Hi Guys,
2016 Road Glide Ultra. Did a rear tire change, reset the belt tension using the HD tool, and following the manual instructions. Ease-peasy. Rolled the belt to 3-4 different locations, all the same tension. Go for a ride and 50 miles later I stop for a picture. Randomly decided to finger check the belt tension. It's tight. Like guitar string tight. No deflection at all, way overtightened. I nurse it home, and reset it while hot/warm. Easy-peasy again. Bike cools overnight, and now it's loose. Like really floppy loose, I can move it an inch or more with a fingertip.
Too be honest, I've always set the belt cold, and only rechecked it at a 5000 mile service while still cold. Never needed to adjust it between services.
So, what gives? Does the heat cause expansion causing it to be guitar string tight? Is this normal, and I just never noticed?
Everything expands with heat. The belts teeth expand, then they push away from the sprockets, so they get tighter.
Adjust the belt at ambient temperature. And ambient temperature should be in the 40° F and up.
The sprocket diameters grow / expand with heat also.
Quote from: kd on May 05, 2020, 02:27:34 PM
The sprocket diameters grow / expand with heat also.
This. :up:
Kevlar has a small negative coefficient of expansion in length when heated. That and the size change in the teeth makes the belt tight.
Quote from: Ohio HD on May 05, 2020, 01:22:02 PM
Everything expands with heat. The belts teeth expand, then they push away from the sprockets, so they get tighter.
Adjust the belt at ambient temperature. And ambient temperature should be in the 40° F and up.
At least in my v rod due to mile long swing arm, I shoot for 75 -80* ambient as my optimum adjustment temp. Huge difference between 40 and 75* in the measured result comparing the two . Using this one temp gives me repeatable numbers in tension, otherwise I'm chasing it all over due to the tension measurement moves with the ambient. Colder temps adjustment, the tension will be too tight in hot weather and visa versa. It really is amazing how much tighter the belt gets once up to operational temps. This can take out that trans bearing eventually, yup even the v rod can suffer that. Factory spec is too tight to be bearing friendly if set to the minimum.
Ron
QuoteSo, what gives? Does the heat cause expansion causing it to be guitar string tight? Is this normal, and I just never noticed?
Does on mine, always has. 215000 miles on bike, 3rd belt (second one did break at 70K). Tranny has never been touched. The opinion on this are all over the place.
Quote from: smoserx1 on May 05, 2020, 03:55:33 PM
QuoteSo, what gives? Does the heat cause expansion causing it to be guitar string tight? Is this normal, and I just never noticed?
Does on mine, always has. 215000 miles on bike, 3rd belt (second one did break at 70K). Tranny has never been touched. The opinion on this are all over the place.
Mine, too.
It's completely normal.
I've always said it's overlooked how much the belt tightens when the bike warms up after enough miles ridden, I believe that's a cause of some bearing problems,, primary bearing race walking, wheel bearings, main drive gear bearings, Harley's spec is simply too tight for me.
I have a tension gauge, but rather use my finger while sitting on the bike, I know from experience what my cold and hot belt tension should feel like. roll the bike a little, check, repeat.
Something else overlooked is if the bike has shocks with more travel, hence more sag setting, how much weight was on the bike when the sag was set?, big difference on belt tension when bike is loaded 1 or 2-up, loaded for a road trip, etc.
Quote from: Schex3x on May 06, 2020, 05:59:09 AM
I've always said it's overlooked how much the belt tightens when the bike warms up after enough miles ridden, I believe that's a cause of some bearing problems,, primary bearing race walking, wheel bearings, main drive gear bearings, Harley's spec is simply too tight for me.
I have a tension gauge, but rather use my finger while sitting on the bike, I know from experience what my cold and hot belt tension should feel like. roll the bike a little, check, repeat.
Something else overlooked is if the bike has shocks with more travel, hence more sag setting, how much weight was on the bike when the sag was set?, big difference on belt tension when bike is loaded 1 or 2-up, loaded for a road trip, etc.
Exactly. Many never even think of that. Where you are in the swing arm arc effects tension and where that position is, should be considered for setting the belt tension. Generally the belt gets tighter with load in most bikes, to a point. This again depends on shock length. A shorter shock, it might get looser with load. Boils down to understanding what ones setup is and working with that for adjusting, not just blindly following the SM as being gospel.
Ron
Thanks for the input guys. I'll reset it to the loose side of spec today, and ignore it when it's hot. I was just shocked how tight it was, it felt like it was a steel bar when I was poking at it. Sure seemed like that would play hell on bearings, not to mention trying to pull the rear end out of alignment with all that tension on one side. Also, FWIW, I've found the belt tension changes very little, if at all, when the bike is on a lift vs, on the ground. That surprised me a bit too...
Check your manual, but I thought tension is set with a rider on board.
The belt tension changes a huge amount on my 12 RG from laden to unladen.
