Huff, Puff, and Buff that Aluminum


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During the process of rebuilding my í69 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. Donít read any farther. What follows is for rank amateurs like myself. After reading about what I went through there may be some who say ďwhat on earth would I want to do that for? Iíll just take it to some one and have it done right!Ē 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 wonít 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 ďrightĒ] on extra new parts for the bike, or just really get a kick out of being able to say to some one who asks ďyea, I did thatĒ then youíre 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 arenít 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 valorÖ.you will have to decide.  So, if youíre still with me, lets get to it. 

First, a list of tools and materials.

The one tool which I donít think I could have done with out was a palm sander. The one that I have is a Black and Decker ďMouseĒ There are other brands that are probably just as good but thatís the one that I have. If you donít have one you will need to buy or borrow one because I donít think your arms and hands will last with out it. Hardware stores, tool stores, Home Depot, and Loweís have them for about $30.00. These things are really good for refinishing furniture so if youíre wise youíll find a chair, table, desk or what have you around the house and refinish it. Sheíll swear itís 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! Weíll 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 thatís another possibility. If you canít 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 Iíve 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 donít 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 wonít use it much so you could even do the job by hand if you had to. The arbor and 4Ē 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 ĹĒ pads are great for getting into the screw hole recesses. But this is an extra so I wouldnít 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. Itís really important that you finally ďseeĒ 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 donít have any then you donít need to go farther, just use some Semichrome or Motherís 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 donít want to lose this detail. Fortunately the mouse is very controllable so, with care, you shouldnít 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. Thatís another lesson which I have to continually relearn. Worn out 400 does not 600 make, itís 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. Donít hesitate to do this. I know it will seem that you are going to mess up all your work but itís 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 itís 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 itís 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 donít 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 youíve 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 youíre happy itís 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.


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