This past weekend I inspected S6 and S8 that I had VERY THOROUGHLY packed with dielectric grease 1.5 years ago...keeping the spiders clean and dry by encapsulating the connections with dielectric grease would go a long way to avoiding problems. I suspect that reported spider failures after greasing were caused by insufficient grease. I subscribe to the "wheel bearing greasing" method to applying dielectric grease to spiders where you use you fingers to repeatedly force the grease down into the connector until the sockets are totally surrounded. Then after pusing the spider back in, adding more grease so that when the black cap gets installed there's grease oozing out...
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I know that you have done this and you don't have a failure (so far), but I disagree about this being a good idea as a general fix. Dielectric grease was never meant to be used like this. IMO, it is a bad idea to cram, pack and stuff a high quality insulator, as in the total opposite of electrical conduction, into a connector that suffers from lack of conduction already. If you view the melting temperature of most dielectric grease and for that matter wheel bearing grease it is usually not more than 500º . If you look at the melting of the high temperature connector bodies and the melted insulation on the wires there is some significant heat being concentrated in a small area. If the dielectric grease starts to get runny it can wick in between the electrical contacts and cause problems. Anyone coming along after you will hate you if they have to work with those connectors, not that it really matters -- unless that someone is being paid by the hour to work on your bike. Should water, road contaminates or pockets of moisture laden air get driven into the connector the grease will hold it in place and make it real hard to dry out again. Part of the problem with S4 is that it can receive a fairly straight shot of water and dirt over the top of the radiator as well as hot steam coming off the header pipes when they get wet.
I know that packing electrical connectors with dielectric grease is the holy grail for fixing electrical problems for some people, but being in the electrical/electronics field I can tell you that this is not a common industry practice for a reason.
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