part 2 - second alton starter failure - the fix

The spacer is supposed to have a shallow "cup" on the wide end that prevents the sprocket from walking out of the sprag clutch - sounds like this has been worn away?

On my dad's bike, this cup was too deep and was fouling on the sprocket, which eventually took out the sheer plugs. He ended up machining about 10-15 thou off of it to allow the sprocket some clearance. It has been fine ever since.

Hope this is of some help.
 
Could this "problem" simply be insufficient tightening of the fastener? I know that sounds silly but when I installed my Alton I torqued the fastener to whatever the torque spec was and used blue loctite. Since I applied blue loctite, the actual torque applied was higher than spec since it would have acted as a lubricant when tightening. So maybe it needs a "bit more" torque than spec. As I have stated previously, the Alton on my Commando has been completely trouble-free since 2013. Maybe over-torquing that fastener is the reason! :)
 
MexicoMike said:
Could this "problem" simply be insufficient tightening of the fastener? I know that sounds silly but when I installed my Alton I torqued the fastener to whatever the torque spec was and used blue loctite. Since I applied blue loctite, the actual torque applied was higher than spec since it would have acted as a lubricant when tightening. So maybe it needs a "bit more" torque than spec. As I have stated previously, the Alton on my Commando has been completely trouble-free since 2013. Maybe over-torquing that fastener is the reason! :)
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Thanks. I am pretty sure that the torque was good (proper torque wrench and all). I have now investigated further and found that the back of the sprocket is seriously "blued" (heat) and appears to be solidly attached to the front face of the sprag so they move together.... Having removed the magnetic rotor ring I find that the body of the sprag (between the sprocket and the front face) moves smoothly and correctly !! I am wondering if the sprocket has a bearing at the back that has failed/welded itself together? Anyone got a section drawing of the sprag clutch unit?
 
I seem to recall back when I installed mine 10 years ago that the kit came with an additional spacer that was to be used with a (specific) belt drive. The OEM chain drive did not use the spacer. If you accidentally installed the spacer with the OEM chain drive it would do as you describe. So maybe it's a similar issue? I MIGHT have it backwards, maybe the chain used the spacer and the belt didn't - I can't remember but incorrect use of the spacer did cause the system to heat up/turn blue, etc.
 
first things first - as you said, contact alton - explain everything in detail and see where they say and do. sounds like you had a sprag centrifugal clutch failure that may impact other components. if you experienced a woodruff key failure, that maybe a separate issue. i'm thinking that may be caused by a tolerance issue with the spacer and/or the clamping nut bottoming out before the full 65# torque was reached. the poly shear pins did their job, but not sure what to make of the "weld" thing.

i feel your pain - good luck with alton. post back when you hear something.
 
joe czech said:
first things first - as you said, contact alton - explain everything in detail and see where they say and do. sounds like you had a sprag centrifugal clutch failure that may impact other components. if you experienced a woodruff key failure, that maybe a separate issue. i'm thinking that may be caused by a tolerance issue with the spacer and/or the clamping nut bottoming out before the full 65# torque was reached. the poly shear pins did their job, but not sure what to make of the "weld" thing.

i feel your pain - good luck with alton. post back when you hear something.
Click to expand...
Good news is that Paul at Alton has already acknowledged that he has my mail and I have also sent some pics. The funny thing about the sprag itself is that once I had the alternator rotor unbolted I found the sprocket and the "front plate" (with the two mysterious holes) are solidly attached to each other. However in between them the sprag "body" moves quite freely as it should and feels really good - no graunching or anything. Have also looked in detail at the Yves solution, I like the idea and also might consider doing it slightly differently. I'll update in due course
 
