Heavy Vibration Issue

Dellis · Nov 1, 2023

no750 said:
Hi, some years ago i recogniced heavy vibration under ++full++ load on my newly restored commando with the conti atf belt.
the reason turned out to be to much slack. the teeth klimb the tooth..
turning the belt on a given degree with disired force is not ease to reproduce. i keep to the "slack" procedure. the red conti atf belt with metal inlays ist very stiff. 18mm slack did it for me the last 12000 miles with no change. see pictures

Thanks for the info. How tight it is when hot?

Dave

Fast Eddie · Nov 1, 2023

Not to go against the flow here, but I think it’s worth pointing out that most belt failures occur as a result of being run too tight.

So whilst all the current talk of the symptoms of being run too slack are perhaps valid, it’s certainly best not to over compensate …

Schwany · Nov 1, 2023

Fast Eddie said:
Not to go against the flow here, but I think it’s worth pointing out that most belt failures occur as a result of being run too tight.

So whilst all the current talk of the symptoms of being run too slack are perhaps valid, it’s certainly best not to over compensate …

Apparently destroys the gearbox too.

Have you tried an RGM belt clutch with Continental AT10 Synchroflex belt on any of the many Brit bikes you've setup? The belt I'm currently using is a Red Gen3, like the belt no750 shows in his post, but I would imagine the standard Synchroflex AT10 belts also skip teeth and/or cause annoying vibration if slightly loose. The vibration is not something I would ever consider correct adjustment.

The belt clutches with the softer 8mm pitch belts probably don't skip pulley teeth as easily and/or cause the vibration being discussed when slightly loose. Just a guess though. I've never used another belt clutch on any motorcycle I've owned.

The polyurethane steel corded Continental AT10 Synchroflex belts are stiff, smooth surfaced, and a little slippery. The 4 I have are anyway. I also have a 5th AT10 belt that is from another manufacturer, and it is really a stiff slippery thing. The Continental AT10 Gen3 belts are the better belts.

If I didn't dislike cold weather and how my glasses and face shield fog up, I go for a ride and see if I could snap it as adjusted. I rev'd the bejebbers out of the motor no load with the bike sitting in a bike stand and the belt didn't fly off the pulleys and get chewed up, but that is no load and doesn't really count.

Fast Eddie · Nov 1, 2023

Schwany said:
Apparently destroys the gearbox too.

Have you tried an RGM belt clutch with Continental AT10 Synchroflex belt on any of the many Brit bikes you've setup? The belt I'm currently using is a Red Gen3, like the belt no750 shows in his post, but I would imagine the standard Synchroflex AT10 belts also skip teeth and/or cause annoying vibration if slightly loose. The vibration is not something I would ever consider correct adjustment.

The belt clutches with the softer 8mm pitch belts probably don't skip pulley teeth as easily and/or cause the vibration being discussed when slightly loose. Just a guess though. I've never used another belt clutch on any motorcycle I've owned.

The polyurethane steel corded Continental AT10 Synchroflex belts are stiff, smooth surfaced, and a little slippery. The 4 I have are anyway. I also have a 5th AT10 belt that is from another manufacturer, and it is really a stiff slippery thing. The Continental AT10 Gen3 belts are the better belts.

If I didn't dislike cold weather and how my glasses and face shield fog up, I go for a ride and see if I could snap it as adjusted. I rev'd the bejebbers out of the motor no load with the bike sitting in a bike stand and the belt didn't fly off the pulleys and get chewed up, but that is no load and doesn't really count.

No I’ve never used an RGM belt kit. But I have used Synchroflex belts a lot, on road and track, and still use one on a road bike today.

Schwany · Nov 1, 2023

Fast Eddie said:
No I’ve never used an RGM belt kit. But I have used Synchroflex belts a lot, on road and track, and still use one on a road bike today.

AT10 spec belts on a clutch and I guess never an issue?

I must be getting too old to use wrenches.

Fast Eddie · Nov 1, 2023

Schwany said:
AT10 spec belts on a clutch and I guess never an issue?

