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Commando alternator

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Commando alternator

Posted by steve_elston at August 01. 2014

Hi all

Could someone give me some advice regarding the maximum possible air gap between the stator and rotor.I recently replaced the stator and set it up with a plastic shimming around the rotor ,008" thick all seemed fine.

stripped the primary drive this morning, only to find it had started to melt the plastic compound used to seal the windings

I've checked the stator via the two green/yellow wires and have continuity between both wires and no reading from either wire to earth so I don't the stators shot

I've yanked on the crankshaft and can find no great amount of play,so I don't believe the drive side main is shot.

As I understand it by increasing the clearance the charge level will decrease,I'm looking at maybe .015" after cleaning up both parts on a lathe,and hope the drop in charge will be negligible

I'll let you know

steve

Re: Commando alternator

Posted by michael_sullivan at August 01. 2014

Steve:

Are there any indications that the rotor is rubbing on the inside of the stator?  If not, where is the heat being generated from? 

Maybe one of the electrical gurus will tell us if the running clearance makes a difference in the heat generated. 

Mike

Re: commando alternator

Posted by Gordon Johnston at August 01. 2014

If there is no rubbing contact your stator should not be getting so hot. Does your bike have a belt primary drive? It is just possible that the lack of oil splashing around to spread any heat produced may account for the problem. Seems unlikely though. A short circuit somewhere leading to heavy currents  is another possibility.   

Re: Commando alternator

Posted by Neil Wyatt at August 01. 2014

Is there any play?  Are all the screws etc holding the charging systen together, tight?  Many years ago I forgot to use star washers and one of the screws actually dropped out.  When I came to  change the primary chain oil I found bits of plastic in the bottom of the chaincase. So, alignment might be an issue in this case.

I don't think you can go wrong with the Lucas stators and rotas, even the pattern ones. You select the one that goes with the other.  Only I could get it wrong, using a Wipac rotor with my Lucas stator and of course the air gap was so big that you had to rev quite high to get a charge.

Re: Commando alternator

Posted by steve_elston at August 04. 2014

 Hi all

spun the stator up in a lathe/ bore size now 75.5 mm so roughly a sixteenth of clearance on the rotor which when new was 74mm. cleaned up the rotor with emery cloth and file

Re-assembled both using plastic drinks bottle cut in a strip and wrapped around rotor to ensure clearance all around. kicked her over a couple of times the plastic shimming didn't move .so even if the rotor was running slightly eccentric I know it won't touch the stator

Fired the bike up 14.45 volts at battery doing 3000rpm, slight dip to 13.8 when switching on headlight returning to 14.45, so I think I got away with it

The only conclusion I can come up with is I may have missed some crap when I changed the stator last year, lodged in the chain maybe getting trapped between stator/rotor and started a snowball effect, because the stuff on the rotor was a plastic residue

steve

Re: Commando alternator

Posted by nick_fowler at February 23. 2017

Hi Steve

Just pulled cover off to check my belt drive on my M50 I have found the same problem stator  seems to have over heated and melted it was new with the rota about 500 miles ago. Set up with spacers and has no sign of metal to metal contact even had a coat of black plastic on the rota are was full of black plastic the hole thing is destroyed cracker and pieces breaking apart. At first I thought it was the belt breaking up but the belt was unscathed.

Still have no idea what has caused it to over heat was still showing a charge.



Re: Commando alternator

Posted by john_holmes at February 23. 2017

I have seen this on 2 Wassell stators, even with the recommended gap all the way round and with the crank rotated so checks were in several positions the stators still overheated in one spot. As Wassell now own the rights to use Lucas and so all the latest ones in Green Lucas boxes are Wassell (does anyone know any different ?) the only alternator you can rely on is a pattern part made by LAP in England on the original Lucas tooling. A very perverse result, the branded product is a pattern part and the unbranded is made on the original tooling.

The LAP version can be found hidden away saying non Lucas but made in England. Cost is £5 to £10 more than the Wassell/Lucas version.

Re: Commando alternator

Posted by robert_tuck at February 23. 2017

Beginning to feel glad I ignored the usual advice and kept my 47 year old alternator.

Re: Commando alternator

Posted by boo_cock at February 23. 2017

I read an article recently on the pitfalls of chinese made Lucas alternators. It seems they have a nasty habit of doing that. I may have read it in the Roadholder, not too sure.

So Wassel, if you are reading this, get your act togeather  and produce quality parts.

Re: Commando alternator

Posted by boo_cock at February 23. 2017

I read an article recently on the pitfalls of chinese made Lucas alternators. It seems they have a nasty habit of doing that. I may have read it in the Roadholder, not too sure.

So Wassel, if you are reading this, get your act togeather  and produce quality parts.

Re: Commando alternator

Posted by ian_goodhall at February 23. 2017

I have no experience of the Wassal ones but have heard of a couple of Electrax (I think that's how you spell it) alternator stators self destructing by all the insulation melting. Could be that they are made in the same place of course.

 

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