Nuts, Bolts and screws

[Dick Bottis]

HELP!

I have a 69 L68 that has been through a lot. I know I can never return it to its original splendor but when I do replace parts I try to replace them with original or reproductions. I am restoring the vinyl seats when I noticed that the seat back adjustment bumpers were from a 70 vette. I have the 69 bumpers but the screws and washers are missing. The screws that hold the bumpers in place are 9425148 upper and 9413317 lower. Also the catch assemblies were held in place with bolts instead of screw 9413317. This is just the beginning I know I'll find many more wrong nuts, bolts and screws.

Has anyone ever compiled a detailed list of nuts, bolts and screws and there specifications? The assembly manual provides part numbers; does anyone have a cross-reference guide?

[Joe L.]

Re: Nuts, Bolts and screws

Dick-----

Regarding fastners, there really is no "cross-reference" guide or similar source of information. Paragon has available some reproduction fastners, but, in the context of the large number of fastners used on Corvettes over the years, the available reproductions represent a tiny fraction of the Corvette fastner universe.

In the "old days" fastners were described in the section 8.9 of the General Parts Catalogs. Later, GM started printing a "Standard Parts Catalog". This catalog contained all of the fastners available during the period for which it was effective. I have many of these catalogs dating back many years, but certainly not a complete collection. It is also very difficult to locate a fastner in these since you first have to know the specifications for the particular fastner before you can look it up. "Reverse-indexing" can only be performed if one is willing to look through all of the possible fastners, which is VERY time-consuming, especially if one has to go through multiple catalogs.

Also, the standard parts catalog only provides information relative to fastner ENGINEERING specifications and finish; it does not provide any information relative to head markings or other non-engineering configuration differences. Many manufacturers may have supplied fastners for a particular GM part number, so non-engineering specification differences are common.

Another problem relates to the fact that fastner part numbers were often changed in service very rapidly(from year-to-year)or were discontinued. Also, and this throws a MAJOR OBSTACLE in fastner part number searches, many fastners used in PRODUCTION and shown in the AIM were NEVER AVAILABLE AS A SERVICE PART.

[Joe L.]

Re: Nuts, Bolts and screws

Dick-----

Regarding fastners, there really is no "cross-reference" guide or similar source of information. Paragon has available some reproduction fastners, but, in the context of the large number of fastners used on Corvettes over the years, the available reproductions represent a tiny fraction of the Corvette fastner universe.

In the "old days" fastners were described in the section 8.9 of the General Parts Catalogs. Later, GM started printing a "Standard Parts Catalog". This catalog contained all of the fastners available during the period for which it was effective. I have many of these catalogs dating back many years, but certainly not a complete collection. It is also very difficult to locate a fastner in these since you first have to know the specifications for the particular fastner before you can look it up. "Reverse-indexing" can only be performed if one is willing to look through all of the possible fastners, which is VERY time-consuming, especially if one has to go through multiple catalogs.

Also, the standard parts catalog only provides information relative to fastner ENGINEERING specifications and finish; it does not provide any information relative to head markings or other non-engineering configuration differences. Many manufacturers may have supplied fastners for a particular GM part number, so non-engineering specification differences are common.

Another problem relates to the fact that fastner part numbers were often changed in service very rapidly(from year-to-year)or were discontinued. Also, and this throws a MAJOR OBSTACLE in fastner part number searches, many fastners used in PRODUCTION and shown in the AIM were NEVER AVAILABLE AS A SERVICE PART.

[Jack H.]

More words....

The nice research Paragon has done and gives in their catalog (and they have a wall poster too) can be misleading. Tooling at fastener suppliers wore and was changed over the years too. For instance, an 'M' head bolt obtained as reproduction may well have the 'M' in a different font, placement on the head, and outdented with zinc plating where originals from your era had different 'M' font/placement, were indented and cad plated. So, just getting 'correct' repro heads is ONLY one aspect of the originality challenge.

Next, NCRS member Fred Oliva, has a reasonable assist tool through his company Vintage Automotive Research -- "The Interchange Manual". This item comes in print as well as disk for reference. It only covers each of the mid-year Corvettes, but that's a pretty good start as many of these parts are common to earlier SA and later Shark cars.

The tool lets you look up a component by GM P/N and gives a cross reference to other CHEVY PASSENGER CARS of the era whose AIMs also invoked the part. Does NOT cover Chevy/GMC trucks nor does the data base extend to other GM car lines.

But, if you're into walking scrap yards for 'original' parts/fastners this gives you a 'heads up' on likely donor candidates for your component. Of course, you can't be certain the part you pull from the donor car hasn't been changed out over time and you also can't be sure there weren't multiple suppliers of the component where Corvette/St. Louis only used certain ones (transportation cost/volume specifics) while other final assy plants in other locations binned a different mix of alternate/substitute components....

[Jack H.]

More words....

The nice research Paragon has done and gives in their catalog (and they have a wall poster too) can be misleading. Tooling at fastener suppliers wore and was changed over the years too. For instance, an 'M' head bolt obtained as reproduction may well have the 'M' in a different font, placement on the head, and outdented with zinc plating where originals from your era had different 'M' font/placement, were indented and cad plated. So, just getting 'correct' repro heads is ONLY one aspect of the originality challenge.

Next, NCRS member Fred Oliva, has a reasonable assist tool through his company Vintage Automotive Research -- "The Interchange Manual". This item comes in print as well as disk for reference. It only covers each of the mid-year Corvettes, but that's a pretty good start as many of these parts are common to earlier SA and later Shark cars.

The tool lets you look up a component by GM P/N and gives a cross reference to other CHEVY PASSENGER CARS of the era whose AIMs also invoked the part. Does NOT cover Chevy/GMC trucks nor does the data base extend to other GM car lines.

But, if you're into walking scrap yards for 'original' parts/fastners this gives you a 'heads up' on likely donor candidates for your component. Of course, you can't be certain the part you pull from the donor car hasn't been changed out over time and you also can't be sure there weren't multiple suppliers of the component where Corvette/St. Louis only used certain ones (transportation cost/volume specifics) while other final assy plants in other locations binned a different mix of alternate/substitute components....