Cam Belts

[ianess]

For something so cheap that needs replacing regularly and is capable of doing untold damage if forgotten, why on earth do manufacturers not use a `Desmodromic` gear system instead of a plastic belt?  Is it all part of a cunning plan to build in obsolesense and keep up servicing costs?

[Westminster]

I don't know what a 'Desmodromic' gear system is. Some manufacturers fit cam chains, which should have a longer life than a belt. I always have the belt changed the service before the recommended time. At the risk of sounding cynical, it's worth remembering that car manufacturers don't make much money in making and selling you a car. They make it on the spares and repairs.

[Clanad]

Gears were used (some still are) but with the advent of the OHC (overhead cam) engines, the cam was placed at a distance from the crankshaft and gearing became impractical.  Chains of one kind or another were (and still are ) used, but, again lengthy chains often developed "slap" and were not the best application. Hence the use of belts. Check here for a more detailed discussion... http://www.valvoline.com/carcare/articleviewer.asp?pg=cc r20020301tb

[ianess]

Thanks for the reply Westminster. Reasonable point made about chains v Plasic belts.

A Desmodromic set-up is where the opening and closing of valves is controlled by intermeshed gearwheels....similar to the workings of a Swiss watch.  That way there is no possibility of any belt or chain breaking.....purely for the reason that they do not exist.

As you say, ultimately the accountants control everything..........sad isn`t it?