So, i know theres an article in the magazine that i can't find.
Im looking for a crash course in fasteners. When to use a washer, when to use one grade over another, when to use fine thread, etc.
Im starting to assemble the nascar chassis, and want to use new stuff where i can, but not sure what to spec. Things like the suspension, etc. Engine i can reuse the ls factory hardware, etc.
Also, a lot of the old bolts on the suspension have the attached marks. I have no idea what the marks mean. 
Illuminati bolts. You've already said too much....
"Screw to Win" is a great place to start:
Some reading from the archives that should help:
How the Right Fastener Can Prevent Hardware Failure on Track
That headmark is for Barnes distribution. They were bought out by MSC about 10 years ago. I'll see if I can find an old catalog to see what specific series that bolt is.
Edit: Based on the current MSC line branded Bowmalloy with the same 12 radial lines I would guess this is a "Grade 9". Basically a hex head cap screw made to socket head cap screw strength of 180-200k PSI tensile.
Bowmalloy - 3/4-16, 6" Long Hex Head Cap Screw - 54436720 - MSC Industrial Supply (mscdirect.com)
Fantastic. Thanks everyone!
What about flat washers? When and where should they be used?
You can't really go wrong with flat washers under the head of the cap screw and under the nut to distribute the load as long as there is room for them and they aren't interfering with other components.
Fine thread are slightly stronger than the equivalent size and grade of coarse thread due to the larger minor diameter. My suggestion would be to replace like for like unless you don't know what was there before.
General rule for washers that I use is the hole size. For instance, if you're bolting a fender with a slotted hole to a radiator support, yes washer. If you're bolting something like a tie rod end into a hole that is the same size as the head of the nut/bolt, no washer.
Sometimes washers with lube are called for to reduce friction when using a torque wrench, like some head bolts/studs.
Washers are typically primarily for spreading the clamping load over a larger surface area.
Tom_Spangler (Forum Supporter) said:"Screw to Win" is a great place to start:
Came to post this, including the alternate book title
Not to short Carroll Smith but the, IMHO, best reference for fasteners, and most things mechanical, is the FAA's AC43.13. Best part is that it's free on FAA.gov.
I use a flat washer under the heads of nuts and bolts on aluminum, don't really need them on cast iron. The washers I use are just bigger than the nominal head of the bolt or nut, not great big ones.
Slotted holes in sheet metal def use a good flat washer. There are different grades and thicknesses of flat washers too.
I buy all grade 8 fasteners, you don't need it in most applications but from Bolt Depot dot com (where I buy most of my stuff) it seems most grade 8 stuff is cheaper than grade 5.
I also stick grade 8 in everything. I bought a large assortment several years ago with a bin. It's well worth not digging through a bucket of old hardware.
The assortment I bought came with washers and lock washers so I generally use a washer on everything.
Thanks everyone.
Y'all confirmed what I thought i knew, and added some key missing pieces. Specifically fine thread. Never messed with it much.
I have a large selection of grade 8 coarse from tractor supply, but don't want to skimp on the suspension hardware.
In reply to Dusterbd13-michael :
Ford used to specify fine thread everywhere so they could save money on lockwashers.
I spent a lot of time on a '34 and there wasn't a single coarse thread fastener that wasn't from a Chevy.
For me coarse threads go into aluminum, fine threads into cast iron.....tho not exclusively. For example, Mini cylinder heads are held down with studs that are coarse going into the block and fine where the nuts go on
For me coarse threads go into aluminum, fine threads into cast iron.....tho not exclusively. For example, Mini cylinder heads are held down with studs that are coarse going into the block and fine where the nuts go on
If I remove something with a fine thread, I'll normally replace it with fine. Unless it's obvious (to me) it is not critical to be fine, and I don't have a replacement, but do have a corse thread that's a good replacement.
Normallt using coarse. Almost never use grade 5... if a good quality bolt (I try to never use the REALLY cheap stuff) needs to stronger, I skip to 8, like others have mentioned
EvanB: on the Barnes marking - knew that mark meant a good bolt... did not know the rest (and I'm a sme on bolts and torque!) Thanks.
Never seen Smiths book. I'll check that out sometime.
Triumph7: also never looked at that reference. I'll definitely be checking that out! My dad was an air frame electrician for the army air corps. I was trained as a Journeyman Outside Machinist. We were taught slightly different stuff on fasteners (specifically washers and lock washers) so that'll be a very interesting read for me!
