Drive belt tracking question/problem. - Star Motorcycle Forums: Star Raider, V-Max, V-Star, Road-Star Forum
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post #1 of 13 (permalink) Old 04-19-2016, 03:14 PM Thread Starter
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Drive belt tracking question/problem.

I have installed several rear tires on my bike and have never had an issue. This spring, I keep getting a odd noise that is difficult to explain. I first checked my drive pulley and it was finally loose, torqued it.

Noise continues. More or less its the speed of the wheels, hard to tell if its coming from front to back but my passengers claim its back. It either isnt doing it on accel or I cant hear it over the engine. I drop the throttle and it starts almost instantly (on coast).

I inspect my belt and pulleys, clean the pulleys and belt. As I rotate the tire causing the belt to turn, it squeaks at the front pulley. Looking closer, the belt is riding the outside edge but there is almost 1/4 inch on the inside edge. Basically the belt isnt centered in the front pulley and its rubbing the outside edge of the belt causing ware and noise.

So I measure my rear axle centers to several common points including the swing arm pivot and other places..It is right on the money. SO I check my wheel center in the rear fender and it looks good. I measure it from a common point and the tire is centered.

All that back story for this...how can I make the belt track in the center of the front pulley when the rear axle is perfectly straight and even?

I have buzzed the factory service manual and find nothing on belt tracking, only belt tension and replacement.

Help!
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post #2 of 13 (permalink) Old 04-19-2016, 03:44 PM
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does the front pulley have shims behind it that can be changed to get it aligned properly. you can also pry on the pulley to check for a worn shaft bearing
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post #3 of 13 (permalink) Old 04-24-2016, 07:39 AM
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How many miles on the belt? Hard usage or typical riding (whatever that is..)
If you don't find anything else, it could be the belt causing the tracking issue.

There are heavy duty threads that are wound into the belt when it is made to give it the tensile strength needed to maintain it's length on the pulleys.
If a thread or more break then the tracking of the belt could be affected as the broken threads would allow the belt to stretch, possibly on one side.

I am guessing the broken threads would be hard to detect as they are internal to the belt.

If you end up changing the belt and nothing else is changed and the problem is resolved then it was probably the belt.

uhmmm.. the loose drive pulley you tightened, could the belt have gotten damaged (irregular wear, broken threads, etc.) because the drive pulley was loose ?
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post #4 of 13 (permalink) Old 04-24-2016, 10:24 AM
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I had a nightmare with my 950 and the front pulley problem. It's a long story and when I tried to attach it, the site said 'too big'.

I'm always working very diligently to discover the obvious.
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post #5 of 13 (permalink) Old 04-24-2016, 04:29 PM
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Quote:
Originally Posted by commonground View Post
I had a nightmare with my 950 and the front pulley problem. It's a long story and when I tried to attach it, the site said 'too big'.
did the nightmare have something to do with the counter shaft bearing getting trashed because of pulley misalignment? i'v posted on several forums to run the belt a tad loose if the pulleys aren't in perfect alignment. a tight belt on misaligned pulleys will put a lateral load on the bearing destroying it eventually. this is true for any type of belt not just motorcycle drive belts. any belt that's a bit to tight will cause more damage than one that's a bit loose, bearings cost way more than belts to replace. most 950 tourers iv seen have the drive belt to right side of the rear pulley not in the center where it belongs
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Last edited by pauli466; 04-24-2016 at 04:37 PM.
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post #6 of 13 (permalink) Old 05-23-2016, 12:54 PM
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my pulley was bad

hi, had my pulley loosen up. it was caused by excessive belt tension. i live in minnesota. i put new rubber on the bike in march when it was still pretty cold, mid 30 deg days. i set the belt tension and thought i was good to go. about 2 - 3 thousand miles and my bike started to make noise. i was on a ride and i checked the belt. it was so tight i couldn't even move the belt. it was like a banjo string. this is caused from the aluminum frame,swing arm expanding when it warms up. it pulley on the pulley so hard it loosened up and moved around on the shaft. the nut was still tight and tightening it more didnt work. it was worn out and it still moved around no matter what. i had to buy a new pulley, nut and spring washer. if you just tightened the nut the pulley is probably still lose. on my bike the splines on the pulley and shaft were both worn, replacing the pulley helped but i'm sure this will happen to me again because the output shaft is a bit worn now. not sure if this is what caused the pulley to loosen up but if you live in colder climate area you might want to keep a close eye on the belt tension.

