Belt Tensioner

[ofdave]

There are dozens of hits when you google Harley Drive Belt Vibration - it's a problem but the engines on those shake so bad most people don't notice the belt vibration.

another Harley myth.
The engines that shake at idle are those that are rubber mounted. The solid mounted engines do not shake.
The shaking goes away at riding speeds.
Being a V-twin, they have inherent vibration that inline or flat engines do not have.

 

[Rigsby]

I have recently fitted a damper from Doc Humphrey and it was straightforward to fit and works really well, but probably more important than that he is a great guy to deal with and I would highly recommend him :thumbup:. thanks Doc :clap:

 

[IdahoMtnSpyder]

I just don't understand why these machines need a belt tensioner at all .! If Harley has the same final drive system with no vibration then is there an engineering issue here ..??!

Here are a couple of comments from a Gates publication from back in 1993. ww2.gates.com/IF/facts/documents/Gf000280.pdf

Q. What causes belt-drive vibration and how can it be corrected?
A. Drive belts experience both vertical and lateral vibrations when their natural frequencies coincide with resonant
frequency of connected equipment.
Belt tension can affect the amplitude of this vibration. Therefore, to correct the problem, first check for proper
tension. A common method to control vertical vibration uses a restraining device (metal rod or idler pulley) placed
perpendicular to the belt span and close to or lightly touching the belt. This device should be positioned roughly
1/3 of the span distance from the larger pulley.
If this does not work, consider changing other drive parameters to reduce the amplitude of vibration or alter its
frequency. Such parameters include span length, belt type, misalignment, inertia of driving or driven machinery,
pulley diameter and weight (inertia), speed, and the number of belts. In some cases (where original unit was
oversized), it may be possible to downsize the drive by reducing the number of belts or belt width, and increasing
the static tension to alter the belt’s natural frequency so it doesn’t coincide with the excitation frequency of the
machinery. When it can be done safely, it is preferable to reduce the static tension to keep the operating belt tension
below the belt’s natural frequency range.

Q. What is the proper procedure for tensioning a drive?
A. First, consider another question: Why is proper tension necessary? V-belts use friction between the belt
sidewalls and sides of the sheave to transmit power. By contrast, synchronous belts use the engagement of teeth to
transmit power.
Over-tensioning either a V-belt or synchronous belt causes excessive bearing load, reduced belt life, and excessive
pulley wear. Under-tensioning a V-belt causes belt slippage, whereas under-tensioning a synchronous belt can lead
to severe tooth wear and even ratcheting (jumping teeth).

Doc has gotten it right it looks like, lightly at 1/3 of the span.

Mike, you might be interested in noting the last sentence in the quote above.

 

[hillbillywhisperer]

I have recently fitted a damper from Doc Humphrey and it was straightforward to fit and works really well, but probably more important than that he is a great guy to deal with and I would highly recommend him :thumbup:. thanks Doc :clap:

This. Very easy to install and better built then the BRP one.

 

[JimSter]

I just received a Gates 91132 Krikit II Drive Belt Tension Gauge from BajahRon's to check the tension on my F3 drive belt.
It tells me that I have 200#'s of tension on the belt.
However I'm getting the vibrations when letting up on the trottle.

Now the belt tensioner will supposedly eliminate the vibrations even though the belt is that tight?


Thanks much, guys, JimSTer

 

[canamjhb]

Easiest thing to do is reduce belt tension. Yours is way too tight. TST61y014s05 suggests the tension on an F3 be set at 300N +/-100. I would adjust your belt before adding a damper...... Jim

 

[JimSter]

Hello canamjhb:

Thanks so much for your input. You've solidified my thoughts that I need to loosen the belt tension some.
However my tool measures in pounds. So can you translate 300N +/-100 for me?
I saw 160-180 pounds somewhere on here.

Thanks again, JimSTer

 

[ssmcclub]

My new 2019 special series can am spyder came with belt tensioner from the factory I guess they released that it needed one

 

[h0gr1der]

Hello canamjhb:

Thanks so much for your input. You've solidified my thoughts that I need to loosen the belt tension some.
However my tool measures in pounds. So can you translate 300N +/-100 for me?
I saw 160-180 pounds somewhere on here.

Thanks again, JimSTer

300 ±100= 200-400N

200 N= 45 Lbs (rounded)

400N= 90 Lbs (rounded)

 

[Revalden]

I put the BRP tensioner on my RT and on first ride with it installed I heard a clicking sound. So, went home to pull the Tupperware and have a look. And right next to the pulley in the belt is A DAMN PEBBLE STICKING UP THRU THE BELT!! :banghead: Spyder God looking out for me? I haven't ridden it since I found it. I need to wait until next month's payday to buy a new belt. I just hope it hasn't affected either sprocket.

 

[Peter Aawen]

I put the BRP tensioner on my RT and on first ride with it installed I heard a clicking sound. So, went home to pull the Tupperware and have a look. And right next to the pulley in the belt is A DAMN PEBBLE STICKING UP THRU THE BELT!! :banghead: Spyder God looking out for me? I haven't ridden it since I found it. I need to wait until next month's payday to buy a new belt. I just hope it hasn't affected either sprocket.

If it's only a smallish pebble (damage site is less than 1/4 of the belts width) and it hasn't torn or frayed any, especially on the edges of the belt, then as far as the belt is concerned, you should be fairly safe to simply remove the pebble & ride on.

