1970 Trans Am 12-Bolt Axle Color
 

I had started a thread the other day pertaining to the correct color of the 67-69 Firebird Axle Colors. This thread is "69 F Body Rear Axle Color *Latest Consensus*"
With some great response it is easy to conclude that PONTIAC axles in that time period were shipped from PONTIAC and were bare steel and were hit with overspray of black after install into car. See the photos on that thread. So the proper restoration is Cast Gray center section and natural steel tubes and backing plates with the overspray of black.
It was also concluded that all CHEVROLET axle ship from a different axle plant and were always painted ALL BLACK. Everything except the yoke and the wheel studs.So the question is that since all 1970 Trans Ams along with 71-72 GTOs with the 455HO had CHEVROLET 12-Bolts installed it should be easy to assume that these axles were also painted ALL Black just as the Chevrolet Counter parts were. I inquire as I have been restoring a 70 RAIV TA for some time now and currently have the 12-bolt axle painted in the way you would a 67-69 Firebird or GTO i.e. Cast Gray and Natural Steel. I am thinking this is incorrect and should be ALL BLACK based on the evidence as shown on the previously mentioned thread. I know there are some TA experts out there on this forum and would love to have comments / thoughts before I post same question on PY Forums. Seems there is more expert participation on this site.
Thanks to everyone who chimes in.
RA

I'm sure they didn't intend to paint the studs but occasionally got carried away.

A lot of great information has been shared. There were standards (method sheets, process controls) in each gear plant. It appears as though there were variation in how paint was applied on Chevrolet, Buick, Olds, Pontiac axle assemblies....

I thought you might find this interesting. Here is a book/document from Chevrolet Engineering Center. It provides overview of the Exterior Paint Process.

As I noted in the other thread, the wheel studs had some sort of sleeve (I assume cardboard or tubing) slid over them before the paint was applied, so the threads did not get painted. On low mile survivor 65-67 Chevelles you can see a donut of bare metal on the drum face around each stud, that shows where the outer diameter of the sleeve was. You can also see paint on the very end of the studs, so the sleeve was open on the outer end.

The studs were plated with a black finish to begin with, explaining why the threads also appears black in that pic.

Also note that hex shaped bare spot around one of the studs in that pic. Suggests that at that time frame (is that a 68 in the pic?) one nut was run on one stud to hold the drum on during shipping and until final assembly of the car.

Yes. Later the one nut was changed to a push nut.

Photographic evidence indicates that the axles were usually all black for the 12 bolts and the early 10 bolts.

By 1973 the center section was typically shipped natural and the remainder of the axle was still painted black.

By 1975 GM discontinued painting axles all together. The shipping racks and the assembly process at Norwood left significant cosmetic damage to the underside of the axle tubes and quality scoring was tightening to create competition between plants. GM Assembly Division was pushing to get rid of the paint altogether in order to raise the quality score due to demerits that the assembly plant had to score against their own assembly process as the scratching was a normal and unavoidable outcome of how Norwood handled the axles for assembly. As a compromise GM engineering adopted the position that surface rust alone provided a sufficient corrosion barrier to meet the survivability standards required by the warranty commitments at the time of sale and since there was no paint to mar or scratch - the quality demerit issue was removed making Norwood slightly more competitive with the other assembly plants using more up to date conveyor material transport systems.

Just putting this here for the record. This is my low-mile 1970 Trans Am after evapo-rust bath. There was nary a hint of black paint on the axle anywhere. dark cast center section, bare tubes.

Great Pic Tracker1. This is pretty much what i have seen on my survivor 70 TA. Very Very Light surface (almost impossible to describe as) Rust. You ca brush it off. Easy to see it was Bare Metal as well.
Thanks for posting....Look at all that over spray.

Hopefully this helps. This is how I restored my 70 L78 camaro rear 12 bolt. Pretty much painted everything with the drums on it semi gloss black. The paint used on the rear axles wasn't very good and didn't hold up well.

Were the axles painted (specifically 12 bolt Camaro) as a completed unit.? (Rear cover attached/bolted to center section) I thought the covers were painted seperately and the attaching bolts remained blk oxide/not painted.?

All indications are that the '70 F-body 12-bolts were painted as a completed assembly.

Worth the time to read the other thread mentioned above: https://www.yenko.net/forum/showthread.php?t=174044

It sounds from all of this like axles for installation in Chevrolets were painted black through 72, but at least some (if not all) Pontiac axles were not painted.

Don't want to get too off-topic here, but are the sway bar bracket caps silver or is it just the flash?
Now, back to your regularly scheduled thread......

The sway bar drop rods and caps were NOS and came with no paint natural steel. The sway bar mount caps at each end are the originals and are painted semi gloss black. When I removed them there was black paint inside the caps. So based on that I painted them semi gloss black. Also after a evaporust treatment evidence of black was on the exterior. The rear end appeared to never been out of the car when I removed it. So I went with the finishes I saw.

I think we are determining here that what happened with Chevrolet did NOT necessarily happen with Pontiac. In this case in seems that the 12 bolt installed in the PONTIAC F Body did not get the black paint as researched through several original cars now including one that I own. In the case of Chevrolet who DID get the axles delivered to assembly painted black YES the entire assy was painted after being built including the axle cover and bolts. The axle backing plates however seem to have been painted just around the tube leaving much of the backing plate natural metal. If you look at the other thread I started before this one
"69 F Body Rear Axle Color *Latest Consensus*"
you will see the discussion of the Chevrolet axles a little more in depth.

I'm on the "Chevy side" of this discussion but my understanding was that the 1970 F-body 12-bolt was the same regardless whether it was installed in a Firebird or Camaro and even carried the same codes. If this is the case, would it make sense to have a different paint process and how would the production plant differentiate Chevy vs. Pontiac?...I know, I'm trying to instill logic in a mass production environment from 52 years ago... My theory, (unsubstantiated, but plausible), is the paint used on the rear axle assembly was the same as used on master cylinders and brake calipers...and it "evaporated" early in the vehicle's life...but again, that is just a theory.

Not Trans Ams.

yeah this one was crazy with overspray - the line painter must have been a new hire from a Mopar plant :)

Mine is the color of dirt... :(