Posted by Brain Guptil (sailordude@…>)
Brien
Yanmar parts meet Yanmar specifications, like oil and fuel filters. I only use Yanmar parts on those locations. But belts are the exception. If you study the stock charging system, it is designed for truck, industrial or farm implement usage where the battery is typically charged and only needs to be replenished from overnight leekdown and starting power usage. therefore, the belt does not need to handle 4 hours of full alternator load and so just about any belt will do. As you put regulator controllers (highly recommended) that fully field the alternator to do a full three phase charge cycle, the load on the belt goes way up. Heating occurs, etc. And then upgrading to a larger alternator just exceed the capacity of the stock belt. Higher quality belts can handle the load. That is the way to go.
The Belt I am using is a Gates Automotive XL series. The Gates web site has a conversion page, so if you have a correct fitting belt from another manufacturer, you can convert, or call one of there service reps who may be able to help. The belt I have is a 9470, which is probably the wrong length for the 3GM series. It is 47 in long and the “top” width is .5 in and may be correct except for the length.
Going double belt has some real draw backs. One is that the belts are further out from the bearing so the leverage increases on all bearings and finding match set belts is a pain. It has been my experience on 3 Freedoms, that going to a high quality belt has allowed larger alternators, two of which are 100Amp class, with out the “slippage/belt squealing” or longevity problem.
Brian