Diff Paint Markings

[Kenneth T.]

I am cleaning the pumpkin on my '71, it is nasty cause I drive it.
I noticed that on the top front of the carrier there is a blue stripe of paint and the head of the pinion has the same color of GM blue.

The back half is what stopped me. Small brushing revealed Chev Orange on the rear case. This is the original unit as I am the only owner. I have never had the diff apart or touched by anyone.

It is like a Archeological dig here, I stopped everything. I will take pictures for myself, but my question is is it important in any way? Should I reproduce this look after the cleanup? Thanks

Ken

[Jack H.]

Re: Diff Paint Markings

"It is like a Archeological dig here, I stopped everything. I will take pictures for myself, but my question is is it important in any way? Should I reproduce this look after the cleanup?"

That's your decision (put it back like you found it, or clean it off)... I'm pretty sure the 'party line' would run this way:

(1) The differential met up with the car on the chassis/power train feeder line at St. Louis.

(2) Therefore, it was nowhere near the traditional sources of Chevy Orange paint (Flint SB engine plant or Tonawanda BB engine plant).

(3) Since we judge to 'typical' factory production norms, the burden of proof falls on the owner to document exceptions.

I'm not sure that an explanation of "I'm the original owner and that's how I found it" constitutes acceptable 'proof'... Where I'm coming from is can you testify that the car was NEVER in the dealership service bay without you being there to witness/observe? The orange 'could' have gotten on the differential after the car was assembled/shipped...

I believe there WERE a few items shot Chevy Orange at St. Louis (e.g. the upright posts supporting the distributor ignition shielding), but it's a stretch to see how that paint process might have transferred to the rear differential housing!

So, this one is your personal call...

[Kenneth T.]

Re: Diff Paint Markings

Thanks Jack,

The reason is mentioned the orange is that is seemed to be covered with a black paint which flaked when I brushed it with a brass brush.

I am not looking to plant my stake in the ground. I was just curious and have learned to lean on the side of caution and was not sure if anyone else had ever see this.

Ken

[John H.]

Re: Diff Paint Markings

I believe there WERE a few items shot Chevy Orange at St. Louis (e.g. the upright posts supporting the distributor ignition shielding)

Jack -

I think you'll find that those supports were painted at Flint V-8, not at St. Louis.

[Chuck S.]

Re: Diff Paint Markings

Thanks Jack,

The reason is mentioned the orange is that is seemed to be covered with a black paint which flaked when I brushed it with a brass brush.

I am not looking to plant my stake in the ground. I was just curious and have learned to lean on the side of caution and was not sure if anyone else had ever see this.

Ken

In my opinion...Put it back like you found it if you lean toward perserving originality. Since you are the original owner this confirms there have been no prior attempts at restoration.

I found orange paint on both my front spindles along with a couple of other colors, and I believe it had to have been applied at St. Louis. Otherwise, like the orange on your differential, it served no other purpose since it was unrestored. The shade of orange on my spindles was also very close to Chevy orange, proximity to Flint engine plant not withstanding.

[Kenneth T.]

Re: Diff Paint Markings

In my opinion...Put it back like you found it if you lean toward perserving originality. Since you are the original owner this confirms there have been no prior attempts at restoration.

I found orange paint on both my front spindles along with a couple of other colors, and I believe it had to have been applied at St. Louis. Otherwise, like the orange on your differential, it served no other purpose since it was unrestored. The shade of orange on my spindles was also very close to Chevy orange, proximity to Flint engine plant not withstanding.

Chuck,
Upon further cleaning, the rear cover only, not the carrier, has Chev orange. No doubt.

I know that original owners are a pain in the A&*&$. But,this car was a no problem car and never went back into the dealer from the day I drove it out. Only me, and I never had a wild night out with the spray cans.

It is all in fun and I will take your advise and put it back as it came.
I respect the judges who put time and effort into this hobby and if they ding me, it's OTAY.

[Chuck S.]

Re: Diff Paint Markings

Chuck,
Upon further cleaning, the rear cover only, not the carrier, has Chev orange. No doubt.

I know that original owners are a pain in the A&*&$. But,this car was a no problem car and never went back into the dealer from the day I drove it out. Only me, and I never had a wild night out with the spray cans.

It is all in fun and I will take your advise and put it back as it came.
I respect the judges who put time and effort into this hobby and if they ding me, it's OTAY.

Once you have the area clean, I would simply document the marks with photos for future reference, and leave them unmolested.

My experience has been that judges do not attempt to assess the originality of chassis markings or judge them. This could have changed in the last couple of years, but in my opinion, trying to judge the authenticity of chassis markings is fools folly. Chassis marks can be similar from one car to the next, but there is great variety in the type and number of chassis marks. That's why restorers should not solicit information about all the chassis marks that have ever been observed to restore their chassis...it's just not realistic. If a project car has chassis marks, replicate them in restoration; if not, then restorers shouldn't be trying to fake them.

At one time, each of those marks meant something to someone, maybe a dozen individuals...now most of those guys are past caring and/or belong to history; we can only speculate about what those marks meant, but they had a very specific meaning at the time.

