Replace Alternator Rotor??

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What do you think what should be the difference between rotor OD to stator ID?

Excellent feedback.
I have 0.009"/0.010" clearance and based on your post will machine a mandrel to reduce the new Lucas rotor to something more suitable for piece of mind.
At least double what I have now.
 
I had a rotor rub even at a measured 10 thou gap.

I now turn the rotor down to ensure a 20 thou gap ie 40 thou undersize and have no rubbing, and no noticeable downside in terms of charging etc.
 
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Hello everybody,

i rebuild my engine this winter.
(BTW: many thanks Jim S.! I am so happy with yours parts! My Norton runs wonderfully and is a pleasure to ride!)
I fitted also a new Lucas RM24 stator – because the wires of my old Sparx were looking unhealthy where they come out of the bakelite….
When i put the new on I controlled several times in several crankshaft positions (turning engine and controlled again) the stator – rotor – gap : of course!
Gap was less then with the Sparx – but in the specs given by Lucas.
First start……engine runs several minutes without driving: no problems
First testride and inspection of engine and primary – no problems
Second testride this friday: Stator cracked and damaged.

Same happened to a friend of mine with his Commando and a new Lucas stator 2 years ago…

Next: I made a total rebuild of a 1962 T100ss Tiger the last months.
Same procedure as I always do with recontioned or new engines:
First start: engine running without driving – no problems
First testride: no problem
Second testride: stator cracked and damaged

Measured ID of both new Lucas RM24: hardly 75mm (some 74.8mm)
Me thinking this is too less!!!
Sparx got 76mm ID and non problems the last 10 years……..with many many kilometers of hard riding in hot and cold climates

What do you think what should be the difference between rotor OD to stator ID?
What would be the maximum difference so that the power output is not influenced in a bad way….?

Difference between Sparx stator to rotor is 2mm and works fine………I think this is the minimum gap that works....

Too many recent stories about cracked or melted Lucas stators. These aren't always from rubbing.
 
Too many recent stories about cracked or melted Lucas stators. These aren't always from rubbing.

I dug out my 47 year old 850 stator and rotor (which have no rub marks)

The new Lucas stator to rotor clearance 0.010"

Old parts 0.020" (Rotor around 73.8 mm OD - Stator around 74.7/8 mm ID or a 1 mm / 0.040" difference.

The new rotor will be taking a spin in the lathe for sure based on that to match or better what the old parts had.

Edit.
I measured the new Lucas rotor at the same OD as all the old ones I have so any variance seems to be in the stator ID which seems odd being a contemporary but still Lucas part.
 
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Yesterday I received 2 new stators from a local dealer here in Austria. 2 x RM24 produced from LAP. I describe the differences I noticed between "Lucas" (which is Wassel me thinking), Sparx and LAP stators: smallest ID has got Lucas. Sparx got bit more, aswell LAP. Sparx and LAP diameter gap overall between stator and rotor (measured on the workbench with feeler gauge) is 0.9mm. ......divide in 2 = 0.45mm gap installed! Lucas: 0.6mm diameter gap. The Lucas and Sparx look like mass products....all the same appearing...clean, exact - just good looking..... "professional". the LAP has the appearance from an old product and comes packed in a simple cardboard box without fancy schnickischnacki (saying in german) and the stator is wrapped in some oilpaper .. the bakelite forming looks like and is imo handmade. there are also handscratched notes on it....type of stator and week of production. One Stator to the other doesn`t look the same looking at the bakelit forming. the main difference between Lucas and LAP (ignoring appearance, marketing, ID and preferring craftsmanship over industry) is: the Lucas transformer plates (inside - facing to the rotor...) is flush with the bakelite. The LAP transformer plates aren`t flush - they stick a bit (est. 0.5-1.0mm) out of the bakelit. in my technical understanding - an very important fact! conclusion: LAP is handmade, man controlled, well packed, more ID clearance, transformer plates and bakelit design inside.......overall a product I like and imo: that`s the real Mc Coy!
 
