G12 650 CSR Alternator

flyingdogboy · Post by **flyingdogboy** » Tue Aug 10, 2010 2:21 pm

I recently fitted a Lucas alternator to a lightweight for a customer and that to was a tight fit. I cleaned some of the encapsulation material with a rotary burr and it fitted fine. The encapsulation is pretty thick material.

Don Madden · Post by **Don Madden** » Tue Aug 10, 2010 5:50 pm

I would prefer not to machine the case as it locates the stator & the next replacement may be the correct size. Also the stator is the faulty part, not the case. Precision location is vital for the rotor to run true within the stator without excessive clearance, which will greatly decrease output, (inverse square law-double the clearance yeilds 1/4 induced current). This means that the reason the rotor seems to large must also be determined. Cheers, Don.

Malleon · Post by **Malleon** » Wed Aug 11, 2010 12:07 am

Thanks, Geoffrey and Don,
The new rotor is not too large to fit the stator, but clearance is minimal.
I was hoping to avoid having to make a wooden pattern rotor for centralising the stator, but this would seem to be the most accurate method without removing any material.
Thanks again.

wilko · Post by **wilko** » Wed Aug 11, 2010 1:00 am

I've skimmed rotors in the past with no ill effects.

Don Madden · Post by **Don Madden** » Wed Aug 11, 2010 3:28 am

If all the parts are correct, it should not be necessary to centralize the rotor/stator. The rotor is a close fit on the crankshaft, the stator a close fit in the outer case which has the solid dowel & the center stud or bolt to align the the back half. The back half has a spigot that is a close fit into the crankcase. It is best to find out where any errors lie & correct them to prevent future complications. As I recall from measuring them the rotor/stator cleance is about 0.050in. Any skimming that increases the clearance will reduce the marginal output of the original design but should not harm the rotor nor its' magnetism. Cheers, Don.

Ib-Denmark · Post by **Ib-Denmark** » Wed Aug 11, 2010 3:36 pm

quote:
Thanks, Geoffrey and Don,
The new rotor is not too large to fit the stator, but clearance is minimal.
I was hoping to avoid having to make a wooden pattern rotor for centralising the stator, but this would seem to be the most accurate method without removing any material.
Thanks again.

Ib-Denmark · Post by **Ib-Denmark** » Wed Aug 11, 2010 3:37 pm

Hi
You defenately must make a dummy oversize rotor of aluminium or wood and then assemble to make sure the pins slide easy.
Just to be sure!

Regards
Ib
p.s. I use Sparx single phase (150W) in my G12 1965 and it has no problems.Edited by - Ib-Denmark on 11 Aug 2010 2:42:26 PM

wilko · Post by **wilko** » Wed Aug 11, 2010 9:58 pm

I just used engineering blue on my rotor to see if there was any contact and kept skimming the rotor until it was clear.This was a secondhand unit from a 250 triumph.

wilko · Post by **wilko** » Wed Aug 11, 2010 10:01 pm

I just used engineering blue on my rotor to see if there was any contact and kept skimming the rotor until it was clear.This was a secondhand unit from a 250 triumph.

Malleon · Post by **Malleon** » Thu Aug 12, 2010 12:47 am

Thank you all, gents.,
I will try to change the rotor if my supplier has an alternative which has clearance as per Don's recommendation.