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Discussion Starter · #1 ·
Hey folks. I was wondering what the consensus is on the best way to polish those old crankcase covers and other aluminum parts? I have read everything from scotch brite wheels to 600 grit wet sanding to clean, and then sisal wheels and compound to polish. Is there a way that works better than the rest?

My 73 CB450 is in serious need of cleanup, but I want to start out with a method that works.

Any advise?

Thanks!
 

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I'd suggest a search of the forum on the subject of polishing, you'll find quite a few discussions. I personally like HerrDeacon's method. If you look at his results you'll see why.

Here's a link to some info that helps us all to help each other.

viewtopic.php?f=4&t=3797
 

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I'm working on my goldwing and have worked up a process the comes very close to the factory finish. It should be a durable as well. In the factory Honda either paints the cases or polishes them. The polished cases are sprayed with clear lacquer. I used a similar process at home with great results. I will post some pictures of the finished product. The castings have a nice deep luster and the clear coat has great adhesion. This is process based:
1. strip the factory finish using aviation stripper
2. polish the aluminum to the desired luster.
3. detergent wash the excess buffing compound
Note: At this point do not touch the parts with bare skin.
4. Deoxidize the aluminum with Turco Alumiprep No. 33* per the instructions on the bottle
5. apply Alodine 1001* (not 1200 as it is gold colored) per the instructions on the bottle. This is similar to passiviting steel
6. apply your favorite clear coat. I used Dupont Acrylic clear
* Available from Aircraft Spruce and Specialties http://www.aircraftspruce.com/menus/cs/ ... plies.html

Note: the chemicals listed are hazardous to your health. If you like you kidneys be sure to use protective gloves and read the MSDS sheets.
 

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AS promised, here are my carb parts for the goldwing. I'm not restoring this bike. My 450 parts will not have the spots in the clear coat.[attachment=0:275wfdq0]IMG_2457_web.JPG[/attachment:275wfdq0]
 

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Discussion Starter · #9 ·
Jim, the carbs look sweet. How can I tell if the clear coat is still on the crankcase covers and what not?

I do like the idea of protecting the newly polished parts, although I am not too sure about all the chemicals. Is there anything else that people use to protect their newly polished parts?
 

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Keith,
Besides getting my Goldwing back on the road, objectives are to develop processes I can use to restore classic Honda motorcycles. I would like to have a small hobby business doing this.
Over time the stock Honda coatings will take on a dull cloudy look. If the metal looks corroded (white powdery) then the coating may have worn off. It is hard to tell if it is there or not. I have used chemical stripper and removed it on the buffing wheel. On my carb parts, the Honda finish was easily removed on my buffer, but the carb slides required stripper.
I'm accustomed to using these chemicals in the aviation industry. Basically, they are acids. They are much more benign that plating chemicals. It is not a big deal as long as you protect yourself and the environment. That means understanding the information on the MSDS sheets. They are available from the vendor. That will list the personal protective equipment and disposal requirements. My county run waste department will take hazardous materials as long as they are identified to what they are and are processed per the county requirements.
I have worked in aviation for over 37 years. Airplanes are primarily made out of aluminum. The process I outlined is the same as how many aluminum aircraft parts are processed. The difference being the the organic (clear) top coat. Aviation parts get a two part chromate based primer.
Honda uses high zinc content alloys in their aluminum castings. This is a very tough alloy. If you compare a Honda motorcycle engine case to say an old Triumph or BSA, the English bike cases are much heavier. The down side is zinc based aluminum alloys are fairly high up the galvanic scale. Zinc and Aluminum makes a pretty good battery. Some Honda castings will have gray streaks on them that cannot be polished out. These are zinc concentrations.
I have read there are three ways to preserve restored motorcycle aluminum castings. 1. buff and keep the bare aluminum polished. Some metal polishes provide some protection. 2. buff and apply WD40. I don't like this because it will attract dirt. 3. buff and apply clear coat. You could try to buff and clear coat your parts. The issue will be paint adhesion and cloudiness. Before clear coating I would carefully degrease the surfaces to be coated to obtain a water break free surface. Let me know how it works. I could be putting too much into my method.
 

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JamesPal said:
I'm working on my goldwing and have worked up a process the comes very close to the factory finish.
5. apply Alodine 1001* (not 1200 as it is gold colored) per the instructions on the bottle. This is similar to passiviting steel
Jim:
Thank you for taking time to share your refinishing techniques. I restore vintage Hondas and Yamahas, and am always seeking ways to improve my aluminum refinishing- it's something that is critical to the final appearance of so many parts. I too am only interested in achieving a factory original look and dislike "over restored" or over polished alloy on my restorations. They just stand out and look wrong to me, though I understand some really like that look. I personally do not, and I like the "satin glow" of factory original aluminum finishes on wheel hubs, fork legs, and sidecovers.

