Isn't it true that the fixed mechanical tensioner is either too loose at low temperatures or too tight at high temperatures?
Most people set it tight a low temps and, therefore, it is too tight at high temps.
The lore was that if you go to a fixed tensioner you need to change the timing belt more frequently because you are putting it under more stress than it was designed for.
Variable tension was the logic of the original design. https://www.alfabb.com/bb/forums/alf...tml#post237620
Good point, Maldi, but let's remember that all technology advances, and this certainly includes power transmission systems like toothed synchronous drive belts. Drive belts today are far better and more forgiving than they were in the 1970's and 1980's, for sure. We also have to remember that Ing. Busso did not have a lot of timing belt drive history or collective experience (on automotive applications
) to draw upon when he designed that beautiful V6 engine. I seem to recall that Pontiac introduced a SOHC inline six in the mid 1960's, with a belt driven camshaft. But prior to that, how many other manufacturers tried this technology? Not many, if any. Busso was plowing new ground, and he might tell us today, that he had concerns over maintaining the ideal tension. Indeed, he makes this very point in his patent description of operation, if you read it through.
I don't believe that timing belts today require such critical tension parameters.. they are more durable and more forgiving. Whether you buy a Pirelli, Dayco, or Continental belt for Alfa's V6, you're getting a modern improved product. And let's take some credit as Alfa owners, also-- I feel that those who do belt changes are doing a better job on tensioner setup and rebuild, either hydraulic or thermo-mechanical. Thank this forum for that.
I hear your logic about over tensioning with a fixed tensioner, but how can we doubt the success of this product when everyone here who has used a fixed tensioner, reports that they never have any belt failures? It's hard to argue with success. For this reason, I feel like the belts are more forgiving than we think.
Great discussion! I really appreciate everyone's feedback.