Starter Ring Gear -- ISSUE

I'm not sure if this is a known problem or not but it is a potential problem that should be noted.
The RING GEAR (the gear that the starter is driving/spinning) can come loose as it is held on with five shoulder bolts and threebond. The problem, in my opinion from an engineering view is, the shoulder bolt diameter is not counter-bored into the ring gear with a tight enough tolerance (this could be only on some bikes and not others), so with every start only the thread, which isn't as strong breaks. Once one breaks, it wont take long for all to break as the others are now taking more load. If they and or when they all break, then the gear can spin and JAM!!! I personally think that the dealers should be inspecting each bike when they come in and assess if this will be a future issue or not.

TO CHECK;
Remove the primary cover and see if the ring gear can move on the bolts, if it does, DO NOT START IT!!! CALL YOUR DEALER!!!!

Hope this helps others to prevent this problem.

I think this is what has happened to my bike this morning. The starter is grinding/crunching.

I bought this bike 2nd hand last week for £11k privately so no dealer coverage. I can't begin to describe how angry/upset I am. This is my life savings put into a bike that is broken after 9 days. I don't have the first clue where to start with fixing it.

If you are in the UK I would get on to the factory pronto, I am sure they will at least take a look and advise on what the
Problem might be. With so few bikes sold they will want happy owners out there as adovocates. Good luck

I'm hoping to God it's just a dead battery. I need to chop the head off a tank bolt to check first though as I've found out that's threaded now!

If I get the battery fully charged and it's still doing it I shall be on the phone to the factory. I found an earlier thread on here saying they know somebody the earlier bikes have the teeth cut wrong on the starter motor. I live 3 hours from the factory unfortunately. Really starting to wish I'd bought from a dealer with a warranty rather than a private sale

Have you found the battery charging plug yet ? It is there like Der said. I found it on my bike today . If what you need is to charge the battery , and cannot get the tank off. Then you must find this plug. It is behind (directly behind the top l/h shock bolt) . It is in a recess , just look for a cable going into the frame by /behind the top l/h shock bolt. It is a white plastic two prong plug at the end of this wire. Again left hand (as you are sitting on the bike). You may need to adapt your charger to this type of plug or install your own plug.

Here is a picture I took to share with you guys. The arrow points to the RING GEAR.

The two bolts above are the STARTER BOLTS. Just an FYI that to remove the starter you need to remove the clutch housing.

Hello Richard, So what's the fix ? Does the ring gear work its way loose over time ? There is 72 degrees between the 5 bolts that hold the ring gear on. it probably should have been 8 bolts 45 degrees apart. Does your Dad have a fix in mind ? One could add an additional fixing bolt between the current 5 for a total of ten. OR replace the current 5 with a slightly larger better fitting ? Or are just Loctite and reinstall ? Did your Dad tighten his ring gear before he left for the trip ? Thanks for the info . Hope it goes well for all of us on this Norton journey.

The problem is not the amount of bolts. The problem, in my opinion being an engineer at a tool and die company, is the type of fastener. Shoulder bolts should never be used for positioning. And in this case they are which isn't the worst thing in the world if the fit is super close. But in a WORST CASE SCENARIO if the hole is greater than the size of the OD of the straight Ø, the bolts break off at the undercut before the thread. Resulting in a super loose ring gear flopping all over when spinning. Keep in mind this issue has been addressed so the only time this could possibly come up is in a combination of events. OLDER BIKE or NEWER BIKE WITH AN OLDER STYLE CLUTCH HUB, and of this scenario, the OLDER CLUTCH HUB having a tolerance a little too large. This does not mean every older bike or older clutch has this issue. It really is less than a handful. And it's easy to check or easy for a dealer to check like I stated earlier in this thread. I pinned my dads using press fit dowels. I don't feel comfortable sharing the picture or expanding too much on this because I don't feel everyone should be running off to a machine shop or even be worried they are going to have a problem. But, this is a HEADS UP WARNING, that if and when your bike is in for service, or you feel like you can do this yourself, remove the primary cover and inspect yourself so you know for sure if yours is loose or tight. I don't think it would take more than 100 starts to unveil an issue. So if you have had at least this, take it off, and if it's tight, I would think you're okay. HOWEVER, inspecting it is the ONLY way you will know where you stand.

You seem to have a good communication with Norton Canada , just based on the numbers and facts you have. This is good. When was the issue resolved ? Your Dad had a 2013 , was the problem present here still. ? Well , so If I find that my ring gear is tight Im Ok ? and If not bring it back to the dealer ? What will they do for it I wonder ? Keep it a long time for sure , Id rather fix it myself. I still think it should have been 8 bolts. not 5 . I see what your saying , the starter ring gear needs to be precisely positioned on the back of the clutch hub. Maybe a raised lip to centrally locate the ring on the back of the hub. What did Norton do to fix this ? You mention a new hub or ring gear or both. I suppose no chance of getting this installed at no cost hey. One thing for sure Norton (factory) are very quiet about these things. I suppose you can understand , everyone wants to be compensated , lots of money involved for them . TA

Harley have the same ring gear/clutch basket and starter type of configuration on their machines as the 961.
Would be informative to see how they join the ring gear to their clutch baskets.