IME tighter is better than loose. Loose belts will spit teeth, have seen it on more than one occasion. One would have to crank it down hard to affect bearings/seals. Using a tension gauge, ambient temps, to adjust, have put 350,000 + miles on rear drive belts, solo, 2 up fully loaded, you name the scenario, no problems. I also don't drop the hammer until everything is heated and expanded.
Quote from: Coyote on May 06, 2020, 09:29:11 AM
The belt tension changes a huge amount on my 12 RG from laden to unladen.
:up:
Quote from: Deye76 on May 06, 2020, 09:40:26 AM
IME tighter is better than loose. Loose belts will spit teeth, have seen it on more than one occasion. One would have to crank it down hard to affect bearings/seals. Using a tension gauge, ambient temps, to adjust, have put 350,000 + miles on rear drive belts, solo, 2 up fully loaded, you name the scenario, no problems. I also don't drop the hammer until everything is heated and expanded.
:up:
Quote from: Hossamania on May 06, 2020, 09:22:23 AM
Check your manual, but I thought tension is set with a rider on board.
Depends on the bike. Some yes, some no.
Quote from: Hossamania on May 06, 2020, 09:22:23 AM
Check your manual, but I thought tension is set with a rider on board.
It's changed through the years. Manual on my 16 says, "Measure on side stand or upright, saddle bags empty, no rider or luggage". I know on previous Road Glides I've owned, it's been different. I did the work with the bags off, on a rack with the wheels off of the ground, and torqued the axle. Once I sit it down and rechecked it, it didn't change, which surprised me...
Loose belts are a death sentence and will leave you on the side of the road somewhere. :embarrassed:
I've always set my belt tension cold at the loose side of spec, within spec but at the loose end of it. It gets damn tight when it's warmed up after a long ride.
Thanks for the input Guys.
I set it to spec, a fat ½" as 9/16" is the loose end of the limit. Did it on the center stand this time, rear wheel on the ground. Double checked it on the side stand after rocking it back & forth in gear, and bouncing it a few times. Measurement stayed the same. Going for a ride here in a bit, get it nice and warm and recheck it hot. I'll post those numbers for the curious, or for someone that searches this thread in the future.
Thanks Again for everyones input. I love this site, great info that gets to the point...
I bought my 2007 Ultra used with 4800 miles.The dealer serviced it before I bought it. I checked over the bike and found at room temp cold the belt was as tight as a banjo string. Anyway I adjusted it to my spec of a close to half twist. No chirping on decell or werring at highway speeds.
Went for an 80 mile ride, same day we hit our first 100* temps. Pulled in the garage and measured it hot, radiator fans were still running. it's right at ¼" deflection with 10 pounds pressure now. ⅜" is the tight end of the spec cold. I'm within ⅛" of that hot, so I'm calling it good and not going to mess with it anymore. It is amazing how much difference the belt "feels" between 9/16" and a ¼" though. The difference is night and day.
Thanks again for the help, beers on me...
had the same experience when adjusting belts, i always adjusted to the loose end of the spec. don't know where i heard or seen it but somewhere i heard that a rule of thumb on the belt is to grab it mid point with your thumb and pointer finger and twist it from vertical to horizontal. it should just rotate 90 degrees with a good amount of effort.
Quote from: mkd on May 10, 2020, 08:59:29 AM
had the same experience when adjusting belts, i always adjusted to the loose end of the spec. don't know where i heard or seen it but somewhere i heard that a rule of thumb on the belt is to grab it mid point with your thumb and pointer finger and twist it from vertical to horizontal. it should just rotate 90 degrees with a good amount of effort.
90* ? Maybe if your name is Dwayne Johnson. Most of us struggle at 45* LOL.
Ron
Quote from: rbabos on May 10, 2020, 12:41:53 PM
90* ? Maybe if your name is Dwayne Johnson. Most of us struggle at 45* LOL.
Ron
:up:
Quote from: rbabos on May 10, 2020, 12:41:53 PM
Quote from: mkd on May 10, 2020, 08:59:29 AM
had the same experience when adjusting belts, i always adjusted to the loose end of the spec. don't know where i heard or seen it but somewhere i heard that a rule of thumb on the belt is to grab it mid point with your thumb and pointer finger and twist it from vertical to horizontal. it should just rotate 90 degrees with a good amount of effort.
90* ? Maybe if your name is Dwayne Johnson. Most of us struggle at 45* LOL.
Ron
naahhh, it's easy when the belt is way too loose...... :emoGroan:
Quote from: Ohio HD on May 10, 2020, 01:06:08 PM
Quote from: rbabos on May 10, 2020, 12:41:53 PM
Quote from: mkd on May 10, 2020, 08:59:29 AM
had the same experience when adjusting belts, i always adjusted to the loose end of the spec. don't know where i heard or seen it but somewhere i heard that a rule of thumb on the belt is to grab it mid point with your thumb and pointer finger and twist it from vertical to horizontal. it should just rotate 90 degrees with a good amount of effort.
90* ? Maybe if your name is Dwayne Johnson. Most of us struggle at 45* LOL.
