Fasteners 101

The official TGR guide to stop you doing your bolt or getting screwed. Note to the purists: I am gonna interchange bolt and screw as I see fit. Colloquially I’ll use bolt for straight fasteners and screws for things like wood or plaster screws (usually self tapping screws).


Aluminium: aluminium bolts are awesome. They are light (about 1/3rd the mass of steel-based fasteners) but aren’t as strong. Good for engine case bolts and the like. Can be anodised pretty colours.

Button-head: round headed bolt

Cap screw: Allen key bolt. With no other details, it’s a round headed bolt with flat sides and an Allen socket at the top for you to chuck ya key in.

Counter-sunk: unique in that their length is from the top of the countersinking part, not from the base of the head (like most fasteners).

Dzus fasteners: quarter-turn race fasteners. Skookum. Expensive as frig if you buy genuine, and the ebay cheapies sometimes aren’t much chop. Rad and worth throwing onto things like belly pans for fast removal. Can purchase ones with appropriate backs and lengths to go onto standard road fairings, really race is to rivet in the wire clips for them.

Grades: gets a bit tricky to go into a short version of grades for bolts, but basically the lower the grade the weaker the bolt. (This has an impact on torque setting). 8.8 are pretty weak, 10.9 not so bad, 12.9 high tensile. A good way if you need high tensile bolts is to grab capscrews, they’re usually only made in high tensile strengths. Be wary of grades of bolts where you’re changing type, e.g. stainless replacing some other bolt. Make sure it’s strong enough, or that you carry enough spare bolts so that when one busts you can put another one in and get home (or finish the race meeting).

Helicoil: a type of thread insert for thread repairs. Recoil is another name for these. Compare with time-sert. Narrower than a timesert, they do not positively lock into the hole but they do work great for certain applications. As strong as a thread into steel and stronger than a plain thread into aluminium.

Hex head: your traditional bolt with a 6 sided top.

Lock wire: also called safety wire or aviation wire. Race as shit on your street bike, necessary for race bikes in certain areas. We will be covering how to do this in other articles. Pro tip: some heatshrink (not necessarily shrunk) is great for protecting where this can rub on metal stuff.

Locking nut: some form of nut that can lock onto a thread. Nylocs are pretty common, but you can have distorted head nuts or ones with additional parts to dig into the threads. The latter can end up ruining the threads on whatever you’re locking onto. Nylocs work well but don’t like heat and the nylon slowly ends up gaining a thread & then they don’t work so well.

Locking washer: if this is a spring washer, they’re fucking useless. Other designs that gouge the crap out of whatever you’re locking onto can work, but spring washers do gouge the shit out of things and yet are useless. If the nut is loose enough that a spring washer can spring up enough to dig into the nut, the nut is so loose it’ll fall off anyway.

Loctite: the other way to make sure a bolt is done up tight enough – glue the bastard in there. People usually think of loctite (or other threadlockers) based on the colour: purple (loctite 222) for weak, blue (loctite 242/243) for moderate, red (262/263) for “never come undone you prick”. Purple and blue will come undone with hand tools, red needs a bit more shock and awe. No, literally, heat and a good solid thwack on the head of the fastener usually helps here. Also comes in nice glue stick style products these days (loctite 248 for medium strength blue, and loctite 268 for high strength red). Another colour you might come across is green, which is the wick-in product and is nominally as strong as blue (but as hard to remove as red). This is primarily used by manfacturers who are lazy – you torque up all your bolts, then dab this around near the head and it gets in and seals it up over a couple of days.

Machine screw: Phillips headed bolt.

Metric: Metric fasteners are pretty simple to work out sizing. M to denote metric, a number which is the nominal diameter (e.g. M8 being an 8mm nominal diameter fastener), and then there’s the thread pitch. This is the amount that the bolt goes in when threaded, but it is also the distance between two successive thread roots or peaks.

Nutsert: see rivnut.

Pan head: synonymous with button head, through usually button head implies a rounded head cap screw and pan head is for Phillips or flat screws.

R-clip: removable clip, often used in place of a split pin. Race as fuck if you use these for caliper bolts for speedier wheel changes in the local Coles carpark.

Rivet: if you don’t know what a rivet is, well, maybe this is the wrong place for you. Pop rivets are great at holding things together, especially if you chuck a washer on the ‘back’ side (the side that gets pulled into the clamping surfaces). Pain in the arse to do lots of rivets by hand but they are strong.

Rivnut: threaded insert that you insert into a hole and pull it in like a rivet. Doesn’t require as much setting force as a pop rivet (if you give it that much force it’ll strip the threads out of the insert) and gives you nice standard threads. Great for stuff like sharks fins on swingarms!

Speed nuts: metal clips that go onto bodywork etc to give you a thread (or accept a self-tapping screw in some cases).

Split pin: also called a cotter pin. Can be reused if you’re broke, I like to use new ones where I can. Multi-grips (/channel lock pliers to you yanks) are great for folding over one leg. I cut the other one off short as it makes removal faster between races.

Stainless steel: usually comes in two grades: A2 (304) and A4 (316 ‘marine’ grade, which kinda isn’t still). Not as strong as high tensile steel bolts as stainless is more brittle, and a real prick when it comes to lockwiring (it work hardens, especially A4/316)… but they look rad and that’s what counts.

Tap drill sizes: there’s proper ways to work this out, but a simple way for metric fasteners is nominal diameter minus thread pitch. So, for M6 (1mm standard sort of pitch) use a 5mm drill bit, 6.75mm for M8 (standard pitch 1.25 in coarse) yada yada. I also use a tap and die app on my phone to look this shit up.

Titanium: the duck’s guts. Properly ghetto as excess titanium is consistent with living the thug lyfe, these bolts are half the mass of steel-based bolts and almost as strong. You’ll want to use some form of anti-seize on them as they have a tendency to gall up and get stuck. Non metallic anti seize for the most awesomeness, but good results can be had with metallic based ones.

Torque (setting): a bodgy but time-honoured way to get a fastener correctly tightened. What you’re actually after is to get a bolt to about 60% of its yield strength; torque tables are a way of doing this. Note that torque is gonna vary according to how lubricated your hole is: torque tables are often calculated dry. Some manufacturers specify a torque and also to use loctite or anti-seize on a bolt, but they may not take this into account in their torque tables either! (Ducati are notorious for this. Torquing is not the be-all and end-all, but for critical fasteners it’s good for both consistency and doneuppedness.

Wellnut: rubber nut that compresses. Provides some vibration dampening. Great for windscreen and fairing installations.

Zinc plated: (sometimes denoted zp) a nice way to coat bolts so they don’t rust and look arse. Not quite as shiny as stainless steel bolts but pretty tidy nonetheless.