Dave F said:
Good news is that Paul at Alton has already acknowledged that he has my mail and I have also sent some pics. The funny thing about the sprag itself is that once I had the alternator rotor unbolted I found the sprocket and the "front plate" (with the two mysterious holes) are solidly attached to each other. However in between them the sprag "body" moves quite freely as it should and feels really good - no graunching or anything. Have also looked in detail at the Yves solution, I like the idea and also might consider doing it slightly differently. I'll update in due course
Click to expand...
super!!! IMO, the yves fix is a godsend. solved all my woodruff key issues. i had to go to six shear pins, however i 'm using a slightly softer material, because of availability. i'm thinking alton pins are 95 on the shore A hardness scale, mine are 80. i'm going on several months now without any problems - knock on wood! BTW, have paul send you the .pdf file - ALTON ESKN. The One Way Clutch assembly . very helpful information. i can't seem to link on my file copy. if you don't go with an yves type fix, at a minimum, use a serrated bellville washer behind the clamping nut and bump the torque 5 or 10 pounds along with some blue thread locker. i'm thinking the clamping nut's step flange maybe bottoming out on the crank's mating flange giving a false torque reading, thus incorrect clamping pressure on the sprag clutch. besides the locking feature, the bellville washer should kick out the nut enough to eliminate the crank to nut flange interference issue.
 
joe czech said:
super!!! IMO, the yves fix is a godsend. solved all my woodruff key issues. i had to go to six shear pins, however i 'm using a slightly softer material, because of availability. i'm thinking alton pins are 95 on the shore A hardness scale, mine are 80. i'm going on several months now without any problems - knock on wood! BTW, have paul send you the .pdf file - ALTON ESKN. The One Way Clutch assembly . very helpful information. i can't seem to link on my file copy. if you don't go with an yves type fix, at a minimum, use a serrated bellville washer behind the clamping nut and bump the torque 5 or 10 pounds along with some blue thread locker. i'm thinking the clamping nut's step flange maybe bottoming out on the crank's mating flange giving a false torque reading, thus incorrect clamping pressure on the sprag clutch. besides the locking feature, the bellville washer should kick out the nut enough to eliminate the crank to nut flange interference issue.
Click to expand...
I know that the crank nut wasn't loose as it went in at 65 lb ft and it took about 80 lb ft to remove it - the thread lock worked!. However I accept that I don't know what exactly was clamped up - to your point about bottoming out. I was delighted yesterday to find that the crank scoring was very slight, all polished up now.
 
Dave F said:
I know that the crank nut wasn't loose as it went in at 65 lb ft and it took about 80 lb ft to remove it - the thread lock worked!. However I accept that I don't know what exactly was clamped up - to your point about bottoming out. I was delighted yesterday to find that the crank scoring was very slight, all polished up now.
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this is kind of hard to explain, but there is a step flange on the end of the crank, and i'm thinking the nut that clamps the sprag clutch may be bottoming out on that flange, and the 65# torque is applied there and not the nuts clamping force on the sprag clutch assembly - thus giving a false torque reading of the nut to the sprag clutch assembly. i've always thought there might be a tolerance issue between the norton parts and the alton parts, most specifically the alton spacer. if there is an interference issue, a washer behind the clamping nut should kick out the nut enough to eliminate the problem. a serrated bellville washer, along with bumping up the torque 5 or 10# along with thread locker should eliminate any problems.
part 2 - second alton starter failure - the fix
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joe czech said:
this is kind of hard to explain, but there is a step flange on the end of the crank, and i'm thinking the nut that clamps the sprag clutch may be bottoming out on that flange, and the 65# torque is applied there and not the nuts clamping force on the sprag clutch assembly - thus giving a false torque reading of the nut to the sprag clutch assembly. i've always thought there might be a tolerance issue between the norton parts and the alton parts, most specifically the alton spacer. if there is an interference issue, a washer behind the clamping nut should kick out the nut enough to eliminate the problem. a serrated bellville washer, along with bumping up the torque 5 or 10# along with thread locker should eliminate any problems.
part 2 - second alton starter failure - the fix
.
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I agree, and like you I will be treading very carefully when I reassemble, measuring everything. BTW I thought my crankshaft was scored but by comparison it has just been "lightly honed" by the sprag slippage!!
 
Dave F said:
I agree, and like you I will be treading very carefully when I reassemble, measuring everything. BTW I thought my crankshaft was scored but by comparison it has just been "lightly honed" by the sprag slippage!!
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if i would have one more woodruff key failure, my crank most likely be needing replacement or removed for serious repair. anyway, good luck on your repair. give serious consideration to the yves, or a similar, fix.
 
