C1 Rear End Housing Inspection Marks

[Steve H.]

Hello to all,
I have seen photographs of the rear end housings of different C1 cars with the inspection yellow markings on the top on some and on the bottom on others. What is the consensus of where these markings were placed?

Thanks,
Steve 28428

[Ken K.]

Re: C1 Rear End Housing Inspection Marks

Here are five photos of my '59 car's rear end that was built in January Original markings.
Note the large yellow paint marks on the top and bottom of the housing. The number "50" was done in a blue paint.

http://classic-cars-online.com/DSCN2115.JPG

http://classic-cars-online.com/DSCN2116.JPG

http://classic-cars-online.com/DSCN2117.JPG

http://classic-cars-online.com/DSCN2118.JPG

http://classic-cars-online.com/DSCN2119.JPG

Lets see some more examples of these markings...

Thanks Ken

[Steve H.]

Re: C1 Rear End Housing Inspection Marks

Ken,
Very interesting to see that yours was marked on the top and bottom.

Steve

[Richard M.]

Re: C1 Rear End Housing Inspection Marks

Steve, Here are a few shots of the late Feb 59 my friend and I are restoring. The 4th photo is the bottom, so both top AND bottom. I was surprised so much yellow there also.

Rich

[Tom P.]

Re: C1 Rear End Housing Inspection Marks

In the past, I've asked similar questions and posted pictures regarding the various paint markings on rearends. No responses. Again, so far, no one seems to be able to furnish a response related to the locations, colors and meanings of the various hand painted paint markings on rearends---------------------------or even paint markings on other positions on the cars (front suspension, etc).
Over the years, with numerous EARLY rearends, both Vette and Pass cars, I've seen green, yellow, white, blue, (and orange on frontends) at various positions on the rearend parts. Frequently, some rearends have the same colors on the rears, but not always in the same locations. Thus, it SEEMS that when these paint markings got applied, it was somewhat random. I can only speculate (from 40+yrs of personal observation when rebuilding these rears) that at different positions along the machining/assembly processes at the plant, there must have been an open can of paint (various colors) with a paint brush in it and the worker pulled the brush from the can, dabbed on a splash of paint (to indicate whatever), then stuck the brush back in the can until the next rearend (or front suspension part or whatever) came along, then splashed or dabbed on the paint again. Furthermore (from many years of experienced observation), I've noticed that the 55(for pass car rears), 56 and EARLY-57 rearend case AND differential case (ring gear carrier) were painted (inside and outside) with a red oxide type of paint. Then, sometime in mid-57, the cases/differentials were left unpainted, EXCEPT for the black paint that apparently was applied sometime after final assembly (possibly AFTER the rear was assembled into the axle housing).
Botton line: DOES ANYONE HERE KNOW THE SIGNIFICANCE OF THE VARIOUS COLORS OF PAINT WHICH WERE APPLIED AT VARIOUS LOCATIONS ON THE REARS, FRONTENDS, ETC?????????????????

Not long ago, I rebuilt what APPEARED to be a virgin EARLY 57 Corvette rearend for John Neas. It had 3 different colors of paint markings and was painted red oxide inside and out. Posted pictures. ZERO responses as to the meanings of any of the paint markings.
Since you NCRS folks are such fanitical sticklers for correctness and accuracy and the time frames for when various changes occured during production, it would SEEM that these kinds of questions/information would be of great interest and generate some valid answers. But then again, rearends don't seem to generate much interest. I mean, it took YEARS for me to FINALLY convince folks that the little round discs indicating 3.36 and 3.55 gear ratios were were reversed. Finally, it's now changed.

[Chris H.]

Re: C1 Rear End Housing Inspection Marks

I worked on various GM lines during college. Flint Engine and Saginaw steering gear. I put a lot of paint on inline 6 cyl crankshafts as they came off the grinding machines.

I ran an inspection machine. I would pull the shaft off the line where it was hanging vertically. Place it in the machine and spin it by hand. As I recall there were air jets that blew on the shaft journals and across the face of the machine there were balls in tubes suspended by air. There were marks across the tubes that gave the proper clearances and I watched these balls move up and down and assured they were within tolerances.

If the shaft was good I would dab a certain place on the shaft with paint (yellow?) and put it onto a pallet. If it had oversized journals, it would be dabbed in another spot and put back on the line for the grinders (huge machines run by guys that would manually watch for proper grinding and then remove) to redo. If they were undersized I would dab in another position and put it on the pallet for use with undersized journal bearings.

