72 Alternator Adjusting Bolt Head Marking

[Ed D.]

I had my 72 alternator rebuild some months ago, and had a heli coil installed. I brought the alternator with the original bolt in the alternator so the he could see the need for repair. The repair and rebuild was great, but he replaced the original bolt with a bright,shinny new one with no makings. My bad that I did not see this when I installed the alternator. I am trying to find and original bolt, some information out their says the head should be WB, but my memory says it was not WB. This is not shown in the JR guide. Anyone know what the original bolt head marking is? Buy the way the judges pick up the plain bolt in Mobile Judging.
Ed

[Leif A.]

Re: 72 Alternator Adjusting Bolt Head Marking

The adjusting brace bolt from 1963-1978 was GM #3742420. Mine is a "WB" bolt head. I may have seen a "TR" at one time but not sure.

[Patrick H.]

Re: 72 Alternator Adjusting Bolt Head Marking

Here is mine:

alternator.jpg

[Ed D.]

Re: 72 Alternator Adjusting Bolt Head Marking

Patrick,
I missed you at the National, needed to settle up with you on the labels. I did look at your on line album but I could not definitely make out the markings. Could you give me a better picture or describe the makings. They dont look like WB.
Ed

[Mike E.]

Re: 72 Alternator Adjusting Bolt Head Marking

Ed,
This is from 72 #6899, a very original car with original alternator.
Mike
alternator arm adjusting bolt (2).jpg

[Gary B.]

Re: 72 Alternator Adjusting Bolt Head Marking

This is what the 70-72 TIM&JG says...

The bolt is zinc or cadmium plated with a dark split-ring lock washer (with no coin-like edges) and a zinc-plated .090 inch thick flat washer. Typically this bolt is Grade 5 with three radial lines and has a headmarking of WB, NAT, SB, or L5. Other headmarking are seen, but these are the most common. (See Fig. M 12.0, 12.1 & 12.20)

The bolt shown in Mike's post is an ELCO, made in beautiful downtown Rockford, IL. Still open today. Can only drive down there during the day though :-)

By far, I see SB the most often.

Gb

[Ed D.]

Re: 72 Alternator Adjusting Bolt Head Marking

Thanks Gary, I need to go back to the JM as I did not see that information. I think the old bolt that I lost was an SB, but not sure as memory is not as good as it use to be.
Mike thanks for the Elco picture as I have never seen that making before.
Leif, the WB bolt that the Corvette suppliers are selling do not have the hardness marking
Thanks to all for their responses
Ed

[Owen L.]

Re: 72 Alternator Adjusting Bolt Head Marking

What a menagerie of bolt markings! My LS-5 '72 has this one - though I've no idea if it's original until I see other TT alternator bolts:
IMG_0495.jpg

(I think the "dogbone" mark is one of my favorites - but I've got a soft spot for dogs in general.)

[Edward J.]

Re: 72 Alternator Adjusting Bolt Head Marking

Ed a detail about bolt length is it, Does not extend out beyond the ear of alt. Ends at the edge of ear.

[Ed D.]

Re: 72 Alternator Adjusting Bolt Head Marking

Yes Ed, but the Corvette supply house bolts with the WB markings are substantially shorter.
Ed