My question concerns step 5 of your process- the use of Alodine 1001. Has this proven to be critical or necessary for long term clear coat bonding? I ask because I've been trying to follow the aluminum refinishing procedures of Vic World, well known as the best restorer of sandcast CB750's. In a past issue of Moto Retro Magazine, he outlined his aluminum refinishing techniques, but unfortunately didn't give quite enough specifics for me to nail it all down. He mentioned the use of a chemical treatment that seems to do the same as your use of Alodine 1001. Vic World recommended using Chromic Acid Solution (H2CrO4 20% from http://www.chemical-supermarket.com) for promoting adhesion of the final laquer clearcoat. I bought 250ml and tried it- no luck. It's very orange in color, and removing the resulting orange tinge from the parts defeats the application. Sure wish I knew exactly how he used it, he doesn't say- is the Alodine you use do the same thing here? Do you dilute it, brush it on, or soak the parts in it?

Another step in his process was ultrasonically cleaning the aluminum parts, but as a cleaner large enough to do hubs and fork legs is $1500-$5000+, I can't justify that.

I appreciate any insights you can offer to us all here, as we all have to deal with alloy corrosion and refinishing at some point with our vintage Hondas! :ugeek:
 

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As an experimental airplane builder I have a little bit of experience with aluminum finishing as it relates to the aviation world. My process used to follow along pretty much with what JamesPal posted and is great for airplanes that will live near any sort of salt water/air enviroment. It's overkill for an airplane that's going to spend it's life in a dry, arid environment.

I used PPG's version of Alodine which is DX503. Alodine is a trademark name and there are other companies that make a comparable product.

The process we used was to etch with a solution (PpG DX533), alodine (PpG DX503) then prime with a PpG Epoxy Primer. The conversion coating process (Alodine) is primarily used for corrosion protection and the etching process gives the AL some "teeth" for the primer to grab onto.

I have since stopped using the Alodine (Ppg DX503) since I thought it was overkill with the new style epoxy primers. Essentially, if you use an Alodine type conversion coating then a top coat is not really necessary for corrosion protection.

In your case, since you will not be using a primer coat (just a clear coat) then the conversion coating might be desirable. As JamesPal mentioned, there is a version of Alodine (and PpG products) that has a clear conversion coating instead of the gold color.

The next question you had dealt with the application of the conversion coating. There are basically 3 types of application; immersion, spray bottle and brushing. They each have their proponents but I always preferred the immersion method. The downside to this method is that it take a large quantity of the (fairly expensive) product to do the job. The product can be saved and reused quite a few times but you have to put it into an airtight container and then leave it setting around the garage. I'm pretty sure these products have chromates and the EPA has a problem when them going do the drain so that's also a concern. Spraying the product and letting it dwell for about 10 minutes is a good process as is brushing it on. It uses less product but you have to monitor it and make sure the part doesn't dry out. In all cases a through rinsing is required, of course, there will be some slight residual chromates in the rinse water as well.

Going a little further with the first step, etching, is a whole other process. The etching is also used as a cleaner which is necessary. About 75% of the Aluminum I deal with is Alcad coated which, by itself, is a protective coating but primer doesn't like to stick to it very well, hence the etching. If the part is not Alcad then a scrubbing with brown scotchbrite pad and a good degreaser is all that is needed before Alodine or top-coating.

I don't know if I've answered your questions or not but when you start talking about this stuff it's tantamount to a discussion about what oil is best or what tires should I use, there is no best answer. The aviation world this topic has be beat to death ad nauseam.
 

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I've had a few people tell me not to clear coat my aluminum because of heat dispersion issues. I don't know the truth to this since the covers come stock w/ a coating.

I have a client who creates billet aluminum parts for cars and trucks. He gave me a quick lesson the other day. Basically what they do for their flat items is sand them w/180 grit (seems a touch coarse for my blood, then again they have 15hp buffers) and then they bring them over to the buffer and start by using a red compound. They load the wheel w/ compound and drag the item towards them against the rotation of the wheel and then push the item w/ the rotation of the wheel to remove the compound/polish so they chan check their work. After they repeat this process with a green compound, the drop them in their ultrasonic. From what I understand they don't coat it or anything, must work ok for them as they are one of the main manufacturers for this stuff in the states.

For odd shaped pieces like crank case covers, they run them through a tumbler first using plastic beads that look sort of like chocolate chips and then they tumble them through again using walnut shells.

You may want to check your local listings for people who CNC aluminum there's a good chance they have an ultrasonic that they will clean your pieces with.

Sorry if this dosen't tie exactly in w/ your post, but I thought some of it may be useful for people searching the subject.
 

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Sorry,
I fell off of this discussion. Here are a couple of comments:
Sandman; there are two major types of Alodine, one contains a orange-ish dye and the other is clear. The clear is used in aviation for decorative surfaces. The orange one is used for parts that are later painted. The color indicates the part has been treated. An example of clear in aviation is the treatment applied to bare aluminum skins (American Airlines) after washing.
Mike; Experimental aircraft builders know their stuff. It is your tail end in the cockpit. Your alodine description is correct. It is a trade name. To use alodine or not is a personal choice. At Boeing our airplanes are designed to last 20 years. The maintenance really depends on the operators. Some are better than others. The choice of corrosion protection is based on Boeing design standards. Bare aluminum sheet is normally anodized. Clad aluminum sheet typically is alodined. 6000 series aluminum has very little alloying content. Since pure aluminum is relativity stable, it does not corrode like a 7000 series alloy. The 7000 series alloy contains a lot of Zinc and copper. It requires a high level of corrosion protection. I understand Honda engine cases are high in Zinc content. I believe they should have some kind of protection, hence my anal process.
 
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