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Unchain My Bike... Or So I Thought...


BusyLittleShop

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Here a German guy selling belt conversion kits. But no Honda's in his range....

http://www.vh-motorradtechnik.de/index.php

Good find but I can't find any belt pitch numbers... the photo shows a belt with small teeth which

makes me believe its the light duty 8mm pitch belt... what we need to crack the RC45/ VFR belt code is

a robust 11mm pitch belt because the Harley 14mm pitch belt will not bend around a sharp enough radius

to fit in the space of the counter shaft sprocket...

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here ya go http://www.vh-motorradtechnik.de/en/Belt-Drive-Kits/Kawasaki

The site does have a button top right with a union jack, but if you need more translation or help let me know

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here ya go http://www.vh-motorradtechnik.de/en/Belt-Drive-Kits/Kawasaki

The site does have a button top right with a union jack, but if you need more translation or help let me know

Thanks Dutchy, does not show on mine .

WOW $1095 euro PLUS 19% tax PLUS shipping. Good luck with that.

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  • 4 weeks later...
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Hi Larry,

Sorry to resurrect a sore subject but Gates manufactures an insane number of different belts. Have you contacted their engineering department to see if they have what you need or are you just checking publications regarding motorcycles? Maybe they manufacture the belt but its for a car, industrial equipment, etc?

PM sent to bring Larry`s attention back to this subject and providing a little bit more information.

No problem... yes I have contacted Gates engineering and the 11mm pitch belt are

only custom made upon demand for Eric Buell and BMW... the 155T Buell is too

short and the 172T BMW is too long... what we need is a 166T to have any chance

at a RC45 / VFR800 11mm belt drive conversion...

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Did I ask this before Larry? What about a herringbone pattern belt like the GoodYear NRG belt?

Eagle.jpg

I think it came up before Rob... there's just not enough tooth grip...

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Did I ask this before Larry? What about a herringbone pattern belt like the GoodYear NRG belt?Eagle.jpg

I think it came up before Rob... there's just not enough tooth grip...

Hmm, Goodyear seems to say otherwise:

Goodyear Engineered Products Eagle NRG advantages:

Up to 25% more power capacity

Static conductivity

Up to 19dB quieter than straight tooth belts

Over 1,500 possible sprocket combinations

Rated for continuous service at 200° F

Up to 98% energy efficiency

- See more at: http://www.goodyearep.com/ProductsDetail.aspx?id=3400#sthash.vi1TLecL.dpuf

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Did I ask this before Larry? What about a herringbone pattern belt like the GoodYear NRG belt?Eagle.jpg

I think it came up before Rob... there's just not enough tooth grip...

Hmm, Goodyear seems to say otherwise:

i have seen HD DRAGBIKES use this on the buell primary. but, they may have been 1.5 inches wide..

but they did take 154 HP with no problem.

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Did I ask this before Larry? What about a herringbone pattern belt like the GoodYear NRG belt?Eagle.jpg

I think it came up before Rob... there's just not enough tooth grip...

Hmm, Goodyear seems to say otherwise:

i have seen HD DRAGBIKES use this on the buell primary. but, they may have been 1.5 inches wide..

but they did take 154 HP with no problem.

It looks heavy to me anyway.....

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Hmm, Goodyear seems to say otherwise:

True but Eagle NRG’s patented Helical Offset Tooth only comes in 8mm which not enough tooth grip and

14mm which has tooth grip but the primary sprocket is too large to fit in the parameters... the only

answer is the 11mm pitch belt which has tooth grip and small enough sprockets to fit... keep in mind

that each belt require certain radius to live... you can not bend a 14mm pitch belt around the tight

circumference of a 11mm sprocket...

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So it would seem like this ones been beaten to death more than a few times, but alas, we'd all like to see it work.

In reading through this a previous poster had suggested that a 2 tooth increase in the rear sprocket would take up the slack needed to totally eliminate the whole belt-tensioner problem. However, then another problem arises due to lack of clearance on the swingarm (the front I assume).

What about offsetting the gears the 3/8" or so ...