Latest from here is good news. Paul at Alton (top man, very helpful) is sending me a replacement clutch, spacer and nut. All being well we'll be back on the road soon.
Considering all the "add on" solutions - has anyone considered or tried adding a pair of serrated belleville washers either side of the spacer? I would assume that the spacer would need to be machined down to allow space. In theory this would provide resistance to the possibility of the sprag hub turning and threatening the woodruff key. Maybe? If it worked then it would be a far simpler job than dealing with the alignment and machining issues of the Yves solution
 
Dave F said:
Latest from here is good news. Paul at Alton (top man, very helpful) is sending me a replacement clutch, spacer and nut. All being well we'll be back on the road soon.
Considering all the "add on" solutions - has anyone considered or tried adding a pair of serrated belleville washers either side of the spacer? I would assume that the spacer would need to be machined down to allow space. In theory this would provide resistance to the possibility of the sprag hub turning and threatening the woodruff key. Maybe? If it worked then it would be a far simpler job than dealing with the alignment and machining issues of the Yves solution
Click to expand...
the only problem i can see by adding a pair of washers on each side of the spacer is that it MIGHT kick out the spag clutch assembly enough to cause an alignment issue with the clutch chain in relation to the two sprockets. one washer under the clamping nut would keep everything aligned.
 
If the crank nut bottoms on the flange of the crankshaft, you can torque whatever you want, but the clamping force wil be insufficiet , or non-exesting.
Check this carefully when installing the starter kit.

Removing the woodruff key, like Cliffa sugested is a good idea, and will prevent damage to the crank when slipping occurs, only drawback is tha the timing mark will become useless.
 
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joe czech said:
the only problem i can see by adding a pair of washers on each side of the spacer is that it MIGHT kick out the spag clutch assembly enough to cause an alignment issue with the clutch chain in relation to the two sprockets. one washer under the clamping nut would keep everything aligned.
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Indeed, that's why I mentioned the potential need to machine down the spacer.
Anyway there is further news from here. I have successfully dismantled the sprag clutch unit (on the basis that all I need to run without the starter is the alternator rotor). I have finally found the cause of my grief - not the sprag clutch at all but the needle roller bearing that the sprocket runs on. This bearing has partially collapsed and has about 6 rollers out of line and a load of wear on the cage at that point. I suspect that this was what caused the key to shear before the final stoppage, and it was certainly the source of the heat that has blued up the sprocket centre. It also gave the impression that the sprocket and sprag outer race were "welded" together. I would happily post a pic but have yet to fathom out the instructions!! (I'll get there in the end)
I am very surprised as I would expect a needle roller bearing to last pretty much forever given that it carries no load for 99%+ of its life.
joe czech said:
the only problem i can see by adding a pair of washers on each side of the spacer is that it MIGHT kick out the spag clutch assembly enough to cause an alignment issue with the clutch chain in relation to the two sprockets. one washer under the clamping nut would keep everything aligned
Click to expand...
 
Dave F said:
Indeed, that's why I mentioned the potential need to machine down the spacer.
Anyway there is further news from here. I have successfully dismantled the sprag clutch unit (on the basis that all I need to run without the starter is the alternator rotor). I have finally found the cause of my grief - not the sprag clutch at all but the needle roller bearing that the sprocket runs on. This bearing has partially collapsed and has about 6 rollers out of line and a load of wear on the cage at that point. I suspect that this was what caused the key to shear before the final stoppage, and it was certainly the source of the heat that has blued up the sprocket centre. It also gave the impression that the sprocket and sprag outer race were "welded" together. I would happily post a pic but have yet to fathom out the instructions!! (I'll get there in the end)
I am very surprised as I would expect a needle roller bearing to last pretty much forever given that it carries no load for 99%+ of its life.
Click to expand...
Dave, I reckon your idea of using Belleville washers each side of the spacer could work. As you say you may need to remove a bit off the spacer, but that should be doable. These “Schnorr” safety washers (double sided serrated Belleville washers) look good and a 20mm version is only 1.8mm thick when tightened.

www.schnorr.com

Serrated Safety Washers | Schnorr Corporation

Learn about our serrated safety washers, common usages, materials and surfaces, tightening torques and more. Request a quote online!
www.schnorr.com www.schnorr.com
 
cliffa said:
Dave, I reckon your idea of using Belleville washers each side of the spacer could work. As you say you may need to remove a bit off the spacer, but that should be doable. These “Schnorr” safety washers (double sided serrated Belleville washers) look good and a 20mm version is only 1.8mm thick when tightened.