TonyA said:

You seem to have a good communication with Norton Canada , just based on the numbers and facts you have. This is good. When was the issue resolved ? Your Dad had a 2013 , was the problem present here still. ? Well , so If I find that my ring gear is tight Im Ok ? and If not bring it back to the dealer ? What will they do for it I wonder ? Keep it a long time for sure , Id rather fix it myself. I still think it should have been 8 bolts. not 5 . I see what your saying , the starter ring gear needs to be precisely positioned on the back of the clutch hub. Maybe a raised lip to centrally locate the ring on the back of the hub. What did Norton do to fix this ? You mention a new hub or ring gear or both. I suppose no chance of getting this installed at no cost hey. One thing for sure Norton (factory) are very quiet about these things. I suppose you can understand , everyone wants to be compensated , lots of money involved for them . TA

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It's a torque thing, not a concentricity thing. Two dowels is all you need. If Norton did this they would never have a claim. I understand that there were only a couple issues one on this board from a guy who had to get his trans replaced. The tolerances have been tightened as I understand (I cannot verify this). I still think the design is wrong tho. But I doubt you will see too many problems from this. I pinned my dads and let me tell you the ring gear is over 62Rc. So you need carbide to get thru it.


Ill reluctantly share this but I would pass it by your dealer first. And don't get all scared thinking this is what you need. After my dad had a close call, I pinned it for him. AND - we are a very qualified shop. I would NOT trust this to just any old machine shop. It's actually harder than it looks. PLEASE DO NOT DO THIS UNLESS YOUR BIKE IS OUT OF WARRANTY!!!!!!

Good info thanks for you response. Looks like great work you did. Tony

I have posted about this in the past,it happened to me last year,it took Norton over 3 months to fix it.
Part of the problem is that when Norton changed to a different supplier,the Taiwanese ones,the the angle cut on the starter gear was slightly different causing the starter bendix to contact the ring gear at the wrong angle.This in turn lead to the bolts coming loose and the ring gear falling off and locking the back wheel.It needs sorting before someone gets hurt.
Richards mod is perfect,come on Norton admit the problem and sort it out.

Story,

Did your ring gear come loose, and lock the rear wheel?
Were you at speed on the highway at the time?

With very little warning,very loud noise pulled in the clutch,locked up anyway.The ring gear had fallen off and done a whole load of damage.There was also a black SF in the workshop when I took mine back that had done the same thing.

Thanks for the reply.

deja vu for owners of old 750/850 Commandos.
Sounds like the layshaft bearing failure all over again.
That would tend to lock the rear wheel upon failure also.

How fast were you going when the failure occurred?
Must have been a high pucker factor moment, I'm sure.

Hello Brit Twit , What is the warranty on the Norton ? 2 years unlimited miles right ? Going through the dealer /factory will take a very long time ... Removing the clutch basket after warranty should not be too difficult.

Hello Brit Twit , What is the warranty on the Norton ? 2 years unlimited miles right ? Going through the dealer /factory will take a very long time ... Removing the clutch basket after warranty should not be too difficult. Also do you remember the Aussie fellow who had starter trouble almost within days of getting his new bike and just a few hundred km's.? He was on this forum just a while ago. I was hoping he would report back as to what it was. It seems then that if this is going to happen , it may be sooner than later . So you've gone how long (miles) and how many starts since new ? Quite a few I think by now. So that may be good news for you . I only have about 900 miles on mine so far.

TonyA said:

Hello Brit Twit , What is the warranty on the Norton ? 2 years unlimited miles right ? Going through the dealer /factory will take a very long time ... Removing the clutch basket after warranty should not be too difficult. Also do you remember the Aussie fellow who had starter trouble almost within days of getting his new bike and just a few hundred km's.? He was on this forum just a while ago. I was hoping he would report back as to what it was. It seems then that if this is going to happen , it may be sooner than later . So you've gone how long (miles) and how many starts since new ? Quite a few I think by now. So that may be good news for you . I only have about 900 miles on mine so far.

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Tony,

Yes the warranty is 2 years, unlimited mileage. Removing the clutch basket isn't the problem. Finding a qualified machinist who can do the required modification will be difficult, as Richard-7 noted. My bike has only 1600 miles, and it's currently in the shop since the starter bendix failed last month. I have been waiting 6 weeks for the factory to send a new replacement. It always sounded like a box of rocks when the starter engaged the motor. Now I'm thinking I should have the shop check the ring gear to be safe. Been thinking, did the starter bendix fail because the pinion was not meshing properly with the ring gear? Possibly because the ring gear is loose? Perhaps the ring gear teeth have the wrong pitch?

Things are getting a bit dicey now to be sure.

Clearly , Your time is now... Talk to the dealer/mechanic . Don't assume they know about all the issues like you do. This IS the time to get it all resolved .. new basket , ring gear , bendix etc.. Lots of people are very negative about Norton , you were one of a few who remained upbeat,. There are others , not too many though. The Aussie had I thought a 2014 model , he had trouble. So just because I have a 2014 doesn't mean I am good either.