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  • 8 months later...

there is a good engineering Reason to add either tensioner(s) or idlers.   If you add two idlers above and below the swing arm pivot then within some limits the belt neither gets too long or two short (too loose or too tight) during swing arm movements but stays at a constant tension .   I do not think it was chance which led Buell to place his idler almost directly under the pivot.   With a pair,  mounted on the swing arm above and below the swing arm pivot point the belt would be at a fixed distance from the swing arm and suspension travel  would neither tighten nor loosen   except at extreme ends of travel. .pair of toothed inside idlers paired with smooth outside idlers aligned with the swing arm pivot and displacing the belt so that from the pivot back to the back sprocket the  upper and lower belt runs would always both be parallel to the swing arm then suspension movement would not affect belt tension and belt tension would not affect swing arm movement.   I recall that some motorcycles in the past used an idler sprocket mounted over the swingarm pivot to prevent chain tension from compressing  the rear suspension. this idea has been used before with chains.    By the way I figured out the formula for the length of the belt b which is symmetricly mounted on wheels of radiuses R(big) r(small) and d distance between centers.   It is complicated and there is a chance ive made a mistake and if anyone wants it I will upload it the derivation when I get to a computer and can enter it in.   Notice that the belt leaves the large pully in a tangent direction.  A radius R drawn to that tangent point is offset from vertical by some angle theta.   Theta is given by Theta = Arcsin((R-r)/d).  Using The radian measure for theta I arrived at the following formula for b the length of the belt.

 

B= pi×(R+r) + 2 Theta×(R-r) + 2 (R-r)× cot(Theta)

The cotangent function can be eliminated  but the formula becomes more complicated.  If I can type my derivation into a computer soon I'll upload it so that you can check it.  One of my favourite classes to teach is college trig and I may save this problem for the next trig class I teach as  project bonus question.   Remember.that Thetanis written in radians.

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there is a good engineering Reason to add either tensioner(s) or idlers.   If you add two idlers above and below the swing arm pivot then within some limits the belt neither gets too long or two short (too loose or too tight) during swing arm movements but stays at a constant tension .   I do not think it was chance which led Buell to place his idler almost directly under the pivot.   With a pair,  mounted on the swing arm above and below the swing arm pivot point the belt would be at a fixed distance from the swing arm and suspension travel  would neither tighten nor loosen   except at extreme ends of travel. .pair of toothed inside idlers paired with smooth outside idlers aligned with the swing arm pivot and displacing the belt so that from the pivot back to the back sprocket the  upper and lower belt runs would always both be parallel to the swing arm then suspension movement would not affect belt tension and belt tension would not affect swing arm movement.   I recall that some motorcycles in the past used an idler sprocket mounted over the swingarm pivot to prevent chain tension from compressing  the rear suspension. this idea has been used before with chains.    By the way I figured out the formula for the length of the belt b which is symmetricly mounted on wheels of radiuses R(big) r(small) and d distance between centers.   It is complicated and there is a chance ive made a mistake and if anyone wants it I will upload it the derivation when I get to a computer and can enter it in.   Notice that the belt leaves the large pully in a tangent direction.  A radius R drawn to that tangent point is offset from vertical by some angle theta.   Theta is given by Theta = Arcsin((R-r)/d).  Using The radian measure for theta I arrived at the following formula for b the length of the belt.

 

B= pi×(R+r) + 2 Theta×(R-r) + 2 (R-r)× cot(Theta)

The cotangent function can be eliminated  but the formula becomes more complicated.  If I can type my derivation into a computer soon I'll upload it so that you can check it.  One of my favourite classes to teach is college trig and I may save this problem for the next trig class I teach as  project bonus question.   Remember.that Theta is written in radians.

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Two idler pulleys would be ideal.   One of the problems with most motorcycle drive systems is that unless the front drive sprocket is concentric with the swing arm pivot the needed length of the chain or belt that is needed changes with suspension travel.   The further away from straight horizontal the loosed the drive medium (belt,  chain) becomes.   With an idler on either side of the swing arm pivot (above and below) the drive media length can become fixed length.  

