UPPER A-ARM SHAFT DESCRIPTION

[Sheldon S.]

I just got back from the Barrett-Jackson auction and while there was looking at a 65 L79 coupe. It was owned by a NCRS judge and I made a comment about the upper a-arm shafts as they were different than the ones in my car(same as his). Where the shims and bolts go through the a-arm shaft on mine are square and on his they were rounded. He informed me that my shafts were over the counter replacements and his were correct. I then proceeded to go and look at all other midyears that I could find and found that all 63-66 a-arms were the square style except one 65 that had one of each. 67 cars all had the rounded style. I came home and checked mine again and also a 64 and both are the square style. While this judge was telling me this another person was listening and commented that as this person was a judge he has to be correct. I beleive he new he was wrong but was using his postion to verify something that wasn't correct. Can someone verify that this is correct or not.
Thanks
Sheldon

[Joe L.]

Re: UPPER A-ARM SHAFT DESCRIPTION

Sheldon------

Some guy thinks that just because someone is a judge that person has to be right? Once-upon-a-time someone told me that, on earth, only the Pope is infallible. I never even believed that, though. Still don't.

Anyway, the difference in the configuration of the bolt bosses on upper a-arm shafts is quite common on ORIGINAL mid-years, particularly the pre-67 variety. Some have speculated that GM had 2 different suppliers of these parts and each produced them a little differently. That's a good possibility, too. I think that there may have actually been 2 different part numbers for these shafts. The first was GM #3820483. I THINK that this is the one with the SQUARE bosses. It was discontinued from SERVICE in April, 1964 and replaced by GM #3845244. This is the one with the ROUNDED bosses. However, I think that both continued to be used in PRODUCTION until 1966 and, possibly, later. I've never seen a known GM #3845244 which had anything but the rounded bosses. Since the part numbers are nowhere to be found on these pieces, though, the only way to know that one is the 3845244 is to have an NOS example in the box. I have many and I've looked at many. All were rounded. I've never been able to get my hands on an NOS, in-the-box GM #3820483 since it was discontinued so long ago.

So, actually, I think that the SERVICE examples of the square boss control arm shafts were gone far before the rounded. In fact, the GM #3845244 is still available in SERVICE to this very day. It seems to me that if one has a square boss control arm shaft on his car, that part is much more likely to be original than if one has a rounded boss control arm shaft on his car. But, either could be original and probably is original. These shafts are not too often in need of replacement, anyway.

By the way, it's also not unheard of to find one of each on totally original cars.

[Gene M.]

Re: UPPER A-ARM SHAFT DESCRIPTION

From my experience on known original cars I have never seen a round configuration previous to a late 66. Known late 66 are the first seen with rounded type upper A-arm shafts in production. All 63 thru 65 should have the squared configuration. I don't know the p/n's but sure on the configuration.