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This is an instruction for polishing; in this article we will polish an eaton m112 supercharger
First of all you need to remove and then disassemble the supercharger, remove the pulley while it’s still on the car. Once you’re out of the car, remove the bypass valve, sensors, and anything else that’s screwed on, including the intercooler. At this point you can remove the paint, or do it later, notes below on this step.
Next, you will need to disassemble the blower; it’s as easy as unscrewing the muzzle and pulling it out. Once you remove the muzzle you will need to take out the center section, the rotors will come with this section.
Now that you have the blower in 3 pieces, you can go all out and break each piece off, for example removing the gears, shaft, etc, or just taping off areas.
It’s much easier to tape off the areas, so once you’ve removed the gasket maker on the edges of the mouth, center section, and box; you can seal them with tape. Tape the back of the snout, the gear side of the center section, then on the rotor section you can wrap the rotors in bubble wrap, then tape them all the way down, you want to seal all the internal areas with duct tape. Clean the inside of the case with acetone on a rag and carefully clean the area around the rear bearings, tape them down now, you can’t let anything get into those bearings.
Now that all the internal parts of the blower are sealed, you can remove the paint, simply brush on the aircraft finish remover and let it sit for 10 minutes, then brush off the paint with a wire brush. You can also do this while the blower is still assembled.
Now that the paint is off, it’s time to start sanding. I use a 2hp polishing machine with specific sanding grit wheels, this is not practical for the weekend warrior so I will explain the sanding process using simple tools, if you are curious about my specialized polishing machine feel free in sending me a private message, it is an investment of approximately $800 and will reduce a polishing job from 20 hours to 2 hours.
The first step in sanding is selecting your sandpaper, Home Depot sells 20 sheet packs and you will want a lot of paper, buy 80, 120, 200, 300 and 400. You may need to visit an auto shop to get the finest grits. ; you will need 600, 800, 1000 and 1500.
You’ll need a sanding block, a vibrating palm sander (not an orbital sander), and some small pieces of wood that you can wrap in sandpaper. A dremel with some pointed cone sanding bits and some drum sander bits will save you a lot of time, however nothing more than 150 grit for this. You’ll also want some polishing wheels with dremel bits.
Start sanding, flat areas of the blower are easy to hit with a palm sander, start with 80 grit and do as much as you can, hard to reach areas are difficult, you can wrap sandpaper around small pieces of wood to get into those areas, or you can try the dremel. For this project a dremel is a tool of skill, too high a number of rpm in one spot for a second too long will cause a low point, you don’t want this so be very careful when sanding with this tool.
Take your time sanding, once you’ve sanded the entire blower to 80 grit you should move on to 400 grit, it will take a long time but the end product is only as good as this prep.
So now you have finished sanding down to 400 grit; by now you’ve probably figured out how to get into the small areas of the blower if you don’t get creative worst case is you’re just making a ball of sandpaper on your fingertip sometimes you have to get that raw for the sake of the finished product.
Now it’s time to wet sand. I like to mix water and sunrise soap in a spray bottle and use it as a liquid, not only does it keep the sandpaper free of residue, it cleans the metal as it polishes. You can continue to use the palm sander, but the dremel is worth nothing for now. Wet sand 400, 600, 800…
You’re probably tired by now, you can stop wet sanding at 800 if you like, but for that little extra gloss on the finish, continue up to 1500 and then even 2000 if you like.
Now that you’re done sanding it’s time to clean the blower, make sure there’s nothing on it, use acetone to clean everything, you should be left with a smooth, dull surface.
Ok this is what you will need for polishing, I suggest a bench grinder, the more amps the better. The key to polishing is being able to force the part onto the polishing wheel while keeping the speed of the wheel constant by creating heat and moving slowly over the part, you can also use a hand drill.
If you are using a 1/3 hp bench grinder, 5″ wheels are good, a drill uses 3″ wheels, on my 2 hp polishing machine I use 8″-10″ wheels. The wheels you’ll need are spiral stitched cotton wheels, look them up on yahoo, you’ll want at least 3 as you can’t mix compounds on different wheels, 6 would be better in case you screw up one. You will also want several dremel polishing wheels, these wear out quickly so get them in sets of 3.
You will need 3 polishing compounds, these look like crayons, Emory, Tripoli and White rouge.
If you decided to use a hand drill, Sears sells a polishing kit in their dremel section, it comes with 3 wheels and 4 compounds, this will work too.
Start polishing, place a wheel on your polisher, bench grinder or drill, spin it and press the Emory compound against the wheel. What happens is that the friction of the wheel melts the compound and it sticks to the wheel. Slow and even movements are essential, heat generation is ideal. Do as much as you can with the blower, for the small hard to reach areas use the dremel with a buffing wheel, same process.
Clean all polished surfaces with acetone, now using a new wheel repeat the entire process using the Tripoli compound.
Clean the blower again with acetone and repeat the process one more time using the final compound, white blush.
Clean the blower like crazy, you can’t leave chips or compound on the blower, clean it with acetone, use an air compressor to blow it out.
Remove all the taped up areas, clean the edges to prep for the new gasket maker, I also picked up a can of high temp bearing grease and added some more to the rear bearings.
You are ready to reassemble the blower, wrap a copper bead to make gaskets on the front of the box, slide the blower rotor section into the box, do it slowly and carefully, do not force it, push it in until it is flush against the box.
Next, the front of the section you just pressed in with the gasket maker and press it in, make sure to align the muzzle coupler with the gear, press it all together.
Now 18tq each bolt back to the muzzle, make a zigzag pattern to lock evenly.
Once it’s back together, let the gasket maker dry for a while. Now add some oil you can just 5w-30 that’s what I used. Put everything back together and put it in the car and voila!