The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: limeyrob on 23.11. 2023 22:20
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My bitza came with several mags (K2F) in various states of repair. The best looking one produces no spark but one of the spares is a cracker, easy 1/4" just hand turning. Unfortunately the drive gear is at an angle and it looks like the input shaft is bent. Obviously I can strip them all down and build one good one - probably. But why do the obvious? I'm thinking I could put an old gear on, then lever the gear to straighten it up. I've got a dial gauge. I suspect it got bent by levering so doing the reverse makes (some) sense and this way I keep all the parts that make the great spark together.
10 reasons why this is very bad plan.........
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Be careful.
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To endorse Julian's picture, there is not a lot holding the steel taper to the brass armature end cap. This is an ideal time to strip the armature, (straightforward but requiring wires to be unsoldered and a fair bit of care) and substitute/mix'n match the best bits from your stash. Discard the Joe Lucas condenser and move into the modern EasyCap solution. The taper can be drilled and tapped from the backside and bolted on to improve its fixing to the armature end cap....without the original condenser there is room for the bolt head.
On reassembly the armature needs to be set up to run true, the caps are dowelled and final tightening of the through bolts along with a tap in the right direction is usually all they need.
Purists may loudly protest, but that's what I'd do.
Skinflint Swarfy.
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Many thanks, that picture says it all. So its quite possible there's a crack in the end. I like the idea of drilling and fixing through, that offers a realistic repair.
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I like the idea of drilling and fixing through, that offers a realistic repair.
It does offer a realistic repair.
I've usually drilled and tapped 5/16 Cycle or UNF up the blunt end of the taper, and made screws with oversize shallow-depth heads from hex bar to get max contact area inside the mag. Plus plenty of loctite. A wide hex also gives the option for an extra-security dowel into the brass through the head.
One could debate whether a left hand thread would be preferable on an anti-clock mag . . .
The ones that seem to break more often are the earlier ones (mostly pre-'52-ish) with the 15mm drive end shaft, and the ones of those I've dealt with had (most of if not all) been supporting the load of an ATD.
Repair is preferable, imho, to mixing and matching armature parts (plan of last resort!), as that can be a minefield in terms of the dowelling Swarfy mentions, and for general 'truth'. Each one is a tiny bit different in the land of Lucas . . .
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Yes, I'd like to get the bent one straight as the spark is so good. I could mix and match and never end up with a decent one as there are so may combinations once I go down that path and there's probably only one that works. :!