17 FLTRU Drivetrain whine
 

I have a 17 Road Glide Ultra with ~4300 miles on it. About a week ago it started making a whining noise I could hear in 3rd through 5th gear. The whine happened on acceleration or deceleration but mostly went away if I pulled the clutch (although some was still present). The dealer who sold me the bike picked it up and ultimately told me the belt was too tight. They've adjusted the belt and are returning the bike to me on Friday.

Could a tight, or loose belt cause the drivetrain to make a whining noise? I asked the dealer to look at the belt deflection as I thought it was off while they were investigating the whining noise. While this dealer is very reputable (Black Diamond HD in Marion, IL), I'm concerned they only adjusted the belt because I asked and didn't really investigate the problem. The service writer did confirm the tech who test rode the bike heard the whine, so at least the problem existed in the shop and they claim it's gone now.

I've got a 3400-mile trip planned for next week and don't want any surprises with my ride.

Thoughts?

hmm..went away when the clutch pulled in..not sure..if anything it got looser not tighter on its own after the 4300 miles of not whining....but if the whine was consistent and repeatable I'd be ridding it asap after their adjustment to try and duplicate and validate, and if still there, obviously get it right back in immediatley before the "3400-mile trip planned for next week"

A Harley final drive belt is kind of a strange beast. Normally we expect something like a drive belt to loosen up or sag when it gets warmer with use. That is not the case with a Harley final drive belt. It is actually designed to tighten up when it is used and gets warmer. Sometimes, even when adjusted properly using Harley's tension tool, a belt will tighten up to the point of whining slightly while being ridden. The only solution I am aware of (assuming that you don't have rear wheel bearings that are going south) is to retention the belt and give it a little bit more slack and hope the whine goes away.
This sounds like what your dealer has done. The factory contends that it is better to run a tight belt than a loose belt and for this very reason most belts are adjusted pretty tight when you buy a new bike. I seem to remember the factory telling dealers 5 or 6 years ago to stop checking belt tension on new bikes because it was factory adjusted. So it is no longer part of the check off list when setting up a new bike. Of course, after replacing a tire it will have to be retentioned according to spec.

Thanks for all the feedback. I'm getting the bike back tomorrow. I'll give it a ride and see if the whine is still present. I've never adjusted a HD belt before, but I have the measurement tool and I thought the belt was too tight before the dealer picked it up. Assuming the noise is gone, I'm happy it was something easy. I'm fortunate that I don't have any real complaints about my M8. No sumping, and very very minimal fluid transfer, to the point where it could be measurement error.

Yes, tight belt will whine. My 2018 RGU drive belt was very tight when I picked it up at zero miles. I didn't measure the tension at that time, but could tell it was too tight by how it felt when I deflected it by hand. I figured they set them a little tight at the factory to allow for break-in stretch.

I gave the bike 1500 miles to settle in, but the belt was still too tight, so I adjusted it.

Once I had the tension set, with the tight spot on the belt allowing the minimum deflection according to the spec, the whine was gone. The bike now has 6k miles on it, with no "abnormal" whining, and the tension has held where I put it at 1500 miles. I doubt I will have to adjust the belt again for a long time.

Bear in mind, even with the belt properly adjusted, there will still be some belt noise, as well as other whining sounds coming from the drive train.

Put a couple hundred miles on the bike this Friday/Saturday. No whine. Seems it really was a tight belt. Glad it was nothing serious.