Hey guys..

After abit of searching - i havet found anything that comes to close.

this is just a small guide on the basics of bolts...

A few Bolts Terms:

Note: Due to the fact that we're basically all using metric bolts - i will only deal with that, unless there is more demand.

Bolt Diameter: Bolt diameter is the distance from one side of the thread to the other. Measured into mm, this is usually in even numbers for toyotas. will vary between 6mm to 14mm for larger applications



Thread Offset: Thread offset is a really tricky one, if your physically minded like myself, think of 'offset' as wavelength. That is, the distance between 2 peaks of the thread... in toyotas, all threads to do with the engine, block and gearbox are 1.25mm. This can be tricky to find for thread diameters >10mm... and will be quite costly.. they are also referred to as 'metric fine thread'.


Thread Length: There is abit of a tricky difference between understanding 'bolt length' and 'thread length'...thread length is just the THREAD length, bolt length encompasses the head - and any non threading buffer.

Head Size: Similar to bolt diameter - is usually seen in even series, however dont be surprised to see a few 13's in the mix there!

Hope this helps understand a little bit about the basics of refferring to a bolt.

So from now on asking for a "12mill bolt" you know you will piss off the guy

ask for bolts using the following manner:
Thread Size x Thread Length x Offsett
So,
M12mmx 50mmx 1.25mm will get you a Metric, 12mm wide, 50mm long, 1.25 mill offsetted bolt.

from there you can ask for:
Bolt Head sizing - usually one to two 'steps up' in terms of thread diameter.
a 12mm thread will probably get you a 14mm head.
tensile strength - what application is this being used for?
Bolt buffer - part of the bolt after the head that doesnt have any thread.

This is all getting into specialist BOLT terrirtory...and i doubt you'll eveer need to go there

A Few Questions that i had about bolts which may help you:
What is the difference between larger offsets and smaller offsets? The main difference is cost to make, demand and industry standards. The reason automotive companies use metric fine threads is due to:

- Greater surface area to 'grab', helps in tension and sheer situations.
- Less tendency to 'rattle out' due to the smaller thread incline - great in ranging, non static mobile applications
- very good for smaller applications, get more 'rotations' of grab for the same surface area.
- less torque to get bolt in.

however, as we all are aware - they have downsides:
. much larger chance of cross threading the bolt (can take less stress per ridge)
- need more engagement threads (to get it on track)

what is this strange broken washer i keep finding? This is called a locking washer, once tightened - it exherts a force back upon the bolt head, stopping the bolt from vibrating out. it also serves as a good indication for the user as to where the bolt head lay relative to the surface of application. it will get much harder to screw down due to the force of having to push the washer as well.

a third and obvious reason for using the split washer, is exherting the bolt head force over a greater area.

it is highly recommended that you buy a couple of each size for each bolt you use...coz your always gonna loose them.

what is a nylock nut? a nylock nut is a patented nut which has a non metallic cross thread at the end of the nut, once you break this (its cherry), the weaker (plastic) inside grips the thread of the bolt and holds it. This ensures a vibration proof situation. however, they can only be used once.

if you have any more questions
feel free to ask this..

hope this has helped you all

Regards
Tim