"I think the catch is (based on plenty of OEM parts still working fine) are the modern replacements (only time will tell) as good as those decades old parts."


Every repair I make, this is always a consideration.
 
Yesterday I received 2 new stators from a local dealer here in Austria. 2 x RM24 produced from LAP. I describe the differences I noticed between "Lucas" (which is Wassel me thinking), Sparx and LAP stators: smallest ID has got Lucas. Sparx got bit more, aswell LAP. Sparx and LAP diameter gap overall between stator and rotor (measured on the workbench with feeler gauge) is 0.9mm. ......divide in 2 = 0.45mm gap installed! Lucas: 0.6mm diameter gap. The Lucas and Sparx look like mass products....all the same appearing...clean, exact - just good looking..... "professional". the LAP has the appearance from an old product and comes packed in a simple cardboard box without fancy schnickischnacki (saying in german) and the stator is wrapped in some oilpaper .. the bakelite forming looks like and is imo handmade. there are also handscratched notes on it....type of stator and week of production. One Stator to the other doesn`t look the same looking at the bakelit forming. the main difference between Lucas and LAP (ignoring appearance, marketing, ID and preferring craftsmanship over industry) is: the Lucas transformer plates (inside - facing to the rotor...) is flush with the bakelite. The LAP transformer plates aren`t flush - they stick a bit (est. 0.5-1.0mm) out of the bakelit. in my technical understanding - an very important fact! conclusion: LAP is handmade, man controlled, well packed, more ID clearance, transformer plates and bakelit design inside.......overall a product I like and imo: that`s the real Mc Coy!
Chris Zet. I hope your right!. My experience when the lucas encapsulation changed from the hard honey yellow material to the softer green material was,nt good. The earlier honey coloured stators were much more robust apart from the usual frying of the output wires after a reasonable mileage. When the encapsulation changed to the green material, it would crack in quick time. The first green stator I fitted cracked and was replaced 2/11/2017 and I have cracked 4 more up to the present date. None of the stators stopped working but I did,nt want the encapsulation caught between the primary chain and engine/clutch sprockets. This was on a 1970 Fastback, standard 2 wire alternator, Boyer power box and Motobatt gel battery. Mileage covered from 2/11/2017 to now was 28,000 miles. Every engine oil change (3000 mile), I would inspect the primary assembly and have a new stator ready to fit if the old one was cracked. I have an LAP stator as the next replacement.
 
As previously stated on several posts that i am in the final stages of a Mk3 rebuild, I am very disappointed on what is currently offered as OE or what is advertised as replacement parts for my current rebuild for this thread I purchased the correct p/n Lucas/wassell ignition switch, of the 4 positions- ACC off ignition, ignition/lights- you could not remove your key in the ACC position, there was no detent between Ignition and lights. And to top it off I brought a Genuine Lucas Flasher relay in a red box- after fitting a dummy battery and change in relay off ag the wattage in my Lucas indicators from 23- 21 watt they flashed normally once then sped up, I managed to borrow a factory relay from a friend with a low millage 850 which proved that the relay was faulty, I contacted my supplier who appeared to know of the problem and advised that Lucas/wassell stated that 20 watt bulbs were required, a credit was offered and accepted.
 
I am over using wassell CRAP
Me too. I'll use only as a last resort. Its got to the stage where I now specify with sellers that I do not want wassel crap. Its particularly bad with Triumph spares, and there's just no justification for them as LF Harris parts are generally top drawer.

I had a brand new wassel T140 primary chain tensioner fail a while back. It's not an expensive part but wassel chose to use the wrong material. Just how much did they save by making something unfit for purpose vs making it correctly?! They then flood the market with these things causing countless failures for years to come !

It jus' ain't right !!
 
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A quote, attributed to John Ruskin

"There is scarcely anything in the world that some man cannot make a little worse, and sell a little more cheaply. The person who buys on price alone is this man's lawful prey."

 
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