second alton starter failure - WTF?

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i'm really bummed out here. i may have sheared the alton starter, rotor-clutch, woodruff key for a second time - this time after 200 miles. first time, i gave them the benefit of doubt that i may have not installed the kit properly. second time, i installed it by the FRIGGIN' book. i pulled the primary cover to check the retaining nut torque and saw, by paint marks, the rotor-clutch it had shifted by about 60°. problem is when the key is sheared, it makes it near impossible to get the starter clutch/rotor out without some sort of damage. i viewed a fix by member "yves norton seeley" and going to get with my machinist friend, hopefully to end this nonsense. just wondering if the keys are not sufficiently hard for the application. i realize the clutch/rotor is held firm by the torque on the retaining nut and is not dependent on the woodruff key, but in reality, i think it somewhat is. if this mo-fo fails again, i'm going back to stock and sell the friggin thing as scrap metal! in a perfect world, the alton system may be a good design, but not sure about the real world. i'm somewhat worried about screwing up the crank end, to the point where i may have to tear into the engines bottom end for repair.
 

grandpaul

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The early Altons had numerous failures of the shear lugs, they were up-rated and that malady seems to have waned over time.

As you state "after 200 miles", it sounds like your bike doesn't get ridden a lot, so maybe you have some of the old lugs?
 
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Most car/motorcycle shops that sell spares have woodruff keys by the boxful in different sizes. Looks like uou might not be tighting the nut/ bolt enough while using washers as spacers to provide the necessary grip to stop it moving around the shaft.
 

phippsy

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I had the same problem , mine was caused by 45 years of loctite on the thread it would torque up to the correct poundage without gripping anything . Try the nut without rotor etc you might get lucky like I did
 
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Most car/motorcycle shops that sell spares have woodruff keys by the boxful in different sizes. Looks like uou might not be tighting the nut/ bolt enough while using washers as spacers to provide the necessary grip to stop it moving around the shaft.
The early Altons had numerous failures of the shear lugs, they were up-rated and that malady seems to have waned over time.

As you state "after 200 miles", it sounds like your bike doesn't get ridden a lot, so maybe you have some of the old lugs?
tightened the retaining nut to 70 ft.lbs. and a dab of thread locker. updated alton notes says 65 ft.lbs. w/ thread locker. as i said, fairly sure is was anal about things when i installed it the second time. bike gets ridden couple times a week. the new woodruff key came from old britts - i assuming it was a correct part. as i said, the stock OE key locates the stock lucas rotor. i think it's doing double duty with the alton assembly by locating the rotor/clutch and keeping the assembly from rotating on the crank. may need a hardened key. not sure what washer-spacers you are referring unless you're talking about the engine drive sprocket spacers - ???
 

cliffa

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I also used a pretty heavy duty Belleville washer on mine and it’s been ok so far.
 
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I take it yours is a straight shaft and not a taper?
Sorry, I have to ask, I've broke several of them.
 
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I take it yours is a straight shaft and not a taper?
Sorry, I have to ask, I've broke several of them.
yes, straight shaft - the tapered end (w/key) fits the engine sprocket - the straight end positions the rotor/clutch. the key is supposed to position and locate the rotor/clutch assembly and the nut is supposed to secure everything in position. even torqued to spec, i doubt the contact area of the nut is sufficient to keep the assembly from turning on the shaft. the "yves norton seeley" fix looks like a winner.
 
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The Alton relies on two methods of power transmission between the starter and the engine.



The major reliance is upon clamping force between Alton’s “sprag clutch rotor assembly” and the factory “crankshaft engine triplex sprocket”.

This necessity often gets overlooked, and it is not covered in detail in their otherwise excellent fitting instructions.

If the threaded part of the crankshaft is a little shorter, or the shoulder of the rotor nut a little taller, then this clamping force is not sufficient.

Of course, because the “sprag clutch rotor assembly” is mounted on the plain portion of the crankshaft and not the tapered part, the shaft itself cannot be used reliably for power transfer.



The fallback is power transfer through the woodruff key – absolutely not what it is designed to do, and not at all ideal by any means.

Woodruff key failure is mainly due to two things:

1) the material type of keys fitted (the universal kits available, often use lower cost carbon steel, instead of EN8 key steel)

2) shock loading – the instant torque, and explosive nature that a starter operates will give any woodruff key a hard time.
Plus if the clamping force is not sufficient (as covered above) the small amount of backlash can massively multiply the effect of shock loading.



