That Pesky Sand Cast Aluminum

[rbenash]

Hey folks. For those of us that have done full restorations on bikes that were from the factory with sand cast aluminum covers/cases (1965 - 1968 HD FLH for example)
Once you are all judged, nice and shiny - how do you detail that part of your bike for shows after running it as we are supposed to?

I know a moderately high pressure wash in general is typical for most everything as a start. But you know what I mean - the sand cast covers dull out and oxidize. We know why original SC parts are rare now because original owners got tired of it and just had them polished out. That doesn't work for a restoration or judging for "as original"

What do you do to bring them back up for a show without affecting the other engine/bike components. Have you found a product that brightness all that nicely?

I'm tyring to prep my '65 HD FLH 99.5 WC bike and want to pimp it out and bring that timing cover and primary cover back up to some brilliance.

[RichO]

It was never really shiny when it came from the factory was it? Those motors reminded me of an industrial compressor. I have an early 1940 EL and a 1967 FLH and they both have sandcast cam covers and that's how they were.

[joe fxs fxr]

Acetone or Lacquer thiner?

[rbenash]

It was never really shiny when it came from the factory was it? Those motors reminded me of an industrial compressor. I have an early 1940 EL and a 1967 FLH and they both have sandcast cam covers and that's how they were.

No it wasn't but not oxidized as it get's sitting in your garage. When you try to brighten it up I think it might take something a bit acidic since a mineral based thing. Will have to pick something light to brush it with as to not get any of the solution anywhere I don't want it to go and rinse.

[rbenash]

Acetone or Lacquer thiner?

I've tried that, they are great for oil based stuff but do know brightening. I'll definitely be using a solvent like this first but will need to use something a bit more aggressive for the final dress up I think.

[exeric]

I use Scotch Brite, and dish detergent with water. You can never get the original finish back, but S B pads come in a range of grades and are very controllable for finish depending on how you use them. The picture is of a front backing plate that I didn't want overly polished. Off-hand, I can't think of any pre-'58 cast aluminum part that H-D highly polished.

drum1.jpg

[rbenash]

Thanks exeric:

But that's a ground/polished part. I'm talking about original from factory sandcast/not ground finished unpolished parts like the 65-68 primary cover and timing cover, as well as the lower fork legs on bikes that did not have the KOH group. KOH group provided polished lower fork legs that look like your part above for example.

That said the right scotch brite and cleaner might be worth a try on the rough cast pieces I'm talking about.

[T. Cotten]

I thought everyone had a blast cabinet with walnut hulls, Folks!

(And one with steel shot for re-texturing repairs, removing plating,etc., one for ALOX when its really crusty, and then one for beads of course; I'd have more cabinets if I had more space):

BLASTPIT.jpg
Walnut hulls, with some finesse, give a satin finish without "brushiness", if you know what I mean.
(It also removes surface oxidation without damaging Parkerizing.)

....Cotten

[exeric]

Golly Moses, Tom; what don't you have in your shop? I'm not kidding, I'm impressed.

P.S. You're missing a stool.

[T. Cotten]

Golly Moses, Tom; what don't you have in your shop? I'm not kidding, I'm impressed.

P.S. You're missing a stool.

At least there are three art-deco-vinyl-two-tone bar stools in that pic, Eric.

How many can you sit on at a time?

Indian Red and Birch White!

(They ain't so pretty decades later..)

...Cotten
PS: The whole shop's for sale, but the tools go last.

[rbenash]

Folks just talking about how you maintain after the fact - I've already had that done when the bike went through restoration. Talking about maintaining not remove covers and starting all over ;-)

[D.A.Bagin]

Carb cleaner. Works on my 68 unpolished sand cast parts. Choose the right one. I believe the one I use is not available in Commifornicater. Be careful with it. ALWAYS do a test on something off the bike. Check a painted part to see if it damages it. Again, be careful but it works great for me on my 300 point bike.

[exeric]

I'm tyring to prep my '65 HD FLH 99.5 WC bike and want to pimp it out and bring that timing cover and primary cover back up to some brilliance.

Your first post made many think you wanted to do something aggressive, and abrasive. I think you should post a picture of what you have so members can see what you're trying to 'preserve'.

[T. Cotten]

I polished out my '65 cover about 1976, Ray!

Re-texturing cast aluminum isn't hard, but 'restoring' authenticity requires a little artful finesse. Here is a Linkert bowl where the hammermarks were polished off, then hit with steel shot, beaded, and then Adalox fine brushed.

HAMRMARK.jpg
Even fine beads produce a 'mil-profile' that collects dirt and advances oxidation, but the fine Adalox brush smooths and brightens the surface.

Often motorcase repairs and the like need a lot more preliminary texturing, so I distressed them with simple tools like these...

UNPOLISH.jpg
The techniques work with bronze, too!

UNPOLSHD.jpg
My Adalox wheel is 14", and pulleyed down to maybe a dozen revs a second, giving a nice, safe satin "polish" to many different applications.

....Cotten