabs - I meant the tabs for the positions of the switch pods and master cylinders on the bars. Most people end up with wrists bent upwards as they lean forward and rest on the bars. This can have a negative influence on your comfort. Controls can (and imo, should) be rotated to accommodate your wrists being straight, in line with your arms.

 

Vario or Convertibars may not be cheap, but few items of worth typically are. They're certainly less expensive than a new bike. 

 

17 hours ago, cuoccimix said:

 

About the clutch, master cylinder was  serviced one year ago with new gaskets and everything. Still has some squeaking noise though - not very sure if the workshop did a good job, also because i replaced clutch plates 2 years ago (with spring spacers that i will remove) and now they slip again in 6th gear. So there is still some work to do. Braided line is also a good advice. Sure there are still lot of things to do, but the basic fact is that the Oberon slave alone is not resolutive, and with a negligible difference other things being equal. Mine is CLU-3038 specific for my bike. 

 

This paragraph changes the entire conversation... 

 

Why was the clutch master serviced? Faint squeaking is usually a simple lack of lubrication at the pivot and/or plunger.

 

How many miles on the bike, total? How many miles on the old clutch plates? How many miles on the new plates? What brand are the new plates? Were the friction and steel plates replaced as a set, or just the friction plates? Why have spacers been added to the springs? There is no need for this. There is a specification range for the springs - they are either collapsed from use and therefore useless with or without spacers(spacers do NOT affect spring rate!), or they will be within factory spec per the factory service manual and will perform as expected as part of a properly serviced system.

 

What kind of engine oil is being used? Incorrect automotive grade oil will cause clutch slip. Clutch slip is NOT gear-dependent, it is rpm dependent. It sounds like you have one or more system issues that need to be properly diagnosed. It sounds like you may be short shifting to 6th gear, and then as you build rpm to highway speed, you are experiencing slip. Is that correct?

 

Inadequate system pressure due to deteriorated seals/hose, and/or air contamination will cause the clutch to be difficult to DISengage via the lever, not slip. 

 

A partially or fully blocked return hole in the master cylinder can cause pressure to remain built up on the slave piston after releasing the lever, which can cause slipping. This, and incorrect engine oil, are the most common causes of clutch slip.  

 

 

 

17 hours ago, cuoccimix said:

 

Radial master would be nice, but it would alter the originality of the bike (yes , i'm a bit conservative about that...supercharger is cool though 😉  ). And more €€€ on the way. 

First thing to do will be to fix the slipping problem, so i will remove the useless preloader spacers installed on the original clutch springs. And then....well, i will try with more cortisone and more hyaluronic acid! 

 

I assure you, my bike is quite original... just not in the way Honda intended it. 😉 

[cuoccimix]

Thank you to all for the punctual replies and analysis. I have a (partial) update. 

 

I have tested the bike on a short distance. That did not allow me to fully accelerate in 6th gear, but i have noted that the clutch DOES NOT SLIP anymore in 6th. 

That must be confirmed with a faster (and longer) trip, but apparently the slipping has disappeared. Not sure, but the clutch works way better,

 

This leads to what i was thinking long before purchasing the Oberon slave (and to what Sebspeed said).  I live in a very warm area (South Italy) and during summer it happens often to ride in a quite chaotic traffic. Once the coolant reached a temperature of 100 C, the clutch was struggling - not a lot, but in quite noticeable way. That was a red flag. Blame to me for not spotting the problem, but i'm not a mechanic. Probably the original slave was already half-cooked. 

 

Less than two years ago, the original clutch began slipping in 6th gear at 7000 rpm (just at first, then it stopped after some other accelerations). Diagnosis by the workshop, "replace clutch plates". I bought a complete set by Newfren, a good quality brand in Italy. They did not say anything about the slave.  Clutch replaced, master cylinder serviced, springs preloaded with spacers. Worked fine for some time, then my hand began to hurt, and after some time the clutch began to slip again, The response - "you're driving too hard". 

I drive fast, but i don't use my VFR for drag races...

 

The Oberon cylinder did not fix my hand problem -on the contrary, it fixed the slipping problem. And the gearshift works MUCH better now - it was working like sh*te lately.

So, as alternative spare part, the Oberon slave makes much more sense. 

 

Conclusion: probably i have burnt 2 clutches because the original slave did not work well, and the workshop did not said to replace it. Not bad, uhuh?

 

First of all, i will change workshop. It's an Harley workshop and probably they have no time and will to fix an old viffer - big HD bikes make big HD money. Would be the same with a BMW or Ducati workshop of course.

 

Second, i will make remove the preloading spacers from the clutch springs (if the springs are still good). That should improve the effort on the lever. 

 

About the riding position, levers and switches are already aligned in the best possible way for the current stock setup. I would like to move the clutch lever/pump 1 cm to obtain a better leverage, but the bar does not allow that, being thicker near the fork stanchion. 

 

Step by step i will fix the situation.