The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Rien on 19.03. 2026 09:40
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Hi all, see the pics. I've several Lucas ATD 47503, also one with a steel gear, 44 teeth, width of the gear is about 13.45mm.
I wanna sell it to a guy who is interested: can anyone tell what the value of this one is?
And can I (or he) change the gear into a fiber one? Thanks in advance.
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G'day Rien.
Very hard to put a price on it but a new one is advertised here https://tinyurl.com/239v49j8
Cheers
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As Musky says. With VAT/TVA well over £300.
But a reference point that is much more sensible would be Andrew at Priory Magnetos once again. Where a rebuilt unit can be had for £120 when available, or a unit can be reconditioned for round about the same, and tired units are taken in at up to £40 in part exchange. Fibre or alloy pinions available, fibre recommended by him. (Silent running, potentially sacrificial in event of a lock-up, etc).
In the past, I've regarded usable but not reconditioned units as worth between 50€ and 80€, or up to 110€-ish (tops) if I've fitted a new fibre gear.
Whether there is any premium attached to a steel gear (sold attached or sold separately), I doubt. And yes, it can be swapped for a fibre one, but need to check that the big circular shim that goes between the pinion and the mechanism is there, as it might have been omitted with a metal gear fitted.
Can't see a lot out there on e-bay etc at the moment (except some replica parts from the usual suspects), but haven't looked too hard. There was one yesterday at around £75 from memory.
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Hi Musky and Bill, thanks for the explanation and information! Next step following...
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. (Silent running, potentially sacrificial in event of a lock-up, etc).
That's interesting, and diametrically opposite in the world of Velocette, where fibre pinions are definitely considered to be no-no's due to their ability to shed tooth/teeth and block oil ways, leading to an engine strip and clean at best and an engine rebuild at worst.
I have a good condition ATD with a fibre gear, and no takers at 40 quid. *conf*
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velos have loads more teeth to wear and shred , i will now open the bar *beer*
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Oddly, I too have one of the steel gear type, also not on a bike. My fiber type probably came with the bike 71 years ago and is, so far *bash* (knock wood?), doing fine.
Richard L.
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. (Silent running, potentially sacrificial in event of a lock-up, etc).
That's interesting, and diametrically opposite in the world of Velocette, where fibre pinions are definitely considered to be no-no's due to their ability to shed tooth/teeth and block oil ways, leading to an engine strip and clean at best and an engine rebuild at worst.
I have a good condition ATD with a fibre gear, and no takers at 40 quid. *conf*
That's why my Velo now has a steel gear.
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Maybe because Velos use very fine pitched timing gear teeth.
My velo problem was the auto-advance steel gear splitting (the hole for the spring weakens the taper). Given that and the lack of any performance parts (cams etc) made me change to BSA.
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As an AMC and Norton person in the vertical twin department these days Rex, I have no problem with steel drive gears or sprockets myself. No choice, and no ATD option (nor the space) on the AMC twins anyway.
But silent and sacrrificial is what folk say ref A10s, 7s, Tri-hards, Vincents and Velos etc etc. BTH took the same approach as Lucas, all straight-toothed bar the Velos, and all susceptible to stripping as we know.
Regardless of that I ran an alloy one for quite a while on my own A, after a toothless and inconvenient failure to proceed in the middle of nowhere.
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. (Silent running, potentially sacrificial in event of a lock-up, etc).
That's interesting, and diametrically opposite in the world of Velocette, where fibre pinions are definitely considered to be no-no's due to their ability to shed tooth/teeth
Not just on Velocettes. Same built-in breakdown on the various makes that used Tufnol pinions.
Fibre gears fail in service far more often than magnetos “lock-up, etc.”
Silent running! *smile* ;)
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Given that and the lack of any performance parts (cams etc) made me change to BSA.
Understandable. The difficulty there is attempting to tune an already tuned engine.
The parallel would be trying to find high performance additions for an E Type, as opposed to tuning up a Morris Minor.
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My MSS goes better then my B31. Good enough for me!
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My MSS goes better then my B31. Good enough for me!
Most excellent machine, indeed so. How does it compare to a B33 I wonder, just to be fair on the cubes front?
(Apropos 'tuning the tuned', there's actually rather a lot one can do to an E Type . . . . triple Webers, upgraded head and cams, exhausts, 5 speed box, cooling system mods, suspension braking and wheel upgrades etc. Did a fair bit of that in my 40s - must have been barking mad - but sanely back to motorcycles and the camaraderie of their owners 'cos the air of the classic automobilist is too rarefied for me. And large car engines & transmissions are b****y hard to handle single-handedly as we get a bit older.)
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MSS would kill a B33, A Venom even more so.
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Sure would, but to be fair those two bikes weren't aimed at the same market when they were new.
BSA would have never even dreamt of attempting to lap Montlhery at over a 100mph for 24 hours on a B33 way back then.
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So far, I've had three fibre gears shred and one ATD fall apart. This resulted in the Berg's rebuild as, despite my best efforts, I couldn't prevent some of those bits of fibre gear circulating round the engine and causing chaos. In the end, I bought a brand new ATD with fibre gear during the Berg's rebuild, and it's been fine since.
I'd have no problems with an alloy gear. As somone said, sudden maggie seize-ups seem extremely rare, and you would probably get some indication that the maggie was on the way out prior to it locking up completely.
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The MSS is quicker throughout. Change into top at 50 mph and cruise at 60-65. It will gallop along at 75 if you wish but I only do that if overtaking lesser modern machines. You notice the extra urge climbing long hills.
Handling is good, but then again swinging arm BSAs handle superbly too.
The BSA 4 gallon tank is much better than the 2 gallon Velo one. The B31 has managed 250m miles on a tankful. On the Velo I start to get mild panic after 100 miles. The Velo stepped seat is more comfortable. Both have E3L dynamos and 6v halogen headlights.
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Yes the Velo is designed to rev, whereas the b33 is more of a low down 'plonker' isn't it. Fellers new to Velos sometimes 'under-rev' them, which the big end doesn't really like too much of.
And the beauty of Velos is that this MSS is easily turned into a faster Venom, or Clubman, -just the cam, a higher comp piston and maybe carb change will give you something that'll get close to 100mph, maybe change the front sprocket (a 10 minute job because it's outside of that infamous clutch).
(The later 4 1/4 gallon tank gives much better range, and it's dead handsome too).
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There was a Velo press release often reprinted on the Net and the Velo club where Veloce said that there had been complaints that the Venom was actually slower than the MSS, so they recommended that to get the best out of the Venom it needed to be revv'ed hard.
It wasn't a big single "get it into top gear and sit there" plodder and shouldn't be used like that, they said.
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There was a Velo press release often reprinted on the Net and the Velo club where Veloce said that there had been complaints that the Venom was actually slower than the MSS, so they recommended that to get the best out of the Venom it needed to be revv'ed hard.
It wasn't a big single "get it into top gear and sit there" plodder and shouldn't be used like that, they said.
Which is a reminder to us all, that attempts at performance tuning can easily get you less of a bike than you had before, because you lose flexibility.