Huff, Puff, and Buff that Aluminum
During
the process of rebuilding my ’69 I was forced to deal with the aluminum on the
three cases. They were in
pretty sad condition, partly because the bike had been sitting for so
long and partly due to their age. What follows are the steps
which I took to bring them back to life.
At
this point I need to make clear several caveats.
First,
if there are any professionals out there or others who have had some
professional experience with aluminum buffing and polishing, please close your
eyes. Don’t read any farther. What follows is for rank amateurs like myself.
After reading about what I went through there may be some who say “what on
earth would I want to do that for? I’ll just take it to some one and have it
done right!” To those folks I will respond that they are absolutely right.
There is nothing wrong with that approach. If you are one of those who would
rather be out riding than enduring mind numbing drudgery you won’t get any
argument from me. If, on the other hand, you are working on a budget, would
rather spend that extra money that it costs [to pay a professional to do it
“right”] on extra new parts for the bike, or just really get a kick out of
being able to say to some one who asks “yea, I did that” then you’re some
one with whom I can relate.
Second,
if you do decide to buff and polish the cases (or even have them polished) you
have to know that unless some one knows how to keep from having to continually
maintain them ,you are letting your self in for an endless routine of
maintenance.
Third,
boy is this a lot of work.
And
forth, if the cases are damaged, gouged, dented, ect., you may want to consider
whether you might be better off replacing them with better cores or leaving
them as they are. On the other hand, small dings, casting flaws, and the like
are not too noticeable once the job is done. All in all it will have to be a
judgment call on your part. I found casting holes in my head which were
obviously not going to go away. They aren’t bad enough for me to care about.
Some thing else I ran into was tiny pinholes in by transmission case. I kept
trying to remove them only to find more in their place. I finally gave up. Who
knows how deep they would have gone, maybe a few more thousands or maybe all the
way through. At any rate, discretion being the better part of valor….you will
have to decide.
So, if you’re still with me, lets get to it.
First,
a list of tools and materials.
The
one tool which I don’t think I could have done with out was a palm sander. The
one that I have is a Black and Decker “Mouse” There are other brands that
are probably just as good but that’s the one that I have. If you don’t have
one you will need to buy or borrow one because I don’t think your arms and
hands will last with out it. Hardware stores, tool stores, Home Depot, and
Lowe’s have them for about $30.00. These things are really good for
refinishing furniture so if you’re wise you’ll find a chair, table, desk or
what have you around the house and refinish it. She’ll swear it’s a great
tool and be glad you bought it.
Next,
you will need sand paper. I know, I know, I can hear it now. WHAT DO YOU INTEND
TO DO WITH THAT! We’ll get to that soon. For the mouse you need medium grit
probably 180 to 220. After that you will need wet and dry paper in the following
grits, 220, 360, 600, 1200, 1500, and 2000. Two to three sheets of each will
probably do but if it is hard to go back and get more you may want to buy a few
extra. The 220 through 600 you can probably get at the auto parts store but the
micro grits you will probably have to get at an automotive paint supply place.
Just a suggestion, NAPA parts stores sometimes have a paint section so that’s
another possibility. If you can’t get 360 then 400 will do, if not 1200 then
1000 will do, and any thing between 1000 and 2000 will do. But you will need
2000 to finish off with.
Next
you will need something to buff with. When I started, all I could think about
was buffing. In fact, when you get to the buffing, you are 90% done. I used an old
Sears sander/polisher that I’ve had for years. I used a buffing pad that I had
used to compound paint (washed and dried it first). I strapped it to the bench
but, if you can anchor the part, you can use it free hand. If you don’t have a
buffer or something like it you can use a small buffing wheel on an arbor that
is chucked in a hand drill. You won’t use it much so you could even do the job
by hand if you had to. The arbor and 4” wheel that I bought was only about
$10.00. You will also need buffing compound. It comes in a stick and costs a
couple of bucks.
Another tool which is nice, but not necessary, is a Dremel type tool. The
little ½” pads are great for getting into the screw hole recesses. But this
is an extra so I wouldn’t buy one just for this.
At this point it is time to look at what ever you are going to buff. Pick the smallest part that you have, you will need some positive feedback as soon as possible. Once you have a nice shiny part to look at you will be motivated to keep going. When I started buffing I found that the parts got shiny but did not have that nice white almost chrome look that I expected. What I finally noticed was that there were fields of corrosion pits in the surface which gave the metal a gray look. You have to look closely to see this. For us old guys we need to get our strongest glasses or even a magnifying glass. It’s really important that you finally “see” these pits.