BTW, I would have doubts about the mark's authenticity if it was applied with an aerosol can...chassis inspection marks were applied (generously daubed with runs) using paint brushes or marked with crayons. If the mark is sprayed, it's not original in my opinion.

[Michael G.]

Re: Diff Paint Markings

Ken,
I finished my71 (12/70) diff this past winter and found these markings;

Small dab (dime size) of blue on outer edge of pinion flange.
Entire tip (end) of pinion shaft painted bright yellow.
Entire "cup" of both 1/2 shaft flanges dabbed with white paint.

I have no idea what any of this indicates, but do believe these to be original factory applied. Low mileage vehicle with no signs of molestation

[Rob M.]

Re: Diff Paint Markings

My personal believe (which is higly speculative) is that these marks were used to indicate that oil was applied an items (diff, steering box, etc) or to indicate that cotter pins were applied (maybe checekd by safety/quality inspector). You will typically find markings in these area's. Also when a specific option was selected some markings were often applied on the car(parts).

regards,
Rob.

[Chuck S.]

Re: Diff Paint Markings

My personal believe (which is higly speculative) is that these marks were used to indicate that oil was applied an items (diff, steering box, etc) or to indicate that cotter pins were applied (maybe checekd by safety/quality inspector). You will typically find markings in these area's. Also when a specific option was selected some markings were often applied on the car(parts)...

Rob, I have thought (speculated? ) that as well, but try to keep my counsel or preface such beliefs with "in my opinion..."

Although marks were added during the entire assembly process, some marks (in my mind) no doubt represented a "check-off" during a final quality/safety inspection. As I noted above, there is no uniformity in what marks were made during inspections (it probably varied by inspector). I can't remember personally seeing or hearing of orange paint applied to a differential case. Since this is an original owner car, however, I can believe that it occurred at least once if the paint has the appearance of factory application (daubed or brushed; not sprayed). Additional, collaborating observations on 70-72 MY would strengthen my belief.

What's a little "speculation" between friends? If we stop sharing observations and speculating/exchanging ideas about the how and why of Corvette assembly, we'll never have any better understanding of the process. Those old guys aren't coming back to give us seminars on how they made a living for their families. We don't want "speculation" and false conclusions to corrupt the judging manuals; but if we remember our speculations are only privately-held theories as "one way it could have happened", I doubt there is danger of that.

[Michael H.]

Re: Diff Paint Markings

Although marks were added during the entire assembly process, some marks (in my mind) no doubt represented a "check-off" during a final quality/safety inspection.

Most of the "markings" that are found on components are for identification. Others are for assembly.
An example would be the paint swipe on the differential pinion flange. That paint swipe indicated the alignment/clock position of the driveshaft (which also had a matching paint swipe) for proper balance of the combined components.
It's possible that different colors were used on some components to ID it's exact comfiguration/ratio/positraction etc.

Over the years, most restorers have decided that there were inspectors running around on the assembly line with their little paint brushes adding paint swipes if a part was correctly installed or a cotter pin inserted in a bolt. It just didn't happen that way.

[Chuck S.]

Re: Diff Paint Markings

Most of the "markings" that are found on components are for identification. Others are for assembly.
An example would be the paint swipe on the differential pinion flange. That paint swipe indicated the alignment/clock position of the driveshaft (which also had a matching paint swipe) for proper balance of the combined components.
It's possible that different colors were used on some components to ID it's exact comfiguration/ratio/positraction etc.

Over the years, most restorers have decided that there were inspectors running around on the assembly line with their little paint brushes adding paint swipes if a part was correctly installed or a cotter pin inserted in a bolt. It just didn't happen that way.

Michael, I hope I didn't make it sound like marks were painted throughout the assembly...most of the assembly marks I can think of were crayon marks.

For example, the option marks on my subfloor were made once the subfloor was designated for my job number, and before the body was assembled. The same is true for the shim marks on the frame. Another mark that is unique to my car, as far as I know, is a white crayon mark encircling one end of the drag link and drawn straight down the length of the link. My guess is it's about secure drag link and tie rod connections, but that is strictly my personal opinion.

There were other white and yellow crayon marks on the steering and suspension components. The orange and violet/olive drab paint daubs on the spindles are less obvious...one paint color should be enough to identify the sides, so why was the orange paint needed for ID?

[Steven B.]

Re: Diff Paint Markings

Ken, like some others I would clean and leave all markings. I can remember removing markings, tags/stickers, or altering something that was thought original and learning years, or decades, later that it was original and maybe even rare. I have made it a practice not to change anything on verified orignal cars---but then I do not remove tags on pillows or matresses for fear of federal prosecution.

Steve

[Wayne M.]

Re: Diff Paint Markings

Here's some more, on end of pinion gear. These must have been painted before assy of the diff. (the orange is far down the splines); so either these were earlier inspection marks at Warren MI, or, they were used for a quick identification of ratio (left is 4.56 gear dated 11-65; right is my 396's 3.70 gear dated 6-65).

[Kenneth T.]

Re: Diff Paint Markings

A picture is worth a thousand words they say, so I posted two. One with the blue on the pinion and the blue strip on the carrier. The rear cover is the chev orange, some removed as I started cleaning it.

Ken