Polishing the LU

**Techno** · 10-25-2002, 09:01 PM

I was wondering if polishing one side would provide enough drag to reduce the trim tab? I'm sure this is one of those already tried things.

On the subject of polishing has anyone scuffed up their painted LU so it's rough like it's suppoda be? If the paint is blasted off what about brushing the bare areas?

JW · 10-26-2002, 07:49 AM

I'm strongly considering removing all of the paint from my Torquemaster and finishing the aluminum like the new Sportmaster cases. I work on aircraft, and to properly protect the aluminum skin, it is sanded or chemically etched and then treated with alodine. The Sportmaster cases DO NOT have the 'alodine' look to them. Anyone know what Merc does to treat the Sportmaster cases' aluminum? Or do they do nothing? If I treat my case like we treat the aircraft skin, it'll have that ugly brownish hue to it.

**Jacob** · 10-26-2002, 02:34 PM

I don't know if your looking for the protective coating or a shine on your lower unit, but if you just want it to shine here you go. On some of the four cyl. automotive engines I've built, i took mothers mag aluminum polish and a dremel tool with a polishing wheel and shined the s*%t out of it. It comes out very shiny. I know they make buffing wheels for the 4 inch angle grinders for larger jobs. You can also use jeweler's polish, although I've never tried it on cast aluminum. GOOD LUCK!

**xMitchx** · 10-26-2002, 03:32 PM

I would think that they would have do something to them. I also work on aircraft and we have a clear alodine that we use on the skins. It doesn't stain like the other alodines do. Maybe that's what they use.

**Barefoot Bob** · 10-26-2002, 04:07 PM

Well I dont know what Merc uses but the fin on my air chair will tarnish very fast if not protected. It is a polished mirror finish though. Once it starts to tarnish I have to use Mothers and a buffer to re-gain the shine. Then give the finished product 3 coats of a clear protectant that the manufacturer sells. It does help alot but is still a high mantanance job. It also helps to stay in real clean water.

JW · 10-26-2002, 04:17 PM

I'd be interested in that stuff! Can you get me details??

Jacob, the idea of making a faster lower unit is to give it some roughness (to a point). A highly polished (super smooth) case will actually 'stick' to the water, slowing you down......

**Barefoot Bob** · 10-26-2002, 04:21 PM

I am a dealer for Air Chair so I can get you some. There is onlt a few ounces in a can and costs about $35.00 if im not mistaken. But it does go a long long way.

**Barefoot Bob** · 10-26-2002, 04:30 PM

Well I just went and checked price on the sealer. 8oz can is $34.95 plus freight about $4.00

**xMitchx** · 10-26-2002, 04:37 PM

I'll see what I can do.

**pyro** · 10-26-2002, 04:46 PM

I think everyone is missing Techno's point here: Can you get a torque tab effect by gritting up one side, and polishing the other?

You can polish aluminum with just about any metal polish and it will shine. It will soon go dull again, unless it is treated or finished. The polish residue must be removed first with solvent and then re-buffed before any kind of finishing is done.

Ok, we all know and understand this, but what about Techno's question? Sounds like something to try. But, I suspect that it will do little or nothing. As it is, the torque tab by itself does not add much of any considerable drag, but helps the steering torque. I doubt that the drag would be enough off-center to effect steering torque. If the drag was sufficient enough to reduce the pull, it would have to be great enough to slow the rig down.

I have heard that changing a cast-in tab so that it has a sideways "sweep" of uniform thickness instead of a "wedge" shape by filing down the opposite (port) side of the tab, has helped in some way or another. If nobody had ever tried this, we would never know...

Give the rough/shiny thing a try, Techno, let us know how it works out. All of our tinkering and experimenting has given us great ability to improve all that we enjoy!

-Chad

**Techno** · 10-26-2002, 06:31 PM

I know some of the LUs have an asymetrical airfoil shape and this idea was for helping this. Kind of a lot of tiny things add up to one large affect.
Plugging the stbd intake holes, stuff like that.

The drag might be increased but might also decrease another drag, like the LU crabbing sideways or the turbulence and drag from the tab.
I figured this was one of those things where I thought it was new but was tried years ago.

Since the LU is supposed to be rough has anyone roughend up the nice paint on them?

Also I was wondering if anyone has scratched the LU in the direction of flow. Like the fwrd scratch on the pads. Not random or straight back but where the water naturaly flows on the LU.

JW · 10-26-2002, 07:12 PM

Ran his drag boat with a painted case, got some gps numbers, pulled the boat out, sanded off all the paint, ran it again, gained serious speed. I've been up close and personal with a Sportmaster, they do not have a rough gritty surface, but definately not a sticky-smooth painted feel.

**woodco** · 10-26-2002, 08:04 PM

This one needs a lil waxin ...... But they are faster without the paint !!!!!!

**NPK2003** · 10-26-2002, 09:00 PM

if you want shiney, even on one side, and then are going to use Mother's products to seal it, buy a muscle car and enter it in a custom car show. ( I'd be a Super Chevy Guy if U need to know.)

I suggest you do the baker mod and use a good acid etching primer on the unit when done. Easy to touch up and breaks coefficient of friction too. Tecno. TECNICALLY you are correct in your prediction of one side polished, but I doubt you would notice less steering torque. Heck, I am a Gemini and even I wouldn't consider pulling out of the ramp with one side shiney and one side nasty.

Just yanking your chain fellow STV'r. But which chain I don't know!?!?

Hehehe,

Nick K

**Techno** · 10-26-2002, 09:15 PM

On mine it would look strange. I'm polishing the whole mid & clamp then Kandy red and gold. Then here is this partially polished thing on the bottom without any kind of paint!
Just seems that if polished is slower then it can be used as an advantage.