Here it is: (I will archive it under the same subject)
By: Jim Ferraro
Many people from the 300zx board have asked what the proper procedure is for sanding/polishing aluminum (rims, etc...). Here is the best/easiest way to do it:
First, make sure the surface is clean. Use a caustic based all purpose cleaner. Acid works very well, but remember that it does eat through aluminum surfaces so be sure to rinse it off. Donít ever use acid after polishing the rims.
The factory 300zx rims come with a clearcoat. In order for the rims to be sanded/polished, the clearcoat must be removed along with the "machine lines" on the rim. Remove them by wetsanding with 320 grit sandpaper.
Itíll take some time and patience. Also, when polishing the rims, be sure to do only the flat surfaces and the outer edges. The inner slats should just be left how they are, and they create a nice looking contrast. Some surfaces, such as the manifold cover or the throttle body, have a different texture than the rims. The only difference in polishing them will be the grit of paper that you start with.
Sanding can be done either by hand or power sander, but be VERY careful with a power sander. Adding some padding (like foam)to the backing is a good idea, since the metal clips on palm sanders tend to gouge the surface of the rim. Always finish off each step by hand to get any areas the sander may have missed, and be sure to have plenty of fresh sandpaper as it will wear out rather quickly.
To sand the rims:
- wetsand with 320 grit paper
†† emphasis on Ďwetí. Use a LOT of water in a spray bottle
†† (320 grit will leave sand scratches. This is normal...duh!)
- remove 320 grit scraches by repeating step 1 but using 400 grit instead of 320
- wetsand with 600 grit to remove scratches from previous sanding
- repeat the same step with 1000 grit, then move on to 1500 grit
Be sure to take your time while sanding and not to miss any areas.
Once the sanding is done...take a high speed buffer (the faster, the better) with a coarse "synthetic" wool pad and buff all of the 1500 grit sand scratches out with a good buffing compound. I would recommend 3M Perfect-it 2 rubbing compound...itís pretty incredible stuff.
Itís in the compounding step that the rims will really start to shine and youíll get to see how good of a job you did. The key here is to generate HEAT with the buffer. It will not damage the rim in any way. After buffing the rim out completely with the 3M compound...repeat the procedure with a good aluminum polish. The best on the market is probably Motherís California Gold Aluminum & Mag Polish. Buff it with a high speed buffer until it shines like a mutha. After that is done...just slap a good coat of wax on the rims to protect them. The best waxes are made by Meguiars and Mothers.
This is all a pretty time-consuming process, but it is worth it if you really want to get a lot of complements on your rims.
To maintain the shine just wax the rims periodically. It only takes about 5 minutes to wax all 4 rims so do it frequently. If they get dull or have excessive caked-on dirt, use the Motherís polish by hand then wax them again. Contrary to popular belief, aluminum rims are easier to maintain than chrome as they will not rust and can always be repolished if they get really bad.
E-mail me if there are any questions.