Parts expert question...

[Timothy B.]

For those of you who know such things: I need to replace one lower a-arm cross shaft on my 67 (right side). What is the right part number for that piece, and does the same part fit 63-82? Also, I think MOOG and maybe others made the part too, and I wonder if either GM or others are available from regular parts or only Vette specialists?

[Joe L.]

Re: Parts expert question...

Tim-----

The lower a-arm shaft for 1963 through 1982 Corvettes is GM #3749296. This part fits either side as these shafts are not side-specific parts. It's still available from GM and carries a current list price of $99.84. Many original GM shafts, both PRODUCTION and SERVICE, carry the forging number of "3738505". Whether the ones currently available do, or not, I do not know. It's possible that, by now, this part has been outsourced and/or consolidated in configuration with the aftermarket-available part.

The a-arm shafts are or were available from aftermarket sources like Moog. These should be orderable from any Moog dealer. The GM part would be available only through GM dealers, but other Corvette parts sources may re-sell them after obtaining them thusly. The shafts are not a Delco parts system-available item.

[Patrick H.]

Re: Parts expert question...

As a non-expert....

I believe that produciont originals of the era had a "flat" bottom configuration, whereas later GM ones (and likely any OTC ones now) had a depression in the bottom, giving more of a scooped-out appearance. When you see the two next to each other it is relatively obvious, and is also obvious when installed on the car.

So, I think he will have to find a used/refurbished part if there will be any judging in his future. The function of each is the same. My 71 has one of each style, and I have good reason to believe that on my car the scooped-out later one is a real GM item, just not of the original configuration.

Patrick

[Timothy B.]

Re: Parts expert question...

Thanks for the responses. The two I have now I think are original, and both are "scooped" out as you say. Problem is, one is bent...

[Joe L.]

Re: Parts expert question...

Patrick and Tim------

This is one of those deals in which I don't know if the "I-beam" configuration lower a-arm shaft is the "anomly" or the standard. My 1969 known-original shafts are of the "flat-on-both-sides" variety. I believe that many other cars in the 63-72 period, if not later, may have used these, too. However, I don't know that ALL cars during this period originally used the "flat" type. Here's why:

The GM #3749296 lower shafts were originally used for 1958 Chevrolet passenger cars and were subsequently used on passenger cars through the 1964 model year. Of course, they were also used on 63-82 Corvettes (which, incidentally, share much of the front end componentry and design with the 63-64 passenger car).

As far back as 1958 GM specified that the 3749296 shaft packages contained a shaft with the forging number "3738505". I have several NOS shaft packages of GM #3749296, some over 20 years old. ALL of these have the "I-beam" configuration and ALL carry the "3738505" forging number, just like Chevrolet said they should going back all the way to 1958.

Unless the forging dies were later modified (very unlikely) but kept the same forging number, I don't see how the "I-beam" construction could have been anything but the original configuration.

What would be extremely interesting would be to see what, if any, forging number is on the "flat" configuration shafts. I can't see the ones installed on my car very well. So, if anyone has any of these out of the car or can get under and see the numbers on the ones on their car, I'd be VERY interested.

[Eugene B.]

Re: Parts expert question...

Joe et al,
The numbers on the cross shaft are facing against the frame when the lower control arms are installed, so seeing the numbers isn't possible.

I did however document the shaft numbers when I had my c-arms apart for restoration. Numbers are 3738505 and shafts on my original '65 are flat bottomed.

Hope this helps.
Gene