I keep the bolt bins stocked with grade 8 bolts ranging from 1/4" to 7/16" fine thread in a variety of lengths along with corresponding flat washers, lock washers and nuts, and use them for all non metric purposes. That seems to cover most of my needs. Can't see where the grade 8 overkill would ever be a bad thing. Plus I like the nice gold color.
Metric wise? Hell, I live in Canada, ain't nobody ever figured that metric E36 M3 out. I got a bucket or assorted hardware from scraped Japanese cars and dig around until I find what works. ie 10 mm all the things.
In reply to NOHOME :
The GRM article on metric is awesome. It explains a lot of things.
Fasteners have a kind of etymology. GM (wisely) chose to only switch to metric for items designed that way, which is why small block Chevy and V6 Buick engines had "standard" bolts up to the end of the production run, even though GM went metric in 1981. But accessories designed after 1981 were metric, so you'd have things like stud bolts that were SAE where they threaded into the engine and metric where the accessory attached.
And then there is my favorite example, my NEDCAR built Volvo, which was a group effort of Swedish, German, and Japanese design, and you could tell what was why by what used DIN and what used JIS thread pitch/hex size fasteners. Once you knew that it made sense that you needed 12/14/17 on the chassis, and 13/15/18 on other parts, and sometimes a 16mm.
In reply to Pete. (l33t FS) :
Never picked up on your reasoning on the mix on '80s GM. Don't know if I'll need to remember; prolly won't work on another much!
Always hated working on the "mix" cars. GM was the worst.
In reply to 03Panther :
Volvo went all-in when they went metric. This meant a lot of incompatibility before and after (I think) 1973.
Imagine getting a replacement cylinder head, then finding out that none of your fasteners will work because they are the wrong flavor. Makes one appreciate that ALL SBCs had, say, 3/8NC bellhousing bolts.
LSs did not, because they are a different engine, even though it is the same pattern.
I am in the process of putting a Japanese drivetrain and suspension in an English/German car. The fasteners are wildly schizo. We got 12x1.50, 12x1.25, AND 12x1.75. Just to keep things interesting, there are also some 1/2NF.
The (Japanese) rear diff has studs that are 12x1.75 where they thread into the diff and 12x1.25 for the nuts. I would kinda like to know the story behind that.
Oh, another one! Escorts and Capris. (1960s/70s). Apparently some were metric everywhere and some had metric nowhere. The difference was if they were made in the UK or in West Germany. US-bound Capris were all built in Cologne (Köln) so they were all metric, but I understand that on the other side of the pond it can be a bit of a hassle.
The word I heard on GM was they went metric as they re-engineered parts. Newly engineered parts were metric, but anything they hadn't recently engineered stayed SAE to save money on engineering costs. It wasn't as simple as changing the threads in the part or changing the bolt. The entire part had to go back to engineering and be redesigned as metric and then had to go to their suppliers to be built. By staying with SAE on ongoing parts they saved a pile of money.
Pete. (l33t FS) said:Oh, another one! Escorts and Capris. (1960s/70s). Apparently some were metric everywhere and some had metric nowhere. The difference was if they were made in the UK or in West Germany. US-bound Capris were all built in Cologne (Köln) so they were all metric, but I understand that on the other side of the pond it can be a bit of a hassle.
I've owned several Capri's and worked on many more. What was SAE and what was Metric depended on the item. The OHV 1.6L engine is all SAE, the 2.0L and the 2.6L/2.8L engines were metric. On the car itself it depended. Any US required safety items or pollution control equipment was mostly SAE. In fact you will find on most cars sold in the US the bolts attaching your seat belts are 7/16 fine thread because that's what was in the original specs when they were written.
In reply to jimbbski :
That also tracks, because IIRC the 1.6 is English and the V6 is German. At least, the 1.6 is usually called the Kent engine and the V6 is usually called the Cologne 
Ford had two concurrent V6s in the Capri, the one we didn't get was the Essex, which I assume wasn't German.
I thought it was a world standard that seatbelts had 7/16NF thread, to be honest. I can't recall removing a front seatbelt that wasn't, no matter where the car came from or how old it was. REAR seatbelts are all over the place, now that I think of it. The one I can most clearly picture is the M37x that I had the rear seat out of last week and I can assure you that the rear seatbelts were held in by the same M10 fasteners as everything else in the rear seat hardware.
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