pancake generator

[ERIC BAYLISS]

Does any one know where I might be able to pick up a pancake generator from for a late Scott

[Jan Buchwald]

Didn’t Sunbeam use them too?

[BRIAN MARSHALL]

It was a Lucas MC45 dynamo on the Sunbeam S7 and S8, similar, but with different drive arrangement, to the ones fitted to the last (coil ignition) Shipley Scotts, and also on the early Birmingham Scotts. The later Birmingham Scotts had Miller electrics and an alternator, which was a much slimmer device than the dynamo. The method of mounting on the Sunbeam is different to the typical Scott crankcase door and drive disc. I don’t know which type Eric is referring to.
Brian

[ERIC BAYLISS]

Hi Brian its the slim line one Im after.as fitted to late Scotts and Silk Scotts

[andy rowett]

Hello Eric,
I am just attempting to run an AC generator inside the MC45, it means gutting the original and fitting a small AC generator and reg/rec, if it works, it should give excellent electrics, and still look original. Whatch this space.

[Stan Thomas]

The generator used on the Sunbeam S8 and S7 is not the same as late Shipley/Birmingham Scotts (only the yoke and field windings) as the armature on the Sunbeam is different as it attaches direct to the crank. Apparently, Scotts provided the end castings to Joe Lucas to build the dynamos, as it states “Scott part” in their catalogue.

[Stan Thomas]

Hi Eric. Just re-read your post. When you say the “slim-line” generator, are you referring to the A.C. generator which superceded the D.C. “pancake” dynamo?

If so, this was made by Miller, only fitted to Birmingham Scotts from about early 1958.

Now you have a choice!! – The A.C. generator is electrically the better instrument, but the internal magnetic reluctance makes them very noisy in operation at low speeds, whilst the dynamo runs smoother producing about 70/80watts. The best set-up is probably the pancake dynamo with an 12volt electronic regulator, requiring only a change of coil and bulbs.

[BRIAN MARSHALL]

The late Roger Wheeler found a way of quietening the Miller alternator, which at very low speeds, even at kickstart operating speed, can sound like a broken crank ! He just put a nylon (?) sleeve on the crankpin screw drive spigot, and enlarged the slot in the drive disc to accommodate it. This stops the terrible clack-clack noise, as it stops the metal-to-metal contact.
I doubt that the MC45 dynamo produced anywhere near 70/80 watts. Perhaps 45 to 50 watts, on a good day with a following wind! Perhaps that is why they called it the MC45 …..?
Brian

[ERIC BAYLISS]

Yes its the AC one I am after, if nothing turns up ,probably end up making one. if I can get small enough windings, most Lucas type seam to be about five inches across witch is rather to big.

[richard rawson]

you can get the wassell windings and magnet to fit the pancake alternator I got one last year from a man in southend area
you have to machine the woodruff key as the new magnet slit opening is not as wide as the lucas one on the shaft
I think it cost around £120 for the winding and magnet if you want I could try to find his mame and address

[Stan Thomas]

The “45” in M45 is the Lucas reference to the diameter of the dynamo. Output is dependant (among other things) upon the air gap between armature and pole pieces. Correctly set, the dynamo will produce 70 watts at 3000 rev/min on Lucas’s original test-rig. Mine did.

Stan Thomas.

[dave bushell]

Hi Stan
Your MC45L dynamo performed just as it should. According to the Lucas “Service Notes and Test Data” the dynamo should have an output of 10 amps at 1,250-1,400 rpm at 7.0 dynamo volts taken on a 0.7 ohm resistance load without regulator.
Dave

[ERIC BAYLISS]

Hi lads thanks for the imfo, on output unfortunately it does not help me to find one.

[dave bushell]

Hi Eric
I may be able to help out with about 90% of what you want. I have the casing (inner and outer), rotor and stator, but no shaft/drive-disk or bearings.
I will need to check out whether the stator coils are ok.
Dave

[BRIAN MARSHALL]

Quoting Lucas figures for dynamo output “WITHOUT REGULATOR” are surely irrelevant, as on the bike the dynamo’s output is always controlled and affected by the regulator ! Typically these cut in when the dynamo output voltage rises to about 6.3 to 6.5 volts, and at that voltage the amperage is around 7 to 8 amps. Wattage=Volts X Amps, and 6.4 X 8 equals 52 Watts, a little of that then being used by the regulator itself.
Lucas may have quoted “10 amps at 7 dynamo volts at 1250-1400 rpm, without regulator”, but the regulator, if working properly, would not let that happen, because it operates at 6.3 to 6.5 volts remember.
As I commented previously, “About 50 Watts on a good day, with a following wind”. Blame the regulator or the dynamo, but the answer is still the same…
Brian

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