Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plated?

[Gary B.]

I heard some interesting speculation today that all GM washers (split lock?) from the 1950s and 1960s with part numbers starting with 103, like 103321, 103328 and 103331 all have a plain finish. And washers with part numbers starting with 131, like 131044, 131047, 131101, 131139, 131140 all have a zinc finish.

Also, the speculation extended to the belief that the plain finish is typically dark gray because of the heat treatment, and because of that the finish is sometimes mistaken for a black phosphate treatment.

Does anyone have any comments about these ideas? John H.? Joe L.? Others?

Are there examples in the GM parts books that counter the 103 vs 131, plain vs. zinc algorithm?

Thanks,

Gary

[Joe L.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

I heard some interesting speculation today that all GM washers (split lock?) from the 1950s and 1960s with part numbers starting with 103, like 103321, 103328 and 103331 all have a plain finish. And washers with part numbers starting with 131, like 131044, 131047, 131101, 131139, 131140 all have a zinc finish.

Also, the speculation extended to the belief that the plain finish is typically dark gray because of the heat treatment, and because of that the finish is sometimes mistaken for a black phosphate treatment.

Does anyone have any comments about these ideas? John H.? Joe L.? Others?

Are there examples in the GM parts books that counter the 103 vs 131, plain vs. zinc algorithm?

Thanks,

Gary

Gary------

Yes, this is the way it is. However, not all washers with a plain finish have part number beginning with "103" and not all with a zinc finish have part numbers beginning with "131".

[Gary B.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Joe,

Do you have any NOS example of any plain finish 103XXX lock washers and, if so, are they dark gray in appearance?

Gary

[David L.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Gary,

Many years ago I went through my 1966 AIM and listed all the bolt, nut, and washer part numbers and the various pages in which they were used. I also have more then 55 different vintage Chevrolet & Corvette parts catalogs (1957, 1963-1977, and 1981-1983). The 103xxx washers seem only to be listed in the AIM, not the parts catalogs (Gr. 8.929, 8.931,and 8.932). There are many "131XXX" lockwashers (Gr. 8.931) listed in my 1969 parts catalog but the description is either "Med." or "Heavy". There a several flat washers (Gr. 8.929) described as "Cadmium" but nothing with a part number "103XXX" or "131XXX". All of the cadmium washers listed have 7-digit part numbers ("36XXXXX" or "37XXXXX").

My "GM Standard Parts" catalog (Sept. 1980) does specify "Cad.", "Zinc", or "Plain" for the finish but the only "13XXXX" part numbers listed are 131014 and 131016. There are several "12XXXX" washers listed.

Dave

[Joe L.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Joe,

Do you have any NOS example of any plain finish 103XXX lock washers and, if so, are they dark gray in appearance?

Gary

Gary------


Yes, I have some but trying to get to them is more than I even want to think about.

[Gary B.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Joe,

I was mostly wondering if you can confirm from memory if they are dark gray.

Gary

[Joe L.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Gary,

Many years ago I went through my 1966 AIM and listed all the bolt, nut, and washer part numbers and the various pages in which they were used. I also have more then 55 different vintage Chevrolet & Corvette parts catalogs (1957, 1963-1977, and 1981-1983). The 103xxx washers seem only to be listed in the AIM, not the parts catalogs (Gr. 8.929, 8.931,and 8.932). There are many "131XXX" lockwashers (Gr. 8.931) listed in my 1969 parts catalog but the description is either "Med." or "Heavy". There a several flat washers (Gr. 8.929) described as "Cadmium" but nothing with a part number "103XXX" or "131XXX". All of the cadmium washers listed have 7-digit part numbers ("36XXXXX" or "37XXXXX").

My "GM Standard Parts" catalog (Sept. 1980) does specify "Cad.", "Zinc", or "Plain" for the finish but the only "13XXXX" part numbers listed are 131014 and 131016. There are several "12XXXX" washers listed.

Dave

Dave------


In general, "103" part numbered fasteners were not available in SERVICE. Most likely, this is because there was a plated equivalent to just about every size and GM decided that it was more "appropriate" to sell the plated version. For SERVICE, the minor additional cost was irrelevant. However, there were a very few "103" part numbered fasteners that were available.

[Joe L.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Joe,

I was mostly wondering if you can confirm from memory if they are dark gray.

Gary

Gary-------


They might have been but my very vague recollection is that they were sort of a "brownish" color (NOT an iron oxide or rust color, though).

[Gary B.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Gary,

Many years ago I went through my 1966 AIM and listed all the bolt, nut, and washer part numbers and the various pages in which they were used. I also have more then 55 different vintage Chevrolet & Corvette parts catalogs (1957, 1963-1977, and 1981-1983). The 103xxx washers seem only to be listed in the AIM, not the parts catalogs (Gr. 8.929, 8.931,and 8.932). There are many "131XXX" lockwashers (Gr. 8.931) listed in my 1969 parts catalog but the description is either "Med." or "Heavy". There a several flat washers (Gr. 8.929) described as "Cadmium" but nothing with a part number "103XXX" or "131XXX". All of the cadmium washers listed have 7-digit part numbers ("36XXXXX" or "37XXXXX").

My "GM Standard Parts" catalog (Sept. 1980) does specify "Cad.", "Zinc", or "Plain" for the finish but the only "13XXXX" part numbers listed are 131014 and 131016. There are several "12XXXX" washers listed.

Dave

[Joe L.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Dave,


One of the few GM parts books I own is “Chevrolet Chassis Parts and Accessories Catalog”, 1938-1968. In Group “8.931 Lock Washers (Cadmium Plated)” it lists twenty-four part numbers for lock washers arranged according to size from No. 6 to 57/64” ID. It lists the following 131XXX part numbers:


131044, 131100, 131101, 131139, 131140, 131141, 131046, 131142, 131047, 131144


It also lists several 120XXX and 121XXX lock washers. So, all of these would have been cad plated.

The list doesn’t contain any 103XXX lock washers, but since the group heading is "Lockwashers (cadmium plated)" I wouldn't expect to find any parts numbers in that list for lockwashers that were plain. I can't find any other group in the parts books that lists non-plated lock washers. Would that imply non-plated lockwasher were never available in service?


Gary

Gary------


GM #103321, 103322, and 103331 were once available in SERVICE. I have some of the 103321.

[Gary B.]

Re: Do washers with GM 103XXX have plain finish; and GM 131XXX washers are zinc plate

Joe,

Yes, I just checked an old e-mail and another person I know has some 103320 and 103321 lockwashers he obtained as NOS service parts. He said they are not zinc/cad plated, so again this is consistent with 103XXX lockwashers not being zinc or cad.

Gary