Accuspark Dynamator No longer available

[Dennis Nicholas]

Didn't there used to be a conversion using a VW part?

[Bob Culver]

6v Beetle dyns have been adapted. Rotation is reversed so the brush location is not ideal but that trifle seems not to trouble users.

[Geoff Halstead]

Bob,
Wasn’t there some info that the beetle gen doesn’t produce the necessary at low rpm?

Geoff - Still no progress on the Ruby???

[Stuart Giles]

6v Beetle dyns have been adapted. Rotation is reversed so the brush location is not ideal but that trifle seems not to trouble users.

Bob,
Wasn’t there some info that the beetle gen doesn’t produce the necessary at low rpm?

I think that what Bob was referring to was that most people kept the Lucas brush orientation when they fitted the VW internals. The Lucas brushes point at the commutator centreline. the Bosch brushes on the one I converted are arranged to point past the centreline as in this diagram.



This "past the centreline" orientation needs to be maintained when the rotation is reversed, otherwise (from my experience) the charging performance wasn't good.

[Bob Culver]

When current flows the field twists, the basis of fixed load 3rd brush voltage control. There is an  optimum brush main axis for each output and least sparking (due volt difference between adjacent segments). The DEL dyn has an adj but requires more patience than I possess.
Early Beetles were common here (following great success in rugged around Australia rallies) and whilst upright had a better reputation than most small Brit cars.
Few elementay texts depict the 2 brush windings as shown and so can be a puzzle for amateurs (Each winding actually embraces the whole armature . Poor commutator connections can be easily found with the very low ohms range of digital multimeters.)

[Dennis Nicholas]

A 12/4 Riley dynamo is run direct off the front of the crankshaft and has the luxury of having the brushes mounted on a clamped ring.  My method of getting them in right position was to remove inspection cover and slightly loosen the brush ring then start car, hand throttle to max charge revs position then lie under front of car and gently prise ring around until zero or minimum sparking at brushes.  A bit startling to passers by if you do this in a convenient lay-by if out on a run and you see charging not quite right. 

Leaving brushes in wrong place will cause sparking and burning of the armature copper segments and destruction therefore of armature so do get it set up properly soonest.  Long time since I worked on A7 dynamo so can't remember set up.

Dennis.

[Geoff Halstead]

Thanks.

Geoff