Alternator problems

[ChrisB]

I've asked in another, very old thread but thought i'd start a new one as well as this seems to be a common problem.

Just trying to get a motor running which has stood for 10 years since apparently being rebuilt. Problem traced to the alternator rotor which, when i take the outer cover off, spins up nicely yet doesn't spin up when all together.
Suspecting crash damage to the end of the crank, i've measured the out of round right at the end of the taper on the crank to 0.13mm, and 0.03 at the bearing surface of the starter clutch.

The tapers are in a pretty rough state with the woodruff key deformed (notched to one side slightly)

If anyone can suggest an easier/cheaper fix than splitting the engine to have the crankshaft replaced or fixed and buying a new rotor i'm all ears!

How much clearance does the rotor/commutator need to still work as i thought maybe a slightly smaller rotor might get me out of the do do.

Thanks guys.

[z1bman]

is the rotor touching the stator?

[ChrisB]

yes, it must be. I can turn the crank over with a socket on the points end with the generator cover in place but it won't turn on the starter motor. With the cover and stator off, the engine spins easily on the starter button.
Rotor does appear to have a slight wobble but could be due to the irregular shape of the outer surface.
This was why i was thinking there may be a slightly smaller rotor or maybe i could turn it down by 0.5mm without knackering it?!

[z1bman]

when you say you can turn it over with a socket does it turn freely? have you removed the plugs so you can feel if its catching the stator? does the large starter gear turn freely ?

[ChrisB]

yes, the plugs are out and when turned it definitely has resistance in parts of the arc, as though turning past a compression stroke, or the magnets are working in phases. (Lumpy but doesn't sound particularly metallic)
The starter clutch is nice and free and seems in good condition.

[z1bman]

have you removed the starter clutch from the rotor to make sure the core of the rotor has not become detached from the aluminium

[ChrisB]

yes, it's all complete. Had the large starter clutch gear off on the bench ehile trying to give the rotor/crank taper a bit of a lap. The clutch works smoothly too. Everything looks ok apart from the tapers both look rough. Lapping is helped a bit but i haven't got the crank taper completely smooth yet.

[z1bman]

have you removed this as well


http://www.ebay.co.uk/itm/CMS-Starter-C ... Sw-0xYkU02

[ChrisB]

yes, that all looks good, locks up immediately, spins freely.

[1962royp]

I once had this with my A2 the roller bearing was shot in the clutch basket so when i went to set off it locked up the clutch fitted a new roller bearing its not this is it.This fixed it.