Alton Makes Good...really fast!

'I checked Altons installation instructions and their correct rotor/stator gap is .016"

FWIW, the instructions that come with the kit state a gap of .4mm and plastic shim material for that dimension is supplied by Alton. If working in inches is more comfortable, then it seems close enough to call it .016"

These are pictures of the rotor and the sprag on the Alton starter







The outside of rotor is made out of aluminium. I haven't taken it apart, but it looks like the magnets are held in place in a steel and aluminium sandwitch. The magnets appear to be placed every 8.5(ish) mm apart with north and south poles alternating. The rotor is 107.5mm in diameter (4.233") The stator measures 108.7mm (4.279") so there should be 0.6mm (.024") of clearance all the way around. Can't explain your failure, but clearance if yours is the same as mine should not have been an issue unless the crank on the Norton flexes way more than anyone thinks.

Jean

If the magnets and retainer weigh 50 grams and it is swinging on a 50mm radius then the centrifugal force is going to be over 2000 lbs at 7000 rpm. Of course this is spread evenly around the circumference but that makes it easy to see how it could expand enough to make contact with the pole pieces if it is encased in aluminum. Jim.

If you pull the hex screws from the front of the rotor, the magnet assembly/retainer can be removed from the rotor. The stainless steel retainer itself is approx .24 mm thick. Of course, my magnet retainer removed itself for whatever reason. It was heard to measure because of the distortion caused when the retainer separated in the center of the circumference.

By design, it appears that a new magnet/retainer assembly could be bolted onto the rotor, assuming that just that portion is available. Of course, we would not like that to be necessary!

Norvil contacted me on the 27th and offered to put me in touch with Alton; I advised them it was not necessary. Les advised that this was only the second case of this he has heard of and indicated that since they had not done the install on the two cases, that it was likely due to a faulty installation. Though I don't agree with his assessment,I replied that whether correct or incorrect,I would probably have come to the same conclusion were I in his position. But it appears to me that if you have an issue with an Alton product, it's much quicker to go directly to Alton rather than from the seller - the seller is going to send you to Alton anyway.

I'd sure have a pow wow with Alton on the recommended red line in 850 size crank deflection. Only 850's I've read of playing in red zone and getting away with it are cheater racers w/o any chargers to worry with. Comstock's wonder 8850 is exceptional in many ways, one being its not got a vulnerable magnet snagging charger. With thermal expansion differences adhesives aren't up to it. I spent some years on the windmill sites seeing how they hold magnets down. Most their DIY alternators are flat plate affairs made out of automotive disc brakes so magnets face out flat like clock numbers that sweep past horizontal arranged coils. They are completely embedded in epoxy mainly under side shear stress not pulling directly away from their base. http://www.instructables.com/id/DIY-100 ... d-turbine/



Others adapt magnets on inner armature, this one looks like magnets soldered on but don't know w/o contacting vendor.
http://blondesearch.ru/play/eX166iDh8Fs ... WANDS.html


photo instructions of construction, for us that ain't involved.
http://www.norvilmotorcycle.co.uk/Start ... sembly.pdf

how it should behave at idle blip rpms
[video]http://www.youtube.com/watch?v=XlM90xBeZnw[/video]

That bike needs some work! Mine started instantly on the first Alton start !

There should be no issue with 7k rpm. The engine takes it and the Oem alternator takes it. So it's hard to believe that Alton designed a rotor that could not handle the stock engine's specs. As noted earlier, you would design an aftermarket item to take the oem rpm plus a healthy margin...there are such things as missed shifts, etc. the stock 850 engines don't come apart at 7000, aftermarket parts shouldn't either.

Personally, I'm confident this was an aberration - perhaps a bad retaining ring or something similar. I don't expect any issues at all from this point on as far as the starter is concerned!

850's don't come apart at 7000 but their crank ends could wobble enough to snag exposed magnets edges. I'll ask Alton about this if no one beats me too it.
I'm not really happy with Peel's over kill 600 watt 8-9 lb 3 wire alternator, in way to drive it and the space it takes up, so still have in back of mind to roll my own charger. Would be a double shame not to enjoy maxing out an 850 and second install comes apart because real fault is still a mystery. MIght pow wow with Alron to donate parts till its discovered if Alton or 850 Norton or throttler or all or em at fault.

Today we're driving up to San Miguel, where my Commando lives, and I'll be reinstalling the replacement parts that Paul (at Alton) shipped to me under warranty. I received them from France within 5 days of my first email and that was over Christmas! The Mexican Customs folks did charge me about 18 USD for duty but there was no delay at all and I was quite pleased.

I exchanged several emails with Paul and sent him hi-res pics of the rotor/sprag, the retainer, and the alternator coil assy. One thing that was obvious was that the center of the rotor/sprag had gotten very hot - areas of the metal had turned blue from the heat. Turned out that although I had ordered the chain drive kit, the kit supplied included a washer that is intended to be used for BELT drive commandos. The washer was installed on the rotor/sprag when I received it so I ASSUMED that it was supposed to be there on the bike. There was no mention of the washer in the instructions. Using the washer on a chain drive motor eliminates the clearance that is supposed to exist between the sprag and a spacer which fits between the sprag and the triplex gear on the crank.

The rotor/sprag-washer fit was tight enough to cause a lot of friction but not enough to actually lock the crankshaft/spacer/rotor which would have caused the engine to spin the starter motor once the engine was running. When I pulled the assembly apart, the washer was almost black from heat and the center of the sprag was the same.

