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The NGW Project Bike. Brake rebuild

Posted: Sun Jun 04, 2006 4:11 am
by octane
IMPORTANT !
BEFORE YOU GO ON;
PLEASE READ
*THIS*.

Please take into consiteration that you are dealing with brakes here;
they define the thin line between being a happy smiling GL rider
and a not-so-happy ex-GL rider in a wheelchair
or even a very dead GL rider.

If you haven't done this kind of thing before
please have someone qualified, check your work !

Thanks.



OK so lets have a look at the front master cylinder
(please note this is for the 75-77 range. The later models are a bit different)

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here's an exploded view
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you'll need to have parts ready for this.
I don't care what my brakes on a 'new' bike look like;
I'll rebuild them no matter what,
so I've bought
..2 sets of front caliber sealing kits (aftermarked)
..one front master cylinder rebuild set (genuine Honda)
..one rear master cylinder rebuild set (genuine Honda)
a few other parts ,like some sets of shims. Didn't know
they were available, but found them at CMS in Holland
The rear caliber sealing kit is still in the mail somewhere out there
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OK so take the master cylinder off your bike
(remember; brake fluid is an exellent paint-strippe, so protect your paintwork)
and go to work.
Handle comes off
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together with this plate
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that hold this rubber-thingie.

Our friend Randakk has a nice little piece on the subject
of brake-handle and that rubber-thingie:
Odd Front Brake Lever Problem

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then off comes this rubber boot
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witch is held in place by a plastic washer and a clip
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for the next step you gonna need one of these
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now put the assembly in a wise (with those aluminum/rubber protectors you can see on the photo)
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down here you'll see the circlip that keeps hold of all the parts inside
the cylinder bore
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spray down some WD40 or similar as
the circlip can be a real b**** to get out, but here it comes
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this is what you'll find inside
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close up of the piston assembly
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now for a look down the fluid reservoir,
clean a much as you can and take out screws.
mmmm....nice! looks OK !
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there's every chance it could have looked like this .-(
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take off reservoir
(note the dark dirt down there)
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Time for a bath.
I use a household bathroom cleaner for this first cleaning
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then submerge in a bath of fluid that dissolves rust/lime/dirt
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and finish off with brake cleaner and giantuargianatronic(?) quantities
of compresed air.
CLEANLINESS is the key to a good brake rebuild
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here we have old parts/new parts
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check valve goes on spring (only 75-77 models)
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you'll have to mount the secondary cup on the piston.
Compare to the old piston
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and be really really really carefull when you slide it on.
Use a bit of brake fluid to help it along, and remember
ONLY brakefluid, NO oil/grease or anything goes!!!


squeeze it
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and be absolutely sure you get it right
...NOT like this
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but like this
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check it up agains the old one
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now for the rest of it
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NOTE the primary cup goes in THIS WAY
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now check the reservoir O-ring and the grove that holds it.
The o-ring is normally not part of the rebuild-set but it's available
as parts# 45516-371-003 or if you have a good O-ring supplyer
yol'll ask for a 45 x 2,4 mm
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now take a good long look down the cylinder.
Check for dirt, scratches etc.
You really should check to see if the bore diameter
is inside service limit witch is 17.515 mm
(more on that later)
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in the bottom of that LEFT recess there is tiny tiny hole,
(can't really see it in the photo)
that you need to check to see if it is blocked
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one way of doing that is to block that hole on the right of the above photo
and then light down like this
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and by looking into the cylnder you can see if the hole is 'clear'.
Yeah, it's that small blue blurry dot. (I couldn't keep the camera still)
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...more later

Posted: Tue Jun 06, 2006 11:31 am
by octane
Time to check if the cylinder diameter is within service limit:

75-78 = 17.515mm / 0.6896"
79 = 15.925 mm / 0.6270"

so walked over to the Oil Cave to get some help, as I don't have the tool for that.

"HP" took out the old probe-diameter-measuring set (or whatever it's called)

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stuck it in

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and moved it about a bit.

This is the probe itself that measures inside the cylinder

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and the measurement is checked with the micrometer

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fortunately everything's fine; it read 17.48 and something.

Time to put everything back together again

GREAT WORK

Posted: Tue Jun 06, 2006 1:22 pm
by Rat
Fabulous stuff.
Very valuable and useful.

Thanks Gord :P

Posted: Wed Jun 07, 2006 9:58 am
by octane
Thanks Gord. I'm glad you enjoy it!
Octane

Posted: Wed Jun 07, 2006 10:27 am
by octane
here's the parts in the order they go in: (note the check valve at left end of the spring; only for early models)

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in goes spring(and check valve)

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note the direction of which the primary cup goes in. 'Dress' it with little brake fluid.

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make absolutely sure it's sitting right in the cylinder

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and then drive it in with a socket or something similar

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then the piston. Dress with brake fluid

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drive it in (can be a little tricky; it's a tight fit and it has to 'pass' the grove in the cylinder.) Check that it moves freely up and down, by pressing with a rod

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the next part is a little tricky as well: getting the (stop-plate/washer and) circlip in. It helps if you (or a helper) presses down the piston a bit with a rod, so you can get the circlip down to the grove

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make absolutely certain the circlip is well seated in the grove, ALL around

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in goes rubber boot etc.

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and reservoir O-ring (again dress with brake-fluid; makes it easier to put the reservoir back on)

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screw down reservoir

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... and that's it: one piece of rebuild front brake master cylinder.

Tricky

Posted: Fri Jun 09, 2006 3:09 pm
by Rat
Tricky, tricky.... :twisted: .

Nice work, nice pics, as I said before, very useful stuff.

Gord :P

Posted: Mon Jun 26, 2006 7:01 am
by octane
so now for the calipers.

