belt drive primary

Keith, I assume the outside diameter of your measuring socket is the 30mm you mention, set at dead cold?
thanks

Yes it is, that's the special fixture!! Forgot that was in place when I took the pic. Norvils recommendation was to have the belt outer just able to touch the dowel boss at full deflection.

Can I just point out that I believe the tooth profile for the Tansdev RGM belt drive is different to the standard HT type belt.
I would be very wary of swopping belt types until you know what is compatable. The RGM belt is an 'AT10' pitch, I think, whereas the HT belt is a 14M type. I could be wrong with the designations but I don't believe they will fit the profile.

Foxy said:

I see different colored primary belts, Im assuming different compositions? The primary belt drive kit I purchased from RGM came with a bluey/grey colored item, Fullauto,s a red (is this a fast model?). Does anyone know or believe theres a better quality one to source? Perhaps the racing fraternity amongst us knows.

FOXY

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Foxy, The belt on RGM's website is beige, like the one I got from Tony. If you search syncroflex on this list you'll see posts mentioning a red GenIII Syncroflex. They mention grey/green ones too. Counting your blue/grey, that makes four. Different generations of the Syncroflex polyurethane? Does yours have any printing on it?

just got back home after a 20 mile ride, took the primary cover off to check the belt
Things sure do expand when hot! There is really no easy slack at either top or bottom rung.
I suppose this is correct now that it is hot.
I am going to wait until it cools down and use Keith's 30mm socket to measure the top rung slack.
I LOVE my belt drive, so light, quiet, no leak primary, and DRY clutch plates.

Anyone care to guess WHY Norton chose the right instead of the left side to place the gearbox stock adjuster?
Doesn't make any sense, given the left side is without the oil lines to fight with to adjust, and it would seem
much more stable to have the adjuster on the main drive side.
Some might speculate that it was cheaper to put it on the right side, if so why would it have been?

I joined a couple months ago, just want to say how really experience and helpful everyone here is, GREAT GROUP !
Kick start, long stroke torque, wonderful wall of sound, smooth above 3500 rpm, Commandos are STILL terrific !!!

bigstu said:

Also whever you can remove oil from a british bike has got to be a good thing!

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I believe this is a built-in feature... :mrgreen:

That's twice today I damn near fell out of my chair cracking up! LOL LOL! :lol:

bill said:

the stock primary ratio is 2.19-1 and the standard belt kit from norvil is 2.187-1 with pulley's that count 70-32. he offers overdrive options up to 1.97-1. if I ever have to replace my belt drive I WILL OVERDRIVE it.

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The cogs on a Tony Hayward I bought about 15 years ago are 28 and 56, so 2:1.

Fullauto, Was your belt red when you got it? Mine started out beige and has turned red over time. Today I swapped it out for a spare. It's so much easier in the garage than roadside. Ask Steve Snoen, but he did it in less than an hour and got an IronButt pin too.

highdesert said:

I joined a couple months ago, just want to say how really experience and helpful everyone here is, GREAT GROUP !
Kick start, long stroke torque, wonderful wall of sound, smooth above 3500 rpm, Commandos are STILL terrific !!!

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Welcome!

Do want to point out that your Commando should smooth out somewhere between 2600-3000 RPMs. If it's taking until 3500 RPMs to do so, perhaps your isolastics need adjustment? Not an expert in the area, others can provide better/more detailed info I am sure.

Commandos are indeed terrific!

I remember my 750"S getting smooth under 3000, but my three 850s got smooth around 3500.
Don't know why, maybe the heavier pistons on the 850.

My isos are both rebuilt about two months ago, and have plenty of slack, more than the 10 thou recommended,
but I don't go by that as they are the no shim adjustable's for pre 75.

Hi
The belt colour! On triples the supplier informed us that the manufacturer has improved the belt for harder running in hot conditions & to denote this they are coloured RED.
This is the one to buy.
Hope this helps Chris

ps saying that I run a Norvil a RGM/Hayward & a NEB all of them are superb! I have had a problem with the Norvil kit as the clutch center seemed oversize & the plates would not slide freely. I fitted a Maney center & problem solved.