 

One objection to belt is that one would need to remove the swing arm to replace it.   But the final drive on the VDR is topologically outside of the swingarm already.   If you could get enough slack to jump a chain off the teeth of the sprockets You could remove a chain without breaking it.   Same thing for a belt.  This means that for a belt drive with idlers you might be able to remove and install a new belt strictly by loosening the idlers.    

 

I read at least one analysis which indicated that chain was inherently jerky and thus we have a need for cush drives in our wheels.

This same article indicated that in terms of drive efficiency chains win by a slight margin over belts.   However,  a few hundred miles into your trip when some of the chain lubricant is use up the belt catches up and becomes just as efficient.

 

We could make chains better.  A fully enclosed chain with idler tensioners would be better than a belt in every way except weight.

 

But since the chain is topologically outside the swingarm one can deduce that the Honda engineering was originally for a belt.

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The pivotless frame used on the 800 series VFR's & the VTR1000 & CBR929/954's, was not intended for belt drive. It was designed as a weight saving & space saving measure. If a bike is lighter its usually better regardless of power output, if its narrower where your feet sit, it needs less ground clearance for the same lean angle, a lower CofG results in more stable/predictable handling.

 

That said when I look at how much alloy is saved from the frame, but recreated in the back of the crankcase & the peg hangers (or cushion as Honda call it) I don't think much weight was saved, but they certainly are narrower than full side frame versions.

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18 hours ago, CathyEveridge said:

But since the chain is topologically outside the swingarm one can deduce that the Honda engineering was originally for a belt.

 

Honda had very little (nothing, really) to do with the VFR swingarm design premise.   At the time this was thought out, belts were not in use.
 

http://www.motorcyclistonline.com/elf-racing-elf-motorcycle-chassis-designs-retrospective

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Everytime I see this topic pop up I think BLS has finally succeeded.... 

 

There is time yet... :-)

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Thanks Dutchy... I'm still waiting for another bike to employ the
little known 11mm pitch belt or for Gates to wake up and offer the
11mm pitch belt in their catalog next to the 8mm and 14mm...

 

Interesting thoughts about Idlers but they are not an option based on
the fact that the longer BMW belt are not designed to bend backwards... not
to mention the problem of space given that fact that the idlers have
to be the same large diameter as the primary sprocket...

 

 

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Ah!  The BeltoCeptor project is not dead&buried, merely having a nap!

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  • 1 month later...
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  • 2 months later...

I still live in hope that this can be solved.

 

To recap:-
Model : Sprockets : ratio : Chain(belt)
RC45 : 17/40 : 2.353 : ~110 (not exactly sure about original)
5th Gen : 17/43 : 2.529 :108
6/8th Gen : 16/43 : 2.687 : 110

 

Larry's : 30/76 : 2.533 : [155|172]

 

I understand the problems of min. belt radius and tensioner pulleys etc. and so we need to find an acceptable combination that will result in a suitable distance between the sprockets/pulleys.

 

Any reason not to use odd numbers of teeth?

 

Is the front 30T pulley at the belt's minimum radius, or could a 29 or even a 28 actually be used, even if not perfect? Surely, a slightly smaller radius would just reduce the life of the belt slightly? The tighter the radius the shorter the belt life. So such a small change would surely be acceptable if it's the only way to make it all possible. If a 30T is absolutely fine, I cannot believe a 29T would cause it to instantly snap.

 

Could a 31T or even a 32T front pulley be squeezed in there. I see that the 30 is tight, but the difference in actual radius would be small. Is there any possibility that this could be done?

 

Finally, the figures above support what I read elsewhere that the 5th Gen swingarm is about 25mm shorter than the later models and suggests that the 8th gen length is the same as the 6th Gen. So what about the longer 6/8th Gen swingarm? Would that solve the problem of belt length? It would certainly help.

 

I realise this doesn't help Larry with his RC45, but it might be the solution for VFR owners who really want the convenience of a belt - and having had a belt drive bike, I REALLY do.
 

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