Mounting Bracket Screws

[Eugene V.]

Hello,
I am re-installing the headlight vacuum relay mounting bracket (3966703) on my 1970 coupe. The AIM calls for screw 9420494 to mount the bracket and screw 423595 to mount the vacuum relays. Does anyone know know what type of screws these are? i.e. Phillips drive pan head, hex head, etc.

Thanks,
Gene Ventura

[Paul O.]

Re: Mounting Bracket Screws

Hex head self tapping silver or black finish.

[Eugene V.]

Re: Mounting Bracket Screws

Thank you, Paul.

[Paul O.]

Re: Mounting Bracket Screws

Eugene

Also should add it has a recessed head on the screw.

[Eugene V.]

Re: Mounting Bracket Screws

Paul,
Is this close to the original?

Thanks,
Gene
IMG_3497.jpg

[Alan S.]

Re: Mounting Bracket Screws

Hi Gene,
The bracket mounting screws on my 71 are a bit different than what Paul described.
They're a machine screw, and have a captive star washer.
The screws that mount the headlight relays to the bracket are hex-head self-tapping. Perhaps those are what you're thinking about for the bracket too Paul.
Regards,
Alan

[Paul O.]

Re: Mounting Bracket Screws

Alan

You are correct missed that he was asking about both the plate bracket mounting bolts and the relay screws the ones you posted are correct for the plate bracket and the relays are the self tapping type.

Eugene

Those look close to the originals and would be functional I also said silver or black finish black would be better it is seen more often.

[Eugene V.]

Re: Mounting Bracket Screws

Alan and Paul,

Thanks for your replies. I did note the impressions left on the plate from the star washers.
It looks like the search is on to find those screws.

Thanks again,

Gene

[Alan S.]

Re: Mounting Bracket Screws

Hi Gene,
You might try Richard Fortier. His advertisement for fasteners appears in the DRIVELINE each issue.
Also, you may find a suitable hex-head machine screw but without the washer, that you could put a loose star washer on. I think the trick there is to find a washer of the suitable size so it's 'teeth' don't extend out too far beyond the screw's head.
Good Luck!
Regards,
Alan

[Eugene V.]

Re: Mounting Bracket Screws

Alan,
Thank you for the photos, they are very helpful.

Paul,
Thanks for the info. Do you know if the black finish was black oxide or paint?

Gene

[Paul O.]

Re: Mounting Bracket Screws

Black oxide

[Patrick H.]

Re: Mounting Bracket Screws

Black oxide

That looks sparkly enough that it's probably black phosphate. Perhaps Alan can tell.

[David L.]

Re: Mounting Bracket Screws

While researching the 9420494 screw I came across this thread so I thought that would add my 2 cents. The 9420494 screw is also used on the starter shield as shown on UPC 6, sheet B2, in the 1970 Corvette AIM and UPC 6, sheet B1, in the 1966 Corvette AIM. The 9420494 screw shown in the photo below is from a 1964-1968 Corvette starter shield/starter brace. There may be more than one vender that made this screw so the logo may vary depending on the supplier. The logo on this particular screw has a small letter "L" inside a large letter "G". This self tapping screw is 10-24 X 3/8" with hex washer head and "BT" point. I count 9 threads in the 3/8" length, O.D. measures 0.18" (9 x 8 / 3 = 24 threads per inch).

Also, I have a similar screw from a 1969-1974 Corvette starter shield/starter brace that is exactly the same except that the hex washer head has a single slot (for a standard screwdriver) instead on a logo. My 1970 Corvette AIM lists this screw as GM # 9420494.

Dave

[Bill L.]

Re: Mounting Bracket Screws

If I am not mistaken, the back up light switch that attaches to to the mounting bracket on the side cover of a muncie uses 423595 screws as well.

Bill

[Alan S.]

Re: Mounting Bracket Screws

Hi Bill,
Good one! Made me look!
How about the bolt that mounts the switch shield too has a star washer, but the other bolt that mounts only the switch base has no star washer on my 71!?!
The part description in the AIM indicates 'assembly' for both, and the drawing indicates a washer on each.
I wish I had known enough 25 years ago to take a picture in addition to bagging the screws separately.
Regards,
Alan