Rear bulb holder(s)

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Phil T
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Re: Rear bulb holder(s)

#11 Post by Phil T » Tue Aug 31, 2021 7:43 am

I see, I would only count the 'poles' as the contacts on the bulb.

Difference of definition. :)

torque2me
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Re: Rear bulb holder(s)

#12 Post by torque2me » Wed Sep 01, 2021 6:32 pm

Phil T wrote:
Tue Aug 31, 2021 7:43 am
I see, I would only count the 'poles' as the contacts on the bulb.

Difference of definition. :)
So would I and my holder has three.

Kev

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Re: Rear bulb holder(s)

#13 Post by Clifford Pope » Thu Sep 02, 2021 7:04 am

Three little springy contacts inside the holder, and three blobs on the end of the bulb? I've never seen one like that - must be after my time. :)

I do know that there are/were two kinds of bulb with 2 connections - those where the two corresponded with two filaments (earthed through the casing of the holder) and those with only one filament for live and earth but no earth through the metal of the bulb/holder. I've been caught out replacing old caravan bulbs getting the wrong kind - each has two connections and superficially look the same.

Terminology -I think "poles" apply to switches, not bulbs?

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Re: Rear bulb holder(s)

#14 Post by Alec » Thu Sep 02, 2021 8:04 am

Hello Torque2me,

what you are saying is three contacts plus earth, that is most unusual. Can you post a picture of it?

Alec
0465

MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.

torque2me
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Re: Rear bulb holder(s)

#15 Post by torque2me » Thu Sep 09, 2021 7:55 am

Alec wrote:
Thu Sep 02, 2021 8:04 am
Hello Torque2me,

what you are saying is three contacts plus earth, that is most unusual. Can you post a picture of it?

Alec
As my original post Alec, the vehicle has a tow bar and I would think the extra connector is for earth continuity or power to the tow socket to enable the workings of any light bar on the towed vehicle.

Kev

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Alec
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Re: Rear bulb holder(s)

#16 Post by Alec » Thu Sep 09, 2021 8:49 am

Hello Kev,

that would be most unorthodox, light bars or a trailor socket has connections to several different parts of the loom to duplicate what exists on the car. A simple matter of tapping into the loom at the necessary points.

Alec
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MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.

Mike Stevens
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Re: Rear bulb holder(s)

#17 Post by Mike Stevens » Thu Sep 09, 2021 10:28 am

I'm pretty sure that the original bulb holders did not have separate 1/4" tab connections for the earth, that was done by the springy clips into the lamp assembly. However, the lamp assembly is mainly plastic so may not give a good earth return for the bulb current, especially at the age of our cars!

I seem to remember that in the past someone found or had made some special ones that had a 3rd connection for the earth onto a tab - maybe that is what you have.

Bulbs. Some bulbs use the metal bit at the base as the earth return connection, and some have 2 solder 'blobs' at the end - and some have 2 filaments 2 blobs and still use the metal case bit for the common earth return. The latter usually being 21/6W stop/tail lamps. To distinguish those from the single filament 2 'blob' ones, the bayonet pins are offset in that one is higher up the bulb than the other. This is to make sure the bulb goes in the right way round.

I'm sure it is possible to add an extra tab connector to a standard bulb holder for the earth return - even if just on a short flying lead. Another thing to try is to take the lamp assembly apart and clean the inside of the lens and either clean the reflector (carefully!) or stick new silver/aluminium EMC tape to the old, tarnished reflector. I did that on the Stag and the difference was brilliant! (Sorry, couldn't resist that!)

Cheers, Mike.
(South Oxfordshire)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)

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Re: Rear bulb holder(s)

#18 Post by torque2me » Thu Sep 16, 2021 3:57 pm

Mike Stevens wrote:
Thu Sep 09, 2021 10:28 am
I'm pretty sure that the original bulb holders did not have separate 1/4" tab connections for the earth, that was done by the springy clips into the lamp assembly. However, the lamp assembly is mainly plastic so may not give a good earth return for the bulb current, especially at the age of our cars!

I seem to remember that in the past someone found or had made some special ones that had a 3rd connection for the earth onto a tab - maybe that is what you have.

Bulbs. Some bulbs use the metal bit at the base as the earth return connection, and some have 2 solder 'blobs' at the end - and some have 2 filaments 2 blobs and still use the metal case bit for the common earth return. The latter usually being 21/6W stop/tail lamps. To distinguish those from the single filament 2 'blob' ones, the bayonet pins are offset in that one is higher up the bulb than the other. This is to make sure the bulb goes in the right way round.

I'm sure it is possible to add an extra tab connector to a standard bulb holder for the earth return - even if just on a short flying lead. Another thing to try is to take the lamp assembly apart and clean the inside of the lens and either clean the reflector (carefully!) or stick new silver/aluminium EMC tape to the old, tarnished reflector. I did that on the Stag and the difference was brilliant! (Sorry, couldn't resist that!)

Cheers, Mike.
Thanks for the input Mike, most appreciated. Certainly no earthing possibilities with plastic - our units are plastic backed and the the metal petal ring on the outside of bulb holder is there as a spring tensioned fitment. I might make contact with Canley Classics on this as he might have some thoughts/experience.

I would take a unit apart but the thought of accessing those inner studs with the 3/8" (?) nut which seems to need an eternity to come to the end of thread is not giving me any exciting vibes! :cry:

Kev

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Re: Rear bulb holder(s)

#19 Post by Mike Stevens » Thu Sep 16, 2021 4:08 pm

I have a number of 'spare' Mk2 rear lights. Maybe I should try to take one apart...

Cheers,
Mike.
(South Oxfordshire)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)

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