Rotor stator problems

Iam trying to get an air gap from rotor to stator (10thou) . I seem to have a high spot on the inside of the stator , I have a piece of paper witch is (10thou) thick, which I can get around rotor/stator all bar 2inch piece , measured stator and it seams it is 30thou out of round on the High spot. Will it be ok to remove high spot with light file or light sand paper rotor seams ok(no movement on the centre boss) any Eli would be great . John. Norfolk. U.k

You need three shims /feeler gauges .010 tho thick inserted equally around the rotor before tightening up – if as you say you cannot do this then I would first take the rotor off and get it checked on a arbour between centres to make sure it does not run out of concentric, as the magnets maybe coming away from the inside.

I usually just dunt the stator studs ,never measured the stator as long as the air gap is to spec then it is good to go. There are some rough looking brand new ones out there right enough.

Jg

A great spacer is to cut the top off of a liter soda bottle and slip the bottom portion over the rotor. That way it's even all the way around and plastic being slippery is easy to remove once you get the stator cinched up.

To answer your question....

I would take the stator to an occilating spindle sander (Yes, I have one) and carefully grind off a bit of the stator (half from one side and the other half from the opposite side) that is out of true...

*****The reason I would do that, and risk ruining the stator, is because my bike was sold to me 40 years ago because of rotor/stator misalignment. The frustration of the bike's charging system failures prompted the previous owner to sell the bike to me. IF there's contact between the rotor/stator then they will both grind against each other and burn the windings up. (which is what happened to my bike prior to my purchasing it) IF the stator is so far out of round that it's air gap can't be adjusted properly, then it's crap anyway, you might as well try truing it up a bit, just be careful and don't take the entire amount off one side. IF you grind into the windings, the stator is toast... but I bet you could safely take a little bit off it. In a certain way, you have nothing to lose by trying because it's not usable if you can't get the required air gap anyway... good luck

measuring the maximum tolerance between the inner diameter of the stator and outer diameter of the rotor is a good starting point, this will tell you what you should reasonable expect by way of gap all around. You can "tweak" the mounting studs with a little heat and a length of pipe slipped over for leverage (make sure to protect the stud threads). A plastic or cardboard sleeve slipped over the rotor during installation is a good way to ensure even gap all around.

Bernhard said:

You need three shims /feeler gauges .010 tho thick inserted equally around the rotor before tightening up – if as you say you cannot do this then I would first take the rotor off and get it checked on a arbour between centres to make sure it does not run out of concentric, as the magnets maybe coming away from the inside.

Click to expand...

I use a business card to check the air gap. It is flexible enough to allow it to wrap around the rotor,

John in Texas

eskasteve said:

A great spacer is to cut the top off of a liter soda bottle and slip the bottom portion over the rotor. That way it's even all the way around and plastic being slippery is easy to remove once you get the stator cinched up.

Click to expand...

Beer can works well too. Whatever you do, make sure that you have enough clearance all the way around because bad things happen when you don't. Ask me how I know!

On second thought, I see you are in UK so UK beer cans may be too well made and too thick. You need an amerikan beer can. You know, the watery, tasteless stuff

Coors or Pabst. Porters are too thick. :shock:

Drink beer out of a can? Horrors!

American can culture vs. solid English as it should be. Don't forget to chuck the stoopid can out the car window after drinking it fast. What a world we live in. America.

I have a strip of plastic I cut out of a milk carton. I work that between the stator and the rotor before cinching up the stator. Sadly, this is the only bike I can do this to.

I chewed up two stators on my Ranger - no way to check the cap except trial and error - and a little Prussian Blue

o0norton0o said:

To answer your question....

I would take the stator to an occilating spindle sander (Yes, I have one) and carefully grind off a bit of the stator (half from one side and the other half from the opposite side) that is out of true...

Click to expand...

God knows how you get the stator to run concentric :!: :?: :shock:
I suggest you use a stator to check it is running concentric on a mandrel, on a lathe and if you need to skim-NOTE I said lightly skim it- run the lathe at its highest speed up to 6,000 rpm for2-3 minutes then check if the rotor magnets are coming away from the main body.
For a short period Lucas churned out stators that were not up to scratch of withstanding high revs.

lucas-alternator-rotors-t21334.html?hilit=Search%20tlucas%20rotors%20his%20forum…#p278563

Yes I think I will have a go with some emery cloth and see what happens. The tight spot is on one side only.and the stator Sean ok when clamped in a vice with 2 large nut each side of the centre boss. Like you say I have nothing to loose. What you think of emery cloth or small file to take down tight spot. John. Norfolk. Uk

John, I was the only one who answered the question you asked, probably because the odds are better that your stator is misaligned rather than actually not perfectly round as you claimed. If I was you, I would be certain that the stator is actually out of round before I tried to true it up. It's very common that stators are misaligned, so most of the answers to your post were alignment techniques, rather than methods to true your stator.

When I didn't have the inexpensive occilating spindle sander (pictured below)


I would put a sanding drum in a drill press (like the one pictured below) and use it to grind curved material. If you have good dexterity, it's easy to make accurate adjustments. IF you do have a drill press, a sanding drum will probably cost you $20. and will make short work of licking off 30 thousanths off your stator accurately.

Thanks for the reply, oonortonoo yes it seams to work by sanding down the stator. Once again. Thanks. John