Commando sprag gear

Hi Andrew,

What do you mean by slipping ? Does the starter just spin without any nasty noises or does it sip and make some nasty juddering ?

If you are running a belt, are you running it dry ? If so the sprag will not last long as it must run in oil.

Regards

Tony

The gears in the gearbox are in constant motion, those in the starter drive train should only move when the button is thumbed... hopefully! So no comparison there.

It's the sprag clutch that needs the lubrication, general consensus is that running in oil is best, though I am surprised in this day and age that there isn't a grease (maybe from aeronautical background?) that would be up for the job.

As it's an RGM belt, what's their take on wet/dry running?

I am not familiar with the alloy front pulley on a belt drive for the electric start. Are you saying that the sprag 'teeth' bear directly on an aluminium face and there is not a hard steel sleeve inside the pulley?

Perhaps you had best discuss it with Les and get his advice on making it work at its best.

Norm

are the sprag bearings moving parts non magnetic. if not wouldnt the magnetism surrounding it have an effect on its operation.

Barry

The sprague is made from hardened steel and should run between a hardened journal and a hardened ring. Any alloy components will not survive first contact with the starter button.

Previously andrew_windsor wrote:

Hi,

Sorry my mistake the belt drive kit was from Novil in the end. A bit of a story i had ordered one from RGM and after a long wait i got a refund and placed an order with Norvil, you hit 50 and the mind goes.

Like you say the sprag clutch needs lubrication its just the best way going about it, would grease be too heavy or PJ1 a chain lube be too sticky.

The answer i got from Les was why on earth would i want oil in there .

Does anyone else with a belt drive run oil in the primary drive casings.

Kind Regards

Andrew

Hi Andrew,

Not a lot of point asking Les anything then. (Does he ever actually have a happy hour.) The reason you need to run oil in the primary chaincase is because there is a needleroller race in the middle of the sprag clutch When the engine is running this bearing is in constant motion at whatever rev's your engine happens to be running at, no oil in the case meansbearing runs dry, not good engineering practise. It is possible that the spragclutch device was not originallydesigned to start a Norton motorcycle engine as I believe the designers recommend running with at least 50% oil immersion.

Regards, Ian.

Andrew

Fitting a belt drive to a mk3 and running it dry WILL eventually destroy the starter motor. The sprag, needle roller bearing and the starter motor drivetrain all need the lubrication provided by the primary drive case oil.

what WILL happen is the sprag & needle roller will seize, locking the engine to the starter motor drive train, the starter motor is then subjected to a speed it cannot take and the rotor windings explode wrecking the starter motor.

The worse case is the starter motor seizes when your at speed,locks the engine and brings you off.

I consider it extremely irresponsible of the the supplier of your belt drive for a MK3 and not point out what will happen if you fit the starter mechanism and the belt is run dry

There have been quite a few posts warning of the perils of belt drive mk3s with the belt run dry. If you want to run a belt on a MK3 (with its starter) it has to run in oil.

I've just noticed that i have repeated what i said to yourself back in September.

Regards

Peter Shand

And just to make it clear. The synchroflex belt is happy to run in oil. Have a look at http://www.farnell.com/datasheets/58291.pdf

Tony

Previously andrew_windsor wrote:

Back Again, the belt i am running is a H T C and a H T D cannot run in oil as it swells and softens the teeth. I have just spoken to RGM for a bit of advice and they wouldnt give it as the belt drive was purchased elsewhere, so i rang happy hour and he is not back untill Monday 4-5 pm.

I have to find the pitch out 8 or 10mm of the belt and the difference between H T C and H T D . Hopefully the belt i have runs in oil has anybody came across this problem.

Andrew

Hi Andrew, I was just looking through your posting as I am currently fitting a starter motor back to my Mk 111 commando which has a belt drive fitted to it and was looking for advice on how the gears, sprag clutch etc should be lubricated. Did you identify which type of belt can run in oil?