Front brake master cylinder rebuild

[docc]

The 2000 Sport was courteous enough to wait til we got home from the South'n SpineRaid to let its brake lever creep toward the grip with a hard, sustained squeeze. Thinking this means a master cylinder rebuild . . .

Any insight as to what Brembo kit is correct?

[MartyNZ]

A few years ago I bought a "Rebuild kit 12mm master cylinders $32" from Moto International. But they have now closed. It had a Brembo kit part number on it, but I can't look for it until next week.

Not much help, am I?

Oh wait, that was a clutch master cylinder I rebuilt. I suspect that the brake master cylinder is 11mm, but you should check.

https://www.mgcycle.com/index.php?main_page=product_info&cPath=110_112&products_id=2649

https://www.stein-dinse.biz/product_info.php?products_id=296#prettyPhoto

 

A great source of information on Brembo parts is here.

http://www.cyclebrakes.com/html/brembo_cylinders.html

The V11 front master cylinder PS16 is listed as Brembo  PN 10.5053.27 on page 44, but I can't see a seal rebuild kit listed for this part.

http://www.cyclebrakes.com/Brembo_catalog.pdf

 

[Lucky Phil]

5 hours ago, docc said:

The 2000 Sport was courteous enough to wait til we got home from the South'n SpineRaid to let its brake lever creep toward the grip with a hard, sustained squeeze. Thinking this means a master cylinder rebuild . . .

Any insight as to what Brembo kit is correct?

Its a 16mm isnt it docc? I have a nasty feeling you can't buy kits for these particular M/Cylinders. Hope I'm wrong.

Ciao

[docc]

Thanks, gentlemen! I did a crude measurement of the outside of the barrel and could see it is at least 3mm bigger than the clutch side which, as Marty says, we know is 12mm.

This is the inside diameter of the cylinder, yes?

Here I thought this is a common Brembo, but I’m not seeing it on any Ducati (after the 916?) or common Aprilia. 

[docc]

Messing around with the lever, parked, I was able to squeeze it close to the grip a time or two, but the last time it recovered pressure and seems to stay. What is that? Some air in the line after the last bleed/flush 1,000 miles back that finally burped through the master cylinder? Deformed seal that reset?

As bad as intermittent electrical problems are, I definitely don't want an intermittent brake failure!

[Chuck]

Docc.. try pumping and pulling the lever as far to the grip as you can, and zip tying it to the bar. Let it sit overnight or longer. I *think* the micro bubbles migrate to the master cylinder, and when you release the pressure.. vent to atmosphere. It has worked so well for me that I don't even try to get brakes completely bled any more before doing this.

[docc]

I forgot about this method! I've seen it used on rears, but not front . . .

Thanks, Chuck! 

Trying to understand how this occurred, but the operative term may be, "I just bled those brakes!"

[Waddington rears his head once again?]

[Lucky Phil]

10 hours ago, docc said:

Thanks, gentlemen! I did a crude measurement of the outside of the barrel and could see it is at least 3mm bigger than the clutch side which, as Marty says, we know is 12mm.

This is the inside diameter of the cylinder, yes?

Here I thought this is a common Brembo, but I’m not seeing it on any Ducati (after the 916?) or common Aprilia. 

Its the same as the unit on my 2003 Ducati 1000ss dual plug docc and my old ST2 although the ST2 was Black not gold.

My V11 one has 9L12 16 stamped on it which I would guess makes it a 16mm piston although I think they measure up at 15.85 or something.

Ciao

[Lucky Phil]

43 minutes ago, docc said:

I forgot about this method! I've seen it used on rears, but not front . . .

Thanks, Chuck! 

Trying to understand how this occurred, but the operative term may be, "I just bled those brakes!"

[Waddington rears his head once again?]

Did you unbolt the M/C off the bars docc with the cap off and rotate it upwards ( so the lever is higher than the banjo bolt and gently actuate the lever slightly? This will break free any bubbles at the banjo bolt joint which will now be the low and not the high point and you will see the bubbles appear in the reservoir.

Air in the system will give you a spongy lever but not generally a "creeping" lever.

Ciao 

[docc]

Interesting. I see "0C02-16" stamped on mine. 

On the lift, I do see the outboard aspect of the m/c is lower than the banjo bolt.  I took it off the lift, and on the sidestand with the bars turned, the reservoir exit is above the banjo bolt.

Still rather disappointed we cannot source a proper Brembo rebuild kit for this master cylinder . . .

[Lucky Phil]

2 hours ago, docc said:

Interesting. I see "0C02-16" stamped on mine. 

On the lift, I do see the outboard aspect of the m/c is lower than the banjo bolt.  I took it off the lift, and on the sidestand with the bars turned, the reservoir exit is above the banjo bolt.

Still rather disappointed we cannot source a proper Brembo rebuild kit for this master cylinder . . .

Just checked the Ducati 1000ss and although it's the same basic design docc it's different to the V11. It has a different style pivot bolt for the lever although I'm sure the V11 lever will still work and it has much smaller brake light switch which is mounted differently and also a bleed nipple in an additional casting directly above the banjo bolt. The bleed nipple would be a nice to have addition. Looks like I've never done a full brake bleed on the 1000.

Oh and the stamped number is different except it also has a 16 so I'm guessing tha'ts the piston dia which rings a bell for 4 piston caliper bikes and the non radial M/C.The 1198 radial M/C uses an 18mm. 

Ciao 

[MartyNZ]

16mm is 5/8 inches, so you may find a local US brake shop or HD dealer who can help you. You would need to measure everything first, as there are suggestions that both 15.8 & 16mm diameters were in the Laverda Brembo range.

I had a clutch master cylinder that had internal leakage. It was caused by a tiny rubber granule from the deteriorating reservoir hose getting into the MC. It got between the little brass washer and end of the piston bobbin that acts as a non-return valve. This allowed slight leakage so the lever could be pulled slowly to the bar without keeping the clutch released. Replacing the reservoir hose, and super cleaning the parts in the MC got it all working again. If you find this, also make sure the tiny hole for thermal expansion relief is also clear of debris. It is really hard to clean out the cavity in the MC housing under the grommet that retains the plastic reservoir hose barb fitting.

And replace that hose.

[po18guy]

It is unlikely that Ducati copied Guzzi's brilliant and weight-saving trick of zip-tying the wiring to the master cylinder's output boss...

Here is a brake reservoir upgrade (non-leaky) that I will soon pony up for. Since I cannot find them stateside, maybe this UK seller has a line on Brembo-Guzzi kits.

https://www.ebay.com/itm/MOTO-GUZZI-V11-SPORT-FRONT-BRAKE-RESERVOIR-CAP-STIFFENER-PLATE-BREMBO-UPGRADE/372899891330?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

[docc]

Well, Zip-tied for even thirty minutes and the pressure is gone. No drop in fluid level.  Pressure immediately returns with another squeeze.

I have a used m/c on the way with 110,000 fewer miles on it. I suppose some wee scrap of trash could have gotten in from my last bleed/flush attempt, but will likely perform the cleaning task on the replacement before installation.

[docc]

So, the replacement master cylinder (from a wrecked '02 LeMans with 9713 miles) is installed and holding pressure. What a major PITA to get it to prime and bleed. Apparently, the hose connecting the reservoir, and that barbed angle fitting, to the M/C is a nasty air trap. Thanks @MartyNZ for the tip!

You're a bright cadre of lads, yah? WTH, we cannot figure out a rebuild for our Brembo® front brake master cylinder? Same master cylinder for the entire V11 series?