Help identifying a vintage Brembo master

[Rusnak_322]

Thanks, I didn't take the brake hose off as I forgot to order new copper washers. I will give it a try.

[wirespokes]

Those copper washers can be re-used many times. I haven't had one leak yet.

[Rusnak_322]

OK, I took the master cylinder apart. I checked all the parts that came out against what I was going to put in and everything looked the same.

Now after I have the master reinstalled and bled, the lever is really far from the bar. The piston is sticking way out of the master cylinder and causing it to be a real reach to the bars. I tried as hard as I could to push it in, but it wont budge. when I squeeze the lever to the bar, it returns that same amount.

Any idea whats causing this? there was a small hat shaped plastic piece, the spring, the piston with two seals, ans a couple of washers on the end that I pressed in with a socket.

Do I have to disconnect the hose to the master to get the piston to go in further? I haven't done that yet at it was a pain to get the system to bleed, but if that is what I need to do, so be it. Any idea how I know when to stop pushing it in?? the parts were Brembo, but the instructions were crap and only showed the rebuilding of a rear master with different parts. I wasn't able to find anything on line or any videos of a old brembo rebuild.

[Rusnak_322]

the lever is marked as a Tommaselli, but it worked fine before I rebuilt the master cylinder.

[Antietam Classic Cycle]

My guess is the retaining ring that holds all the bits into the master cylinder body isn't seated completely.

[Testarossa]

At one point I put the rebuild kit in the 15mm master on my T, and as I recall the job took 10 minutes plus whatever time I spent bleeding it. Then I switched to a 12mm master and a braided steel line and the single-disc braking performance improved greatly.

I still have the rebuilt 15mm unit on the shelf and am astonished that it might be worth north of $400.

[swooshdave]

It's funny all the different responses you're getting on this.

I've found that chart to be worthless. My personal experience has been different.

I think "worthless" is a little harsh.

I think it's good guide. Ratio is one factor and probably has the biggest impact but obviously brake pad and rotor material have a play in it too.

On my single disk 850-T I went with the 12mm Brembo (https://store.bevelheaven.com/Brake-Related-Parts/12mm-REC-Brembo-Master-Cylinder-Front-Brake/) and while the braking is substantially better I think a 13mm would be ideal for single side brake.

Norton Commandos suffered the exact same issues, going from 5/8" (15mm) to 1/2" (13mm) makes a huge difference with the single brake.

[swooshdave]

I still have the rebuilt 15mm unit on the shelf and am astonished that it might be worth north of $400.

Thank your Ducati friends for that... to your Guzzi friends they'd charge you $40 to take it from you. 

[nbags]

i have a 13 mm on my single disc t works great , a little more lever travel but is worth it to me by the way it was a universal one from vintage bike days i picked up for $20.00. Just my opinion

[Testarossa]

Thank your Ducati friends for that... to your Guzzi friends they'd charge you $40 to take it from you

I guess I need some Ducati friends. I have a bridge to get rid of, too. 

[Turin]

The 15mm master cylinder is only really good for one thing. Here is my current set up and it is awesome.





FAC dampers and worth springs too. This set up may not be the best for mushy forks.