Does it stop well before the grip, and get progressively harder along the way?
Or does it go all the way to the grip, with little increase in resistance even though the front pads are firmly placed against the rotor?
New pads, new SS brake line, new MC that MM assures me is appropriate, even though 5T questions the small bore on a.twin piston caliper.
Thanks
The way I read your post, you have a single disc with the older dual 48 mm piston caliper, 76 and earlier. Is this correct?
(Some posters talk about two disc setup here, confusing the issue)
My XS is a 77, but my RD350A has the exact same caliper as 72-76 XS/TX, combined with a new teflon/ss braided line and a 13 mm Brembo master cylinder. This works much better than the stock 5/8" mc. Both with the stock cast iron caliper, and the alloy reproduction I'm currently using (which supposedly is less rigid than the oem iron version)
With either type calipers, the lever does not come all the way to the grip. As I often brake with two fingers, that would not be a good thing...
Also, a buddy had a Grimeca 1/2" mc on his RD, it worked great as well.
Both these match well with the recommendations from MM/ Vintage Brake. That table on the Vintage Brake website is spot on IMHO.
So, regarding your issue, you may have one of three problems:
-Air bubbles somewhere in the system. Bleeding can take a lot of time and effort
-A faulty or low quality master cylinder. You did not state what brand you have...At least theoretically, the mechanical leverage ratio may be too high compared to brand name master cylinders with the same bore. Put differently, all 13 mm master cylinders are not created equal.
-Or you have installed those "anti squeal" shims behind your pads. With these installed, I never managed to get a firm brake lever on the RD. And the brake never squeals without them anyway. So bin them if you have them!