Brembo rear Master cylinder woes

78jotadave

78jotadave

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Palm Desert, California. (near Palm Springs)
The rear brake on my 78 1200 quit working, meaning it had no pedal pressure. I tried bleeding it, but it was no longer building pressure. The M/C on my 1200 has part number 10 2926. 00 stamped on it, can someone tell me the Brembo M/C rebuild part number I need to order, the piston is badly scored,as best as I can see the internals look good, thanks Dave
Update to my first post, I found a Brembo M/C rebuild kit in a stash I have, it is a 15mm kit which I thought was what the 1200 was, but not when pictured side by side. The old one measures 12.67mm, now I am thinking perhaps it is not the original M/C
 

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I'm pretty sure kits are available. I think Piet said he has some in stock in another thread.

But before you order a kit, make sure the little feeder hole between the reservoir and pump cylinder isn't blocked. That's the usual problem that causes failure to build pressure. It can be blocked by a bit of crud in it or by the piston not retracting far enough to uncover the port when the pedal is released.
 
I bought a new Brembo master from Carpimoto, very fast delivery and about the cheapest.
Although, as youā€™re in the States, always a good idea to support the local suppliers and Steve Allen seems good for advice too šŸ‘
 
Seems to be a M/C from a 500. I have kits for these as well.

While the smaller M/C causes more lever travel, it's probably overall more effective than the larger version.

piet
 
The rear master cylinder should be 15mm (actually 15.87mm which is 5/8") and uses the same rebuild kit as the front master. The only 12mm (actually 12.7mm which is 1/2") rear master cylinder I have seen is on 120's. I think Piet is correct and you have a 500 master cylinder???

By the way Dave, if the master is scored inside, I have found a place in Chino that will sleeve it in stainless. Just did the front and rear on my 3CL.
 
Is the rear brake on your 1200 stronger than on your bike with the std m/cyl Dave? I've read many complaints about crappo rear brakes on some model or other. Smaller would as Piet says, make the brake more effective with less foot pressure but more lever travel.
 
piranha-bro2 said:
Is the rear brake on your 1200 stronger than on your bike with the std m/cyl Dave? I've read many complaints about crappo rear brakes on some model or other. Smaller would as Piet says, make the brake more effective with less foot pressure but more lever travel.
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Quentin,

If equipped with rear sets, the smaller M/C would probably be fine in regard to lever travel, the rear set lever is only half the length of the stock lever. Geometry...

piet
 
78jotadave said:
The rear brake on my 78 1200 quit working, meaning it had no pedal pressure. I tried bleeding it, but it was no longer building pressure. The M/C on my 1200 has part number 10 2926. 00 stamped on it, can someone tell me the Brembo M/C rebuild part number I need to order, the piston is badly scored,as best as I can see the internals look good, thanks Dave
Update to my first post, I found a Brembo M/C rebuild kit in a stash I have, it is a 15mm kit which I thought was what the 1200 was, but not when pictured side by side. The old one measures 12.67mm, now I am thinking perhaps it is not the original M/C
Click to expand...
Hi.
Or try : www. Stein Diense
 
piranha-bro2 said:
Is the rear brake on your 1200 stronger than on your bike with the std m/cyl Dave? I've read many complaints about crappo rear brakes on some model or other. Smaller would as Piet says, make the brake more effective with less foot pressure but more lever travel.
Click to expand...
Q I will inform you of my findings when installing the new kit. Honestly I hardly ever, use the rear other than to add a bit of stability when hard braking I never use it as a means to stop the bike. I could live without a rear brake but it is welcome on those rare rides when the roads are wet or the sealed road is replaced by gravel.
Piet, no rear sets for me, old injuries = they just don't fit these old bones.
 
78jotadave said:
Honestly I hardly ever, use the rear other than to add a bit of stability when hard braking I never use it as a means to stop the bike. I could live without a rear brake but it is welcome on those rare rides when the roads are wet or the sealed road is replaced by gravel.
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Ditto here Dave. At a street race meeting in Bunbury my newly installed black linings on the rear drum started binding, so I simply removed them. SFQ rear is a touch too good and thinking of reducing the lever ratio. I don't like the feeling of rear ends locking up under hard braking.
 
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