High Quality Fasteners
Most British cars of the 1950’s and 1960’s use UNC and UNF (imperial) sizes, I have heard it said at classic car pub meets that “you can build the whole car with thee sizes of bolts” and there is some truth in this! By the 1970’s car companies were moving to metric (which we stock – email for prices) although many continued with imperial sizes for some time.
The spanner size is the width of the head of the bolt, bolts are those with threads only on the end of the bolt, sets are threaded right to the end of the bolt.
For those of us used to “spanner sizes” a half inch spanner does NOT fit a half inch bolt! So as you can see in the diagram on imperial spanner sizes and threads, half inch spanner fits a UNF 5/16th diameter bolt.
Imperial Spanner Sizes and Threads
|Threads Per Inch||Spanner Size||Threads Per Inch||Spanner Size|
|3/4″||12||1 3/16″||16||1 1/8″|
|1″||10||1 15/32″||12||1 1/2″|
Thread lengths clearly vary, but you will see from the webshop that on ¼, 5/16 and 3/8th we offer bolt/set sizes from ½ inch to 2 inch, which from our experience covers 95% of the bolts and sets you might need.
On nuts, we offer similar sizes, but you can choose from nylocs or plain nuts. Nylocs, of course, self lock and a normal rule of thumb is to use similar to what the vehicle manufacturer specified when the vehicle was built. Some of the old part manuals (BMC in particular) are superb for showing “blow up” drawings of the vehicle, which specify the bolts, nuts and nylocs, washers etc.
On washers we offer a pretty vast range, in the web shop we sell spring washers (which as you would expect look like part of a spring) flat washers and repair (or penny) washers which are often used with flat washers.
Virtually all the above is offered in stainless as well. You might ask why should anyone use plated bolts when stainless are rust free. It is a common misconception that stainless steel is stronger than regular steel. In fact, due to their low carbon content, many stainless steel alloys cannot be hardened through heat treatment. Therefore, when compared to regular steel, the stainless alloys used in bolts are significantly weaker than hardened steel fasteners.
European & Japanese vehicles
Whilst its clearly not possible to state which sizes are used on what vehicles, as a guide; Japanese made cars needs the 8, 10, 12, 14, 17, 19, 21mm spanner sizes, and that basically all you’ll need. European cars need 10, 13, 15, spanner sizes in the main, as well as 19 and 21mm in the bigger sizes. That said, all makes are different! See below for the actual nut size you will require, M=metric, the number, e.g.8 means 8mm.
As stated earlier, you should always follow the vehicle manufacturers specification, when using fasteners in servicing, maintaining and restoring your classic vehicle.
Types of fastener head
Screw heads are usually flat, oval or round, and each type has a specific purpose for final seating and appearance.
Flat heads are always countersunk or rest flush with the surface.
Oval heads permit countersinking, but the head protrudes a little.
Round-headed screws rests on top of the material and are easiest to remove.
A sheet metal screw (or self tapper) can also be used to fasten metal to wood, as well as metal to metal, plastic, or other materials. Sheet metal screws are threaded completely from the point to the head, and the threads are sharper than those of wood screws. Machine screws are for joining metal parts, such as hinges to metal door jambs.
Machine screws are inserted into tapped (pre-threaded) holes and are sometimes used with washers and nuts.
Question…. When is a bolt not a bolt?
Answer…. When it is a Set Screw.
We are reffering to hexagon headed bolts and set screws – see diagram.
The difference between a bolt and a set screw is that there is thread the entire length of the set screw, whereas a bolt is only partly threaded.
|THREAD LENGTHS FOR STANDARD BOLTS|
|METRIC||Up to 125mm long||2 x diameter + 6mm|
|125mm – 200mm long||2 x daimeter + 12mm|
|Over 200mm long||2 x daimeter + 25mm|
|UNC/UNF||Up to 6″ long||2 x dia + 1/4″|
|Over 6″ long||2 x dia + 1/2″|
|BSW/BSF||Up to 1/2″ dia.||Over to 1/2″ dia.|
|Up to 4″ long||2 x diameter||1.1/2 x diameter|
|4″ – 8″ long||2 x diameter||2 x diameter|
|Over 8″ diameter||2.1/2 x diameter||2.1/2 x diameter|
In the UK we refer to these products as hexagon headed bolts and setscrews, however, in the USA they refer to them as cap screws.
Another confusing terminology associated with these is the fact that a grub srew is also reffered to as a set screw….confusing isn’t it?
As mentioned, a set screw is fully threaed along the length of the body, therefore the length is stated by the measurement from under the head to the end.
The length of a bolt is also stated by the measurement from under the head to the end, but the length of the thread is determined by the diameter, as shown above.
Examples: M10 x 100 bolt = 36mm thread or 1/4″UNC x 2″ bolt = 3/4″ thread or 1/2″BSW x 5″ bolt = 1″ thread.
The plain section (known as the shank) is the remainder of the length.
Note: These sizes are based on the DIN and British Standard specifications for standard bolts, however some manufacturers choose to add an extra turn or two of thread which increase the overall thread length and shortens the resulting plain shank section. There are also less popular hexagon bolts with differing specifications.
Information On Screwdrivers & Nut Drivers
The slotted style is the original type of screw drive, with a straight slotted line going across the screw head, from end to end. These are also very common, though it is becoming harder to find them in applications that require a good amount of torque because the screwdriver tends to slip out of the slot more easily than drivers do for other screw drive types. Slotted screwdrivers have a flat blade that varies in size depending upon the size of the slot.
Phillips is perhaps the most common type of screw drive. It is characterized by a cross in the middle of the screw head, with the four ends not extending to the end of the screw head. The cross also has a ball point in the middle. The screwdriver itself is cross-shaped, with each cross blade being tapered at 57 degrees. Phillips screw drives come in a range of sizes, the Phillips #2 is perhaps the most commonly used Phillips screw drive.
The Pozidriv screw drive is actually an enhanced version of the original Phillips drive. Developed by the Phillips Screw Company and the American Screw Company, the recessed flanks of the Pozidriv screw drive are not angled upward like the Phillips drive is. There are also four additional recessed radial lines, with one in between each of the main recessed flanks that form the cross on the screw head. These radial lines are shallow, but they do create additional contact points. These extra contact points, along with the right angles on the recessed flanks of the cross, make it more difficult for a Pozidriv screwdriver to slip out while turning the screw. This in turn allows for more torque to be applied. Pozidriv screws tend to be used more in Europe than in the United States, and the three most common sizes are #1, #2, and #3.
Hex / Allen Key
A hex key or Allen key is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head (internal-wrenching hexagon drive). Also available as a screwdriver, T handle driver & socket wrench.