Nuts & Bolts Question 67 Fan Shroud/DS Horn

[Kirk M.]

Hey Guys,

Trying to get my fan shroud bolts straightened out. In the AIM on page A4 it shows a bolt (122007), lock washer (103320) and "U" nut (3792259). I think I get those being a WB headmark bolt and the square fixed nut "U" bolt that slides onto the fiberglass of the fan shroud. Pictures of original bolt and U-nut would be appreciated to confirm.

My real question is with the horn mount on the DS. That bolt is listed on AIM page A5 as 3848408, so clearly different from other fan shroud bolts. No lock washer is listed although the pic of the bolt seems to show an integral washer. The attachment to the shroud is called out as a weld nut - is that the same thing as the U-nuts used above?

I would really appreciate if someone could describe and/or post a pic of the original bolt used to mount the horn and then clear up the "weld nut" thing for me as well.

Thanks.

Kirk
67 327/300hp with AC

[John H.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

My real question is with the horn mount on the DS. That bolt is listed on AIM page A5 as 3848408, so clearly different from other fan shroud bolts. No lock washer is listed although the pic of the bolt seems to show an integral washer. The attachment to the shroud is called out as a weld nut - is that the same thing as the U-nuts used above?

I would really appreciate if someone could describe and/or post a pic of the original bolt used to mount the horn and then clear up the "weld nut" thing for me as well.

Thanks.

Kirk
67 327/300hp with AC

Kirk -

The driver's side horn bolt goes into a nut that's welded to the radiator support; that nut was welded in place by the radiator support supplier. It's unrelated to the fan shroud or its attachments.

[Page C.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Hi Kirk,
The 1966 & 1967 air condition cars that I have seen have the drivers side horn installed using the bottom condensor bolt. I don't think you can get it in the threaded hole the non air cars use.
I'm enclosing 3 photos. The first 2 are from a 1967 327/300 5 star Bowtie air condition car and the third photo is and unrestored 1967 327/300 air car.
Page Campbell

[Kirk M.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Thanks Page, that is the exact bolt that I have. Does is attach to the standard U-nut used on the fan shroud in that position?

Kirk

[Gary S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

67 Pictures:
1. Original fan shroud clip nut from famous early VIN 67 Bowtie car...note 4 sided nut, not six like the repro's
2. Fan Shroud bolt head mark on same car in #1. WB's very popular marking for fan shrouds, but others used but never have seen a recessed head used.
3. Horn Bolts...these two are original to two 67's I know....one recessed and the other flat head. However, all real ones I remember seeing have toothed washers, short and blunt ends like these. As said before, the horn bolt is screwed into a nut that is already welded into the radiator shroud..not a clip nut. I have not seen flat intregal washer bolts for horns on non-AC cars as in Page's pictures of a car also known to me as very original.

[Scott S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Thanks Page, that is the exact bolt that I have. Does is attach to the standard U-nut used on the fan shroud in that position?

Kirk

Kirk, if yours is handy, can you post the dimensions and characteristics (head type, across-the-flats measurement, finish, pointed or flat tip, grade and headmark) of your LH horn bolt?

Does it have an loose captured washer, or separate washer?

The '67 AIM (12-A5) shows a bolt at this location with the same part number as the bolt to the starter motor brace (6-B1, Item 10), but this might be a case where they didn't use the "standard" bolt for the LH horn bolt, since they weren't screwing it into the "standard" weld-nut.

[Kirk M.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Kirk, if yours is handy, can you post the dimensions and characteristics (head type, across-the-flats measurement, finish, pointed or flat tip, grade and headmark) of your LH horn bolt?

Does it have an loose captured washer, or separate washer?

The '67 AIM (12-A5) shows a bolt at this location with the same part number as the bolt to the starter motor brace (6-B1, Item 10), but this might be a case where they didn't use the "standard" bolt for the LH horn bolt, since they weren't screwing it into the "standard" weld-nut.

Mine is currently mounted. I could prob take it off and snap some pics. It has a captured washer that has raised nubs around the outer edge on the surface that is gonna contact the bracket. Mounts straight thru the standard U-nut. I will check the other stuff out for you this weekend if I get a chance. It is not like the standard horn bolts shown one post below yours - totally different. John Hinckley said it must have been an on the floor adjustment because that is not how it is called out in the aim. My take on it is that on paper it looked like the condenser on AC cars cleared the proper weld nut hole used on non-AC cars. But, when mounted the condenser edge just overhangs the hole enough that you can't get the bolt aligned properly to seat in the hole (the edge of the head hits the side of the condenser). Believe me, I tried my patience for hours trying to get a bolt to go in that hole when I thought that was where it was suppose to go.

