Ducati Monster Forum

Hello

My brakes work very good  but if I squeeze the lever very slow the lever comes all the way to the bottom to my knuckles.

This only happens when I have to stop very slow like 5 km per hour speed .

I can also duplicate the issue when I am not riding with the bike parked.. if I squeeze the lever wvery very slowly it will go down the the hand grips.

At full riding speed it's fine

The bike is s2r800 that I changed over to s2r1000 master cylinder, caliper and rotors

Sounds like the master.  Find a way to isolate the master, like a fastener and seal that fits where the brake line fits.  If the symptom still exists the master is bypassing internally.

Not sure what you mean? So that the hose off the master plug it up and see if happens again? Correct?

But if it is the master why does it only happen on a slow squeeze?

I hope it's not the master, bought it off this message board from
Another member last year and just got around to putting it on..

there might lay the issue, master was used and then dried . . seals might have rotten . . . Is it an axial or radial type? OK, coffin type or radial?

Axial (not coffin, but black "goldline") off an S2R1000  ;)

Seal probably damaged so that it lets fluid pass when you squeeze lightly, but gets pushed into a sealing shape when squeezed hard - my guess.

Here is what it looks like
(http://uploads.tapatalk-cdn.com/20160701/aa2bddfb944eac963e136b0be0bfe923.jpg)

(http://uploads.tapatalk-cdn.com/20160701/1f6fa48eecb60c5055eb4352a47fd687.jpg)

This does not mean it was not working properly on the previous owner's bike.

Brembo from Motowheels $160   You can use your clamp with mirror hole, but I don't know if it comes with a brake light switch or if your switch fits. Ask them...   http://motowheels.com/c-181198-parts-brake-master-cylinders.html (http://motowheels.com/c-181198-parts-brake-master-cylinders.html)

From your dealer with all the parts included $266

So are you saying don't rebuild it and buy a new mc?

Ok I am now noticing a VERY slight leak of brake fluid from the master cylinder bleeder.. Could this cause the issue,, what is the best tool to tight this ? I am notorious for stripping bleeders. 😀

(http://uploads.tapatalk-cdn.com/20160701/6ff297efae4e98c4cd4b90e3d9cfe024.jpg)

Bleeders only need to be just past snug. If you've already over tightened it and distorted the seat, the master will need to be replaced.

Put a short wrench on it and see if it moves with light pressure.

I think so, since it's difficult to find rebuild kits. You could search here - it has been discussed several times. (they might be called something else)(English isn't my first language and my brain fails me sometimes)

I have not touched the bleeder yet. I figured I would check here first.

There is a few different rebuild kits I found on eBay 11,13,15 and 16 mm kits. Does anyone know which one is the one for s2r1k ?

Seems to be 16mm - Speedog usually gets it right  ;)

http://www.ducatimonsterforum.org/index.php?topic=68638.msg1269265#msg1269265 (http://www.ducatimonsterforum.org/index.php?topic=68638.msg1269265#msg1269265)

You didn't bleed the master on install?

I see where your're going . . .

No I did not Install the master myself, I had the master, the rotors and the forks changed all at the mechanics.. So I would assume they would have..

Why what would have Happened if they  did not bleed the master at the top and just bleed from down by the calipers? I does not accomplish the same?

that might have left some air bubbles in the master . . . now, if you have a leak at the bleed nipple, best would be to replace master if nipple is tight . . .

I would recommend to replace with a new one . . .

Take a look at these:

http://motowheels.com/c-181198-parts-brake-master-cylinders.html (http://motowheels.com/c-181198-parts-brake-master-cylinders.html)

or

http://www.cyclebrakes.net/accossatomastercylinders.aspx (http://www.cyclebrakes.net/accossatomastercylinders.aspx)

Personally I will replace my Brembo masters with Accossato . . .

I tightened the nipple a slight but no more leak. Still soft lever

If there was a leak at the bleed nipple then it needs to be bled again. Master techs are busy in a shop and the junior often does the delegated finishing work (disconcerting if it's your brakes). Those bleed nipples are not real tough so they can get cracks when over tightened. Under torqued can leak, over torqued can break. Air gets trapped in the high points of the system, so just bleeding from the caliper nipples is often not enough. If it was leaking from the nipple I would take it back to the shop that did the work and ask for the head tech to check it. I hope it's just the nipple and not the seat as DP mentioned.

If you are worried about the quality of work at that shop you can try a certified auto brake specialist and ask them to check the components and thoroughly bleed the system.

In theory bleeding is easy, in practice this is often not the case, particularly with motorcycles.  The master needs to be as close to parallel to the ground as possible to avoid trapped air.  A good trick after bleeding as well as possible is to take a wire tie to hold the lever as close to the grip as possible and leave over night.  This allows trapped air to rise into the reservoir.


I second that.  The bike should have been checked and road tested before you picked it up.

I will be taking it back to get it re-bled and I suppose if that does not work, I will need to rebuild the master..

So then if the master nipple continues to leak then I need a new master? This is not something that can be corrected with a rebuild?

Would this be the correct rebuild kit?

https://www.ebay.com/itm/182176993789 (https://www.ebay.com/itm/182176993789)

was the nipple a "non-issue"? Did the dealership HEAD TECH go over the bike, did he himself did the bleed procedure? Remember, if bleed nipple is tight and leaking, is OVER TIGHTEN and as dp? said, NO longer good . . . Unless, you want to go, "third world" repair and teflon tape the nipple . . . just saying, that's one way we do things "south of the border"

I do not know the answers to your question as to who did what...

I assure you , I am not into doing things in a 3rd world manner . 😎

However I would still like to now if that is the correct rebuild kit in the previous post.

The only way to know if that kit fits would be to cross reference it with the part# for a Gold Line kit.  Off hand, I think highly unlikely since Gold Line masters did not exist in that vintage.

Sadly, Yoyodine is no longer a Brembo seller and that would have been the best guide to check . . .

That part number seems to be for Ducati PN 624.4.026.1A rather than Ducati PN 624.4.043.1A . . . IIRC, some "newer" master are NON-rebuildable . . .

Sorry if I offended you with our third world measures . . .

Now, if you can contact the vendor and ask if the part will worn on the second PN I gave you, then, is the correct one if not, check the following:

http://www.gothamcycles.com/Tools/ducati-brembo-13mm-front-brakeclutch-master-cylinder-recrem-seal-rebuild-kit.html (http://www.gothamcycles.com/Tools/ducati-brembo-13mm-front-brakeclutch-master-cylinder-recrem-seal-rebuild-kit.html)

http://motowheels.com/i-14888423-brembo-oem-master-cylinder-rebuild-kit-13mm-piston.html (http://motowheels.com/i-14888423-brembo-oem-master-cylinder-rebuild-kit-13mm-piston.html)

if Yoyodyne were still around selling Brembo . . . WE would know

Rebuild kits here, I don't know if they have the one you need:
http://www.tawperformance.com/sport-bike-taw-performance/brembo-sportbike/brembo-accessories-1/brembo-original-equipment-accessories/oe-master-cylinder-spares-and-replacement-levers.html?p=1 (http://www.tawperformance.com/sport-bike-taw-performance/brembo-sportbike/brembo-accessories-1/brembo-original-equipment-accessories/oe-master-cylinder-spares-and-replacement-levers.html?p=1)

or perhaps here:
http://www.oppracing.com/category/781-brembo-oe-spare-parts-for-master-cylinder-not-including-levers/ (http://www.oppracing.com/category/781-brembo-oe-spare-parts-for-master-cylinder-not-including-levers/)

Yeah, the loss of Yoyodyne as a Brembo distributor is traumatic.  Fred is great!