Ron
naahhh, it's easy when the belt is way too loose...... :emoGroan:
Like off the bike completely? lol
Quote from: Coyote on May 10, 2020, 01:15:00 PM
Quote from: Ohio HD on May 10, 2020, 01:06:08 PM
Quote from: rbabos on May 10, 2020, 12:41:53 PM
Quote from: mkd on May 10, 2020, 08:59:29 AM
had the same experience when adjusting belts, i always adjusted to the loose end of the spec. don't know where i heard or seen it but somewhere i heard that a rule of thumb on the belt is to grab it mid point with your thumb and pointer finger and twist it from vertical to horizontal. it should just rotate 90 degrees with a good amount of effort.
90* ? Maybe if your name is Dwayne Johnson. Most of us struggle at 45* LOL.
Ron
naahhh, it's easy when the belt is way too loose...... :emoGroan:
Like off the bike completely? lol
yep! :SM:
And for that reason I do the 45 degree test. :wink:
YEAH! MEMORY ISN'T THAT GOOD! 45 is good, 90 is too loose! i'm staying home!
One reason the belt so tight is to eliminate harmonic vibrations in the belt. If you get them it feels like the whole engine is self-destructing. Also, there is less drivetrain slack with a tight belt. HD has been using belts for a long time and you rarely hear of a belt failure and I bet the majority of them are set the way they were from the factory.
Update: I finally bought the HD springy tool (40006-85) to measure belt tension. Using the tool the belt is much tighter than I ever expected. I have no idea how the output shaft bearings can deal with that much tension. But the bike rides smooth and I'm willing to experiment so we'll see what happens. I'm pretty sure my Sportster has its tightest belt position with the shocks fully extended. (The swingarm arc is "above" the imaginary line bisecting the axle, swingarm pivot and output shaft.) Maybe that makes a difference. Anyways, the tool is pretty easy to use and it didn't cost a bunch. YMMV!
Every one I've worked on was set too loose.
Quote from: kd on May 05, 2020, 02:27:34 PM
The sprocket diameters grow / expand with heat also.
:agree:
My guess has been a tough 45 also.
Quote from: kd on July 17, 2021, 06:09:01 AM
My guess has been a tough 45 also.
Xyzzy, since setting your belt with the tool, how far can you twist it by hand?
I have used the tough 45° degree method for years, just wondering how close I am.
Back in '94 my Evo softail developed a squeaking noise on the way home from Sturgis. Couldn't find the source, figured I'd deal with it when I got home. Few days after my return I went to cure the noise but it was gone. :scratch:
Oh, that was the year my wife flew to Rapid City to meet me there, & ride home with me.
At least it was only a squeak, and not a whine.
Curiously my other passion, home built aircraft is having a belt discussion on their site right now. Though they have an advantage since there's no swingarm to change the length on them. But it strikes me that in general they use more and/or wider belts to drive a propeller at around 2500 rpm than we use for our bikes. Yet the horse power of both vehicles is in the same general range, up to and including 100 plus hp. Hpwever from around 100hp and up the belts are dropped in favor of gear reduction. Sort of like bikes going with shaft drive.
That said, is it safe to say a belt tolerates/requires a tighter setting than a chain? IOW a chain will better handle being a bit loose. To a point of course. But my thought is with the concern expressed for wear on bearings, wheel alignment and such due to the tightness of a belt, wouldn't going back to a chain be better in such a case? Granted, there are advantages to a belt but in the long run but is it really that much better? Especially should alignment and bearing issues arise from the belt.
I for one never minded doing the maint and cleaning involved with a chain. And intend to switch to one should my belt ever wear out. But then I also recall when a bike was a very simple and basic mode of transportation.
QuoteBut my thought is with the concern expressed for wear on bearings, wheel alignment and such due to the tightness of a belt, wouldn't going back to a chain be better in such a case?
I have never heard of that being a problem if the belt is properly adjusted. When my bike was fairly new I marked each axle adjuster nut so I could loosen them for ease of wheel removal, etc. and always put them back the same, thus maintaining tension and alignment. The belt exhibits a large difference in perceived tension from cold to hot.
When adjusted properly and driven normally, even a bit abusively, on a mostly stock motor, a belt and all associated rotating parts will last 100,000 miles. No chain will do that.
The choice of changing to a chain are due to other goals: off road or much dirt road riding, excessive horsepower usually associated with racing, easy gear changes. Longevity is not the normal reason to switch to chain.
Question can someone tell me what the drive belt deflection is on a 2006 softail , the 200mm tire with the skinny drive belt , I have this on my 01 fatboy but not sure on how tight to make belt , I have it set at 3/8" 10 pounds pressure on side stand but man it feels tight
Thanks
On my RK, I have longer shocks than the stock ones. So, to adjust the belt tension, I lift the motorcycle, I unplug the shocks. I lift the wheel to reach the point of maximum tension. It is in this position that I adjust the tension of the belt ( with the HD specification ).As I turn the wheel, I also look for the tightest point.
I use 45degree twist deflection and find that a perfect method.
Keep using that HD tool and you’re going to go through bearings.
Trust me