www.schnorr.com

Serrated Safety Washers | Schnorr Corporation

Learn about our serrated safety washers, common usages, materials and surfaces, tightening torques and more. Request a quote online!
www.schnorr.com www.schnorr.com
Click to expand...
Yes, I guess it all comes down to whether the axial load on plain steel faces (from torquing down the crankshaft nut) has better "holding power" than running it through the serrations of the washers. Certainly the plain steel faces will have a greater contact area. I'm inclined to try the Alton standard first but bump up the torque to 80 lb ft
 
Thought I should update on the "final" chapter. All new parts arrived from Alton and very carefully fitted. E.g. mating steel surfaces cleaned with Acetone before assembly, crankshaft honed and polished to be a good fit to the Alton sprag hub. I also took the crankshaft nut up to over 80 lb ft (I didn't quite get 85, so I'll stick with 82/83). I decided to go for "pure" Alton set up rather than one of the mods for now partly because I reckon that the force on the mating surfaces at 80 lb ft should be enough to hold against the starting torque. Now I'm "running in" very carefully given my experience with the needle roller bearing. I did add a washer but just the standard Norton part. Don't think it will grip as such but it certainly adds about 1mm to the clearance on the crankshaft thread shoulder. All being well that's it done!
 
joe czech said:
incorporating the "yves norton seeley" fix into my Mk2. my friend knocked out the spacer part in short order from 4140 tool steel. next step, machining the flats on the sprag clutch assembly, and finalizing the fix by transferring drive pins from the engine sprocket to the spacer. will post photos as progress continues...

View attachment 91544

hope to put an end to this "alton starter-sheared woodruff key' issue once and for all.
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I fitted the yves fix after the woodruff key sheared on the crankshaft of my Commando and all was good for 2 months UNTILL.....a screeching from the starter motor but it is not turning the cog with the cush drive. It is the the double gear that connects between the starter motor and the cush drive.
I can feel teeth missing from the cog that is deep in the recess were the cush drive slots into .

To be honest is have been an awful time with this starter motor kit. After a month of fitting the key on the end of the crank shaft that the sprag clutch fits onto sheared off and we had major difficulty removing the sprag clutch. We then had an engineer make us up the "YVES" fix as show on all the Norton forums and we fitted a new sprag clutch...all this at great expense.
Everything worked fine for 2 months and now this has happened and it looks like the whole lot will have to be removed again to hopefully repair the starter motor or gear cogs that go between the starter motor and the cush drive gear.

As said the starter is screeching but not turning the cush drive cog and I can feel bits of metal with my finger when you feel into the teeth of the cog that is connected to the starter motor. Has anyone had this problem AND CAN IT BE FIXED:(
 
Peter Waller said:
I fitted the yves fix after the woodruff key sheared on the crankshaft of my Commando and all was good for 2 months UNTILL.....a screeching from the starter motor but it is not turning the cog with the cush drive. It is the the double gear that connects between the starter motor and the cush drive.
I can feel teeth missing from the cog that is deep in the recess were the cush drive slots into .

To be honest is have been an awful time with this starter motor kit. After a month of fitting the key on the end of the crank shaft that the sprag clutch fits onto sheared off and we had major difficulty removing the sprag clutch. We then had an engineer make us up the "YVES" fix as show on all the Norton forums and we fitted a new sprag clutch...all this at great expense.
Everything worked fine for 2 months and now this has happened and it looks like the whole lot will have to be removed again to hopefully repair the starter motor or gear cogs that go between the starter motor and the cush drive gear.

As said the starter is screeching but not turning the cush drive cog and I can feel bits of metal with my finger when you feel into the teeth of the cog that is connected to the starter motor. Has anyone had this problem AND CAN IT BE FIXED:(
Click to expand...
I have not had any trouble whatsoever with my Alton unit so I cant offer any input on the cause, but surely it can be repaired. For safety reasons, make sure you have disconnected the power lead on the starter before doing any gear inspections with your fingers (if you havent done so)
 
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