gen 1 clutch master cylinder

[19vmax97]

We are taking one last stab at finding a solution to the problems in upgrading the Clutch Master to Brembo on my 1997 Vmax. (OEM Ducati Brembo 848 1098 1198) Brake side is working like a charm, clutch not. New Barnett clutch is installed, Galfer lines, and the last attempt at trouble shooting is to focus on the Slave Master. We have bled every which way, made sure there is play in the lever/pin, and are stymied what the problem might be at this stage. Classic signs: out the gate the ride is amazing, then things heat up, lever stiffens, pressure in the lines increase, clutch starts to slip... Killer set up, if it would work! Thank you in advance.

 

[Traumahawk]

First thing to look at, fluid level. Sometimes if the level is too full, there is no room for expansion, and as the fluid heats up, it puts pressure on the clutch itself.

So, is the fluid level only halfway up the sight glass?

 

[19vmax97]

First thing to look at, fluid level. Sometimes if the level is too full, there is no room for expansion, and as the fluid heats up, it puts pressure on the clutch itself.

So, is the fluid level only halfway up the sight glass?

Thank you Traumahawk. Yes, the fluid level is halfway up the sight glass--that was one of the initial thoughts, expanding fluid. The bike is at DLA Motorsports in Los Angeles, and the final attempt at solving the problem, a Slave Master rebuild kit is on the way. It is the only part of this chain that has not been addressed. We have a mechanic very familiar with Vmax going over the entire clutch side, top to bottom--rebuild kit to arrive later this week. Testing the bike, it completely wails amazingly, until it gets hot... Thanks again for your input.

 

[Fire-medic]

When you remove the cap is there any pressure release? Make sure the holes are clear in the master cyl. Not sure what you have, if it's a remote reservoir, but if you had some gunge blocking a passage in the master, iut will do just that-build pressure and not allow it to release.

Are you using old lines, or did you replace the OEM ones? If I had a problem like you describe, I would break things down into their component parts, and ensure that each line is clear, tests clear, and can sustain continued air or fluid passage at a volume or pressure commensurate with what you would expect. Same for the master cyl, same for the slave cyl. I might go as-far as to remove the entire system with the possible exception of the metal clutch line attached to the chassis, and hook the whole thing up, and test it for correct function. Blowing the rigid line out and being able to see that the airflow is consistent, doesn't lessen or plug-up should confirm the rigid line is OK.

With the system hooked together off the bike, you should be able to see that everything works. Or, that you find the problem.

I've had internally-collapsing rubber brake lines on trucks and cars, and bikes too, you would expect that if you do your own work on used vehicles over 50 years of driving and riding probably a similar number of vehicles.

Did the clutch lever ever get hard to pull like a brake lever? That's a sure sign of a plugged relief hole.

 

[Fire-medic]

An example of what you can do to check the slave cyl, get a spring like a clutch spring (not our diaphragm spring!) or a valve spring, and put it on the piston side of the slave cyl, and hold it in-place with a C-clamp. Put enough pressure on the spring and the slave piston to hold everything together, but enough slack or potential movement available in the spring to allow the clutch slave piston to move fully as the lever comes back to the handlebar. The spring will then push back the slave piston as you release pressure on the lever from squeezing it. You can then check to see if the pressure builds up in the master cyl instead of allowing the master cyl piston to freely move back and forth as you squeeze and release.

 

[19vmax97]

When you remove the cap is there any pressure release? Make sure the holes are clear in the master cyl. Not sure what you have, if it's a remote reservoir, but if you had some gunge blocking a passage in the master, iut will do just that-build pressure and not allow it to release.

Are you using old lines, or did you replace the OEM ones? If I had a problem like you describe, I would break things down into their component parts, and ensure that each line is clear, tests clear, and can sustain continued air or fluid passage at a volume or pressure commensurate with what you would expect. Same for the master cyl, same for the slave cyl. I might go as-far as to remove the entire system with the possible exception of the metal clutch line attached to the chassis, and hook the whole thing up, and test it for correct function. Blowing the rigid line out and being able to see that the airflow is consistent, doesn't lessen or plug-up should confirm the rigid line is OK.

With the system hooked together off the bike, you should be able to see that everything works. Or, that you find the problem.

I've had internally-collapsing rubber brake lines on trucks and cars, and bikes too, you would expect that if you do your own work on used vehicles over 50 years of driving and riding probably a similar number of vehicles.

Did the clutch lever ever get hard to pull like a brake lever? That's a sure sign of a plugged relief hole.

