Author Topic: 6" headlamp shell but lights are 5 3/4?  (Read 749 times)

Offline doughobbs

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6" headlamp shell but lights are 5 3/4?
« on: August 01, 2021, 07:16:16 PM »
Another day and another newbie question from me!
Can people advise if these
https://villiersservices.co.uk/index.php?main_page=product_info&cPath=21_22_34&products_id=1024
https://villiersservices.co.uk/index.php?main_page=product_info&cPath=21_22_34&products_id=748

....will fit this....
https://photos.app.goo.gl/4YG46Ww8L1bGVNJX9
https://photos.app.goo.gl/ceb51ZyrftomLXVB8

I'm struggling to be sure if what I'm looking for sale is a 6 inch headlight even though they show as 5 3/4! 🤔

Sorry if I'm being dim!

Offline R

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #1 on: August 01, 2021, 11:36:30 PM »
Thats a VERY valid question.

I recently bought some 7" rims, to fit common '7 inch' headlamp shells as used in the 1960s and 1970s.
Like your measurements above, no-where could a precise 7" measurement be observed. !!
They fitted perfectly, of course.

I think that means that rim will fit that shell and headlamp unit for you ....

P.S. Perhaps we should have begun by asking precisely what bike/year/model this was for.
No chance of wrongly assuming anything then ...
« Last Edit: August 01, 2021, 11:38:23 PM by R »

Offline doughobbs

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #2 on: August 02, 2021, 06:56:27 AM »
Perhaps we should have begun by asking precisely what bike/year/model this was for.
No chance of wrongly assuming anything then ...


It's a 1953 Sun challenger (plunger) 197cc. A far as I know its the original light shell. I didn't mention make /model as Sun info seems to be sparse at best!

Offline Rex

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #3 on: August 02, 2021, 08:33:38 AM »
Whatever size a Sun Challenger would need you can bet it's an industry standard size. There's no way a small company like Sun would have knocked out their own size of headlamp when there were ranges of lamps and styles available from Lucas etc.
Either take your shell to an autojumble to see what fits or search Ebay, find a likely candidate and ask the seller to measure exactly the shell-side dimension.

Offline john.k

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #4 on: August 02, 2021, 02:13:15 PM »
I believe lights are measured over the open part of the shell...a 6" lamp is going to be a DU42,the 7" of the late 40s is the DU 142

Offline R

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #5 on: August 03, 2021, 12:02:06 AM »
It's a 1953 Sun challenger (plunger) 197cc.

Aha. Can you turn your headlamp shell over, and find a Lucas number on it anyplace.
Does that tang shown on the Lucas rim have a suitable slot in your shell ?

I'd comment that a lotta Villiers powered beasties used Miller electrics.
My little Waratah/Excelsior, slightly earlier than your Sun, rigid frame, has a similar looking shell,
similar measurements. (no ammeter though). It has a Miller Lighthouse headlamp switch.
I've just been figuring out the connections.

Its got MILLER proudly emblazoned on the top of the rim.
https://i.postimg.cc/mDSbTYJb/Miller4.jpg

I would think that Villiers Services are THE most likely folks to have the right rim for you.
As long as its Lucas.
« Last Edit: August 03, 2021, 12:05:55 AM by R »

Offline R

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #6 on: August 03, 2021, 12:18:14 AM »
And, as a final quality control check (!), what does your shell have to lock the rim in place ?

There must be a dozen types of such, usually appearing at 6 o'clock (BDC).
Slot, hole, tang, rivet, etc ??

Offline doughobbs

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #7 on: August 03, 2021, 10:56:36 AM »
And, as a final quality control check (!), what does your shell have to lock the rim in place ?

There must be a dozen types of such, usually appearing at 6 o'clock (BDC).
Slot, hole, tang, rivet, etc ??

And, as a final quality control check (!), what does your shell have to lock the rim in place ?

There must be a dozen types of such, usually appearing at 6 o'clock (BDC).
Slot, hole, tang, rivet, etc ??

I'm afraid with the paint it too thick or there is nothing stamped on the shell - I had a good look around and couldn't see anything.

There is a box of bits that came with the bike though and there is a very similar (bit rusty at the moment!) 7 inch shell in there which is marked up as MU42 - I'm in a quandary now as I'm not sure what size shell is the correct one, guessing the smaller one (later battery equipped SUN's might have gone up a size)?

Offline Rex

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #8 on: August 03, 2021, 11:08:48 AM »
MU42 is the common type where the switch panel (inc ammeter) is mounted on top of the shell, and often seen on 1940s bikes. I wouldn't think this would have been original for a post-war lightweight though.

Offline doughobbs

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #9 on: August 03, 2021, 12:36:08 PM »
MU42 is the common type where the switch panel (inc ammeter) is mounted on top of the shell, and often seen on 1940s bikes. I wouldn't think this would have been original for a post-war lightweight though.

Both shells I have have the same fitting for the switch panel and ammeter so I could move them over - they are different in design though with regard to how the rim is held in place, the 6 inch one has a notch and also a hole at 12 O'clock, a slight flared section from about 4 to 7 O'clock, a cut out at 6 O'clock and another at 11 O'clock - I've tried to take some more pics of the shell that I think is the correct one (the smaller one).

https://photos.app.goo.gl/tk1XNbUCVN7kFMdQ6

https://photos.app.goo.gl/AeKwh62ux3ASoVsv6


The larger Lucas shell is clearly different in the rim design
https://photos.app.goo.gl/LjJU4ZxLg9CpZPMw7


Offline mini-me

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #10 on: August 03, 2021, 02:25:59 PM »
the lucas shell you are holding is for later reflectors, flat glass rims used a differents shell.

over-thinking  a problem only makes it worse.

Offline doughobbs

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #11 on: August 03, 2021, 03:03:25 PM »
well whaddaya know!
Kept digging about and this tipped up eBay which is the very same as mine!
https://www.ebay.com/itm/402997716340





Offline gambole1949

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #12 on: August 03, 2021, 08:22:17 PM »
Hiya Doug a while ago we purchased some rims for our Sun bikes and although it states on the box that they are 5 3/4 the actual size of the inner is 6 inches. hope this helps. I think it is because the lens is 5 3/4 I might be wrong.
« Last Edit: August 03, 2021, 08:25:53 PM by gambole1949 »

Offline R

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #13 on: August 03, 2021, 10:59:32 PM »
well whaddaya know!
Kept digging about and this tipped up eBay which is the very same as mine!

Well thats a new one on me. Unknown territory even.

Its this view thats the diagnostic one ..
https://i.ebayimg.com/images/g/ptkAAOSwikpg6HBa/s-l1600.jpg

I'd run that by Villiers Services, and see if they can supply a rim.

Its not impossible that its still the same size as on my earlier Excelsior/Waratah ?

Offline Rex

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Re: 6" headlamp shell but lights are 5 3/4?
« Reply #14 on: August 04, 2021, 08:31:56 AM »
Too tight to even punch out the ammeter hole and fit one.. ;)