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Discussion Starter #1
I would like to buy bulk nuts, bolts & washers for a GT Junior restoration. What is the most commonly used sizes, not necessarily a list of all used but just head size & pitch. I'm thinking 10s & 13s pitch ??? Any others?

Thanks
Jack
 

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Fasteners are measured by the shank or diameter size, not by wrench size since x diameter nut may come in different wrench sizes. As such, common nuts and bolts will be;

5 x 0.8mm
6 x 1.0mm
8 x 1.0mm
8 x 1.25mm

There are a number of larger sizes too, for suspension, etc.
 

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Discussion Starter #3
Thanks Jim..

I used head size as a reference because on 356 Porsche's its pretty much 8, 10 & 13 - which is nice since you don't have to guess at wrench size
 

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Same wrench sizes on Alfa fasteners;

a 5mm nut/bolt takes an 8mm wrench
6mm takes a 10
8mm takes a 13
 

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Discussion Starter #5
Thanks again Jim ...

Thats exactly what I wanted to know.
 

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I can't think of exact examples now, but some of the 8mm ones take 14 instead, when the other end needs a 13 - so you don't need a second set of spanners. Nice move.
 

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Head sizes are standardized, but are an engineering issue. Parameters are shank size, thread pitch, strength rating.

For example, 8 mm shanks can have 0.8, 1.0, or 1.2 pitch, in grades 6 thru 9. They will have 12mm, 13mm, or 14 mm hex heads. Generally smaller heads go with fine pitch and lower strength.

Robert
 

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The 14mm ATF 8mm bolts and nuts went out of use in the early 105 series; you see them on Giuliettas and earlier, and up through 65/66 on Giulia Supers, Duettos, GTVs, but after that they're all 13mm ATF. Here and there are a few 12mm ATF nuts for 8mm bolts, on the carb mounts, and occasionally elsewhere. German hardware more commonly uses 12mm ATF for 8mm, and Japan has its own standards too.

The Alfa-only 9mm 2000 driveshaft bolts are 13mm ATF. Try finding those at Home Depot.
Andrew
 

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Stay away from hardware store style fasters. ARP makes beautiful fasteners also W and E, Wurth, and other suppliers of automotive fasteners, Also don't substitute grades of fastener sometimes a lower hardness grade is in place to allow for flex.I walk the rows at the JY and harvest from the best BMW,Benz, Volvo, VW,ect.If you are in a spending mood ARP will make you custom titanium fasteners.
 

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Andrew - those 9 mm driveshaft bolts are also grade 9 shoulder bolts. Essentially custom made for the application, and nearly unobtanium!

Robert
 

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Not strictly true, in Europe at least. Someone discovered that these 9mm bolts were a modern Citroen item. I bought a set from the parts counter at one of my local dealers and then never got around to using them. They were about $30, several years ago.
 

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Thanks Alex. I had a near disaster when the U-joint connection came loose because I didn't have these bolts. I'm gonna research a new source to have a few spares! They are, at least, very special bolts!

Robert
 

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Robert,

I just dug out my old post as I knew I'd already measured the dimensions. On second thoughts, might these have an insufficient thread length? I might start digging through the three boxes of fasteners that came with my parts haul a couple of years ago. I've been putting it off as the job of laboriously cataloguing every single nut and bolt was not something I was looking forward to!
 

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Here's a link to a website with information regarding screw threads:

Identifying Screw Threads

Having completed a machinist apprenticeship in the 1980s, a lot of time is spent on threads. There is a lot to threads. Like Forrest Gump and shrimpin', there's a lot to screw threads, and you can't just replace a fastener with just anything you find at the local hardware store, because it could break as you're traveling 80 mph down the interstate highway. (Not that I ever do that). You also have to consider the strength of the fastener (grade), as some have mentioned, the type head (mostly hex head on the Alfa), and other considerations such as type finish, ie: plating.

To buy bulk fasteners, you'll need to supply the nominal diameter (what some have referred to as "shank" diameter), pitch, length and type head.

As Papajam listed:

5 X 0.8mm would be specified as: M5 X 0.8 X length, type of head (hex) and finish.

For most of the fasteners you would buy from suppliers such as Grainger, McMaster Carr, MSC, etc., a specification will be listed with ultimate tensile strength and other engineering particulars.

Here's a website for M6.0 X 1.0 hex head stainless steel bolts:

Metric hex bolts, Metric standard bolts, Stainless A-2 (18-8)

100 each of these in a box is $17.39. These are made from 18-8 stainless steel, and have enough strength for about any application on the Alfa. Drive train, suspension and engine fasteners have some special requirements, so these fasteners would be used for most any replacement where the Alfa had a M6 hex head bolt.

Once you know how to specify these fasteners, you can shop around for the best price, shipping, availability.

Peace,

Duke
 

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stainless bolts: beware

Duke suggests stainless 6mm bolts for non-critical applications, which is a good idea.

I just want to put a little more emphasis on the fact that stainless bolts (or nuts) should NEVER, NEVER be used to replace a regular bolt holding something critical - engine, suspension, brakes, etc.

For these applications stick to regular bolts in the proper grades, as Duke correctly suggested.

High quality A2-70 stainless bolts are just about equal in strength to a hardware store grade 2 bolt, and are more sensitive to fatigue. Grade 10.9 and 12.9 bolts are more than twice as strong as A2.70.
 

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Not advocating using hardware store bolts and nuts on a car- but if you know what you're doing you can order the correct fasteners from suppliers. That's what you PAY ARP to do. You can learn something about fasteners and materials, or you can pay someone to sell you the correct fasteners- its your choice. I'm not picking on ARP or any other vendor. As an engineer, this is what I've trained for and do for a living, although not on automobiles. Most of what engineers do is related to safety. We call it fit, form and function. There are a lot problems with counterfeit hardware, and using an incorrect fastener on suspension, engine parts can lead to disastrous failures where people get injured or killed. The same with using a incorrect fastener of the incorrect material for an application. There are hundreds of fasteners, materials, specifications, and that's why people who don't do this for a living are asking for information. Just as you should do your homework before working on your car, you should do your homework before trying to re-engineer the fasteners. And I won't rush off to buy a package of nuts and bolts someone puts together just because its the correct size.

Yeah, Smithy, I'm not advocating using hardware bolts and nuts- unless you know what you're doing. As you're saying- learn something about fasteners, or be ready to pay someone to sell you the correct fasteners. I'll do the former.
 

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We are on the same page. In my experience the factory fasteners should be retained if possible. Flanged heads, shoulder bolts, and other application specific hardware is difficult to duplicate with off the shelf hardware. A person can grossly devalue their car by rushing off and buying a package of nuts and bolts and replacing the factory stuff.
 

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McMaster Carr carries just about every bolt in every grade and material you'll ever need. I just got a box of ten 2" 5/16's width hose clamps, 2 inches was the larghest size in 5/16's width, put 2 together for the boot on the gear selector lever boot. No seepage on there now. $8 bucks and change for a narrow clamp to fit there, cheap at twice the price.
 
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