(Q. by Mr. matt_gs450)
Does
anyone have a neat trick to getting a brake piston re-installed (for a
1981 GS450)? I'm having a hell of a time trying to get the piston
inside of the piston boot and then back into the bore.
(A. from Mr. DimitriT)
The boot has two places where it needs to seal:
1) In the cylinder, near the top.
2) On the piston, near the top.
The problem is that it's very hard to get the boot in with the piston
already installed, and its very hard to get the piston in with the boot
already installed...
The solution is to do both at once:
1. Lube everything lightly with brake fluid.
2. Put the boot on the piston. But, wrap the piston seal around the
lower end of the piston so that the seal, which goes into the cylinder,
extends below the piston.
3. Insert the part of the boot that goes into the cylinder, where it
needs to go, while holding the boot over the piston. To make sure the
cylinder seal went in correctly, rotate it. It should rotate smoothly.
4. Push the piston down into the caliper. As you push the piston in,
the boot will ride up until it snaps into the groove on the piston.
5. Push the piston in all the way.
(A. by Mr. hampshirehog)
It's
a fiddly job but DimitriT describes it well. One other thing to check
if you've got pattern rubbers - test them in the cylinder first without
the piston - sometimes they don't fit and you've save yourself a lot of
time finding that out later
(A. by Mr. 49er)
Another method.
You can fit up the new boots to the caliper, then lightly lube the
sealing edges with brake fluid. Now place the piston up against the
seal and use compressed air through the bleader oraface to inflate the
boot until the sealing ring expands past the piston surface. You need
to keep adequate force on the piston against the sealing surface to
make this work.
(Mr. matt_gs450's solution)
I was able to finally get the piston in the boot using a couple of wooden barbecue skewers and a dental tool.
I
held the boot open with the skewers, got the boot around about 40% of
the piston, and used the dental pick to pull the boot around the rest
of it. It took about five minutes with that method.
Front Master Cylinder Service Originally posted by Mr. rustybronco
Get a [boat] load of rags and cover everything up, brake fluid eats paint.
Remove the master cylinder.
The
brake light switch has one screw holding it in place. The brake lever
bolt has a jam nut on the bottom. Remove it before you unscrew the bolt.
Remove the lever and brake line.
Place the master cylinder on bench.
Remove the dust boot covering the plunger (circular wire holds it in place).
To
remove the piston assembly, cup, and spring, you will need: (1) a pair of snap
ring pliers, (2) a stout wire bent in a u-shape to hold the plunger down
(90 degree bend, long run to the banjo bolt hole , 90 degree bend
again) while removing the snap ring, plus (3) a small screw driver to clean
the crud off the snap ring area (also needed to un-stick the snap ring
if rusty).
First thing out will be a washer, piston and cup assy, 2nd rubber cup then a spring.
Inspect parts, replace as necessary!!
Clean
well, including sliding the surface under the piston cup. There are
two passages; one may have a very small hole and use a clean lint-less
towel/rag to clean the bore.
Re-assemble master cylinder, paying special attention to the seating of the snap ring!!
Attach the switch to master cylinder with screw (be careful to align it properly).
Don't attach brake lever at this time.
Attach the master cylinder and brake line, fill with fluid.
Push the plunger with a wooden stick to remove most of the air (be careful of JUMPING fluid). S L O W L Y!
Attach lever and finish bleeding in the normal way.
Refill fluid as necessary.
Bleed again, and again (and again, and again) if necessary.
Homemade Stainless Brake Lines with Video Originally posted by Mr. Nessism
Spend
some time making sure the fittings you are going to use have the proper
angles. The type that allow you to twist them around are a few bucks
more but more forgiving – get at least one like this. The crush washers
that Earl's sells are a little small on the ID so you might want to
pick up some new ones from a dealer if yours are damaged.
I've
made my own brake likes several times and the process is almost
foolproof. If you can do your own valve adjustment, you can make a
brake line.
"Adapters" is the wrong word - should
have been "olive" or ferrel. You don't actually need to purchase these
seperate since they come with the end fittings. Also, you might want to
get the crush washers from a dealer if you need them (mine looked
smooth and clean so I just reused them). The crush washers that Earl's
sells are a little small so you will have to open them up with a file
which doesn't sound too cool to me.
A couple of weeks ago I
built a line for {an} '81 550 with Daytona bars (lower than stock). The
stock line is two pieces with a junction attached to the lower triple
clamp. I took off the junction and made a one piece line.
I
bought one adjustable fitting (allows you to twist it into any
position) and one non-adjustable. Attached the non-adjustable fully,
crimped it down, but left the adjustable one finger tight when I put
the line on the bike (toward the caliper end). After getting the line
attached solidly at the master cylinder, I attached the line to the
caliper and before really cranking down hard on it, I tightened down on
the adjustable fitting to crimp it tight. Worked like a champ. Cost me
$40 even - including crush washers I didn't use.
Recommended parts:
Straight adjustable hose end (banjo) is P/N 600403
Straight non adjustable hose end is P/N 600703
Angled adjustable hose end is P/N 600503
Angled non adjustable hose end is P/N 600803
For two piece front lines:
- 2 non adjustable angled hose ends (P/N 600803 x 2)
- 2 straight adjustable hose ends (P/N 600403 x 2)
- 6’ of -3 hose
Use the angled banjos at the master cylinder. You can reuse the long banjo bolt from your splitter.
For three piece lines:
- 2 non adjustable angled hose ends (P/N 600803 x 2)
- 1 adjustable angled hose ends (P/N 600503 x 1)
- 1 non adjustable straight hose ends (P/N 600703 x 1)
- 2 adjustable straight hose ends (P/N 600403 x 2)
- 5’ of -3 hose
Rear Line (verify there is room for a straight at the master):
- 1 adjustable straight hose end (P/N 600403 x 1)
- 1 non adjustable straight (P/N 600703)
- 3' of -3 hose (I think- please check)
Each lower hose is built using one adjustable straight banjo at the
caliper and one non adjustable angled banjo at the splitter. For the
master cylinder hose, use one non adjustable straight banjo at the
splitter and one adjustable angled banjo at the master.
The basic idea here is to have one adjustable hose end and one non
adjustable for each hose piece. Install the non adjustable piece
solidly and the adjustable piece with the crimp nuts snug but not tight –
tighten after you have the hose installed on the bike and the angles
set by the attaching pieces.
AN Plumbing also sells banjo bolts and crush washers. Get new crush
washers for sure. The Suzuki banjo bolts are sometimes a smig large for
the Earl's crush washers but they should work - you might have to open
them up slightly with a needle file.
Enjoy!
Priming the Master Cylinder Originally posted by Mr. Nessism
Make sure the small master bleed hole is open – it’s
extremely small. This helps fluid get down to the piston where is can
be pumped.
After you verify the hole is open, put the master together and install it on the bike.
To prime the master you might have to draw fluid down out of the
reservoir and into the master cylinder bore by applying a vacuum to the
nipple on the caliper. If you have a long piece of clear tubing you can
suck on the tubing to draw the vacuum – the long part comes in
for obvious reasons.
Once the master is primed it should start pumping.