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post #7 of 13 (permalink) Old 05-24-2016, 05:21 AM
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Quote:
Originally Posted by pauli466 View Post
did the nightmare have something to do with the counter shaft bearing getting trashed because of pulley misalignment? i'v posted on several forums to run the belt a tad loose if the pulleys aren't in perfect alignment. a tight belt on misaligned pulleys will put a lateral load on the bearing destroying it eventually. this is true for any type of belt not just motorcycle drive belts. any belt that's a bit to tight will cause more damage than one that's a bit loose, bearings cost way more than belts to replace. most 950 tourers iv seen have the drive belt to right side of the rear pulley not in the center where it belongs
I did not have a bearing failure. I did lose the seal on the counter shaft because of the abrasive Red Mystery Dust from the corrosion fretting. The root of the problem was the nut on the counter shaft was not tightened properly at the factory or the Belleville washer fatigued and flattened. I doubt that the washer failed. I agree that the belt tension is too tight as specified by Yamaha. I would bet that a high percentage of the belt drive motorcycles out there have a little misalignment but that is why belts are as good as they are, they can handle it.

Once there is loosening of the nut, the splined pulley can move longitudinally on the splined shaft and the fretting (wear) begins. The longer one runs with a loose pulley, the more wear on the counter shaft and the inside of the pulley. After a period of time there is rotational movement because the splines are not close tolerance and keeping a nut tight is near impossible because of rotational torque. The Red Dust from the fretting is usually evident and the first sign of a problem.

Folks uneducated on torque procedures think that you can check a staked nut for torque. Even an unstaked nut should be removed and the counter shaft and the nut cleaned to remove old thread lock before retightening.

I'm always working very diligently to discover the obvious.
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post #8 of 13 (permalink) Old 06-08-2019, 10:54 PM
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so it sounds like any of these front pulleys moving in or out on the countershaft coming outta the transmission is bad bad news and simply wears out the pulley and shaft splines by friction when the nut comes loose. Begs the question What is the pulley designed to come up against or bottom out against on the back side when you tighten the nut?? Is there a taper to the splines on the pulleys or countershafts ? Or, is there a ledge cut in the splines on the transmission countershaft that non tapered splines on the pulley come up against?

I need to either move my 2009 950's front pulley out slightly or move the rear pulley in to keep the outside of my new belt from gettin ground off like the ole one. If I put a .100 inch washer behind the front pulley will it screw up the interaction of the nut staking from getting down in the spaces cut in the shaft because everything is moved out to far ?

One other thing I decided to consider after reading another thread on this site is what is the orientation of my rear axle which I've adjusted to keep the belt centered perfectly in the rear pulley? I ended up with an extra "cush drive" and associated parts when I bought my 66 tooth Raider rear pulley for my 950....guess another alternative would be to do some machining to allow the rear pulley to move further towards the center of the rear wheel in hopes that it would pull the belt some off the outside edge of the front pulley.

any help from youall's experience appreciated in advance
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post #9 of 13 (permalink) Old 06-09-2019, 05:27 AM
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Just about all of the belts on the 950's and 1300's run to the outside of the rear pulley. It is nearly impossible to align the rotational center line of the rear pulley to the rotational center line of the front pulley, there're just too many variables. Your only hope is to get the center lines parallel and that the separation of the two lines is minimal. This problem is one of the reasons that belts are used for drive applications. All belts wear just as any other moving part on a motorcycle.

