Featured Weslake Triton

Sorry for the late reply!

Racetech Developments EMX-7

 

This weeks progress consisted of stripping the bike for various coatings, paint, polishing etc plus finessing all the various brackets, plates, bushings etc. I dont particularly like the polishing part but needs must! Once they are polished they shall be coated in ceramic clear. Engine cradle plates were drilled to add a little more lightness,

 

My preferance was to use 6082 in the T6 condition. This grade gives excellent strength combined with good corroson resistance and machinability. "Dural" comes form the 2000 series (copper) which has similar strength properties but poor corrosion resistance x10mm thick. Rigidity is always a plus imho.

 

One of the main goals with my builds is to achieve as much rigidity as possible with the least amount of weight...PWR is all important. I could have lightened them quite a lot more by scalloping while still maintaing the strength against the forces applied....might still do that by the time final build is in progress!

Materials incl polished ally can now be adequately protected using clear Cerakote...good wearing surface and much easier to clean. I am having my new brakes etc cerakoted as the means of protecting magenesium available is very poor nowadays as "proper" chromating is no longer allowed. TS Engineering are very good at mix/matching cerakote to your spec...talk to Simon, he's a very helpful gent.

I have followed Colin's ethos since I first started building race cars including his "no washers" rule although I do use them on alloys. The aviation industry has some fantastic fasteners without weight nowadays...K nuts for example. I use various types of these and AN bolts quite a lot.

 

There are so many to choose from out there. Start of by visiting the LAS Aerospace website https://www.lasaero.com/products/category/V024LMJL7/
Googling "aviation bolts supplier uk" will glean a few more

Each part is certified for aviation use and are very expensive in comparison. However, the tolerances they are made to are very precise both in dimension and form. Perhaps thats not whats really necessary on a motorcycle ? ).

You can sometimes find surplus stock with aviation sellers on Fleabay which may suit needs, perhaps with a little modification in length. I have used them on race cars and aircraft all my days and most formulas still use them.

I only use metric threads where the fastening is non-criticical and if I need to. Metric threads are not an ideal form from an engineering standpoint.

Again nuts and washers as a specialist subject, there are many variables. I have a good stock of 6 point and 12 point UNF K-nuts which are self locking. They have no nylon insert so can be used anywhere and in high temperatures. I managed to source these at a good price from an aviation supplier in Malta about three years ago who was closing up shop. In theory you can only use them once.

In racing I also use various types of "pip" pin" quite a lot, very secure but instantly removeable without tools

 

Big subject that but to put it briefly.......

Whitworth/SAE based threads are cut at 55 degrees, have rounded peaks and valleys, and are proven to perform better in dynamic applications. The rounded root of the Whitworth/SAE thread also greatly improves fatigue performance compared to Metric which is cut at 60 degrees and has sharp peaks and valleys. Sharp threads in Al alloys are especially prone to fatigue point/failure. (one of the major raesons why they are not used in Racecar Formulas, Aircraft etc.)

However, in saying that I generally use SS metric capscrews etc for non-loaded parts on bikes purely based on cost.

 

In a nut shell......

Way way back in time everybody and his dog had there own thread but to make it simple to get parts the Whitworth thread was deemed to be the standard. SAE threads such as BA, UN, BSF etc all then had a common thread design based on the 55 degree tooth.
Some countries in Europe (of course!) had to be different and al lot of them had different versions of threads but eventually they all got together for a common cause (wish they would do that today!) and the ISO Metric system was born. SAE is still popular in the USA but it is now also slowly coming round to ISO now too., probably due to foreign imports such as cars, machinery etc.

I would hazard a guess that its now a good deal more expensive to produce SAE threaded fasteners etc with fewer companies now producing them. Companies in the UK such as GWR and Westfield can supply SAE threads easily enough but they are more expensive than metric.

As to why they are still not using it is probably for the same reason that Betamax deffered to VHS, an
inferior sytstem......mobile phone connections are another that comes to mind...