As far as size of dabbing it did not matter as long as it was visible.

As a side note I worked 3rd shift and back then supervision was lacking. I can recall the grinders working 3 hours, getting in their quota and then going to the bar for LONG lunches. Sometimes the grinders would come back and move me aside and haul butt to get the inspections done much quicker. And sometimes the tolerances were fudged a bit to get the quota faster.

[Chris H.]

Re: C1 Rear End Housing Inspection Marks

I will add that this happened back in 1976 or so. That is almost 35 years and I can barely remember what I did then. I was a young student and most of the guys were quite a bit older than me. Anybody dabbing paint in the 60's is long gone and probably dead so getting exact info would be tough (sorry to the older guys here).

But I would say the dabs signified a certain inspection was done and passed. Most likely all critical joints would be marked when the inspection was done such as torque confirmation on tie rod ends.

[Richard M.]

Re: C1 Rear End Housing Inspection Marks

Here's a left front Steering Knuckle Support, 3733449. Original orange paint on the top of the arm facing rearward. As you can see, the parts wash removed some but you can see the clean metal where it all was.

What would have been done to give it the "OK" orange paint?

Lower Bushing torqued (150-170 ft-lbs)...
Pivot bolt torqued (100-200f t-lbs)....
Pivot bolt lock nut torqued(90-120 ft-lbs)....
King pin tolerance ok, or pinch bolt tight....
Upper pinch bolt torqued....

or
All of the above?

[John N.]

Re: C1 Rear End Housing Inspection Marks

Here's a left front Steering Knuckle Support, 3733449. Original orange paint on the top of the arm facing rearward. As you can see, the parts wash removed some but you can see the clean metal where it all was.

What would have been done to give it the "OK" orange paint?

Lower Bushing torqued (150-170 ft-lbs)...
Pivot bolt torqued (100-200f t-lbs)....
Pivot bolt lock nut torqued(90-120 ft-lbs)....
King pin tolerance ok, or pinch bolt tight....
Upper pinch bolt torqued....

or
All of the above?

Richard
I believe that it was to show that it had a additional step of shot blasting for Corvette use. This was thought to remove stress risers etc as the Corvette was to be more subject to extreme usage. The support forging was also used on the 49-52 Pass car, which did not receive that step.
Regards

[Tom P.]

Re: C1 Rear End Housing Inspection Marks

Here's a left front Steering Knuckle Support, 3733449. Original orange paint on the top of the arm facing rearward. As you can see, the parts wash removed some but you can see the clean metal where it all was.

What would have been done to give it the "OK" orange paint?

Lower Bushing torqued (150-170 ft-lbs)...
Pivot bolt torqued (100-200f t-lbs)....
Pivot bolt lock nut torqued(90-120 ft-lbs)....
King pin tolerance ok, or pinch bolt tight....
Upper pinch bolt torqued....

or
All of the above?

Not long ago, I did a TOTAL disassembly, cleaning and rebuild of a front cross member/suspension for one of John Neas' cars (actually, I've done 3 for him).
Both spindle supports (uprights, whatever you wish to call them), as shown by Richard above, had an orange stripe around the upper portion of the support. It is obvious that this orange stripe (as well as other paint markings I found) was painted on BEFORE the complete assembly was painted black, thus covering up any and all paint markings. John had me leave off the black paint from the uprights and spindles and apply a protective clear coat so that the paint markings would be visible. I'll try to remember to post pictures later.
BUT STILL, WHO, IF ANYONE, CAN AUTHORITATIVELY EXPLAIN THE MEANING OF THE VARIOUS PAINT MARKINGS ON CHASSIS, SUSPENSION AND DIRVELINE PARTS???????????????? The various colors and locations of those colors are somewhat known------------but it's what they mean that is NOT known!
Paint marking gurus, this is your cue!


Here are before and after pictures of the rearend I mantioned above.
I can only guess that the reason for the difference in the shades of red in the after pictures was possibly caused by the difference in lighting when I took the pictures. Maybe the difference was caused by the flourescent lights overhead being on in some and off in another (??????). The paint is the same in all 3 pictures!

[Steve H.]

Re: C1 Rear End Housing Inspection Marks

Thanks for all of the responses. This is good information.
Steve

[Richard M.]

