C2 Half Shaft Flange numbers

[Alan Drake]

First I would like to thank everyone for the past info they posted on C2 half shafts.

FYI, I found two numbers on one of the flanges that bolt onto the axle (the one that gets bent somtimes). Both numbers are in the center by the 1 1/2 hole. One appears to be 3843018 (the last number is very dull) While the other number seems to be GM298, however that's very, very dull. If I have not read the numbers correctly please let me know.

The second flange; can not find any numbers, it was the drivers side which showed less details than passanger side.

Did not find any paint marks, however on one half shaft two 3/4" tear drops stand out on shaft since they are very shiney. Said area is smooth and looks brand new still - so either protected by heavy layer of black out or a so called inspection mark (these inspection marks seem to last longer than the black out)

Removed all rust with RidRust that was slow, however does not destory any details.

Alan

[Wayne M.]

Re: C2 Half Shaft Flange numbers

Hi Alan -- checked my yokes (from same Jan '64 car) and I can see what is cast 3843018, but only top half of the 4 and last 8 are existant, due to machining of the center hole. Both sides show this. Can't find any GM298, but that could have been totally removed in the machining. BTW that part # shows up in my '65 parts book as the valid # for '64 and '65 (at least).

Noticed what appears to be a Chevrolet Bowtie symbol on both yokes, again partially machined out with the center hole.

As to the paint, I'm carefully cleaning one of the driveshafts, and finding exactly what you describe. Where the black paint (or whatever) was heavy, it ran in droplets (towards the outboard yoke). 42 years later, after removing this paint, the surface of the tube is brilliant. Where there was no paint or very little, there is surface rust.

It's sort of like a negative image of what was shiny and what was black at the assembly plant. It's got me scratching my head on how this affects the current thinking on spray blackout, mitting (or whatever), or dipping of these half-shafts.

[Gene M.]

Re: C2 Half Shaft paint drips

Wayne, Do I understand it correctly the drips run along the length or axis rather than radial around the shaft? If that's the case the black out had to be before the shafts were installed or the chassis was turned on it's side (don't think that happened). Another thought....Maybe the supplier blacked out half shafts prior to shipping too as well as GM when installed.

[Joe L.]

Re: C2 Half Shaft Flange numbers

Alan-----

There were only 3 different half shaft flanges used over the 63-82 period. The first was the 63-only flange. It was GM #3832048. This was a cast nodular iron flange that is somewhat "thicker" in cross section than later flanges. It needed to be so that it would have sufficient strength.

The second was GM #3843018, which is the one you have and described. It was used for 1964 through 1974. This is a forged piece. It is considerably stronger than the 63-only piece and it became SERVICE for 63 when the 3832048 was discontinued in March, 1966.

The third is GM #360913. This flange was used from 1975 through 1982. It's also a forged piece and is configured somewhat like the 3843018, although the differences in the 2 pieces are easily discerned. This piece is manufactured by Spicer and usually has the "Spicer" brand name embossed on it. It became SERVICE for all 1963-74 when the 3843018 was discontinued in November, 1975.

The 360913 remains available to this day to SERVICE all 63-82 Corvettes. It carries a GM list price of about 135 bucks, but you can sometimes get it for a lot less from Spicer dealers.

[Wayne M.]

Re: C2 Half Shaft paint drips

Hi Gene --- So far I've only removed the paint ? blackout ? from most of one of the half-shafts. It's slow going as I don't want to be too aggresive and destroy any "evidence". I'll try and post a pic tomorrow.

You'll see that the "whatever" that was applied flowed down and when it approached what I suppose was the underside, it started to flow towards the lower end (the outboard in this case). The heat "blue-ing" is evident near the yoke welds. It's as if the chassis was horizontal with the suspension in the air and halfshafts angled downward.

This rear suspension that I purchased a year ago, was originally bought in California by a local in 1968 or 69 for a hot-rod project that he finally gave up on after moving to Oregon. So it's a bit of a time capsule (CD diff, 9-leaf spring, complete trailing arms w/spindles, brake drums, strut rods, brackets, etc).