Kirk

[Scott S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Mine is currently mounted. I could prob take it off and snap some pics. It has a captured washer that has raised nubs around the outer edge on the surface that is gonna contact the bracket. Mounts straight thru the standard U-nut. I will check the other stuff out for you this weekend if I get a chance. It is not like the standard horn bolts shown one post below yours - totally different. John Hinckley said it must have been an on the floor adjustment because that is not how it is called out in the aim. My take on it is that on paper it looked like the condenser on AC cars cleared the proper weld nut hole used on non-AC cars. But, when mounted the condenser edge just overhangs the hole enough that you can't get the bolt aligned properly to seat in the hole (the edge of the head hits the side of the condenser). Believe me, I tried my patience for hours trying to get a bolt to go in that hole when I thought that was where it was suppose to go.

Kirk

Thanks Kirk, that would be great. Because of the serrated washer aspect, it sounds like it might be one of the earlier model year seat track-to-floor bolts, but I don't know why they would have those laying around when that type of bolt was no longer being used by '67. I can't think of any other bolt at the moment with a serrated captured washer that matches the other characteristics shown in the pictures.

[Kirk M.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Sorry this took so long.

Kirk

[Timothy B.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

IMO, that bolt looks like a 1963 hood hinge to hood bolt. It's serrated so there is a good ground for the horn.

[Kirk M.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

One thing I need to clarify here is that my bolt is for a car with AC. In the AIM it shows that the AC condenser clears the original DS horn bolt hole enough for that bolt to be installed. However, in practice the head of the bolt hits the condenser causing the shaft of the bolt to enter the hole at an angle that is impossible to tighten down on.

We discussed all of this in a previous thread. It was "determined" that there must have been a "field adjustment" made and this second hole (ieriginal fan shroud hole was then used to mount the DS horn ON CARS WITH AC. There were a number of 67 AC car owners who chimed in that that was exactly how their cars were too.

I am not the original owner of this car, so I have no idea if this is the original bolt that was used on all 67 AC cars. It is clearly an "original bolt" and was in place on a properly dated original horn. That is about as far as I can take it. Not sure they would re-purpose a 63 bolt for the job, but maybe so.

You cannot compare this bolt to a standard NON-AC car DS horn bolt as we are assuming it has been modified due to a mounting issue on the line. Hope that helps.

Kirk

[Scott S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Sorry this took so long.

Kirk

Kirk,

Thanks very much for the pictures, looks very similar to the bolt I think Tim is referring to. Is it a 5/16-18 x 3/4" bolt with a 3/4" diameter attached serrated washer? If so, it has the same length (and thread) as the regular 122007 fan shroud bolt. Is it 1/2" across-the-flats?

[Scott S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

IMO, that bolt looks like a 1963 hood hinge to hood bolt. It's serrated so there is a good ground for the horn.

Tim,

Is this the Thread you're referring to?
64 Hood Hinge Bolts

The bolt you showed (post #15, picture #1) appears to be the same as Kirk's, including the "G L" headmark, except the one you showed looks like it's only 1/2" or 5/8" long.

[Timothy B.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Scott,

Yes, that is exactly the bolt I am refering to, I can't recall the length but I bet it's 3/4". To the best of my knowledge the serrated washers were used in 63 and maybe early 64 C2 cars, after that the washers seem to be smooth. The telltale is on my old hinges that show the serrated marks.

[Scott S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Scott,

Yes, that is exactly the bolt I am refering to, I can't recall the length but I bet it's 3/4". To the best of my knowledge the serrated washers were used in 63 and maybe early 64 C2 cars, after that the washers seem to be smooth. The telltale is on my old hinges that show the serrated marks.

So then in 1967 this bolt must have still been in use on some other GM car (or truck) models, being assembled close enough to the St. Louis Corvette facility that the line workers had access to them as needed.

If we can get the specific dimensions of a 1967 C60 LH Horn bolt, we can determine if it is the same Screw Asm. used to attach the 1963 hood hinge-to-hood (GM #3795488). In 1963, this same hood hinge bolt was used to secure the radio (1963 AIM, U69, Sheet 2, Item 3, 3795488 Screw Asm.). The bolt used at the radio location is identified in the 1942-1965 Chevrolet Radio Parts Catalog, depicting the 1963 Corvette dash & radio assembly, showing the dimensions 5/16-18 x 5/8".

This hood hinge-to-hood Screw Asm. changed in 1964 (no mention of the change in the 1964 AIM revision record) to GM #3846201, which was used at the hood hinge-to-hood location through 1967 (and at the radio, 1964-67). That bolt looks very similar to the one Kirk shows, except the conical flat washer is smooth, not serrated. The 3846201 is only 5/8" long, 1/2" across-the-flats, I can't tell for sure what Kirk's is from the pictures.