Re: C1 Rear End Housing Inspection Marks

Richard
I believe that it was to show that it had a additional step of shot blasting for Corvette use. This was thought to remove stress risers etc as the Corvette was to be more subject to extreme usage. The support forging was also used on the 49-52 Pass car, which did not receive that step.
Regards

John, Please explain "shot blasting" and what a "stress riser" is. I'm a novice when it comes to metal materials processing.

I was under the understanding that the orange paint was applied to differentiate between Pass Car vs Corvette, as the Pass Car part was physically different, i.e. the dimension of the king pin housing to the bottom, or was it to the top, I forgot. I read on a thread, here I think, that there is a dimensional difference. It is odd that in 1959, the price of the Corvette knuckle was less than the Pass Car knuckle. If it took more steps to make the Corvette specific part I'd think it would cost more.

Rich
p.s. from my 1929-1959 Parts book

[Richard M.]

Re: C1 Rear End Housing Inspection Marks

Since we have rear end and paint daub and front end talk in this thread.........Tom your info is very informative, thanks for sharing. I would like to know the answers too.

Thanks Steve for letting us add all of the informative info, errr, I mean hi-jack it on you.

So I did a little digging and found this thread about the knuckle differences.....

https://www.forums.ncrs.org/showthread.php?t=73200&highlight=%22steering+knuckle%22&uid=2734

and here's a photo of the two, Corvette on right. Photo courtesy of Sander Van Ballegooij

Rich

[Gary C.]

Re: C1 Rear End Housing Inspection Marks

Most are "identification" paint marks. A few such as the light blue on the pinion nut are "inspection" paint marks. Some of the paints marks are used to denote a process such as shot penning as John Neas points out other such as the pinion nut signifies it was torqued. Other identification paint marks are used to identify Corvette - yellow paint versus passenger car - white paint. Years ago in the 80's attempted to narrow the use and colors down further, but didn't have much luck. Gary....

[Tom P.]

Re: C1 Rear End Housing Inspection Marks

https://www.forums.ncrs.org/showthread.php?t=73200&highlight=%22steering+knuckle%22&uid=2734

and here's a photo of the two, Corvette on right. Photo courtesy of Sander Van Ballegooij

Rich

Well, yes and no.
The 53-62 Corvette spindle support and the 49-52 Pass car support are essentially the same. The 53-54 Pass car spindle support are different ONLY in the location of the knuckle for the kingpin. The 53-54 pass car knuckle was raised 1in, thus lowering the frontend of those cars. Since I have never crawled under the frontend of every early Corvette race car, I cannot verify it as factual, BUUUUUUUUUT, it has always been my understanding that it was fairly common for early day racers to install the 53-54 Pass car supports on their race cars to drop the frontend, thus, lowering the center of gravity, thus, improving cornering. The installation of the 53-54 spindle supports combined with the shorter HD springs (as used in the 57-59 cars with HD suspension) would seriously lower the frontend of any 53-62 Vette.
Surfacing blasting (we need an engineer/metalurgist to step in here to provide the correct information) of SOME types of metals will (supposdely) relieve stress risers (areas of the metal which are under stress due to forging, bending, heating, etc, etc.) and will "relax" those stressed areas of the metal. Thus, this makes the strength of the metal more uniformily distributed throughout the part (OK, metalurgist gurus, your turn to provide specifics). So, as some of us have understood it over the years, the spindle supports that were to be installed on Corvettes were shot blasted prior to assembly. Is this correct? Did it REALLY increase the durability of the suspension parts? Has ANYONE here EVER seen a broken spindle support that was subjected to serious abuse on either a Corvette or a 49-54 pass car? Well, I haven't. I've been driving, abusing, neglecting and exposing the frontend of my 51 Chevy to all kinds of elements since I bought it from Granddad in 1962. Also, the entire front suspension of BOTH my 51 Chevy and my 56 Vette are chrome plated (supposedly, this potentially can cause hydrogen embrittlement, which results in greater chance of the part being broken). Consequently, I've never seen a broken spindle support (excluding, of course, a wrecked car), either one which had or had not been blasted. So, I really don't know if blasting of the supports enhanced their strength or not. But I am quite familiar with their interchangeability.
And now, for a few pictures of paint markings on frontend parts.
These are from John's 57 Airbox racer after I disassembled the frontend.






Here are the same parts after I cleaned them up, blasted them and returned the colors/stripes as close as I could to their original markings.


The book states gray stripes on the HD coils, so, here are the stripes.