Here's what we're looking at rebuilding:

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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 vise)

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it ain't pretty! Remove pads, piston boot/dust cover, clip and pad spring

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to get the piston out; place a rag as shown, apply air pressure through brake line hole while air screw is closed (not shown on photo) and at some point hopefully, it will go WROOOOF and release

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at least on early models you'll have to split the caliper to get the piston out

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it'll probably look as yummy as this

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remove the seal (don't even think about re-using it!)

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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 residue, etc. that has accumulated inside the bore.

[stepping up on soap-box]
Image "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 to remove material from the bore wall. You want to CLEAN it! NOT expand the diameter ! (which 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 cylinder check)

So you fix it up with something which is SOFTER than the bore wall. Tin-foil works perfect for this.

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you'll go through quite a few tin-foil balls. But heck! they're are darn cheap.-)

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and look ! It works! (If not; it's because your bores are scratched and therefore beyond re-use. DON'T USE THEM! These things are vital to your safety!)

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oooooh no, look at that. It looks horrible:

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back to the kitchen. More tin-foil. And they come up brilliantly

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Now if they look like this

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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 applies 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 from Pistol Pete and you'll never have that problem again.

BTW a slide gauge just won't do. I tried it just to make my point; It is not precise enough and it came out differenty for every try:

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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 your safety OR one thing you CAN do and I am not sure I'd recommend it;

one of my Clymers suggests 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 to inset a feeler gauge, to measure the 'slack'

So put CLEAN piston into CLEAN bore (WITH OUT the seal!) and insert feeler gauge

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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 wanna go too crazy with that feeler gauge and scratch the bore !

So....?!

The inside of the pistons will most probably be very rusty which really doesn't matter that much,but I let them stay overnight filled with 'rust-eater'

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so that the worst of it was 'eaten'

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and to protect them from further deterioration I smeared the inside with a high-temp nickel compound. I guess copper/brake grease would do the trick as well

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Time to nice'en up things. Painted the calibers. Not any old paint, mind you. As you know; brake fluid is an excellent paint stripper, so I used a two-pack heat and brake-fluid resistant paint especially made for brake parts: Cleaned them and masked off

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and smartened up various part using the electric buffer

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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.

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smear with pink stuff and place the new seal

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smear with pink stuff and put in piston

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now take daughters face and smear with pink stuff

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OOOOOOPS.....where did that come from ???

fit the new boot

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Check that it's seated in piston groove and the boot clip is seated in caliper groove all the way 'round

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put back together the two caliper halves and tighten to torque spec.
150-200 kg-cm / 11-14 ft.lb

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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 sideways, thereby pushing the other pad into rotor.

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on goes pin covers

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and note that the pins have a straight cut-off that fits into recess on caliper

nice cleaned pad spring

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came out nicely....right?

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Posted: Mon Jun 26, 2006 1:36 pm
by QUEEENlE
You could have painted those red .........

Nice job ....I am so proud to know you ... excellent teacher ...excellent pics and diagrams to help those less mechanically inclined ... wish i had more tools ...i would get busy ...<grin>

...red ...red looks nice.

Hugs
Q

brakes

Posted: Mon Jun 26, 2006 2:18 pm
by the chef
WHEW! I am glad I sent mine to Frenchy to do all this for me ! the chef

Posted: Mon Jun 26, 2006 3:15 pm
by octane
QUEEENlE wrote:You could have painted those red ........

...red ...red looks nice.

Hugs
Q
NOPE !!!
I did that on my daily ride:

Thought it would look like Brembo brakes
ha ha
It somehow looked like like a man with painted toe nails...urgh!

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so I just recently got around to change that
(and a few other 'red-things', like the HONDA-sign on the 'tank')

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Sorry Q, Thanks for your kind words, but it looks so much better without the red calipers
or any other red stuff.

Posted: Mon Jun 26, 2006 7:45 pm
by QUEEENlE
Yes dear ...that looks much better ...i always wondered why you would paint the calipers red and the bike ...orange ..talk about clashing ... i thought that maybe you were colour blind ...so ..since i am mostly polite i didnt say nothing <grin> ...looks much nicer now...that bike. And i am sure that the shade of red would make a world of difference <smiling> ...ok ok .. i ll stop with the red calipers.<wink>

Hugs
Q

Posted: Mon Jun 26, 2006 7:46 pm
by QUEEENlE
Yes dear ...that looks much better ...i always wondered why you would paint the calipers red and the bike ...orange ..talk about clashing ... i thought that maybe you were colour blind ...so ..since i am mostly polite i didnt say nothing <grin> ...looks much nicer now...that bike. And i am sure that the shade of red would make a world of difference <smiling> ...ok ok .. i ll stop with the red calipers.<wink>

Hugs
Q

P.S. Did you tell me Nope again ? ...you are pushing it.

Posted: Mon Jun 26, 2006 7:57 pm
by Whiskerfish
That is a fine looking ride. I am envious! Also one of the most thourough rebuilds I have ever seen. Great job !!

Posted: Tue Jun 27, 2006 3:11 am
by octane
Thanks Rat, Q, WF !

Octane

Posted: Tue Jun 27, 2006 3:59 am
by Needle
Aloha Octane,
We are almost on the same page. I am doing my brakes on my 75 now. I noticed on the rear caliper, there is an o ring in between the halves when you separate them, but it wasn't in my rebuild kit, so I am looking for one to match it. I will be ordering new pistons from Pete, cause mine were really messed up and they didn't come out very easy either. The halves didn’t come apart very easy, had to use an air impact wrench. I will be running a thread tap through it before I put it back together. Thanks for the great work and the tin foil idea is a stroke of genius.