Catastrophic Belt Failure

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I suspect I know the issue with the lollipop. I don’t have definitive proof.

Irregardless it doesn’t matter. I should have had the top bolt tighter and checked the belt more frequently.

In the end I’ll get it fixed and on top of that improve the charging system.
 
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The first Gates belt on my Norvil drive lasted over 20 years, probably 20k+ miles. Still looked good but I changed it as a precaution. Second belt probably now over 10 years and looks fine.

Car/bike dealers make good money changing cam belts. I'm sure that is a factor in the recommended change intervals. e.g I have a Skoda and the factory recommended change interval for cam-belt is 120k Kilometres, there is no time interval. VAG, the UK importers, say must be changed at 5 years regardless of mileage. Form your own opinion why.
Your comments are noteworthy, but nothing lasts forever.
With rubber/kevlar belts they undoubtedly will perish just sitting on the shelves in a dealer/warehouse, I've had one timing belt snap on me in a General Motor engine, I've no idea how old it was or it's mileage, no doubt I should have changed it sooner - I took the risk and could easily have had a expensive engine blow up.
 
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Hi Dave

I have been following your thread with interest as I've just fitted a belt drive to a Commando I'm working on,
and I'm now looking at the old chain drive on the shelf with thoughts of putting it back on.

From your posts I see you have fitted a chain back on. I presume you knew when fitting your belt drive that the tensioning
of a belt drive is different to a chain?

The tensioning and angle of gear box shaft for a belt drive is a bit of a worry for me, especially as I've followed your thread.
 
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Jan said : "well, 87 lb in is not 70lb ft for a start!!"

There are several threads on here saying that 70lb.ft is too high and 40 to 45 lb.ft is better ?
 
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the norvil belt drive on my bike has over 45,000 miles on it. I installed it when I built it in 2004 and I just replaced the belt last year. it was showing a fair amount of wear on the teeth but other than that it has been trouble free.
 

robs ss

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Belts are great!
They just don't like over-tensioning that can be caused by neglecting to check them occasionally.
You didn't hear of primary chain failure - because, if it got too tight, the gearbox bearing would fail first.
Get real and look after your bike.
 

baz

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the norvil belt drive on my bike has over 45,000 miles on it. I installed it when I built it in 2004 and I just replaced the belt last year. it was showing a fair amount of wear on the teeth but other than that it has been trouble free.
Yep same here
No trouble at all even when my top gearbox bolt was loose
And I have only changed the belt because it was old
 
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Hi Dave

I have been following your thread with interest as I've just fitted a belt drive to a Commando I'm working on,
and I'm now looking at the old chain drive on the shelf with thoughts of putting it back on.

From your posts I see you have fitted a chain back on. I presume you knew when fitting your belt drive that the tensioning
of a belt drive is different to a chain?

The tensioning and angle of gear box shaft for a belt drive is a bit of a worry for me, especially as I've followed your thread.
I suspect I wouldn't have had any issues if I hadn't been in a rush and gotten the RGM double adjuster. But I wanted to ride and not wait so I got impatient. As long as you have the double adjuster I wouldn't worry. I knew that just using the single adjuster was a risk and well, I paid for it.

The belt will go back on as soon as I find a solution for the front pulley guide. There's a guy in our club with a massive machine shop but he's retired so he doesn't have any time. Funny how that works out.

In the meantime I'm ordering the RGM dual adjuster and run the chain.
 
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Test ride with old primary chain. I didn't go far but I also didn't have any issues. We'll see if the primary is leaking when I check it this morning.

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mean gene

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Yes I agree with the misalignment causing the failure. But been following this post and do not recall anyone describing the belt's structure. The belt drives I have seen came with an entry level belt, rayon- fiberglass cords. There are Kevlar as a middle load and carbon fiber for the max. I believe the Torque load is more important then HP. What was the cord material?
 

TomU

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Do the ventalated inspection plugs actually reduce primary cover heat, or is it a can't hurt situation?
 
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My experience with a belt drive on my A65 was brief and expensive. Belts were $100 and lasted weeks no matter how meticulously adjusted. It simply removed two chunks of teeth till it lost drive and I was stuck at the side of the road. I only did it twice to realize the triplex was problem free with the crank and G/box shafts with extra bearings to keep the run in line. No failings from the chain even with 73ftlb of engine torque, for the last 18 years.
 
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My experience with a belt drive on my A65 was brief and expensive. Belts were $100 and lasted weeks no matter how meticulously adjusted. It simply removed two chunks of teeth till it lost drive and I was stuck at the side of the road. I only did it twice to realize the triplex was problem free with the crank and G/box shafts with extra bearings to keep the run in line. No failings from the chain even with 73ftlb of engine torque, for the last 18 years.
On the A65 how did you adjust the tension on the belts? It's a unit construction so the crank and mainshaft are fixed, right?
 
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Yes I agree with the misalignment causing the failure. But been following this post and do not recall anyone describing the belt's structure. The belt drives I have seen came with an entry level belt, rayon- fiberglass cords. There are Kevlar as a middle load and carbon fiber for the max. I believe the Torque load is more important then HP. What was the cord material?
I don't know.
 

Fast Eddie

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Yes I agree with the misalignment causing the failure. But been following this post and do not recall anyone describing the belt's structure. The belt drives I have seen came with an entry level belt, rayon- fiberglass cords. There are Kevlar as a middle load and carbon fiber for the max. I believe the Torque load is more important then HP. What was the cord material?
I don’t know either, but, it’s a Maney belt kit. Very well proven on road and track, so it’s certainly not the root cause here.
 
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