Thank you so much. I will forward this text to DLA Motorsports who have the bike. I do know that they are taking an approach as you suggest top to bottom. The Galfer cabling is probably 11 years old. In 2014 when we put the Brembo Masters on the first time, I did experience a stiffening of the lever like a brake lever, and barely able to shift, only when the lever was practically all the way out, would the clutch engage and stop slipping. We burned through the Barnett clutch that I had installed in 1998... We replaced the Barnett, and finally gave up and reinstalled the OE Clutch Master. We meaning, my long time mechanics at the old Honda of Hollywood. The bike recently went in for some maintenance and DLA wanted to give the Brembo another go. I have to admit that this is so over my head--I don't have mechanical chops whatsoever. So, again, thank you. Forwarding your messages... Thank you.

 

[19vmax97]

An example of what you can do to check the slave cyl, get a spring like a clutch spring (not our diaphragm spring!) or a valve spring, and put it on the piston side of the slave cyl, and hold it in-place with a C-clamp. Put enough pressure on the spring and the slave piston to hold everything together, but enough slack or potential movement available in the spring to allow the clutch slave piston to move fully as the lever comes back to the handlebar. The spring will then push back the slave piston as you release pressure on the lever from squeezing it. You can then check to see if the pressure builds up in the master cyl instead of allowing the master cyl piston to freely move back and forth as you squeeze and release.

Thank you. Excellent! I'll get back to you with any questions from DLA Motorsports. Thank you!

(It really is a sweet set up--I have spent WAY too much on this endless problem!!! Pic from 2014 when it was all on the bike...)

 

[MaxMidnight]

From what you have said this seems like an issue with the m/c.

You had the problem when you first fitted the Brembo (burning out the clutch) which went away when yo re-fitted the OE item.

The problem returns when you try the Brembo again.

IMHO your man needs to establish why the fluid is not able to bleed back into the m/c as the system heats up.
I would start by looking at the lever (is it OE?) to ensure that it isn't preventing the piston returning to its resting position.
If OK look at the piston, are the seals original?; does the piston fully return when the leaver is released?; is the piston moving freely in the bore?

If all OK try the Brembo on another bike; if the problem moves with the m/c you most cost effective option would probably be to junk it and spend your hard earned on a know OK one.

 

[19vmax97]

From what you have said this seems like an issue with the m/c.



You had the problem when you first fitted the Brembo (burning out the clutch) which went away when yo re-fitted the OE item.



The problem returns when you try the Brembo again.



IMHO your man needs to establish why the fluid is not able to bleed back into the m/c as the system heats up.

I would start by looking at the lever (is it OE?) to ensure that it isn't preventing the piston returning to its resting position.

If OK look at the piston, are the seals original?; does the piston fully return when the leaver is released?; is the piston moving freely in the bore?



If all OK try the Brembo on another bike; if the problem moves with the m/c you most cost effective option would probably be to junk it and spend your hard earned on a know OK one.

Thank you very much. Forward your thoughts to DLA Motorsports. I agree... before too much more time and stupid money is spent, on the table is to junk it, and secure another. The lever is adjustable Rizoma--one of the things that has been adjusted is the pin to allow for clearance and some play. Pistons, seals, movement in the bore, all being looked at when they tear it all apart shortly. I'll let you know where we end up. Thank you for your advice.


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[Traumahawk]

Since you have aftermarket levers, consider this. I had aftermarket levers, and when it was cold, everything was fine. When the bike would warm up (and the Oklahoma heat) the clutch would start slipping. It turns out, the the hole in the clutch lever that the pin that actuates the MC fits into, was too shallow. So, the pin was pressing in on the MC just a bit.....so when the fluid would heat up, and the MC would act like the clutch lever was pulled in slightly all of the time.

I took the Aftermarket lever off, and measured the depth of the hole, vs the depth of the hole in a stock lever. There was about a 2 mm difference. I ground about 3 mm off the lever (just to be safe). Problem SOLVED.

Other people took the lever off, and just drilled the whole deeper. I guess that anyway would work, I just went what i thought was the easiest route.

Hope this helps.

 

[Gulrok]

If you're looking for replacement levers and master/clutch cylinder..

This is what I purchased

http://www.ebay.com/itm/Silver-Clut...oir-For-Yamaha-Thunderrace-alle-/161967191819

Has worked for me, and so far has been pretty great. No clutch slipping, brakes fine.