I am impressed by Yves and the like who have applied a decent solution to the problem and have provisioned a better mechanical unison between these two components that is better suited to transmission of the high level of torque involved.
 

baz

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I take it yours is a straight shaft and not a taper?
Sorry, I have to ask, I've broke several of them.
If you have broken several of them on your Alton spag clutch maybe change to the Yves design and drive directly onto the threaded puller holes of the engine sprocket
Do you have a 750 or 850 or 920 etc ? High compression?
 
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baz

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The Alton relies on two methods of power transmission between the starter and the engine.



The major reliance is upon clamping force between Alton’s “sprag clutch rotor assembly” and the factory “crankshaft engine triplex sprocket”.

This necessity often gets overlooked, and it is not covered in detail in their otherwise excellent fitting instructions.

If the threaded part of the crankshaft is a little shorter, or the shoulder of the rotor nut a little taller, then this clamping force is not sufficient.

Of course, because the “sprag clutch rotor assembly” is mounted on the plain portion of the crankshaft and not the tapered part, the shaft itself cannot be used reliably for power transfer.



The fallback is power transfer through the woodruff key – absolutely not what it is designed to do, and not at all ideal by any means.

Woodruff key failure is mainly due to two things:

1) the material type of keys fitted (the universal kits available, often use lower cost carbon steel, instead of EN8 key steel)

2) shock loading – the instant torque, and explosive nature that a starter operates will give any woodruff key a hard time.
Plus if the clamping force is not sufficient (as covered above) the small amount of backlash can massively multiply the effect of shock loading.



I am impressed by Yves and the like who have applied a decent solution to the problem and have provisioned a better mechanical unison between these two components that is better suited to transmission of the high level of torque involved.
I purchased Yves setup from him
I wanted to use it with a norvil belt drive so I copied his drive adapter plate and made one to fit my drive pulley
I also incorparated the original Alton woodruff key
So mine drives at 3 points
It's over the top really but while I was in there I thought I'd do it
Cheers
 
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If you have broken several of them on your Alton spag clutch maybe change to the Yves design and drive directly onto the threaded puller holes of the engine sprocket
Do you have a 750 or 850 or 920 etc ? High compression?
850 - standard factory compression ratio, i did do a compression test a while back - 150/145, so a good healthy motor. compression is high - depending on there the crank is, compression will stop the alton starter dead in it's tracks. i've been dealing with this since i first got the bike.
 

Mart UK

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tightened the retaining nut to 70 ft.lbs. and a dab of thread locker. updated alton notes says 65 ft.lbs. w/ thread locker. as i said, fairly sure is was anal about things when i installed it the second time. bike gets ridden couple times a week. the new woodruff key came from old britts - i assuming it was a correct part. as i said, the stock OE key locates the stock lucas rotor. i think it's doing double duty with the alton assembly by locating the rotor/clutch and keeping the assembly from rotating on the crank. may need a hardened key. not sure what washer-spacers you are referring unless you're talking about the engine drive sprocket spacers - ???
Has your torque wrench calibration been checked? Just a thought.
 

baz

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850 - standard factory compression ratio, i did do a compression test a while back - 150/145, so a good healthy motor. compression is high - depending on there the crank is, compression will stop the alton starter dead in it's tracks. i've been dealing with this since i first got the bike.
Actually I was replying to Bernhard about him breaking his woodruff keys
But it's interesting you say the Alton struggles to turn over a stock compression 850!!
 
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Hmmm...I don't understand this. I've had an Alton E-start on my Commando since '12. Initially I had two rotor failures. Alton then redesigned it/sent me a new rotor. Since the installation of the redesigned rotor, the Alton has been trouble-free since early '13 - it spins the motor very rapidly almost as if there are no spark plugs in the motor and I have the same static compression that you referred to - 145-150.

Is it possible there is some problem with the starter motor itself or insufficient voltage to the motor? Maybe something binding in the mechanism? If it's having trouble spinning against compression, that would contribute to kickbacks. The Alton on my Commando spins the motor faster than the starters do on any of my modern bikes.

Have you done a voltage drop test when you engage the starter? That would be a definitive test for sufficient power available to the motor.
 

BERT

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There is not much compromise in a tapered fit coupling. If the taper is not spot on, it is useless. A key won't help much either, no matter what it is made of. I think Yves' solution is best, and I may go that route if I reinstall the Alton on this bike. Sorry about your luck Joe and thanks for sharing your issue with others for them to have a "heads up" and discussion about it.
 
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