120706 bolt length

[Timothy B.]

Can someone post a description of this bolt, it's used on the accelerator support to firewall on a C2. Is it indented head and what's the length.

Thanks as always..

[Rich P.]

Re: 120706 bolt length

Tim,

the repros are too short. I'll measure an original tomorrow. I think it is 9/16 or 5/8". They are grade 2 7/16" hex. Typical headmarking is L and RBW. Most originals are flat head not recessed.

Rich

[Ronald L.]

Re: 120706 bolt length

120706 is shown on the GM bolt chart that has been posted on this DF as a 1/4-20 1/2" Zinc or Cd.

Anyone have a legible copy of that they are willing to share?

[Timothy B.]

Re: 120706 bolt length

Rich and Ronald,

Thanks for the help, I am curious about the length and if it's not to much trouble a can someone post a picture.

I appreciate the help, Tim

[Ronald L.]

Re: 120706 bolt length

Tim,

I looked at the GM document, if you tell me where that PN is used I can look tomorrow on a 66, and 64 but no guarantee on the 64's originality.

[Rich P.]

Re: 120706 bolt length

Tim and Ron
,
I have seen 4 different bolts for this application. I'll list them.
First 7/16 flat hex with a seperate split ring lock washer.
Second 7/16 recessed hex with externally toothed star washer.
Third 7/16 recessed hex with captured split ring lock washer.

My thoughts (take them for what they are worth, not much)
The flat head hex is what is called for in the AIM.
But to make the life of the installer easier they would steal the star washer bolt (top ignition shielding) and captured split ring lock washer bolt (ignition wire supports and boomerang shielding to block bolts) remember they had to install the entire accelerator lever assembly with sealer on it and put the bolts with seperate lock washers on all at the same time.
The 4th bolt is a flat head 7/16" with a seperatl split ring lock washer...but it is like I mentioned in my earlier post, longer.
Tim I would be interested to see which car of yours has recessed head bolts. I have restored a few 63-64's with recessed head bolts.

Rich

I'll post pics of the 4 bolts later today

[Timothy B.]

Re: 120706 bolt length

Rich,

My 67 has never been apart and I can feel the indented head on the bolt. Also, the bolt sticks through from the inside and protrudes approx 1/8" further than the square nut on the nut plate so I would guess it's 5/8" or 3/4" long. I can't see if these bolts have a split ring or star washer.

On my 63 I am not sure because it was apart when I bought the car. I installed indented head anchor bolts and I believe they have a captured split ring lock washer. That is the reason I asked because I wanted to look through my stash to see if I can locate the correct bolts per the AIM. The anchor bolts I wanted to use in the hood support to hood location.

Ronald, the location I am refering to is the accelerator support to firewall but these same bolts are called out for C-60 inner fender brackets holding the A/C hoses to the dryer.

[Rich P.]

Re: 120706 bolt length

Tim,

my money is on a split ring lock washer. This bolt (hood prop to hood) is also used on convertables. It is used in 4 places to bolt the release cable clamps to the lid. 99% of the time they are split ring lock washers.
I did a 67 6 years ago that used external toothed star washers for the 4 clamps on the convertable lid. They were RBW's recessed head 5/8", this is what is used for the fuel pump mounting plate. So as John H. mentioned in another post the assembly line workers would use what ever would make thie life easier to do the job.

Rich

[Scott S.]

Re: 120706 bolt length

Can someone post a description of this bolt, it's used on the accelerator support to firewall on a C2. Is it indented head and what's the length.

Great timing Tim, if you are talking about UPC 6-D1, Item 1, I was just working on this yesterday.

Ronald, the location I am refering to is the accelerator support to firewall but these same bolts are called out for C-60 inner fender brackets holding the A/C hoses to the dryer.

Yep, same part number is called out for the mysterious disappearing 3841336 Hose Clip. From pictures I have seen (and what the vendors sell, e.g., Paragon 1450-k) it appears to be a regular hex bolt being used for the Hose Clip application. I have not found this bolt listed in the regular parts books, but it is listed in at least three official GM sources as being 1/4-20 x 1/2", and one source confirms it is a Grade 2 bolt, Cad plated.

Besides the accelerator support and the inner fender Hose Clips, the only other application I can find for Bolt 120706 is to secure the automatic transmission Cooler Asm. (M35-A4, Item 11).

Regarding the two bolts used to secure the accelerator Support Asm. (UPC 6-D1, Item 1), mine were both indented hex, cad-plated bolts with attached split-lock washers, flat tips, Grade 2, Anchor headmark, measuring 1/4-20 x 5/8" (7/16" across-the-flats). The bolts holding my Hose Clip to the RH inner fender were obviously incorrect, and I don't have an auto trans., so I have nothing else to compare with my accelerator support bolts.