Gday All,
yep I took youre advice Bob and checked out Synchroflex,s web site. Plenty of information there including a formula and electronic device( listens to ultrasonic frequency of vibration) to get that belt tension just right. After reading I believe the belt is better off being slightly toward the looser side of adjustment as too tight is detramental to its longevity.

In searching I found aswell ,the red belt is the new Generation 3 belt , red polyurethane with more(smaller but more of & flexable) bifolar steel cord giving it a 25 % increase (strength) in power transmission. To denote this better High Performance belt, Synchroflex made them red. The price in Ozzy dollars Melbourne Australia is $132.80 plus tax, (65 pounds or $105 US).The standard bluey/grey AT10 belt sells for $102.08 Ozzy, thats mine that came with my RGM Kit, with " 814 Synchroflex AT 10/890" printed on it. Hopefully thats going to be the right length fit my Commando in a featherbed? The number of teeth on the drive is 28 & 55 clutch.

Sorry to hear about that oil tank spliting again John, but look at the postives, a bit of oil around stops the Brit bikes from rusting, not a problem hear in Australia, nothing rust in the desert!

Many thanks again for your replys, I must admit Im addicted to this forum! Regards FOXY

highdesert said:

My isos are both rebuilt about two months ago, and have plenty of slack, more than the 10 thou recommended,
but I don't go by that as they are the no shim adjustable's for pre 75.

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the rubber used on new iso's is alot harder than the original one's. been there, done that and fixed it along with NEVER having to fuss with ANY type of adjustment :mrgreen:

Has anyone else used the Gates GT2 belt? I shelled out the original belt I got with the kit after about 10,000 miles. Don't know what belt it was. I've since switched to the GT2 on the advice of a customer service person from Miller Bearing. So far, so good. I've only got some 2,000 miles on it.

Windy, how did you fix the new rubber snubbers are harder problem?
Do you have access to softer ones?
The more I think about it, the more I can remember your comment about the originals being softer.
My Commandos back then would be smooth as silk above 2600, at my 750s.
My 850s have always smoothed out above 3300, but never as smooth as the 750s.
So, what did you do to fix this problem forever?
thanks

Jim
The GT2 was an evolution of the Gates polychain GT belt. The tooth profile of polychain has a flat top and steeper sides, which makes it better than the standard HTD type for power transmission for a given width, which has a half round tooth profile.
Did you know they now have a GT carbon belt, which is an even later evolution. It uses carbon tensile chords. If yours fails again, try that type.
I have the Synchroflex AT10 type that RGM, Tony Hayward and some others use.
Stu.

highdesert said:

Windy, how did you fix the new rubber snubbers are harder problem?
Do you have access to softer ones?
The more I think about it, the more I can remember your comment about the originals being softer.
My Commandos back then would be smooth as silk above 2600, at my 750s.
My 850s have always smoothed out above 3300, but never as smooth as the 750s.
So, what did you do to fix this problem forever?
thanks

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There were a variety of buffers available at one time with differing hardness. I think Norvil had them.

highdesert said:

Windy, how did you fix the new rubber snubbers are harder problem?
Do you have access to softer ones?



The more I think about it, the more I can remember your comment about the originals being softer.
My Commandos back then would be smooth as silk above 2600, at my 750s.
My 850s have always smoothed out above 3300, but never as smooth as the 750s.
So, what did you do to fix this problem forever?
thanks

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the fix that I used was to narrow the large rubbers in the mount about 30 percent.
the fix to never have to fettle the mount clearance is I made a rod link at the front mount. I don't even have the the end caps on mine just the mount housing,tube with rubbers and the abutments now .

My belt was red and the replacement and the spare are both red.
Hayward items I believe.

Regarding vibration, when I replaced my original (?) rubbers with new MK111 design I thought I'd fitted a BSA conversion !! Loosened the tolerances up and it was better but nowhere near as smooth as before. It got better over a month or two to the point that I don't even think about it anymore. It still shakes a bit more down low but is much smoother above 3000rpm.