Bolt Sizes

[GavF]

I want to buy a ruck of bolts to cover all sorts, so i always have spares etc from a fasteners local to me. Looking through the catalogue the sizes stated are M5/M6 etc then 400mm/50mm which i assume is the length.

Anyone want to give me a lesson on this, how do i know for example, that the strut to hub bolts i have just taken off with a 20mm socket and are X long converted into "M" sizes?

Thanks chaps

[LandyManLuke]

measure them, or use something like microcat to get the LR part number, which you can decode to give metric/imperial thread, length etc.

There are some bolts, like calliper mounting bolts, which either have specific heads, or are to a higher specification etc, that you don't want to replace with run of the mill bolts.

[michael calvert]

m refers to a metric bolt, number = thread size, and digits = length of thread

ie

M6x20

is a metric 6mm thread 20mm long

http://www.boltdepot.com/fastener-informat...-Head-Size.aspx

[GavF]

m refers to a metric bolt, number = thread size, and digits = length of thread

ie

M6x20

is a metric 6mm thread 20mm long

http://www.boltdepot.com/fastener-informat...-Head-Size.aspx

Excellent, thanks for the reply both, so simple.

Cheers

[jericho]

http://www.boltdepot.com/fastener-informat...-Head-Size.aspx

Thanks for that snippet of info.I had wondered about varying metric bolt heads.

[LandyManLuke]

Thanks for that snippet of info.I had wondered about varying metric bolt heads.

LR use some other head sizes too, a lot of M8 bolts have flanged 10mm heads.

[Mark]

Don't forget that even on modern land rovers there is a mixture of metric, UNF, and even the occasional BSF none of which will mate with each other...

A good stock of M6 x 20 through 60, M8 x 20 though to 80 and M10 x 30 through 100 will stand you in goos stead. 1/4 and 5/15 UNF are good to have in stock too...

hth

Mark

[clbarclay]

Don't forget that even on modern land rovers there is a mixture of metric, UNF, and even the occasional BSF none of which will mate with each other...

And don't forget the 1/4 Whitworth on the battery terminals, though I have a feeling they finaly sorted that one out some time in the 90's

[Mark]

you would think that wouldn't you? my 1996 disco has one M8 and one 1/4WW on the batter terminals

[michael calvert]

you would think that wouldn't you? my 1996 disco has one M8 and one 1/4WW on the batter terminals

using up stock eh?

[Night Train]

M8x1.25x40 = metric, 8mm diameter thread, with 1.25 threads per mm, with 40mm of length below the bolt head.

Machine screws are fully threaded to the base of the bolt head, Bolts have a plain unthreaded section.

Don't forget that you will also need to know the tensile strength of the bolt, and nut, so that you are not replacing a strong bolt with a weak one.

The bolt will have a number on the head. The standard high tensile bolt would have 8.8 on it for example and a cap screw (one that has a cylindrical head that takes an allen key) would be 12.2 I think and so stronger. Unmarked bolts could be half the strength of a high tensile bolt and will stretch and break.

As spares I had boxes of M6, M8, M10 and M12 bolts at lengths from 20mm up to 70mm depending on size. I also had plain nuts and nyloc nuts and a range of washers. I also had lots of brass M4 and M5 machine screws with washers and nuts for electrical bodges.

All this is good for emergencies and setting up but some bolts should be the proper type, for brakes, suspension and steering for example. Also putting M8 bolts on a prop shaft doesn't work even in an emergency, they break and fall off within a few miles leaving your prop to whip round breaking things and itself.