Motorcycle Repair: Caliper Rebuilding - 1983 Honda, honda nighthawk 550, grit sandpaper

Question
Hi Chris,

Thanks so much for making yourself available.  I have a
1983 Honda Nighthawk 550 - it's been stored most of its
life - has under 3000 miles on it.  Over the winter, the bike
fell and my front wheel locked up.  A local mechanic told
me to hit the caliper w/ a rubber mallet to release it.  And
that worked!  But, if you apply the brake again, it locks
right back up.

So, I think I need to rebuild my caliper.  I wanted to make
sure this sounds on track - and then, if that is what I need
to do, could you offer any tips/other resources to guide me
on my way?  I'm trying to learn more about my bike, but am
at the VERY beginning of that process - and am a little
afraid to take something like this into my own hands.

Thanks much!
Tricia

Answer
Hi Tricia.
 It's always good to see a lady rider willing to do her own wrenching on her bike.  Welcome to the world of real riders.

 It sounds like the caliper keeps sticking, not from the fall's impact, but from the age.  Since the bike sat most of it's life, there will also be other things to look at on the bike.

 The first thing that you want to do, if you haven't already, is to get the repair manual.  Clymer's or Hayne's manuals are both very good, but if you can get the factory manual, that is best.  The repair manual has the step-by-step instructions with diagrams and pictures.

 what is likely the problem is that, over time, the calipers sat and rust has built up inside, thus they stick.

Once the pucks are out of the calipers, you will need to lightly (with 1000 grit sandpaper) sand the rust off of both the inside of the caliper and the outside of the pucks.

Be very careful to not take too much material away from either the outside of the puck or the inside of the caliper.  As long as you stop when the rust is at least 99% gone, you will be fine.  Also make sure that the fluid ports are cleared of any debris before reassembly.

 To reassemble the parts, you will need to heat up (with your oven) the caliper and freeze the pucks.  They will slip together easily, then.  The temps will balance to normal and then you can reinstall the brake assembly and flush the system.  There is also a trick on properly bleeding the brakes as well as hydraulic clutches.  Here it is:

Bleeding brakes, as you know, is not a complicated thing and it works to get air bubbles out of the line.

But, here's the part they don't tell you (which is also not mentioned in any repair manual;

Some bikes have an additional problem with both the clutch and front brakes, including my own on my V65 Magna.  The problem stems from the configuration of the master cylinder, which is that the connection to the hydraulic line at the master cylinder creates a pocket that air bubbles like to hide in (this is called a reverse trap) and the method for bleeding that section is a little tricky if you've never done it before.

 Here's the proceedure;

1) Bleed the clutch/brake line like normal.

2) Put a wrench on the banjo fitting and squeeze the lever.


3) (NOTE: Use a box end wrench for this) While holding the clutch/brake lever in, crack loose the fitting and reclose it quickly. Have a rag over the fitting connection that you are working on because it will spit at you as pressure expells the air and a little fluid.

<<<<<<<IMPORTANT NOTE: DO NOT release pressure on the lever till the fitting is tightened back up or you will suck air back into the line.>>>>>>>

4) Test the clutch/brake again.  If done correctly, you will have pressure near the beginning of the lever movement rather than at the end.

5) repeat as needed, but you should not need more than 2-3 times to get the system working correctly.

Good luck.
FALCON