Origins:
The first grade of 'Ferritic' (magnetic) Stainless was accidentally invented by Harry Brearley in Sheffield UK in 1913, although Krupp of Germany produced the first austenitic (non magnetic) grades a short while later. In metallurgical terms it is still very much a ‘new’ material. Essentially stainless works because it’s surface is covered in a passive film which provided it is not deprived of oxygen will prevent corrosion of the material substrate. If the the passive film material is scratched or impacted it repairs itself immediately as it does when exposed to mild acids and saline solutions.
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The benefits:
Stainless steel is the ultimate 'fit and forget' material. The benefits of stainless can be appreciated best when the disadvantages of the alternatives are briefly considered:

Original equipment (steel) - very expensive, poor quality substrate material, painted or very thinly plated, maybe the reason you are looking at this site!!

Anodised - low strength material with finish liable to fail very quickly if exposed to weather or salt air. (click here).

Titanium(Ti) - approximately the density of Alu overall strength roughly the same as stainless - at a price.

Unlike aluminum stainless will not corrode or become brittle as titanium can. The material can be finished to a degree to suit you. If a bright polished surface of a stainless fastener becomes scratched or suffers minor impact damage it can be taken off the machine and refinished there and then. In terms of price most stainless fasteners cost far less than Aluminium and a fraction of the cost of Ti. Generally speaking stainless is available in a greater range of sizes compared to Al or Ti. There is no other material suitable for motorcycle fasteners providing these benefits.

 
Further information concerning materials used for motorcycle fasteners can be dowloaded in pdf form, right click the icon select 'save target as'.  
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Quality assurance:
Our A2/A4 fasteners are mosly of european origin, there are cheaper fasteners available in abundance from the far east which we will not stock or sell to anybody.
Products machined from T316/303/431 alloys are made by local machinists to the highest standards available. Any machined product we supply (except disc bolts & nylocs) is electropolished.
Quality is the single most important issue to us, be it quality of product or customer service.

 
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Shipped Finish:
Fasteners and components made from stainless can be used straight from the lathe or machine but the 'mill' finish can sometimes look dull even on the best quality alloys. All fastener prices quoted are for plain or 'mill' finish unless explicitly stated.
Quality stainless by definition robustly resists attempts to plate, paint or coat. Stainless finishing involves removing metal rather than covering it up ie electropolishing, bright polishing or under some circumstances a combination of both. Explanations of the polishing methods follow:
Bright Polishing
The face of the hexagon or cap is ground with two seperate grits then manually polished on three seperate mop stages. The finish produced is a deep reflective chromium like finish. If the finish becomes scratched it can be repolished repeatedly!!
Electropolishing
Applications - All stainless components can be electropolished (except nylon insert nuts and T431 alloy- see below).
Involves immersing the material in a hot electrolyte comprised of some of the most corrosive acids imaginable (we cannot treat nylon insert nuts because the plastic evaporates!). Basically the process is the opposite of plating - a few microns of metal are removed by the acid along with the engrained oil deposits and tooling lines etc which provided the original dull look. It is the only practical way to finish washers, full nuts, machine screws and lends itself particularly well to Allen and Button heads as the inside of the socket is left gleaming.
Pleasing to the eye as it is, the electropolished finish generally does not look as chrome like as the bright polish but it is easier to maintain; if the electropolished finish becomes dirty or weathered it can be hosed down etc, left to dry and the finish will look the same as it did when it was shipped. Occasionally we may opt to electropolish hexagons and dome nuts prior to bright polishing (Dual polish). Bright polished socket caps are available dual polished only.
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Physical Properties/Material specifications:
All of the products we sell are manufactured are made from materials conforming to the relevant BS/ISO standard. The screws we supply will be from one of the following groups :
A2 Class 70-80 , A4 Class 70-80 or T303S31/T316S31.

The grades explained:

A2 Class 70-80 (BS970 bar & hexagon equivalents T303/T304)
The 'A2' denotes the alloy type. A2 is often referred to as 18/8 (18% Chrome/8% Nickel) or Type 304. This is the most common form of stainless steel fastener fabrication, it offers excellent general corrosion resistance and is the minimum specifcation we supply. Class 70-80 refers to the strength range. There are two strength ranges available, Class 60 and 70-80. Unlike some of our competition we sell only fasteners made from the higher strength range.

A4 Class 70-80 (BS970 bar & hexagon equivalents T316)
A4 is also referred to as 18/10/3 (2% extra Nickel added 3% molybdenum) or Type316. This is regarded by specifiers as 'marine grade' or 'enhanced corrosion resistant' stainless and is designed for constant immersion in salt water or 'stronger' acids.
316S31 is the material we use for machined items. More expensive than T303/304 to buy and machine.

T431S29
A Martensitic magnetic high carbon stainless alloy with improved shear resistance used only for socket disc bolts and for short studs where necessary. Because of its hardness T431 is the most expensive stainless alloy to machine and is not suitable for electropolishing.
Further information concerning physical properties and corrosion resistance can be dowloaded in pdf form, right click the icon select 'save target as'.
Important Installation note:
It is ESSENTIAL that COPPER ANTI SEIZE compound is applied to stainless fasteners before use and that all threads are cleared of corrosion and debris using a 'plug' or ‘bottom' tap. (click here) For customers unable to source copper anti seize and/or plug taps we can supply them see the 'misc items' section of the main product menu.
   
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Mechanical Properties:
Stainless is not generically a tensile material; no form of standard 18/8 or 18/10/3 stainless alloy possesses the tensility of grade 8.8 steel (the benchmark HT std) beware of any claims to the contrary. Many but not all steel bolts fitted to motorcycles are made from high tensile steel principally because HT steel is cheap and easily available. For the same reason ie cost the factories often use flanged bolts (fastener/washer fused together) ie to save assembly time not having to fiddle with washers and spacers etc.
The fact is that with many applications on a motorcycle - fork castings, disc rotor bolts, engine covers etc the material the steel bolts are threaded into is cast aluminium/magnesium alloy. Al/Mg castings are invariably low density and have little crystalline structure - not a feature of high tensile alloy. If you have worked on a Japanese bike you will know how easily the alloy threads 'pull' - again not really the behaviour of something 'strong' in tensile terms. Stainless might not be as tensile as 8.8 but it is certainly way stronger than those alloy threads - in fact often the shear resistance (resistance to cutting action) of stainless is greater than that of tensile steel and Ti. This issue is also referred to in our Faq section. It should be made clear that if for whatever reason you require high tensile fixings you should use manufacturers original equipment.
Stainless steel requires less stretching to enable it to seat. On the assumption any threads have been cleared and prepared properly you should need no more than 66% of the original tensile steel torque spec when tightening.
Further information on mechanical properties can be dowloaded in pdf form, right click the icon select 'save target as'.
   
         
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