I sent the pics to Paul and he responded immediately re that washer, stating that it is ONLY for use with a belt drive system and also expressing surprise that it was in that kit since I had ordered the chain drive kit from Norvil (only difference between the kits is the addition of that washer). He was also surprised that with the washer installed the starter didn't immediately lock up with the engine; I guess I was lucky it didn't! Paul now recommends that the sprag/rotor be installed and rotor nut torqued without the starter chain attached and checked for free/easy turning prior to final assembly. Had I done that, I would have discovered that there was insufficient clearance with that washer in place. I believe the instructions have now been updated to include that. I did check for free-movement of the sprag but I had not torqued the rotor nut to it's full value when I did that; it was tight but not fully tightened. That final tightening is what caused the interference with the washer.

Paul feels that the washer issue is what caused the problem due to the heat involved and subsequent expansion of the rotor which caused interference between the rotor/coil assembly. For the rotor/sprag to be as blue/black as it is around the center it looks to me like it would have had to become nearly red hot so the expansion/collision with the coils makes sense to me.

So...I'm confident that this will not repeat once I install the new sprag/rotor and new spacer WITHOUT that washer!

Again, I have nothing but praise for the way Paul and Beverley handled this.

Totally unrelated...I rode a new Triumph Daytona 675 R a couple of days ago. I guess we all need a second bike - I may have found it! It even has an electric starter ALREADY installed!

Well.......
I guess good news is that you found the issue and that it didn't permanently mess up your bike.
It is also good that the instructions have been updated (as well was their packaging procedures I hope)
to avoid this happening to anyone else.

Glad to hear you found the issue. I was kind of worrying about what had looked like a well designed product. Jim

I also sent an email to Norvil re packaging/instructions, etc I don't know if they package the Alton kits themselves or simply distribute them but I thought it would be helpful to ensure everyone involved is aware of the potential of using the belt-drive washer on a chain drive bike without clear instructions re the use of the washer. When I ordered from Norvil, their site showed two different kits for chain and belt. IMO, the boxes/instructions should have a bold label stating either belt drive or chain drive. This would ensure that if an incorrect kit was sent, the purchaser would see that immediately. If it is now a single kit that can be used on either engine, the instructions need to clearly explain the use of the washer.

I was concerned about related damage to other chaincase parts caused by the magnets flying all over the place but I checked the triplex chain and the starter chain/sprockets and didn't see any problems. But I'll do it again today more carefully before reinstalling. Hopefully I won't find something I didn't see in my first inspection...

"Glad to hear you found the issue. I was kind of worrying about what had looked like a well designed product."

Thanks Jim, me too!

Ugh Mike thanks for being the first one to discover the washer oversight. Btw them new age balloon tire wonders ain't all that well perfected yet either... Oh yeah start shopping for good rear tires ahead of time, which is a good problem.

http://www.advrider.com/forums/showthread.php?t=224158

http://www.triumph675.net/forum/showthread.php?t=33449

Here are a few pics that might help in visualizing my earlier post...

First is the rotor with the split retainer (I may have posted this one before). The magnets were all over the chaincase.


Next, the back side of the sprag with the large spacer on the left that fits between the sprag and crankshaft triplex gear. THe washer on the right is the washer in question that is for belt drive applications only. It was mounted (in the box) on the back side of the sprag and therefore between the sprag and the spacer, eliminating the very slight clearance that is supposed to exist between the sprag and the spacer. It's hard to see but the center area of the sprag is blackened from heat - this includes the bearings and sprag mating surface inside.


Last, the front side of the sprag/rotor note the localized heavy heat-discoloration on the front.

Glad you found a probable cause for it. Makes sense. So, are you gonna rev it up to 7000 first thing this time? Why not, right?

"Glad you found a probable cause for it. Makes sense. So, are you gonna rev it up to 7000 first thing this time? Why not, right?"

Darned good question! I have to admit I'm a little gun-shy and could quite correctly view it as "why bother, there's no power up there anyway." OTOH, I really would like to know and, as I said before, there is such a thing as missed shifts! It's a definite conundrum... I'll advise the group on whatever I end up doing, either way.

If it was me I'd have to do it.

You ex Dutch Army guys are hardcore!

mike996 said:

The washer was installed on the rotor/sprag when I received it so I ASSUMED that it was supposed to be there on the bike. There was no mention of the washer in the instructions. Using the washer on a chain drive motor eliminates the clearance that is supposed to exist between the sprag and a spacer which fits between the sprag and the triplex gear on the crank.

Click to expand...

MIke
Pleased to hear the cause is identified but I am now confused and a little worried. I have a belt drive kit and I have NOT fitted that washer, but all seems to work OK. If I remember correctly, I left it out because I already had to reduce the big spacer by 1.5mm to get the starter chain sprockets to align, so felt it was not required. Can you clarify what it is there for? As far as I remember the sprag will still rotate freely if it is clamped up tight to the big spacer, or have I got that wrong??
David

A quick update to my last post
I also emailed Alton and Paul Hamon replied within a few hours (another example of their excellent cusotmer care). He says:
"this washer should be used ONLY when the Alton Ekit is fitted on a NORVIL toothed belt primary drive kit.
We will record your remark about the Hayward kit and the modification of spacer item 8."

So that clears up my worry about this spacer. As I am using a Hayward belt drive the washer is not needed.

David - sounds like Paul sorted it out for you, that's great.

I completed the cleaning/inspection/installation of the new parts today and everything is working perfectly - yes, I did end up revving it to 7K with no issue!