[Alan Drake]

Re: C2 Differential Blackout

It appears that the 63/64 differential assemblies were done in blackout as opposed to a natural, however 64 may have been a mixed year. Mine, a Mar64, was done in blackout (or what ever that stuff is) Michael Hanson has some assembly line pictures of the rear assembly showing the black rear end and I have many (5-8) of early 63 showing black.

As Michael pointed out to me; the rear end area was put together as an assembly, blackout then bolted to frame upside down. Exactly what the assembly consisted of I'm not sure, however it seems to be Diff, cross member, half shafts, strut arms and bracket, and maybe the tourque control arms with spindle.

Most of my pictures show black half shafts with dull areas (mitted) in the center areas of both half shafts as if a worker held the assembly by both half shafts to guide the assmebly into palce.

The blackout material I found on the half shafts and joint flange was very thick in areas you would expect paint bulid up when applied heavey.

(Note to Wayne, the RidRust did remove the blackout in the thinner covered areas leading one to believe blackout is not a normal paint compound)

The JG alludes to a black rear end, however it still seems to say a black cast finish and bare half shafts. I'm going to put mine back to what I found, black, and take the point hit untill the JG changes.

[John H.]

Re: C2 Differential Blackout

The '63-'64 rear suspension was subassembled as a unit in the basement, fully sprayed with "chassis black" paint, then hoisted up to the main floor and assembled to the upside-down frame; you can see the terrycloth glove marks on the half-shafts from positioning the assembly. This stopped for '65, as Engineering didn't want to risk getting the gooey chassis-black paint on the disc brake rotors.

[Michael H.]

Re: C2 Differential Blackout

Thanks for the pic John. Lotta guys weren't believing me about how these things looked in 63-64.

This looks like a pic from the pilot line so production likely wasn't coated quite as completely but it was certainly in that direction.

[Michael H.]

Re: C2 Half Shaft Flange numbers

Joe,

Pretty sure there was an earlier flange than the 3832048 for the 63 model year. Believe the 048 was the 2nd design.

[Alan Drake]

Re: C2 Differential Blackout more photos

John, Michael

That's what I suspected!

See the 63 assembly photo labeled '63 074.jpg to '63 084.jpg on the disk sent to you.

Been looking a various early photo and constantly see the black rear assembly for 63/64. See Noland Adams pages 176, 200, 241, 258, 260, 316. The 64's seem to be all before 4/21/64, no extra corner support by body mount 3.

Thanks Alan

[Joe L.]

Re: C2 Half Shaft Flange numbers

Michael-----

I can find no record of any earlier part number. Also, the GM #3832048 shows as not being supercessive to any other number.

Actually, I believe that the 2nd design for 1963 was the 3843018 which is regarded as the 64+ flange. I think that the 3843018 may have been used at the very tail end of the 1963 model year.

I realize that the 3832048 does not look like a part number that would have been used at the start of 1963 PRODUCTION. However, as I've mentioned before, precise inference of part number release date by the actual sequential number is far from a "hard-and-fast" kind of thing. One of the reasons for this, but by no means the only reason, is that some parts have a shorter "gestation period" than others. In other cases, there may have been an earlier part that was, for whatever reason, never released and a "fast track" was done for a replacement. There are many other possible reasons for part numbers which appear "out-of-sequence".

[Michael H.]

Re: C2 Half Shaft Flange numbers

Joe,

Dug out some paperwork on this last night but haven't had time to sort through it yet. Looks like there may have been more than two flanges during the 63 run. I see a 3830253, 3832048 and finally, a 3839830.

There was a multi page tech bulletin that explains all. I'll try to scan and post tonight.

[Timothy B.]

Re: C2 Half Shaft Flange numbers

Looking at the restorer CD and the TSB for this 3832048 flange, I believe that the 048 was machined differently in September or October 62 because of interference from the spindle nut resulting in cracks in the boss around the four bolt holes. If I understood correctly this was the fix until the later design 3843018 flange.

[Michael H.]

Re: C2 Half Shaft Flange numbers

Sorry Joe, my mistake. Thought Alan was talking about the spindle flange, not the 1/2 shaft flange.