I have a 2014 T-Bird Commander. The drive belt on the rear pulley is the most likely cause. I develop a 'chirping' noise every few thousand miles at slower speeds which sounds like a bad washing machine It's pretty embarrassing when you pass folks on the road. The noise goes away after I adjust the belt tension. I don't have the special tools called for in the service manual. One measures tension and the other replaces the axle to ensure you can measure the left and right side to get them even. I just poke the belt with my finger until I think it's the right pressure, and I use the 'dots' on the swingarm to do the alignment. It doesn't seem to make any difference if the belt runs to the left or right side of the pulley with regard to the squeak, and it can change from left to right after a ride. It just seems to be the tension that matters. If you have the Commander, you have to remove the right side silencer/muffler. The belt deflection specification is 5.5 to 7.0 mm when on the side stand, or 7.5 to 9.0 mm when the rear wheel is off the ground - when you are applying a 4.5 kilogram force (10 lbs.). The spindle adjuster nuts need to be 25 Nm and the axle nut needs to be 110 Nm.
BTW - I probably should have said that if you don't normally work on your own equipment or have a pretty good 'feel' for tensions, etc. then you should probably go to a shop to have it done. I don't know for sure, but I imagine that if you put too much tension on the belt you could do some bearing/shaft damage and that will cost you some serious money.
As said Belt chirp down to tension and alignment bit of a well documented issue on Tbirds. If belt tension is ok rub edge of belt with an ordinary wax candle wont do belt any harm and will remove noise temporarily just repeat when it comes back
Six posts in and nobody has suggested you may have a mouse living under your seat. For this forum that's a record! Good luck with your tension adjustments btw...
Sorry, but that sounds like a challenge Two years ago, I took my seat off and this is what I found in my air filter. I feed the wildlife (foxes, opossums, racoons, turkey, birds, squirrels, and deer) around my home. During the winters, mice come into my garage and in the crawl space under my home. We live trap them and move them a couple of miles from the house, but until we get them, they make themselves at home. I know I should just kill them, but I don't have the heart. I reserve that treatment for things that should know better Proof that there was a mouse under my seat. Why they would go to the trouble of walking over to the bike and crawling up to the air cleaner is beyond me.
Dry silicone spray lubricant may help - or it may ruin the belt. Who knows? Not me yer honour. Just passing on what the voices in me head were sayin'!
When I get squealing alternator belts on cars, a quick squirt with WD40 cures it and doesn't damage the belts.
