Hey guys...thought I'd post up a little how-to for anyone interested in half-shafting and polishing their throttle body. This specific example (including pics) is a TB from a 2000 Mustang 3.8L I'm working on now, however I've done this in the past with Honda parts and the general procedure is similar. Just thought maybe some of you would be interested in seeing how it's done. I'm mind-process with one right now, so this thread will only detail about half the job. I'll post the rest as I finish up.

Time To Complete:
-Quick Halfshaft: A few hours
-Polish Too: Hours, Days, Weeks? Depends how anal you are about your polishing!

Tools Needed:
To Half-Shaft only - Phillips Screw Driver, Snippers/Pliers, Hacksaw OR Dremel w/ cutting blade, Locktite, Heatgun/hair dryer.
To Polish too - Sandpaper or Dremel w/ sander wheels in 240 grit, 400, 600, 800, 1500, 2000, Metal Polish, Polishing Cloths or Polishing bits for Dremel.

Alright, here goes. Here's a couple shots of the stock throttle body. Again, this is from a 2000 Mustang 3.8, but most TBs are pretty similar. The TPS and linkage may look different and be in slightly different locations depending on application, but they're easy to pick out. This one's in pretty decent shape.




Here's another shot looking into the throat, showing the material we'll be removing to improve flow.



The first step is to remove the Throttle Position Sensor (TPS) shown in the first image. It's usually held on by two screws - removal is obvious. However, this is usually the single MOST DIFFICULT part of the entire process. Those screws are usually glued in and hold very TIGHT. You likely will not be able to take them out by hand without help. To loosen the glue, heat the entire throttle body up as much as you can. Use a hair dryer or heat gun, or even put it in the toaster oven. Make sure it's good at hot - 70 Celcius or better is preferred. Even at that temperature, I could only get one out of this particular one, and had to use a special screwdriver with an 8" handle to get enough torque to twist the other out. Be careful not to strip the screw, or you get to drill it out instead.

Once the screws are out, the TPS just pulls off. Store it in a safe place and don't play with it as they can be slightly delicate. Next, you need to remove the throttle plate/butterfly in order to get the shaft out. (you may want to mark the shaft with a marker before you remove it so you know where to cut) Again, it's obvious, just two screws. Be careful here, though. You can see somewhat in the second photo that the screws are usually pinched/peened at the back. If you screw them out in that state, they can damage the thread on the shaft. I recommend using pliers or cutters to twist or cut off the back of the screws before removing them. Again, they're glued, so use heat. These come out much easier than the TPS screws, though.

When the screws are removed, you can slide the butterfly out of the shaft, and slide the shaft out of the housing. If the screws left ridges in the metal shaft at all, you should sand them down before sliding it out so you don't damage the bearings. You can't see the holes are smooth in this pic.



Here's the removed shaft assembly. It should all just slide apart. Again, this one's from a Ford, but Honda TBs are not dissimilar.



You're now ready to cut the top half of the shaft off. Use a dremel or hacksaw to cut the shaft at the points you marked before. MAKE SURE YOU CUT THE RIGHT HALF OF THE SHAFT OFF!! You want to remove the half WITHOUT the screw threads. Cut off the wrong half, and you'll have nothing to sink your screws back into! Also, I would remove any rubber seals or bearings before taking a hacksaw to it so that they're not damaged. Here's a pic with the shaft cut.



You may use a metal file to clean up the ends, particularly if you used a hacksaw. It leaves a rough edge.

If all you wanted to do was halfshaft, you can put this back together right now, and you're done!! Simply reverse the steps above. If you want to go ahead and polish, read on (and get ready to use a LOT of elbow grease!)

You want to polish the plate and bore first using the coarsest sandpaper, and work your way up to the softest. You can do it by hand or with a dremel. The Dremel is obviously easier, but it's more expensive. You'll go through a pile of bits. Here are some polishing tips:
-Wet sand, if you can. Rinse the paper frequently, otherwise metal deposits will build up.
-Work in one direction with one grit, then perpendicular to it with the next grit.
-Keep the metal warm to hot. Aluminum polishes better when warm.

The only thing to remember here is do NOT remove too much material from the bore around the area where the butterfly sits. If you remove too much, it will not create a proper seal, and it'll screw up your idle.

Here's my butterfly plate after working through 400, 600, 800, and 1500 grit paper. It's almost mirror finish, but you can still see some sand marks. These will polish right out with the felt wheel and metal polish. If you want to go REALLY nuts, use Jeweler's Rouge, and it'll look like a mirror.



It's hard to see, but I rounded or knife-edged the edge of the plate just a bit. Don't sharpen it to a point or remove too much material, or again it won't seal properly.

I also used a metal file to smooth out the lip on the opening of the TB. See below. This will leave a rough edge, so you'll probably want to go at it with a dremel afterwards, or at least some very coarse sandpaper (200-240). This isn't such a big deal on this particular TB, and Honda parts are generally pretty good at not having huge, obstructing lips. But use your own judgement on this one.



I'll post up more pics as I get on with the polishing, as well as pics of the finished, assembled product. Post up any questions, if you have them. Like I said, sorry this specific example isn't a Honda part, but this happened to be the one I'm working on at the moment. And the info might still be valuable to someone. Enjoy.