I agonized for months over the problem I had on the 950 before finding the the Red Mystery Dust (research that one) and the true cause of my problem. Soon after finding the problem I traded the bike in for a 1300 Tourer and now have 24,000 miles on her. I seldom even look at the belt on this one. I spent too much valuable riding time on the 950 worrying about the drive system.

In any high volume manufacturing operation you are going to occasionally produce a "Lemon". As an electrical engineer I realized that when I learned how electronic components were made. Example: A manufacturer will manufacture thousands of resistors and they all go into a large bin. At the next stage, the resistors are tested one at a time and put in separate bins for the differences in characteristics. After testing and sorting, they are marked with the resistance value and the tolerance. Some are so far out of specification that they are scrapped immediately.

Drive belts for motorcycles are made in large batches also. When I toured the Harley manufacturing facility in York PA. I saw hundreds of belts arrive in bulk in large boxes and randomly selected as the motorcycles moved down the production line. I'm sure that the belt manufacturer had produced thousands of them and some didn't meet the specs and were trashed.

My recommendation would be to ensure that there is no wear on the spline shaft for the drive pulley. I would ensure that the threads are clean of any Locktite residue. Reassemble it with a new Belleville washer and a new nut in accordance with the maintenance manual. Tighten it to the proper torque value using proper tightening procedure for proper torque and then stake the nut. Note: Most people do not know how to properly tighten a nut to a torque value. It is a once and done operation.

Next, align the rear axle using the marks on the swing arm and tighten but, not to torque values. Measuring from the swing arm pivot points as recommended in some manuals is near impossible. Check the belt tension and if not correct readjust the rear axle again. This may take a couple iterations to get the belt tension with in spec. Then tighten the rear axle nuts to the torque value recommended. The belt will probably not run center to center on the pulleys but, there's only one in thousands that may do so. Good luck.

I'm always working very diligently to discover the obvious.
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post #10 of 13 (permalink) Old 06-09-2019, 01:28 PM
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I probably shouldn't loosen my pulley nut as it's tight without any signs of wear in the form of the rust colored dust or oil leaking out of countershaft seal. That obviously leaves only the rear pulley for any modifications to help my problem of the belt wearing on the outside ridge of the front pulley.

Maybe the real question or factor affecting this tracking of the belt is how close to exactly parallel the axises of the countershaft and bolt hole in the frame that the swingarm attaching bolt goes through run. If the front pulley isn't perfectly perpendicular to the long axis of the frame then we would have to be making rear axle adjustments just to correct for that problem.

I've included some pics of the cush. drive, specifically the surfaces of the hub and rear pulley that are up against each other when everything is assembled on your bike. Would machining of either of these surfaces in an attempt to move the pulley over towards the center of the rear wheel affect the overall thickness or measurement of all the parts that are squeezed together and clamped when one tightens down their rear axle nut??? If so, then the two arms of the swingarm would be squeezed too far together and be bent UNLESS however much is machined off those surfaces is replaced with an additional washer one makes and places somewhere on the axle to the Left of the rear pulley. This seems to ALSO be the case on the front pulley where the distance between the staking grooves in the transmission countershaft over to whatever ledge the right(inside) side of the front pulley tightens up against is critical and can't be modified; thus any machining on either area(either side of either the front or rear pulley) would require shimming to make up that distance.

06/13/19 edit: To answer my own question posed above....thinking about this more I'm thinking now that on the back axle, unlike the front pulley shaft, that one WOULDN'T need to replace machined metal taken off either the inside of the pulley or the hub with shim or washer material as they aren't in the line of fire in establishing the total distance made up of all the spacers and bearing races and wheel collar that are pinched tight when you torque down the axle nut. Instead the pulley is just bolted tight on to the side of the hub....so I should be able to move it over .075 thousandths of an inch with machining without any implications to the total distance between the swingarms when you torque your axle nut down. .075 inch removed from studs side of the hub last night.

Thanks for your input commonground : seems all these various yamaha cruiser models are designed the same
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Last edited by bigpig41; 06-13-2019 at 09:58 PM.
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