66 A arms

[Gary B.]

'66 upper A-arm-to-frame bolts

Micheal,

Knowing there were only two choices for length, mine is definitely the shorter, i.e, 2 1/8".

Gary

[Michael H.]

Re: '66 upper A-arm-to-frame bolts

Micheal,

Knowing there were only two choices for length, mine is definitely the shorter, i.e, 2 1/8".

Gary

I wonder if the longer bolt entered production at the same time the new 248 self locking nut showed up? Probably.

Could all of this have something to do with the new for 66 round upper control arm shafts that replaced the square (rectangular) shafts in late 66 production? Was the section of the new round shaft that the bolt passed through slightly thicker than the square shaft?

[Gary B.]

Re: 66 A arms

Michael,

My '66 has the roundish upper pivot shafts and the 2 1/8" bolts work fine.

Gary

[Michael H.]

Re: 66 A arms

Michael,

My '66 has the roundish upper pivot shafts and the 2 1/8" bolts work fine.

Gary

Ok, thanks Gary. Guess the items were not specifically designed to be used with each other.

[Gary B.]

Another late '66 with 2 1/8 long bolts

I just checked some notes from the owner of on another '66 with a early-June build date and the bolts for his upper A-arm-to-frame are also 2 1/8" long, grade 8 with M headmark and used a lock washer and nut. His notes don't mention the thickness of the nut, but since he does include a lock washer I assume the nut was NOT the prevailing torque design. His upper pivot shafts were also the roundish ones.

Gary

[Michael H.]

Re: Another late '66 with 2 1/8 long bolts

I just checked some notes from the owner of on another '66 with a early-June build date and the bolts for his upper A-arm-to-frame are also 2 1/8" long, grade 8 with M headmark and used a lock washer and nut. His notes don't mention the thickness of the nut, but since he does include a lock washer I assume the nut was NOT the prevailing torque design. His upper pivot shafts were also the roundish ones.

Gary

I still wonder if the new round shaft and longer bolt are somehow related. Possible that engineering discovered that the original 2 1/8" bolt was a bit too short when used with the new round shaft? And was the new shaft actually slightly thicker than the old square shaft? Nah, probably not at all related.

By the way, the four upper control arm bolts were the very first parts installed on a new bare frame at the St Louis assy plant.
That info, and ten cents, oughta be worth at least, what, ten cents?

[Gary B.]

Worth ten cents?

Michael,

Some would reasonable say it is priceless.

Gary

[Joe L.]

Re: 66 A arms

I think almost everyone assumed that all 66's used the new style zincad nut Joe. Here's why. The 66 AIM sheet only lists the new 9422300 nut and there's no mention of the previous 3722855 tall nut that was shown in the 63-65 AIM.
The reason why it's not shown as being replaced during 66 production is because the AIM page that we have is not the original page. It's a replacement page.
The original page had 8 revisions and there was no space in the revision box for more so the original page was tossed/replaced with a new page. Note that the revisions begin with revision #9.

I just noticed that there was a new part number for the bolt for 66 too. Wonder what the difference was? Shorter??

Michael----


Yes, the difference in the bolts was due to length as has been reported. I don't think there was any other difference. I expect that the added 1/8" length probably resulted from a need, perceived or real, for accommodation of larger shim packs. The 68-82 bolt is also "officially" 2-1/4" in length (actual, as-measured length is 2-3/16").