I must be getting too old to use wrenches.

I think they were AT10, I used Tony Hayward belt kits, and I see RGM are selling some of his gear, so I’m guessing they‘re the same.

I had a belt fail once, The rear wheel / chain pulled the gearbox back, stretched the belt too tight, and snapped it.

Schwany · Nov 2, 2023

Fast Eddie said:
I think they were AT10, I used Tony Hayward belt kits, and I see RGM are selling some of his gear, so I’m guessing they‘re the same.

I had a belt fail once, The rear wheel / chain pulled the gearbox back, stretched the belt too tight, and snapped it.

Ouch!!

I've got both sides of the gearbox locked down so the gearbox can't move back. I think I've dodged that potential belt failure bullet.

The range for belt adjustment being good or too tight on my bike has a thin margin for some reason. And there could be other reasons. My mainshaft is old and the splines could be a little sloppy. The mainshaft is not bent though.

Two adjustment techniques that don't work on my bike are: 1) the adjustment is correct when you can slide the belt onto both pulleys at the same time without using excessive force, or 2) adjust the belt to where it just skips a tooth when kick starting (recommended by Comnoz many moons ago). Both of those techniques are a total fail for clutch noise and vibration.

I am rattling on about this when in fact it doesn't matter all that much to me. I started out trying to help Dave, but as usual went off the rails. I'm going to swap gearboxes next year and everything related to the clutch will have to be done again. It might just work with the TTi gearbox, and I'll be able to say, "I've got an RGM belt clutch and never had a problem with it."

no750 · Nov 2, 2023

Dellis said:
Thanks for the info. How tight it is when hot?

Dave

actually i checked it once, but i dont remember.

no750 · Nov 2, 2023

Schwany said:
Apparently destroys the gearbox too.

Have you tried an RGM belt clutch with Continental AT10 Synchroflex belt on any of the many Brit bikes you've setup? The belt I'm currently using is a Red Gen3, like the belt no750 shows in his post, but I would imagine the standard Synchroflex AT10 belts also skip teeth and/or cause annoying vibration if slightly loose. The vibration is not something I would ever consider correct adjustment.

The belt clutches with the softer 8mm pitch belts probably don't skip pulley teeth as easily and/or cause the vibration being discussed when slightly loose. Just a guess though. I've never used another belt clutch on any motorcycle I've owned.

The polyurethane steel corded Continental AT10 Synchroflex belts are stiff, smooth surfaced, and a little slippery. The 4 I have are anyway. I also have a 5th AT10 belt that is from another manufacturer, and it is really a stiff slippery thing. The Continental AT10 Gen3 belts are the better belts.

If I didn't dislike cold weather and how my glasses and face shield fog up, I go for a ride and see if I could snap it as adjusted. I rev'd the bejebbers out of the motor no load with the bike sitting in a bike stand and the belt didn't fly off the pulleys and get chewed up, but that is no load and doesn't really count.

my belt drive kit came with a white AT10 belt. i had the feeling the setup became looser with rising temperature, which led to climbing teeth. i changed to the red ...

Continental AT10 Gen3

I guess a to loose setup will also destroy the gearbox and maybe also crank, bearings and engin cases.

Schwany · Nov 3, 2023

no750 said:
my belt drive kit came with a white AT10 belt. i had the feeling the setup became looser with rising temperature, which led to climbing teeth. i changed to the red ...

I guess a to loose setup will also destroy the gearbox and maybe also crank, bearings and engin cases.

I bought the pre-Commando kit but whoever packed it up sent me a huge Grey AT10 belt instead of the Red belt it is supposed to come with. Totally useless to me. Can't even give it away. lol

I agree that with the RMG setup and AT10 polyurethane belt, loose is worse. I did a test run using the looser specified spec chasing down a shifting issue and I was lucky to get back home. It was at its worst off the throttle than on throttle. Only made it about 1/2 mile before things went to shite. Vibrated skipped teeth and felt like the motor was going to come apart.

Heavy Vibration Issue

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