 

[19vmax97]

Since you have aftermarket levers, consider this. I had aftermarket levers, and when it was cold, everything was fine. When the bike would warm up (and the Oklahoma heat) the clutch would start slipping. It turns out, the the hole in the clutch lever that the pin that actuates the MC fits into, was too shallow. So, the pin was pressing in on the MC just a bit.....so when the fluid would heat up, and the MC would act like the clutch lever was pulled in slightly all of the time.

I took the Aftermarket lever off, and measured the depth of the hole, vs the depth of the hole in a stock lever. There was about a 2 mm difference. I ground about 3 mm off the lever (just to be safe). Problem SOLVED.

Other people took the lever off, and just drilled the whole deeper. I guess that anyway would work, I just went what i thought was the easiest route.

Hope this helps.

Awesome. Sent your text over to DLA. Thank you again.


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[19vmax97]

If you're looking for replacement levers and master/clutch cylinder..

This is what I purchased

http://www.ebay.com/itm/Silver-Clut...oir-For-Yamaha-Thunderrace-alle-/161967191819

Has worked for me, and so far has been pretty great. No clutch slipping, brakes fine.

They look great! 14 or 16mm? I'll pass this along as well, if we can't figure this problem out, going to scrap the Brembo/Rizoma and move on...


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[MaxMidnight]

I think you are near to identifying the problem.

Would it be possible to try an OE Brembo lever? That would narrow it down to the Rizoma and by comparing the two together (hopefully) identify what the difference is.

It may be that all that is necessary would be a slight modification to solve the issue.

Cheaper and easier than procuring a replacement.

 

[Traumahawk]

I misstated in my post......it was the pin that I ground 3 mm off of (not the lever)......while some people just drilled out the hole deeper. Sorry for any confusion.

 

[19vmax97]

I misstated in my post......it was the pin that I ground 3 mm off of (not the lever)......while some people just drilled out the hole deeper. Sorry for any confusion.

Yes, got that. I do know that they did shave off the pin, though not sure by how much. DLA got your post last night. Thank you.


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[19vmax97]

I think you are near to identifying the problem.



Would it be possible to try an OE Brembo lever? That would narrow it down to the Rizoma and by comparing the two together (hopefully) identify what the difference is.



It may be that all that is necessary would be a slight modification to solve the issue.



Cheaper and easier than procuring a replacement.

Great. I have the OE Brembo with my spare parts. Thank you! Hope to be back shortly with how this entire mess has sorted out. Itching to get my bike back!!! Thank you.


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[19vmax97]

Hi gentlemen. Wanted to give an update on what has finally been decided and course of action with the maser cylinder problem. Hope to have all of this sorted out shortly.

1. We are starting over with a fresh set of Brembo RCS Masters.
2. We have ordered a complete new OE slave master and will install.
3. We are replacing both clutch and brake galfer cabling.
4. New Barnett clutch will remain.
5. Right now, the mechanic is taking one last look at the OE Master to determine displacement to order up the correct fitment. (I believe we are settling on 16mm for the clutch side, but studying the OE master for final.)
6. We will be using the Brembo RCS levers, not changing that parameter.
7. If this does not work, we will retreat to OE Masters, and I will turn around and sell these mostly never used RCS. So, fingers crossed.

And, thank you again for the comments above, we have referred to them as guidelines. If anything is missing, please chime in!!!

Thank you. Onwards!

 

[COP RUNNER]

Please keep us posted !

Very interesting !

Wish I could work on it !

I would Love to figure it out !

 

[AJBinVA]

Hi gentlemen. Wanted to give an update on what has finally been decided and course of action with the maser cylinder problem. Hope to have all of this sorted out shortly.

1. We are starting over with a fresh set of Brembo RCS Masters.
2. We have ordered a complete new OE slave master and will install.
3. We are replacing both clutch and brake galfer cabling.
4. New Barnett clutch will remain.
5. Right now, the mechanic is taking one last look at the OE Master to determine displacement to order up the correct fitment. (I believe we are settling on 16mm for the clutch side, but studying the OE master for final.)
6. We will be using the Brembo RCS levers, not changing that parameter.
7. If this does not work, we will retreat to OE Masters, and I will turn around and sell these mostly never used RCS. So, fingers crossed.

And, thank you again for the comments above, we have referred to them as guidelines. If anything is missing, please chime in!!!

Thank you. Onwards!

Using the RCS 16 for clutch and RCS 19 for Brake right now and they work great. Bleeding was a little bit long winded but once it was done the feel is solid. Clutch feel is very good and a definite improvement of the stock master cylinder which was functioning perfectly before the swap. Good luck.