Gold Wing brake sticks

1982 GW, rear brake sticks the first time I use it on a given day. If I
persist in riding, it'll let up (or wear down enough pad) after two or three
minutes. Then it works fine for the rest of the ride. If I park it for two
hours, same thing happens all over again.
What do I need to do to fix it before I run out of pad?

 

Best thing to do is do what I did to my '83 Goldwing, which
essentially has the same rear caliper as yours.

Remove the rear caliper and leave the hose attached. Use a series of
spacers and pump the fluid into the caliper until you have both pistons
removed. You have to use the spacers so that the pistons come out at
around the same time, and not push one out way before the other. Make
sure you watch the fluid resevoir. Remove the seals very carefully and
clean the caliper, clean the groove the seals came from, clean the
seals, polish the pistons. Reinstall the seals into the caliper. Lube
the pistons with either brake fluid or silicon grease and reassemble
the pistons into the caliper. Clean the 2 pins that hold the pads in
as well. Make sure all is CLEAN and pistons move freely with
compressed air. When you put the pistons in, used some compressed air,
installed the pads, and put pressure to the fluid connection, and see
if the pistons tighten up to the pads, and release when you remove the
air.

If I was in the DFW area, I'd help, but I am in Austin.

Raymond

 

consider the brake hoses. i've had a problem with them in the past.
naturally, there are other possible problems. good luck, sammmm

 

If I persist in riding, it'll let up (or wear down enough pad) after
two or three minutes. Then it works fine for the rest of the ride. If
I park it for two hours, same thing happens all over again.

Besides cleaning all the crud out of the caliper, check the rear brake
pedal and any associated linkage for binding and make sure the air
bleed hole that is in the brake fluid reservoir isn't blocked. The air
bleed hole is tiny and it can be easily blocked by old brake fluid
crystallizing in the hole...

 

What he said - except that generally, it's not necessary to remove the
pistons altogether and attend to the seals. If the caliper and pistons
are seriously corroded, then yes, absolutely.

FWIW, I've just done this job on my Trophy as the calipers were binding
slightly. I did it exactly as you outlined, including blocking the "not
to be attended to yet" pistons with spacers (14mm socket head!). Except
I just moved the pistons out maybe half an inch.

Pump the piston you're doing partially out, clean round it with a
toothbrush, get rid of all the crap, apply a thin smear of copper
grease, push it back, repeat. When the pistons slide back smoothly,
job's done.

As the pistons are frequently hollow tubes, rather than solid pillet,
you can see how deep they are, which means you're unlikely to push them
all the way out. Just err on the side of caution. The corrosion rarely
goes more than a couple of millimetres down. If it does, then it's would
be wise to do the job as Sam says.

 

Nonsense

 

my 1986 GL1200A, except it was the left front brake (the one not
connected to the rear master cylinder). The master cylinder was lined
with a semi-crystalline goo condensed from old brake fluid. With the
fluid return hole blocked, there was nowhere for the pressure to go, so
the caliper remained locked, nearly to the point of locking the front
wheel.

I learned about the blocked air bleed hole when the front brake lever
on one of my Suzukis became very hard, and had no play whatever in it.
The motorcycle had sat unused for about two months in hot weather and
the brake fluid evaporated, leaving crystals to block the hole...

How is cheap brake fluid made anyway? Out of animal fat?

saponify: to convert (as fat) into soap; specifically : to hydrolyze (a
fat) with alkali to form a soap and glycerol

hydrolysis: a chemical process of decomposition involving the
splitting of a bond and the addition of the hydrogen cation and the
hydroxide anion of water

glycerol:a sweet syrupy hygroscopic trihydroxy alcohol C3H8O3 usually
obtained by the saponification of fats and used especially as a solvent
and plasticizer

But, what happens when the lighter fractions of the polymer boil off?
You apparently get some sort of alkaline glycerin crystals, and
crystals don't flow through hydraulic systems very well...

 

I am glad I removed the pistons, because it gave me a chance to polish
the pistons and clean the seal grooves which had accumulated a bunch of
crud. Plus the rear caliper had about a teaspoon of crud laying in the
resevoir behind the piston. So why not take them out and do it right?
Raymond

 

Depends how old the bike, how long the brakes have been crappy, how
serious the corrosion, etc etc.

When I did the rear brake on my old Kawasaki I did it the proper way -
new seals, clean everything out (and yes, there was a lot of crap behind
the piston there as well).

On a 1982 Wing, it'd probably be a good procedure.

 

Kawasaki I did it the proper way - new seals, clean everything out (and
yes, there was a lot of crap behind the piston there as well).

Besides the buildup of brake pad dust, corrosion caused by salt, rubber
wearing off the seals, there's another problem with disk brakes that
can cause the piston to stick. It's the uneven wear from the rear of
the pad to the front of the pad...

The rear of the pad gets more wear because the rotor rubs it first.
The pad wears at a slight, but noticeable diagonal. The steel backing
plate pushes the caliper piston inward at a very slight angle. But the
piston is almost an interference fit in its bore, you can hardly slide
a piston into its bore even with the seal removed...

So the piston will stick for that reason...

Diagonally worn brake pads can be reversed, swapping the inner pad with
the outer pad to even out the wear if you happen to have the rear wheel
off for any reason, it only takes a few extra minutes to do that
operation...

 

Now *there's* a neat tip which never occurred to me.

Thanks.

 

Thanks to you all for your help.
I'll let you know how it goes.