928 Forum
Sponsored by:
Sponsored by: 928 Specialists

Need a single H4.

Old 10-09-2017, 05:29 PM
Electron Wrangler
Lifetime Rennlist
Alan's Avatar
Join Date: Mar 2002
Location: Phoenix AZ
Posts: 11,930
Likes: 0
Received 0 Likes on 0 Posts

The lens alone can't make an H5 into an H4. The optics rely on the reflector, the lens and the bulb location and specifically the filament locations within the bulb and the low beam shield position.

The reflectors are different between H5 & H4, also the 9004 & 9003 bulbs are very different (Transverse Vs. Axial filament orientations) => obviously differently low beam shielding (filament as 'shield')

You have to have the right reflector type to mount a 9003 bulb it is a radically different mount from a 9004 and does a much better job of dissipating heat to the metal reflector via a large metal mounting flange - which also does a better job of precisely positioning the bulb wrt the reflector.

No way round needing ALL the important parts to make it work right. (sorry about the enormous pictures - but they do clearly show the major differences)

Great to have the lens replacement options. I'd be interested to see what you get with a new lens from Roger on an H5 reflector - hopefully something at least a little better than a H5...?

H4 9003 Bulb (Axial Filaments)

H5 9004 (Transverse Filaments)
Alan is offline  
Old 10-09-2017, 05:36 PM
Rennlist Member

Site Sponsor

ROG100's Avatar
Join Date: Jan 2003
Location: Double Oak, TX
Posts: 15,715
Likes: 0
Received 2 Likes on 2 Posts

Actually in practice the improvement over the crappy H5 is significant. Maybe not as good an an actual H4 but a BIG improvement.
Plenty of customers also used the new LED lights for even better lighting. Proof is in the pudding as they say.

Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014

928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
ROG100 is offline  

Thread Tools
Search this Thread
Quick Reply: Need a single H4.

Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: