I recently had quite an experience bleeding an integrated brake system
and I thought I pass on what I had learned. After taking possession of
my Convert, I pulled the hand brake and installed the integrated half
of a Frentubo plastic coated braided stainless steel brake line kit.
The kit is fine and the brakes felt OK, after just one attempt at
bleeding, so I was a happy camper. With my Convert set up as a
minimalist sport bike and since I use only the foot brake it is
imperative that it work well.  I had set my bike up initially with my
wide Astralites from my Pro Race Bike. Those wheels were each 6 pounds
lighter than the stock Guzzi rims and I had lots of take off race tires
that could very well last me for years. I was able to find a buyer for
my wheels, which along with the tires, a notched swing arm and 2 used
floating rotors fetched $1000. It was a deal I couldn't pass up.
Anyway, when I sold my rims and rotors, I had to go back to the stock
rims and rotors and I found that the F09 caliper (from the rear of my
old SP) that I had put on the front, would not work with the composite
(alum/steel) Lemans style rotors that my Convert came with. It seems
that while the F09 caliper would clear the buttons of the floating
rotors, it wouldn't clear the 9 little bolts that Ferodo/Guzzi used to
bolt the rotor to its alum carrier. Well I figured that I just made
$1000 and if I had to swap calipers it wouldn't be so bad. So I started
swapping an F08 caliper on to the front of the integrated system. At
the same time I also decided that I didn't like the Guzzi
"proportioning" valve and wanted to run via a double banjo bolt at the
rear master cylinder, a single line to the front caliper and single
line to the rear caliper.  I figured this was cleaner and although I'd
have to use a banjo bolt brake line switch at the caliper, it was an
aesthetic cost I would bear because of the aesthetic payoff of removal
of the valve. The Frentubo kit had always bothered be in that it
replaced only the rubber parts of the Guzzi system, so you still had all
the solid steel lines patched into the flexible lines. It looked cobby
to me. As I have said to a friend recently, I am now at a stage in my
life where I actually let form dictate function, don't ask me why,
priorities change. Anyway I was well on my way to a very clean system,
only one problem, I couldn't bleed the thing to save my life. I burned
through an entire large can of brake fluid and I have a Mighty Vac, a
tool I feel is necessary for bleeding brakes. I tried pulling the fluid
through, I tried pushing the fluid through, I removed the calipers and
tried to straighted the run.  I did almost everything. Then I snapped a
bleeder valve. I was livid. Then I snapped an easy out. I was really
%$@%$#@. It was my last good left side (behind fork leg) caliper I had
(except for the F09 unit).  It is worth mentioning that old 2 piston
calipers are named left and right (by Brembo) based on their position
in front of the fork legs, as seen from the saddle.  More modern 4
piston calipers are named left and right based on their position from
the saddle when they are in back of the fork legs, remember that when
ordering, I won't use that nomenclature here.  I ended up having to
disintegrate my system and put the hand brake to the right side caliper
back on. I was able to get that system bled, and still had problems
with the rear brake even when it was the only caliper fed by the rear
master cylinder. At least I had some brakes and could ride the bike.
Finally I decided to give it another go. I gutted the caliper with the
broken bleeder and used its guts to rebuild another caliper I had with
bad seals and pistons. Using this caliper I made another attempt at my
integrated system, this time straightening out the run from master
cylinder to each caliper. Thus I had the rear caliper on the floor and
the front caliper on top of 4 milk cartons. I then unbolted the master
cylinder and rotated it up in the front.  then using a wrench, I tapped
the entire system from rear to front (hoping to free air bubbles) and
when I was done, bled whatever air had worked its way up to the front
caliper.  There is nothing like that feeling that you get when you
tighten up that last bleeder and go over to the lever and press down
and get resistance.

    Its interesting that David Richardson in a recent article gave a
bunch of figures on brake pads.  He mentioned the critical relationship
of front to rear pad compositions in integrated brakes.  I don't
dispute him and only time will tell if my system works, but I have
always used the softest grabbiest pads both front and rear in my bikes
and am currently using my last set of old Asbestos Rich Ferodo 2453's
left over from my race bike. My integrated brake will lock the rear
first on dry pavement and lock the front first on dirt or wet roads. It
is important to note that Guzzi has installed at least 2 kinds of
"proportioning" valves on Guzzis over the years. Most bikes are fitted
with a very simple "valve" that in reality does nothing. It is no more
effective than my double banjo bolt (or any generic splitter) in
splitting the hydraulic pressure front and rear.  Guzzi has always
played with rotor diameter and pad compound to get any proportioning.
Having said that, some SP's came with a much more substantial valve,
identifiable by the bleeder valve at the top. I had one of these valves
lying around after disintegrating my SP. I was considering using it on
my sport convert if I could convince myself it would help my integrated
only bike. I took the valve apart as it has a circlip under a rubber
cap at the top. What I found is a piston with rubber seal and a spring.
As best I can figure, this valve would deliver almost all your foot
pressure to the rear brake and only when you really press on the lever
(and cause the piston to raise) would any pressure make it to the front
brake. I decided this was not the action I wanted, and left it on the
shelf.

    Some may think me a fool for running with only an integrated brake,
but it seems to have plenty of braking power, and I like the single
brake lever look.  Not having a second rotor and caliper on the front
forks helps the fork respond to bumps much better and the decrease in
rotating mass of the front wheel assembly allows the bike to accelerate
faster.

    If I didn't like the leverless handlebar look (don't forget my bike
has no clutch lever) I might run the integrated brake to a hand
master cylinder, leaving my bike foot leverless (my bike has no shift
lever either), unfortunately you can't have it all...


Mike