63 Spindle Flange ID

[Joe S.]

Interesting thing I noticed when I cleaned and blasted the rear wheel assemblies tonight. Although the part numbers on the flanges are the same, as you can see in the pic below, one is slightly different. You can see the thicker bolt holes on the one on the left (Beefier). My guess is that at some point one had to be replaced and one is the replacement part available at the time.

The part #'s are difficult to read but it looks like both end in 9881N (perhaps 3989881N).

Is perhaps my theory correct or is something else happening here?

Thanks!




Joe's 63 FI Convertible

[Bill W.]

Re: 63 Spindle Flange ID

the thin one is the orig. 63 part. the thick one was used on 64 and newer and over the counter.Bill

[Joe L.]

Re: 63 Spindle Flange ID

Joe------

As Bill mentioned, the "thin" piece is the 1963-only flange. This flange was GM PART #3830253. The "thick" piece is the 1964-79 flange, GM PART #3839830, which also became the SERVICE piece for 1963 models when the GM #3830253 was discontinued from SERVICE in October, 1963.

However, are you sure that the casting numbers on the 2 pieces are the same? These look like 2 completely different castings and I thought that the 63-only piece did use a different casting number than the 64+ (although I don't know what the 63 casting number is, I'd like to know)

1963-only used several different suspension/driveline components from later years. Among others, these include the spindle flanges, the u-joint flanges (which mate to the spindle flange), the differential pinion (companion) flange, the spindle supports, front springs and rear spring.

In general, the 63 components are inferior to their 1964 replacements. As you can see, the spindle flanges are thinner in cross section and "beefiness". The 63-only u-joint flanges are cast nodular iron rather than forged steel as were all 64+ u-joint flanges. GM didn't make these changes because the 63 parts worked just as well and were just as durable. That's not to say that the 63 parts are unsafe to have on the car. Certainly, there was no recall of them. They just aren't as good as the 64+ parts.

[Joe S.]

Re: 63 Spindle Flange ID

Thanks for the info guys. I'll try to get a better shot including the casting numbers but I could swear they look identical. However, they are worn quite a bit so the numbers are difficult to decipher.

Is there any possibility as a late (July 3rd week) 63, with Audgust the last run date for 63's, that this flange was starting to be used then. Assuming not, and being they have made it this far and I am just a cruiser, I'll put them back on as they came off. But still wanted to document it and thought it interesting.

Thanks again for the info and I'll try to get some more on this end along with the numbers.

Joe..

[Rick A.]

Re: 63 Spindle Flange ID

Joe,

I have my July 11, 1963 Z06 in resto now and I will check and see what mine look like and report back! See if I can get any #'s, etc. off them

[Joe L.]

Re: 63 Spindle Flange ID

Joe------

I think that it's VERY possible that a late 1963 could have originally been fitted with the 64+ style spindle flange and also VERY possible that such a car could have received one of each. Keep in mind that these flanges were assembled as part of the complete trailing arm assembly. For the trailing arms, there were left half and right half assemblies. It's very unlikely that they were assembled at the same time. Perhaps on the day that one side was manufactured, they were still using the 63 style flange. By the time that the other side was assembled, even if it was just a day or two, they had switched to the later style.

Also, St. Louis did not rotate their stocks of components. It's possible that one side was pulled "from the back of the bin" and the other side from recently received stock of the component. So, there are lots of possibilities.

A few things to check out of curiousity:

1) what is the casting date of the spindle support found on each side? Does the older of the 2 coincide with the side that had the 63-only spindle flange?

2) do both side have the 63-only u-joint flange or does one side have the 64+ style? If the side that has the 64+ spindle flange also has a 64+ u-joint flange, that MIGHT indicate a possible repair at some time. Although it's possible that some late 63's did receive the 64+ style u-joint flange for the reasons described above, it would seem unlikely that a car that got the 64+ style spindle flange would also get a 64+ style u-joint flange on the same car and same side. It could happen, but the odds are against it. The 1/2 shafts with u-joint flanges are completely independent of the trailing arms as far as St. Louis assembly goes.

[Joe S.]

Re: 63 Spindle Flange ID

Joe,

The spindle supports were each dated (May)E63 and both had the same part number although one was cast as GM4 (other mold I guess).

The Halfshafts and flanges (as well as the driveshaft) are over my friends shop getting the u-joints pressed. I'll pick them up later in the week.

The Spindle Flanges may not be at my house by the time I get home tonight as I finished completing the blasting and clean-up last night and my dad was going to run them over to the shop to have the rear wheel bearings installed. I did take some close-up photos though so either way I'll get back with a double check on the numbers.

It will also be interesting to see what Rick comes up with.

Thanks




Joe and Joanne's 63 FI Convertible

[Bill W.]

Re: 63 Spindle Flange ID

Joe the thin 63 spindle flanges break real easy (I know) . The spindle on the left in your photo is a 63. the one on the right is a replacement . originals have the X cast on the face. Probably replaced at same time as flange ? Also 63#20937.... 579 from end of production had both thin flanges. Check yours for hairline cracks in the thin part. ps lug studs should be black. >>>Bill

[Rick A.]

Re: 63 Spindle Flange ID

All,

I have my 1963 Z06 undergoing frame-off restoration at Tony's Corvette in Gaithersburg, MD. I just confirmed with Tony that the spindle flanges on my car are the ORIGINALS and they are THICK. My car has a July 11, 1963 build date, so I would assume that a changeover occurred sometime around this time period.