BUT, as you've already mentioned, a careful inspection of both front & rear pulleys is in order - the pebble may have damaged some of the teeth, either requiring remediation with a careful file, or if the damage is beyond that type of repair, replacement of the affected pulley... in which case you should probably replace the belt as well too! :lecturef_smilie:

Seriously, these belts are well able & up to to handling 'minor' damage from things like small pebbles, and unless there's any fraying or tearing at &/or beyond the initial hole/damage site, the belt will likely show a 'self healing' effect on any small holes thru use & is likely to be perfectly serviceable for many more miles yet. hyea:

But it's your ryde, and if you want to be sure to be sure! :thumbup:

 

[Devious56]

I have to go with the Smoothspyder option. Very good construction of tensioner. Able to adjust amount of tension you need on belt. Easy to install and quiet. Costs a few bucks more then the others but what the heck we paid some 25+ on these things what's a few more.

I am happy with the Smoothspyder option..

JMHO

I took my SmoothSpyder off to try Doc Humphries. The Smooth Spyder was quite a bit heavier and put a lot more tension on the belt. Worked ok, but not near as good as Doc's.

 

[Revalden]

If it's only a smallish pebble (damage site is less than 1/4 of the belts width) and it hasn't torn or frayed any, especially on the edges of the belt, then as far as the belt is concerned, you should be fairly safe to simply remove the pebble & ride on.

BUT, as you've already mentioned, a careful inspection of both front & rear pulleys is in order - the pebble may have damaged some of the teeth, either requiring remediation with a careful file, or if the damage is beyond that type of repair, replacement of the affected pulley... in which case you should probably replace the belt as well too! :lecturef_smilie:

Seriously, these belts are well able & up to to handling 'minor' damage from things like small pebbles, and unless there's any fraying or tearing at &/or beyond the initial hole/damage site, the belt will likely show a 'self healing' effect on any small holes thru use & is likely to be perfectly serviceable for many more miles yet. hyea:

But it's your ryde, and if you want to be sure to be sure! :thumbup:

The pebble is almost dead center in the belt. I'll loosen up the tire/belt and check the sprockets and see up close how much damage was imparted. Maybe put a dab of epoxy in the hole. Thanks for your input.

 

[Peter Aawen]

I dunno about putting any epoxy in the hole... :dontknow:

I'm not professing this as something I know from experience or otherwise, but the belt guru's I've talked to about this sorta thing say these belts will 'self heal' to a certain extent once the offending object/pebble has been removed, so adding something like epoxy or anything that could well form a barrier to that 'self healing' & probably isn't such a good move. :shocked:

The recommendation I got was to simply remove the pebble, check & clean up the pulleys & 're-shape' any partially damaged teeth on them &/or the belt, then ride on as per normal (altho I figured it might be smart just to take it a little gently at first! ) Once you're moving again, the action of rolling the belt over the drive sprockets will generate the self healing effect in the belt and away you go - well, unless the damage is too great of course, in which case the belt very likely fails then & there, with no further harm! But I did show them some pics of stones & damaged belts from here & the Oz forums, and they were pretty adamant that for most of the small pebbles & less than extensive damage shown, the belts should be able to continue safely, just so long as the damage hasn't spread along the belt, chewed or removed any teeth, &/or taken out more than 1/4 to 1/3rd of the longitudinal fibres in the belts.... :dontknow:

So I reckon a small pebble poking right thru the belt that hasn't been there long enough to expand a tear along the belt or start the belt or hole edges obviously fraying a fair bit should be OK... but it is your Spyder & your belt! You can do whatever you like, I just put the info I had out there. :thumbup:

 

[ssmcclub]

brp installed one from the factory on my 2019 f3s special series spyder I guess they are listening on all the complaints, about time brp

 

[PinkRosePetal]

Maybe put a dab of epoxy in the hole. Thanks for your input.

Don't use epoxy, use superglue. It forms a seriously strong bond with rubbers.

 

[PinkRosePetal]

The top of the belt is like a guitar string vibrating and the damper is like pressing a finger on it and stopping it.

Whilst that is true, a tensioned string (belt) will not vibrate on its own, it has to be energised buy some force. In this sense a roller as a damper is a band-aid because it's not dealing with the actual cause of the problem. It's notable that a good many Spyders do not suffer from the vibration, it seems that they do not have the energising force transmitted to the belt sufficiently to cause it to resonate.

My experience, and from what i've read, many others' experience, is that the resonance occurs when the engine applies power as it does when on cruise control when it modulates the throttle. Under these conditions the belt will undergo extra tension applied by the belt driving torque applied at the engine pulley and it seems that engine vibration is the force energising the resonance of the belt. Perhaps some engines are not as smooth in operation as others or perhaps there are engine mounting issues which don't absorb this excitation energy. BRP would do well to get on top of the real issue IMHO.

 

[GaryinWI]

The belt on the Spyders is twice as long as on a Harley or other belt-Drive bikes. That’s why they need an idler/tensioner.

 

[IdahoMtnSpyder]

Old fashioned threshing machines were powered by a long, 20' to 30' or so, flat belt 6" to 8" wide. Too tight or too loose, they wouldn't stay on the pulleys. And they flopped and bounced all over the place. Sometimes they had to be twisted to help keep them quiet. I don't know that there is such a thing as an absolutely smooth running belt of any sort anywhere on a machine.

 

[h0gr1der]

I'm in the belt dampener being a positive thing camp, but I've had an unusual thing happen. I've been smelling a rubber burning smell when I stop for a while now. I've checked my dampener for heat and belt wear, but have noticed none. I removed my arm from the unit to see, no burning rubber smell. I also noticed with the extremely low belt tension I'm running that the vibration, if any is noticed, is so minute that I may leave the dampener off. Pretty surprised by all this, my bike has a pretty good amount of belt vibration above 160 lbs.