alternator case refinish -

[Joe C]

while my NCRS days are long gone, I still strive to keep things looking "factory." I recently rebuilt an alternator for my 85 daily driver, and tried something, while it may not be unique, was something I stumbled across during the case refinish. i know bead blasting may be controversial, but none the less, I did bead blast the case. I have a small blasting cabinet, and the medium is TP Tool's Speed Bead Abrasive (80% glass, 20% aluminum oxide) - pressure at 80psi. cleaned the case, and as noted, typical bead blasted finish. this is where I tried something new - new to me anyway. I used a small piece of "white" scotch-bright and a little Wenol polishing compound (red tube). it was a real light polish - kind of like cleaning the wife's fine china. the scotch-bright/wenol took the freshly blasted look - both texture and color back to, IMO, a pretty decent, OE factory look. I'M NOT TRYING TO SAY THIS IS CORRECT OR BETTER THAN ANY PROFESSIONAL RESTO, just looking for some feedback and comments. (there' a little color shift in the before/after photos, but you get the idea)

BTW, what I've found, at least on my C4, the case is not an aluminum alloy, but it seems to be a zinc-aluminum alloy. what mix, I have no idea, but there seems to be only three ratios used in castings. it's too heavy and the color differs too much to be a straight aluminum alloy.

BTWII - i picked up this alternator on fleabay as a spare for $50. the date code on this thing is one day before my original. not that it matters on a C4 daily driver, but what are the odds???

 

[LLC5]

That looks really good, nice job and find.

Did you clear coat it after the polish to protect it or leave it as is?

 

[Joe C]

That looks really good, nice job and find.

Did you clear coat it after the polish to protect it or leave it as is?

no clear coat. the wenol contains some sort of sealant, so the finish should look decent for some time period - Wenol Metal Polishes, Wenol Red

 

[bill81vette]

Nice!!!
I'll try this on mine!!?

Sent from my XT1650 using Tapatalk

 

[kpic]

Actually the only way of telling what was alloyed with aluminum was used would be be working in GM's design group...

Zinc-aluminum alloys have advantages:
Zinc-Aluminum Foundry Alloys

Pure aluminum is less common that magnesium or zinc alloyed with aluminum:
The Difference Between Aluminum, Magnesium and Zinc Alloys - Die Casting Blog

Glass beading always looks great and lasts...

 

[Joe C]

couple more shots - a little "show-n-tell." another old case -- left to right - white scotch-bright/wenol, blasted (center), and before...

second pic - a little hard to show the texture/color difference - looks better in person. the WSB/wenol gives it that "re-skinned" look.

 

[Tom Bryant]

That's a real nice looking finish. I don't see how anyone could argue with that.



Tom