Pumpkin Color

[Brandon K.]

I'm getting ready to have my differential rebuilt, as my frame is finally almost completely disassembled. Will probably send it out to Van Steel or Florida Caliper for the rebuild. I am a bit confused about what color to have it painted. The judging manual states "natural to black finish as cast". What does that mean?

I assume it means raw steel, but I don't want it to rust after a week in the car, and I'm not too sure of the durability of clearcoating. I also understand that the judges will deduct for cast-blasting. Could I interpret it to mean that painting it black is ok? I appreciate any help.

Thanks, Brandon Korman

[Joe L.]

Re: Pumpkin Color

The differential "pumpkins" were not originally painted. "Natural to black finish, as cast" refers to the variation in color, from gray to VERY dark gray(perhaps described as "black", by some), which is commonly found in iron castings. Most of the ones I've seen tend to be the more common light to medium gray.

As far as MAINTAINING a "natural" cast iron finish, you are absolutely correct. It is VERY difficult to accomplish. The only options that I am aware of are these:

1-leave it the in the natural, unpainted condition. If you don't drive the car and keep it out of humid environments, it might remain "fresh" looking for a while. Then it will rust. If you do drive the car and/or can't keep it out of humid environments, it will rust very quickly.

2-coat it immediately after cleaning with PreLube 6 and let the carrier solvent evaporate. This will leave a rust-protective invisible coating and maintain a natural looking finish FOR A WHILE. You will have to re-apply the PreLube 6 on a regular basis or the "invisible coating" will dissipate and rust will begin. This method is more practical for "trailer queen" type cars. If you drive the car, I don't think you'll be satisfied with the effort required or the results.

3-coat the "pumpkin" with a clear coat type coating. It won't be "original", but it will prevent rust indefinitely. Unfortunately, the best coatings are somewhat shiny(like Nyalac). Satin finish urethanes don't protect as well, but they are more difficult to detect. Either way, you'll probably lose a few points. Always use a very thin coating or the part will look VERY non-original.

4-paint the "pumpkin" with cast-blast. I recommend VHT brand High Temperature cast-blast paint. In my opinion, this provides the most "natural" looking cast iron color/appearance and it's durable. In my opinion, if you drive the car this is the only way to go. Yes, you'll lose points but, unfortunately, there are times in life when you have to select an option that offers the best all-around solution. In my opinion, if you drive the car, cast-blast is the best all-around solution to "preserve" natural cast parts.

[Patrick H.]

Re: Pumpkin Color

I used the PreLube 6 option on my street driven 71 exhaust manifolds for a year, and they looked GREAT! However, if they see condensation for an extended period of time, the part will rust. While the car is in the restoration process, I would "soak" the outside of the differential several times to allow PreLube 6 to penetrate. If I had had my OmniBag the first winter after I did the manifolds, I don't think they would have rusted.

It's available from Quanta or Eckler's, and looks very natural.

[Kenneth G.]

Re: Pumpkin Color

I am currently restoring my 69 chasis and I had all the suspension components and drivetrain parts beadblasted/sandblasted. I painted all the parts semi-gloss black that were supposed to be and then i was left with the (asper the ncrs guide) parts that were supposed to be "natural and unpainted". I was undecided what to do as far as these "natural" parts so i thought about it for a few days whether I would go strictly "by the book" and leave them unpainted or paint them a cast iron gray. Well , after a few days I noticed that the rearend , driveshafts etc all were starting to rust over a few days in my indoor garage while i thought things over!!!! I couldnt believe how fast bare metal rusted and this made my mind up that i would paint the rear. It turns out the cast blast i sprayed looked very nice and i am very happy with the way it looks. It might not be "NCRS" perfect but i put too much time , effort and $$into the chasis to let certain parts just rust.........I also have doubts ab

[Kenneth G.]

Re: Pumpkin Color

got cut off there, i guess i have too much to say!! But seriously , I have doubts about how long that "prelube 6" lasts. In addition I have no intention of having my car judged but even if i was i think i'd lose the points and have a nice looking rear axle than a cruddy , rusty one (it WILL be correct though!!!!!!!!just a little sarcasm, sorry) just my opinion