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[rayivers]

We finally got some rain today after a really nice run of weather, so I figured it was time to try and get my rear brake working more like the front that I'd modified earlier (details here).   I used pretty much the same 5-step procedure as before:

1) denial
2) acceptance
3) try the easy stuff (different pads & fluid, sanding rotor, etc.)
4) machining & re-mounting rotor (semi-floating)
5) increasing master-cylinder pressure

Re 1 & 2...  when I first got the bike (used), the rear brake would usually lock the wheel on dirt - and sometimes pavement - but the amount of pedal pressure required at any given time varied all over the place.  In the back of my mind I was continuously wondering how the brake was going to work this time? - would it be too much, or not enough?  which is not my idea of fun, or even safe riding.  My new FX was more consistent, but the power level was similar.

As in front, step 3 didn't have much effect (although changing the OEM fluid to Bel-Ray DOT 4 did make the brake operate a little more consistently, especially when hot).  The Honda 43105-KZ1-415 semi-metallic pads on there now have a little more braking power than the OEM organics, but not much.  I've got Galfer FD093-G1396 'HH'-type sintered pads en route from CycleBrakes, I'll report back once they're broken in.

If your rotor is true when mounted to the hub and the brake has never squealed, step 4 really isn't critical.  In back I did it mainly for more consistency / reduced unsprung weight and was happy with the results, but it's a difficult and time-consuming operation.  Here's the diagram:



Step 5 is the one I did today, which had the same effect as with the Nissin setup in front; it instantly turned a semi-acceptable brake into a good one.  Instead of replacing the MC, I just changed the clevis mounting point on the pedal extension, which gave 54% more leverage on the piston.  The master cylinder is only mounted temporarily, but the results were fine nonetheless.

Here it is, warts and all (OEM on left) - it won't look like this for long, I promise :



I moved the top MC-bracket mounting hole to the unused passenger-peg frame hole, then used the original bottom mounting bolt to clamp the mount bottom against the frame, using a thick steel washer and two split-ring lockwashers to keep the thick washer level when tightened.  It looks like hell, but the MC is solid as a rock.  A temporary M5 hole was drilled in the pedal extension 15mm closer to the pivot for a new clevis bolt & Nylok nut, and the MC was positioned to give an angle as close to 90° as possible between the pivot and MC-piston centers (it's about 93° with the pads under pressure).  The OEM clevis-pin setup was loose and the first 6mm of pedal travel didn't move the piston at all, but the M5 bolt/nut has no slop and feels much better.  The brake line didn't like the new MC angle; I had to remove the front brake-line clamp, which allowed the line to loop up a little and actually made it better than before.  If you're using the swingarm-mounted sub-fender, you might have to trim its inside RH front corner for line clearance.

Results (knobby tires, on pavement, every single time): a small push down on the pedal immediately slows the bike, a medium push reaches the tire's traction limits and it starts to slip while rolling, and a hard push locks the wheel below 20mph.  The brake isn't perfect - I wish it had more initial bite, which quickly tells my brain 'braking is 100%, just relax & ride' - but now that the pressure's good and power is no longer an issue, I can try out different pads to fine-tune the response.

Next, I'm going to cut a thick aluminum washer to shape and have it welded to the mount at the lower bolt-hole location, then grind & fill a bit so it looks better and blends with the frame lines as before. I'll also have the clevis and new pedal hole re-drilled and a 7mm stainless clevis pin made up.  I was going to make up a new flat mount that held the MC from the frame side, but this will be just as good when finished and so much easier.

Ray

[rayivers]

OK, this looks a little better now:



Ray