Re: CAMBELTS why cant design be better ?
I think its all down to cost!
My last car, a Mercedes, used a chain. At 125000 miles it was still silent. Most of my early cars had chain driven or gear driven camshafts. My Daughters Micra has a chain drive too, you can hear the chain rattle!
The problem with the chains is that they are expensive to produce, and expensive to replace. Situated at the front of the engine, they are also subject to a lot of stress and they stretch and the tensioners have to work harder till they give up. So, cambelts came along as a cheaper and quieter alternative, and, I suspect, a very lucrative source of income for garages and belt manufacturers!
One of the best designs for a chain driven camshaft was used in Alvis cars. My Dad worked on them, designing the tooling and test equipment, and owned a couple. Cars with 500,000 miles or more still ran the original chains, which were at the rear of the engine and subject to less stress, then there were bevel gear driven overhead camshafts too, but of course, these cars were all hand built and were expensive.