Date:         Tue, 10 Nov 2009 10:56:38 -0800
Reply-To:     Marc Sayer <marcsayer@HUGHES.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Marc Sayer <marcsayer@HUGHES.NET>
Subject:      Re: queston on H4 55/60w bulb to fit stock bulb socket
In-Reply-To:  <b34812450911101001h5b8f85f1k832b90fc048fe566@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

There is even more to this. The housing (ie the reflector and lens) is
designed for the specific bulb not only in terms of fit but also
filament location and orientation. The filament has to be located at the
focal point of the reflector and has to be properly oriented to the
reflector as well. It's like those adjustable flashlights where when you
turn the end, the light pattern goes from wide beam to spotlight. What
you are doing when you turn the end is changing the position of the bulb
(and therefore the filament) relative to the reflector (the housing in
an automotive headlight). An H4 bulb has a specific distance from flange
(a reference point relative to the reflector) and the filament itself.
The 9004 has a completely different distance from flange to filament. In
addition, the H4 has an axial filament (filament runs front to back,
parallel to the centerline of the bulb). Whereas the 9004 has a
transverse filament (runs side to side, perpendicular to the centerline
of the bulb). There is no way to install an H4 in a 9004 housing and get
a proper relationship between the filament and the reflector. And that
means there's no way to get a proper pattern.

Mark Tuovinen wrote:
> You have two challenges with this.  The bulb to the light housing and the
> connector to the bulb.  The wiring issue is the easiest you either cut and
> splice the correct connector in place or make an adapter which would be more
> difficult but not impossible.  The bigger problem is that 9004 and H4 bulbs
> use two different methods to secure to the light housing.  If your goal is
> better light output from stock US market rectangular headlights circa 1986 -
> 91 changing the bulb will not do much.  The problem is the lens and
> reflector not the bulb.  There are cars that use a four bulb system and both
> the high and low beam bulbs are the same style, it is the reflector that
> differentiates the two.
>
> What problem are you trying to cure and on what year van?
>
> Mark in AK    living in the land of perpetual dark
>
> On Mon, Nov 9, 2009 at 5:28 PM, David Cohen <Mtbdavid2@aol.com> wrote:
>
>
>> Hi
>>  Is there a H4 55/60w bulb that fits the standard 9004 Bulb  socket?
>>
>> Thanks,
>> David
>>
>>
>
>

--

Marc Sayer
Journalist, Photographer, Dog Trainer (APDT member #062956)
Board member - Western States Great Dane Rescue Association
Director of Operations & Training - Deaf Dane Rescue Inc.
Oakridge, OR USA

My Homepage - http://gracieland.org
Deaf Dane Rescue  - http://deafdane.org
Western States Great Dane Rescue Association - http://wsgdra.org
RescueWatchdogs - http://rescuewatchdogs.org
Association of Pet Dog Trainers - http://APDT.com