so now for the calipers.
Here's what we're looking at rebuilding:
removing them from the bike is straight forward
so let's start here:
remove caliper from bracket
(this you'll do while on the bike, but for this thread I have placed it in a wise)
it ain't pretty!
Remove pads, piston boot/dust cover, clip and pad spring
to get the piston out;
place a rag as shown
apply air preassure through brake line hole
while air screw is closed (notshown on phote)
and at some point hopefully, it will go WROOOOF and relaese
at least on early models you'll have to split the caliper to get the piston out
it'll probably look as yummy as this
remove the seal (don't even think about re-using it!)
after a good cleaning, you go to the kitchen
find that roll of tin-foil
cram it into a ball
and...yes, use it to clean up all that horrible gum,
rubber recidue etc. that has accumulated inside the bore.
[stepping up on soap-box]
"NO NO NO you do not want to use abrasive paper !!!!!"
The bore wall is quite 'soft' and the last thing you want to do is
material from the bore wall.
You want to CLEAN it!
NOT expand the diameter !
(witch you in this case (GL 77) check to see if inside the service limit
of 38.245mm. No picture. Took it to my friend who did the master
So you fix it up with something witch is SOFTER than the
bore wall. Tin-foil works perfect for this.
you'll go through quite a few tin-foil balls.
But heck! they're are darn cheap.-)
and look ! It works!
(If not; it's because your bore are scratched
and therefore beyond re-use. DON'T ! These things are vital to your safety!))
oooooh no, look at that. It looks horrible:
back to the kitchen. More tin-foil.
And they come up brilliantly
Now if they look like this
or are scratched, or in any way look dodgy;
I don't care if you disagree
just throw them away!
No sanding the pitting away, you don't want a undersized and probably
out of 'roundness', leaking piston.
no 'filling' with whatever miracle-liquid-steel in a tube.
I will NOT last.
Also aplies if they are under service limit. Throw it away!!!
For 75-77 the service limit is 38.105 mm. Again I took it to my friend
as I don't have a micrometer that big.
Just get a new one. Period.
Be smart: order a stainless steel item fromPistol Pete
and you'll never have that problem again.
BTW a slide gauge just won't do.
I tried it just to make my piont;
It is not precise enough and it came out differenty for every try:
Very few people have access to a inside-a-bore-micrometer-thingie
or even a micrometer, so you'll either find someone who has,
or play a bit of russian roulette with you safety
one thing you CAN do
and I am not
sure I'd recommend it;
one of my Clymers sugests that
as the service limit of
the bore diameter is 38.245mm
and the service limit of the piston is 38.105mm
the MAX 'slack' is (38.245 minus 38.105 =) 0.140mm:
you can try'd inset a feeler gauge, to measure the 'slack'
So put CLEAN piston into CLEAN bore (WITH OUT the seal!)
and insert feeler gauge
for this one I could hardly squeeze in a 0.05mm
so apparently everything's fine,
but it does not take into account the fact that the feeler gauge
is flat and does not follow the rounded contour of piston/cylinder.
Also; you don't wonna go too crazy with that feeler gauge
and scratch the bore !
The inside of the pistns wil most probably be very rusty
witch really doesn't matter that much,but I let them stay
overnight filled with 'rust-eater'
so that the worst of it was 'eaten'
and to protect them from further detoriation
I smeared the inside with a high-temp nickel compound.
I guess copper/brake grease would do the trick as well
Time to nice'en up things.
Painted the calibers. Not any old paint, mind you.
As you know; brake fluid is an exellent paint stripper,
so I used a two-pack heat and brake-fluid resistant paint
especially made for brake parts:
Cleaned them and masked off
and smartened up various part using the electric buffer
so now things are ready to be put back where they belong,
along with the new hardware (or are the rubber-parts software ?Ha ha)
No ! the pink stuff is not a day-cream.
It's a high-temp sicilone based grease that came with the rebuild set.
MotherShip Honda recommends using this stuff for assembly of brakeparts.
If you don't have it, you'd just use brake fluid.
smear with pink stuff and place the new seal
smear with pink stuff and put in piston
now take daughters face and smear with pink stuff
OOOOOOPS.....where did that come from ???
fit the new boot
Check that it's seated in piston groove
the boot clip is seated in caliper groove all the way 'round
put back together the two caliper halves and tighten to torque spec.
150-200 kg-cm / 11-14 ft.lb
Grease the pins with pink stuff.
WHY ? :
Remember these calipers are 'floating' (pins move inside bracket holes)
meaning they move sideways in relation to the bracket.
Braking--->Piston moves out--->press on brake pad at piston-side--->
when this brake pad touches rotor, the rest of the piston movement will
pull the whole caliper sideway, thereby pushing the other pad into rotor.
on goes pin covers
and note that pins have a straight cut-off that fits into recess on caliper
nice cleaned pad spring
came out nicely....right?