Loose diffuser inside Bosch headlight

TeddyG

TeddyG

Hero member
Location
Portland Oregon
I'm full of questions today-

I discovered that the black metal diffuser is loose inside the Bosch headlight, and unfortunately too big to remove from the lamp opening and impossible to re-attach the 2 metal tangs that hold it in place.

So, is it possible to safely split the lens from the green dome? I know these are scarce and difficult to replace and I don't wish to damage it.

I appreciate advice on doing this, thank you again
 
If it’s the same headlamp as mine, Bosch H4,then, yes, the lens is not fixed to the reflector.
I fitted a new left hand dip lens to mine. It came with a right hand dip one from new.
Carefully ease the lens free, the rubber sealing ring is easy to tear, it should stay attached to the lens.
Re-clip the diffuser. Do not attempt to clean the reflector, the silvering is very fragile.
 
Thank you Sock,
I carefully cut away the rubber gasket w/ x-acto knife and freed the lens- one of the diffuser tangs broke off so it will be hard to re-fit it. What is the purpose of that diffuser?- seems that it just blocks the head light beam, but what do I know. I plan on using a silicone adhesive to join the lens to the reflector dome and won't clean the silver reflector finish.

I tried before to find a sealed beam, but that size is not available so far. I installed a Sylvania auto LED headlight w/ cooling fan that seems to work well w/ minimal flickering
 
TeddyG said:
Thank you Sock,
What is the purpose of that diffuser?- seems that it just blocks the head light beam,
Click to expand...
I believe its job is to work on the low beam so that all the light from that filament is only directed by the reflector and the lens segments such that it does not blind oncoming drivers, no direct forward dispersal of light. Some H4 bulbs have a coating on the end of the bulb to achieve the same purpose. Perhaps somebody here is a headlight legality expert? One reason why putting in LED bulb into H4 housings is that the forward, upward light dispersal is not controlled and tends to shine into the eyes of oncoming drivers - similar to the specific lenses for left-hand and right-side dipped beams?
 
If you're using Silicon to seal or glue the lens to the mirrored reflector, make sure you use Nutral Cure type Silicon. It doest react chemically. There are Ducati reflectors that can be used as a replacement, about $400 from Gowanlocks in Oz.
 
The Ducati ones are more than likely for the triple headlights. As the 750 uses a smaller unit you could try sourcing from BMW. The old 650 models used the same headlights as the 750. IIRC I may have brought a new seal ring from BMW back in the day when those parts were readily available.
Or it may have been part of a replacement lens. Along time ago.
If you do use silicone don't glue the lens into the reflector, rather use it as a gasket as such.
I'm not a fan of silicone, if it was me I'd source a length of squ section o-ring, cut it to length. You can use superglue to stick the ends together.
Alternatively if you can't find the the o-ring maybe use some insertion rubber of appropriate thickness and cut a narrow strip to required width.
My 2 cents worth.
 
For better or worse, I used silicone adhesive to form a bead along the reflector rim and attached the lens with no adverse results so far. Getting the metal bucket to snap in place was another matter however-
 
I ditched the diffuser on both my BMW and my Laverda, they both have exactly the same headlamp.
Having fitted H4 bulbs with the black painted tips I see no difference in nighttime illumination.
Spares forever these headlamps are cheaper and more readily available from BMW parts vendors.
 
  • Like
Reactions: pf1
After much coaxing I got the bucket to snap in place and it,s secure against the outer ring. I,m using a Sylvania automotive LED w cooling fan that,s lasted awhile. The diffuser is secure and I don,t do any night riding.
 
You must log in or register to reply here.
Back
Top