Cotter Pin Sizes

[Bill B.]

Where can I get a list of correct cotter pin sizes? Assembling the chassis on my 72 and using a set I purchased from Paragon which included a handy chart of what goes where and what size they are, but once installed they all seem really long.

[Joe L.]

Re: Cotter Pin Sizes

Where can I get a list of correct cotter pin sizes? Assembling the chassis on my 72 and using a set I purchased from Paragon which included a handy chart of what goes where and what size they are, but once installed they all seem really long.

Bill------


GM used cotter pins of a specific shank size and length for the particular application. By using the particular part number from the AIM and a table from the GM Standard Parts Catalog, you may be able to determine the shank size and length for a particular cotter pin. The problem is that many of the cotter pins used in PRODUCTION were never available in SERVICE so you won't be able to determine the specs for every cotter pin used in PRODUCTION. No real matter, though. There were only a relatively small number of shank sizes used in PRODUCTION. So, simply install the largest shank size that will fit through the cotter pin hole and you will have the correct shank size. Then, trim off any excess length with side cutters. The attached table may be helpful:


cotterpintable.pdf

[David H.]

Re: Cotter Pin Sizes

Where can I get a list of correct cotter pin sizes? Assembling the chassis on my 72 and using a set I purchased from Paragon which included a handy chart of what goes where and what size they are, but once installed they all seem really long.

Bill

In addition to Joe Lucia's advice, Section "0" of your Assembly Manual should have some examples of cotter pin installation.

Dave

[David B.]

Re: Cotter Pin Sizes

GM does have a preferred length etc. for all cotter pins. As Joe shows most but not all are listed in Grp. 8.938.
I think one excluded is 103373 3/4 x 3/32 plain. If you cannot find any other list the part number.

[Gary B.]

Re: Cotter Pin Sizes

Where can I get a list of correct cotter pin sizes? Assembling the chassis on my 72 and using a set I purchased from Paragon which included a handy chart of what goes where and what size they are, but once installed they all seem really long.

[Patrick H.]

Re: Cotter Pin Sizes

Bill,

Could you post an image of the chart from Paragon? I’m wondering how it compares to the chart that Corvette Central provides with their cotter pin kits. Terry McManmon can correct me, but I believe he and Pete Lindahl researched what cotter pins go where, by year, size and part number, and they used to sell complete cotter pin kits for cars of given years. Eventually, I think they gave or sold their information chart to CC.

I believe the cotter pins sold by the big companies are all zinc plated. Many if the original cotter pins were unplated, plain steel. You can still get plain cotter pins in some of the original sizes from AMK products. Also, some people like to use stainless steel cotter pins, but when They were a bear to bend, and went back to regular steel.

Gary

Paragon used to have the chart on their website. I believe you can only get it now if you buy the kit.

A few seconds in muriatic acid turns zinc-plated cotter pins into natural cotter pins.
If you buy catalog parts, you end up de-zincing (new word) a lot of parts to get to the correct finish.

[Gary B.]

[James G.]

Re: Cotter Pin Sizes

Powdered citric acid used for canning can be sourced from the local walmart.
I use a very mild mix with water and a bit of alcohol to remove or at least tone down the "brassiness" off the yellow dichromate passivation on zinc plated parts which are plated incorrectly.
The larger bottle ~ $7 will make 20 gallons - I normally use a qt of distilled water with a teaspoon of powder and a splash of alcohol to remove surface tension. FIRST CLEAN in a strong cleaner, drop in, after done fizzing, remove.
Room temp 65-68 it works pretty quick, 95 or hotter really speeds it up, 40's 50's retards it.

Also I am going to take some other photos this afternoon of a customer car and my unrestored 71 top flight car is right next to it, I will grab a machinists rule and take photos of all the cotter pins with length, orientation, etc.
This is the only one I have a clear photo of...
100_9584crop.jpg

[Joe L.]

Re: Cotter Pin Sizes

Powdered citric acid used for canning can be sourced from the local walmart.
I use a very mild mix with water and a bit of alcohol to remove or at least tone down the "brassiness" off the yellow dichromate passivation on zinc plated parts which are plated incorrectly.
The larger bottle ~ $7 will make 20 gallons - I normally use a qt of distilled water with a teaspoon of powder and a splash of alcohol to remove surface tension. FIRST CLEAN in a strong cleaner, drop in, after done fizzing, remove.
Room temp 65-68 it works pretty quick, 95 or hotter really speeds it up, 40's 50's retards it.

Also I am going to take some other photos this afternoon of a customer car and my unrestored 71 top flight car is right next to it, I will grab a machinists rule and take photos of all the cotter pins with length, orientation, etc.
This is the only one I have a clear photo of...
[ATTACH=CONFIG]110228[/ATTACH]

James------


I'm not sure this is an original cotter pin, at least based upon what I can see of it. There are two reasons for this:

1) The ends of the cotter pin appear to have been clipped. Generally, GM used cotter pins of a specific length for each particular application. These were of lengths to avoid the need for clipping (probably because it saves time on the production line);

2) The cotter pin appears to be of the hammer-set type (irregular shaped head). Most, if not all, cotter pins used by GM in PRODUCTION were of the standard head type. The exceptions MAY have been the cotter pins used for front and rear wheel bearing nuts.

[Joe L.]

Re: Cotter Pin Sizes

Bill,

Could you post an image of the chart from Paragon? I’m wondering how it compares to the chart that Corvette Central provides with their cotter pin kits. Terry McManmon can correct me, but I believe he and Pete Lindahl researched what cotter pins go where, by year, size and part number, and they used to sell complete cotter pin kits for cars of given years. Eventually, I think they gave or sold their information chart to CC.

I believe the cotter pins sold by the big companies are all zinc plated. Many if the original cotter pins were unplated, plain steel. You can still get plain cotter pins in some of the original sizes from AMK products. Also, some people like to use stainless steel cotter pins, but when They were a bear to bend, and went back to regular steel.

Gary

Gary------


Virtually all, if not all, of the cotter pins used by GM in PRODUCTION were plain steel.

I know what you mean about the difficulty of bending stainless steel cotter pins but I still prefer them for most applications where corrosion can occur.

[Bill B.]

Re: Cotter Pin Sizes

Thanks guys for the advice. I have attached the chart that came with the kit. I'm curious if the CC chart differs from this. Suppose I could clip the ends, file flat, then "de-zinc" and re-install.

Distilled vinegar works well to remove zinc, albeit takes a little longer.

[Gary B.]

03F576B8-DE48-4F49-A873-1BC9C6259D8A.jpg