In the picture above you will note how the aluminum on the magneto is mottled looking. It's a rough casting and the low spots have not been sanded.
Note in the circle all the dark specks. This taillight housing has been buffed as best I could with out sanding. The specks are imperfections in the surface which need to be sanded out.
This picture of a machined surface has the same mottled, splotchy look. Ignore the machine tool marks and focus on the dark specks. These are what give the finish a gray look.
Once
you understand what you are looking at it will become easy to recognize at a
glance. Understanding that it is the pitting that you must remove is half the
battle. Clean the part well and look for this pitting. If you truly don’t have
any then you don’t need to go farther, just use some Semichrome or Mother’s
and you are done. If your pitting is very light then go to the middle and start
there, no sense in doing more than necessary. If you do start with a heavier
grit than necessary the only down side is a little more work, you will not
damage the parts by using too course a grit.
Before
you begin sanding be sure to remove all the mechanisms and attachments from your
part. That means all that shift lever stuff in the transmission cover, the seal
and patient plate and such from the timing cover, etc.
All
this stuff will have to be thoroughly cleaned after you are done to get out all
the grit.
Now
comes the scary part. Start sanding with the mouse. Be careful not to grind off
any important edges. My primary cover has a nice sculpted ridge down the side.
You don’t want to lose this detail. Fortunately the mouse is very controllable
so, with care, you shouldn’t have a problem. If you do find that you have
rounded something off, sometimes you can reshape it by carefully sanding the
adjacent areas. It is much better to not let it happen in the first place. You
can always protect an especially vulnerable place with some masking tape if that
is easier.
I
found that I had a bad habit of moving on to a finer grit before I had really
finished with the courser one. It was a lesson which I had to learn over and
over. Until you have sanded down to below all the corrosion it is not time to
move on. When
you finally get there you will have white metal with no defects. If you have
deep scratches or dings you will have to leave them as you would have to sand
all of the surrounding material down to below that level as well. There comes a
point where you have to leave well enough alone.
Once
you have all of the corrosion gone it is time to start on the road back. Get
your self a pot or bucket and put some water in it. Add a little dish washing
liquid, this will help keep the paper from clogging. Now start with your
220/360 grit wet or dry. Tear your sheets into quarters or eights and
toss it as soon as it quits working. That’s another lesson which I have to
continually relearn. Worn out 400 does not 600 make, it’s just 400 which has
quit working. Sand with the finer grit until all of the scratches from the
previous grit are gone. If you are working on an area and are not sure if you
are done, sand perpendicular to the scratch. If your scratch changes direction
you are done. If not, keep working. You may need to go back a grit if you have a
stubborn problem. Don’t hesitate to do this. I know it will seem that you are
going to mess up all your work but it’s often quicker to do this than continue
to work with too fine a grit. You will also be surprised at how quickly you
recover when you do go back a grit. A little work with the finer grit and you
are right back on schedule.
Keep working your way through all the grits of paper until you get to the 2000 grit. Look carefully before you move on to see that all of the scratches that you see are from the current grit and not a previous grit. Two or three grits later those seemingly minor flaws will become much more noticeable. If you have to go back it’s no big deal.
This picture was after cleaning but before sanding.
This picture is after the mouse.
This picture after 600 or 1200, I'm not quite sure.
This picture after buffing.
This
is the same transmission cover. In it you see all of the pinholes that I found.
They are in and under the surface. I would sand them out but new ones
would show up. I don't know how deep they go.
Now
it’s time to buff. What you will see at that point is that the change from
grit to grit and then to compound is slight because it is pretty shiny already.
After buffing you probably ought to thoroughly clean the part. A product
which I used was called Barkeepers Friend. You find it in the grocery store
along with cleansers and such. I don’t know what products are available
outside of the States but this product is used in the kitchen and has
deoxidizing chemicals in it which make it good for cleaning aluminum and copper
pots. When you clean a copper bottom pot it really makes it shine. The point is
that it also cleans the dullness from your aluminum. With an old tooth brush you
can get down into the cracks and crannies and clean all the muddy water that you
have covered them with. The down side of this type of product is that it tends
to dull the buffing you’ve just done. Some touch up with the buffer and maybe
some Semichrome should take care of that. At this point you will have to decide
where to stop. You reach a point of diminishing returns so when you’re happy
it’s time to start on the next part.
This
is not the only way to do this. It is the way that I did it and I can attest to
the fact that it does work. There may be other ways which also work. If some one
else has suggestions please post. Then all can take parts of one and parts of
another and put them together to make a plan for themselves. Good luck.
Art.