Front control arms

[Gary V.]

Is there a technical paper on the front upper and lower control arms, C2 and C3's, somewhere that details the cross shafts "which year the lower ones were flat, round or cast with a concave surface" and the uppers, which years were "flat or semi round"?

Thanks

[Marco H.]

Re: Front control arms

Gary,
As far as I know the upper shaft had a change over point (from flat to round) during the '66 production year in the #12000 to #14000ish range.
Marco

[Gary V.]

Re: Front control arms

Thanks Marco
I sort of thought that with my 66 for the upper control arms. The lowers though i am not sure about. There is flat which is the most common, comcave and round. The round were used i think on 63 - 63?

[Joe L.]

Re: Front control arms

Thanks Marco
I sort of thought that with my 66 for the upper control arms. The lowers though i am not sure about. There is flat which is the most common, comcave and round. The round were used i think on 63 - 63?

Gary-----

I don't think the full round lower shafts were ever used on a Corvette, although I would not rule it out completely. I've never seen one on a known-original car, though. However, the full round shafts were used on some 1958+ passenger cars which used the same shafts as 63-82 Corvettes.

Many original mid year cars are seen with a "flat" and "I-beam" type lower shaft on opposite sides.

[Marco H.]

Re: Front control arms

Gary,
I tend to believe that on the lower a-arms the flat type shaft was used during the mid-year production. The "I-beam" type shaft is a later issue and as far as I know still available thru GM. I have not yet seen an original mid-year with "I-beam" shafts from the factory. However it is likely that cars over the years had their a-arms replaced due to the usual rebuilder/exchanger programs. (Send your originals..... receive some other rebuilt units....)
Marco

[Joe L.]

Re: Front control arms

Gary,
I tend to believe that on the lower a-arms the flat type shaft was used during the mid-year production. The "I-beam" type shaft is a later issue and as far as I know still available thru GM. I have not yet seen an original mid-year with "I-beam" shafts from the factory. However it is likely that cars over the years had their a-arms replaced due to the usual rebuilder/exchanger programs. (Send your originals..... receive some other rebuilt units....)
Marco

Marco-----


The cars that I'm talking about with different lower shafts on each side are known-original cars. In fact, there was another discussion about this sometime back here on the discussion board. I was surprised to learn this was as common as it apparently was. I knew of several original cars with the different configuration lower shafts but, from what was reported, it was, apparently, more common than I thought it was..

I don't know of any C3-era cars that had different lower shafts on each side but it may have occurred with them, too. My original owner 1969 has the "flat" shafts on both sides.

The "flat" and "I-beam" configuration shafts both had the same forging number and the same finished part number. I believe the specs for the part must have provided for alternate configurations and these parts were supplied by different manufacturers, one or more making the "flat" configuration and one or more making the "I-beam" style.

I believe the "round" shafts, which as I recall also used the same forging and part number, were first used in PRODUCTION for 1958 passenger cars and continued to be used until 1961 or 62. Then, the "flat" and "I-beam" style shafts came into use and were used for 63+ Corvettes as well as passenger cars through 1964.

The last of these shafts available in SERVICE from GM were of the "I-beam" style but I don't know that this style was the only style used on later C3's.They may or may not have. It would make sense, though, that at some point, before or after the end of C3 production, GM would have consolidated suppliers for these shafts since volume requirements would have been quite low. I expect that whatever supplier was the "survivor" was the one making the "I-beam" style shafts. The lower shafts are no longer available from GM.

[Marco H.]

Re: Front control arms

Marco-----


The cars that I'm talking about with different lower shafts on each side are known-original cars. In fact, there was another discussion about this sometime back here on the discussion board. I was surprised to learn this was as common as it apparently was. I knew of several original cars with the different configuration lower shafts but, from what was reported, it was, apparently, more common than I thought it was..

I don't know of any C3-era cars that had different lower shafts on each side but it may have occurred with them, too. My original owner 1969 has the "flat" shafts on both sides.

The "flat" and "I-beam" configuration shafts both had the same forging number and the same finished part number. I believe the specs for the part must have provided for alternate configurations and these parts were supplied by different manufacturers, one or more making the "flat" configuration and one or more making the "I-beam" style.

I believe the "round" shafts, which as I recall also used the same forging and part number, were first used in PRODUCTION for 1958 passenger cars and continued to be used until 1961 or 62. Then, the "flat" and "I-beam" style shafts came into use and were used for 63+ Corvettes as well as passenger cars through 1964.

The last of these shafts available in SERVICE from GM were of the "I-beam" style but I don't know that this style was the only style used on later C3's.They may or may not have. It would make sense, though, that at some point, before or after the end of C3 production, GM would have consolidated suppliers for these shafts since volume requirements would have been quite low. I expect that whatever supplier was the "survivor" was the one making the "I-beam" style shafts. The lower shafts are no longer available from GM.

Joe,
Thank you for your detailed insight. I haven't had the opportunity to look at an original C2 with different shafts. What I have mentioned before is purely based on my experience working on these cars over the last 15 years. As you surely know most cars had their fair share of repairs or alterations over their lifespan. As time goes on it gets more difficult to get your eyes on an unmolested original car; which in my book is the ultimate teaching tool available. Again thanks for sharing you knowledge. That's what makes this TDB so valuable.
Marco