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Bled clutch/ broken master cylinder spring


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Yeah, that's the part that has me worried. It's a shouldered nylon ring that anchors the dust seal. I thought about rigging up a rigid tube, or yes a socket, to try and press it in. The mallet idea sounds like a winner.


I didn't know if I should try and seat the rubber dust seal at the same time or put it in after (?)


Also, did you use an assembly lube or just wet the piston with fluid?





Sorry for the slow response - It's been a busy few days with other priorities;


1- Dust seal can go on afterward.

2- Use the assembly lube that comes with the rebuild kit. I just lubed with brake fluid and wish used the grease. Note that many greases react badly to brake fluid so use only the special stuff.

3- You can also pry the metal ring out carefully so as not to damage the cylinder bore. I used a very small flat head screw driver to get behind the ring.


Good luck!

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Darius, thanks for the feedback. I did "OK" with the reassembly, just tearing the dust seal a bit since the installation 'socket' was not deep enough.And I had to reuse the old O-ring as the new one was oversize about a mm. Those wacky Italians!

I did have to rebleed the entire clutch line to get the action back. But, now it is spectacular!

Here is an image of the parts with the bad spring visible on the top row:

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Glad to hear you are back in business Docc. The photo evidence of your problem is pretty compelling!


If your repair goes is anything like my Duc, don't be surprised if you need another bleed to get the last of the fine air bubbles out once they get a chance to form bigger bubbles.


Happy and safe riding.

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I have a Phoenix hydraulic bleeding tool if you want to borrow (or anyone else) to finish the job. If you are thinking about buying one for yourself take a nitroglycerin tablet before pricing it.

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  • 5 months later...
Guest ratchethack
Say Docc

Per my PM yesterday, I've just had much the same experience as yourself, starting with sudden loss of full extension of the clutch lever. unsure.gif

Thanks for "blazing the trail" and posting about it here. I managed to get the dust boot out without removing the retaining ring. The internals came out with the ring still in place, including 3 fragments of the return spring -- very similar to, but one fragment less than in your photo above. ohmy.gif

Now CONSENSUS here would seem to have it that it's automatically time to UPGRADE to the latest and greatest Brembo $360 billet radial RACING clutch master and mandatory new $70 switch and bracket combo ($430 total, plus shipping). Because after all -- the latest & greatest is not only machined from billet, (which, taken as a separate consideration, evidently automatically makes it "higher performance" than the OE cast unit), but since it's also adjustable for "better feel", it makes all previous OE units entirely "obsolete", and o' course, even though none of this translates into anything quantifiable (or even qualifiable in any possible significant sense, particularly on the road), all of this makes it not only "better", but we all know that anything new that can be thrown in the "Bottomless Better Bucket" by sales & marketing, (and of course promoted by those who sell the stuff) makes it the only "rea$$onable" thing to do here. :rolleyes:

. . .And speaking of OBSOLETE, the Principle of Perpetual Upgrading (regardless of any real world performance value) seems to make perfect sense to an amazing number o' moto consumers who really, really wanna believe themselves to be "in the know". It seems that they simply must keep up with all the "latest and greatest" RACING gear, and demonstrate their elite "wisdom" by bolting on the latest "Boy Racer Bling Thing" -- in this case, on a 550-lb. behemoth, air-cooled, pushrod-operated, woefully underpowered (by current competitive standards, that is) anachronism of an engine design from a half century ago -- if for no other purpose than the hope for the sheer joy and satisfaction of parking-lot parading in front of those who have no clue about wot they're looking at, just for a chance glimpse of one or two blank expressions of ignorant, dazzled and dumbfounded wonder on the faces of those whom they have never seen before, and whom they will never see again -- not to mention the sheer joy and satisfaction (Part II) of explaining ad nauseum to anyone daft enough to listen to how much "better" it works than the OE unit ever did. . . But I digress. . . laugh.gif

Now this is just me, but I rather think I'll pass on that kinda value. Having not only a great abiding appreciation for (and fair depth of experience with) superbly performing brake and clutch components for road riding purposes, as well as an abiding appreciation for wot constitutes superb "feel" of both, I've also purchased several fully operational entire moto's, and one fully operational entire car in my younger days for less than a single Brembo billet clutch master goes for today. So I may have a little different perspective on value than your garden-variety Boy Racer Wannabe here. cool.gif

According to my recent exchange with Brembo Distributor and longtime Guzzista Extraordinaire at GuzziTech, Todd Eagan, almost NO ONE rebuilds Brembo brake and clutch master cylinders anymore. He sells replacement units ONLY -- no parts. As Todd also professionally advised, per post above, some rebuild kits are available. Per Docc's experience above, I also found some rebuild kits. Some (but not all) are available from Yoyodyne for about $20 USD plus shipping.

Back to my case here. Since all the components of my clutch master with the exception of the spring appeared to be in pristine condition, with NO perceptible signs of wear wotsoever under a magnifying glass, I considered the operational requirements of the return spring, and figured I could do at least as well as Brembo did with the OE spring (if not tbetter) by replacing it with something a little beefier, so that's wot I did. The dimensions, free length, and rate of the spring are not critical here. It's one o' those spring applications where "ballpark" for replacement is more than good enough for perfect operation. I found a slightly larger overall diameter, slightly larger wire diameter spring of similar rate in a bubble-pak-o-springs at Home Depot for a coupla buck$, made sure it couldn't get anywhere close to coil binding at full compression, cut it to length, heated and bent the end to grip the little OE aluminum ferrule as fitted on the OE spring (see Docc's photo above), installed and bled the thing, and Bob's y'er Mum's favorite brother. :bike:

Well then. There you have it. $3 and I'm back on the road "good as new". Docc, this is of course not a-tall directed at you, but since everything I've thought, done, and posted here is both unorthodox and unconventional, I'm sure it's also waaaaay past wrongedy-wrong, and I'm just a-dyin' to hear all about it when I return from today's ride.

Now let the whining and bleating of CONSENSUS begin! :rolleyes:
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You could at least have tried to find a titanium spring. 8-)


BTW, I understand that many of the newer Brembo systems have a total non-availability of rebuild parts. Might be time to do a little judicious stockpiling.

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  • 14 years later...

My clutch lever action has been compromised for a while (lever getting closer and closer to the grip). I have adjusted the lever as far out as it will go and turned the actuator screw in as far as possible. Today, riding in very high temperatures (95ºF/35ºC), the lever moved clear to the grip and finally gave up. I can see a little fluid at the master cylinder plunger, so I know I can't put the rebuild off any longer. First M/C rebuild at 62,000 miles/ 100.000 km. Another 68,000mi/~110.000 km has elapsed since then. Fair to say that I work the clutch actuation A LOT; love to row the gears. :race:

Very curious to see if the internal spring is in multiple pieces, again . . .

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4 minutes ago, gstallons said:

I assume you see no problems in the bore of the m/c ? I am sure you are using DOT 4 fluid ?

I'll inspect the bore when I get it apart. Yep: DOT4

  • Like 1
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