Question for polishers

C

charlesskelter

Been Around the Block
I am polishing the rear brake and fork lowers on my 175 and I seem to have what I can only assume is casting flaws (real small pitting, or lines of pitting, and low spots) that are very hard to get out. I'm starting with 150 to get them out and it's not really making any headway. What do you guys due to eliminate these flaws?

I'm too far in to paint them, and I'm too anal retentive to polish them up with black pits in them.
 
36 or 60 grit flap wheel and a very light touch. Both grits are hyper-aggressive.

Very easy to destroy fork lowers trying to get the casting wobbles out. Go slow and keep the parts cool to the touch or you will cause other damage. Old aluminum gets brittle.

Best way to deal with the casting flaws? Take it to a machine shop and have the legs turned in a lathe.
 
charlesskelter said:
I am polishing the rear brake and fork lowers on my 175 and I seem to have what I can only assume is casting flaws (real small pitting, or lines of pitting, and low spots) that are very hard to get out. I'm starting with 150 to get them out and it's not really making any headway. What do you guys due to eliminate these flaws?

I'm too far in to paint them, and I'm too anal retentive to polish them up with black pits in them.
Click to expand...

try scotch brite pads on your grinder, there's blue, red and brown, start with brown, then red at 90' to the last one, then blue, 90' to the last, you can put some 220 on a palm sander to take out the rest of the marks from the discs, then start polishing with a hard wheel and brown compound, it's just a matter of removing enough material to flatten the surface before you go to a finer tool
 
120 followed by 240 grit emery cloth... then sandpaper until its smooth enough to use with the buffing wheel. the rear brake is tricky with all the corners... the wheel wont fit, so youll need to polish by hand. get the piece as smooth as possible before buffing- it will save you time, especially seeing as how you need to hand buff a lot of the brake.


thank PJ for the emery cloth.
 
I'll try the emery cloth, as I believe I have some of that, if it doesn't work, I'll try the scotchbrite pads. Thanks for the tips.

I won't be doing the wheel itself, and I plan to take them all to at LEAST 800 wet before taking them to a wheel to buff them up.
 
charlesskelter said:
I'll try the emery cloth, as I believe I have some of that, if it doesn't work, I'll try the scotchbrite pads. Thanks for the tips.

I won't be doing the wheel itself, and I plan to take them all to at LEAST 800 wet before taking them to a wheel to buff them up.
Click to expand...

If you have a polishing spindle you really don't need to go further than 400~600 grit. (depending on 'flatness' of surface)
Start with black/emery compound on a stitched mop, the closer the rings of stitching the 'harder' the mop
use brown compo on stitched mop then swap to a 'soft' (loose) mop
A sisal mop would let you use emery compound after 220 grit sanding- if you can get mop to it
My father was a professional polisher for 30+yrs although I've forgotten most of what he told me about it (except its really dirty, smelly job, polishing 8+hrs a day)

PJ
 
i just did the same thing, fork lowers, caliper, controls.... started with 150 on the real ruff stuff... and it took some time... a lot of fucking time, never even bothered with some of the casting marks on the caliper. just wire wheeled lightly w/ dremel and polish w/ a dremel... not smooth but still shiny! fork lowers, caliper and controls/ mc took me about 60 hours. and its not perfect, some of which i blame on using 150.the controls took most of that time. i personally wouldnt go lower than 220, especially if you dont have the right equipment like me. i have a 4 inch polishing wheel on the end of my dewalt 18v, and it doesnt reach the speed needed by about 300-400 rpm . still gets the job done just takes longer.
just remember aluminum is soft and it doesnt take much to eat it up. id never use a sanding wheel of any sort... just hand sanding, but thats just me. ;D
 
I started at 320grit, then 800/1200.
Then sisal with black compound
then denim wheel with black compound
then buffing wheel with white compound

getting it to a mirror finish just takes time. I got a little lazy, and there's some hazy parts to my job. i'll redo them when they need a rebuild.
I'll post a pic when I get around to it.
 
check out my build thread for pictures of how my rear hub turned out...

i think ill be doing it again. I left in the casting marks which i dont mind, but the micro scratches just kill the look of it xP


http://dotheton.com/index.php?topic=8643.75
 
Rocan said:
check out my build thread for pictures of how my rear hub turned out...

i think ill be doing it again. I left in the casting marks which i dont mind, but the micro scratches just kill the look of it xP


http://dotheton.com/index.php?topic=8643.75
Click to expand...

You probably need to go over it again with 400~600 grit

mysta2 said:
Are they round? The ones off my 360s aren't, is that weird?
Click to expand...

I don't think I've ever seen Japanese fork legs that were not 'oval', (maybe some of the cruisers?)
usually 1/16" to 1/8" 'thicker' front to back.

PJ
 
They likely cast them thicker on the leading and trailing surfaces of the forks for strength.
 
crazypj said:
You probably need to go over it again with 400~600 grit
Click to expand...

ill give that a try.... should i go in any specific direction? i know that polishers are always saying to always polish in one direction, but i find it impossible with this stupid brake xP
 
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