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some advice please from the good ol' US of A.....

Where can I find information on the various nut / bolt / screw sizes used by Packard on my 1930 7-45

I am in the UK so much more used to metric sizes so I am confused about all the various imperial sizes.

I can get them here but at present, I dont know what to ask for.

Thanks

Great thread title! Just hope it doesn't end up getting screwed twisted.

Have you looked at, or better still downloaded, a copy of the 30 - 32 Service Parts List available here on PackardInfo in the Packard Literature and Manuals section?

Virtually all threads on the Packard are UNF, still available from specialist suppliers.

Altho i understand metric/imperial can be confusing i'm not sure what your specific issues are. It can vary.

My advice is to obtain something know as a Drill Gauge. About 3 to 8 dollars US each. Get one in metric and one imperial. They are used for QUICK measuring of drill bit diameters but i use them for sizeing bolts too. Get STEEL drill gauges not plastic.

Also get a thread pitch gauge about 5 or 10 bucks. It measures the TPI THreads per inch.

Imperial nuts and bolts generaly come in FINE thread and Coarse thread.

e.g. a common 1/4 inch bolt can be either 20 threads per inch or 28 TPI. 3/8 bolts are 3/8-16 or 3/8 24.


There are some special application threads that are known as a machine thread where the TPI is kind of a bastard. These are usualy only used on hardened threaded parts such as valve adjuster screws or other similar applications.

Also get a Tap Drill chart. Most machine tool and bolt stores will give them away for free.

Thanks to all for your replies.

Heres a specific example of my problem.

The grille on the front of the radiator should be fixed with two screw-head bolts into a threaded bracket beneath i.e. no separate nut underneath.

Currently there are two smaller bolts which just rattle around. In fact the current bolts are actually electrical socket cover plate screws here in the UK!

I hear what you say about a thread gauge but it would not help in measuring the internal thread.

I guess I can insert a variety of imperial size drill bits in to determine the internal diameter of the thread but it will not tell me what bolts to buy.

As I said, Ican probablyget hold of any size locally but I need to know what to ask for.

Thanks guys

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Equipment this old could very well have been drilled out and a rethreaded the next size larger or any other possible remedies. If the car has long history of NON-US ownership then could very well have some metric or whitworth standard internal threads or head sizes.

Probably just need to buy one of each size and TPI of threaded bolts and screws to use as a gauge that are long enuf to know for sure what any part mite be threaded as.

Even if u can obtain an exhaustive list of every thread, size and length of nut or bolt and screw it will cost u tremendous time and aggrevation running around trying to buy or order each fastener induvidualy for each need that arises.

I'm not sure what your situation is. Most people that work on these cars on even just a sporatic basis have literal 10 or 15 gallon cans of miscellaneous standard parts to use at least as test bolts.

In some cases there are hardness issues or bolt GRADE such as grade 5 thru 8 which determines strength of bolt. Brass vs steel etc.

I doubt that there is any exhaustive list that speels out all specifications for standard parts for ANY vehicle EVER made.

Dear kts68:

If memory serves me correctly what you need for this application are 10-32 X 3/8 inch chrome fillister head screws, nuts, and lockwashers.

You can use stainless steel and buff them to mirror finish.

Packard loved 10-32 fillister head screws.

Good luck with your Custom 8


PS: If 10-32 is too big then try 8-32. You can buy 1/2 length and cut them down to size.

I'd really doubt they were fillister head, perhaps countersunk phoenix, oval or lentil. See the attached for styles. Some of these styles like phoenix and lentil are pretty much obsolete so countersunk oval which is still common may be the best substitute. Otherwise if you're handy you can buy stainless in another configuration with a larger head and shape to style.

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As Mal mentioned, the parts lists usually have the screw sizes and quantity needed to attach an item listed further down in the group categories. In many cases where it is not obvious as to what is needed, the part number for the fastener can be found and then looked up in the utility section where more details, and in many cases illustrations of the actual piece are shown. Utility items were fairly standard throughout the years so a later parts manual may show an earlier screw if it isn't listed in the years manual. If that still doesn't work then the expert knowledge available here will soon have an answer.

I don't know of any complete charts that give a direct correlation between metric and US sizes either but if you do a google search for metric to imperial screw interchange, there are several individual charts of varying categories that show in the first few listings which do show some common features--hole sizes, etc. Here is an examplefreespace.virgin.net/matt.waite/resource/handy/screwsize.htm

If you don't have a good US hardware source available in the UK, some companies do offer complete fastener kits for various other cars (no Packards as far as I know) with common sizes. Unfortunately, Packard might use the same screw thread and length somewhere but a different head. As O_D mentions, many head styles are now obsolete. If you just want a source of modern quality grade US screws to have on hand without buying in bulk quantities, that might be an option. Here is one such companyamkproducts.com/default.htm I would avoid buying any of the common screw kits available in many stores because of the unknown grade.