Koito H4 headlamps?

[Mr. Merk]

How about the Kioto 7" H4? Last I heard, it was a better pick than the Cibie.

 

[-Virgil-]

That is correct; the Koito (is how the name is spelled) H4 headlamps are significantly superior to the Cibies. There's more light within the beam, the light distributions are smoother and they have better formation -- the hot spot is located closer to the axis for longer seeing distance on low beam, there is much better control of stray light, etc. Also the construction quality is much higher.

 

[theastronaut]

I just installed a pair of Koito H4 7" rounds with relay harness on my new to me Miata and I'd say that the low beam performance is well under that of Cibie H4 7" rounds. It's like driving with fog lights only on low beam; lots of foreground light but I can't even see the cut off unless I'm in a rural area with no other lights around, and even then the light out at the cut-off is very dim. My Cibie H4s (both older Z-Beam and newer e-codes purchased in 2017) have the hot spot right along the cut off and less lower, so light is pretty evenly distributed. High beam performance is very good with the Koitos, just the low beams are dissapointing. I haven't changed bulbs from the ones supplied, but I'm not happy with the low beam performance at all. Maybe the low beam filament position is off? I even have (for "research", don't ban me ) a pair of 7" chinese/Amazon leds that have a much better low beam pattern than these...

 

[-Virgil-]

That doesn't sound like the experience most people have with Koito H4s, and it doesn't line up with the objectively-measured output performances from the Cibie and Koito headlamps. Sounds like there might be a problem with your bulbs, wiring harness compatibility, and/or headlamp aim.

 

[John_Galt]

I think it would be worth your time and aggravation to check a couple things, namely the bulb that was supplied, the components of the relay harness, and lastly, most importantly, what voltage that relay harness is actually feeding.

 

[theastronaut]

I did pull the bulbs and the low beam filaments were wavy. I swapped in Flosser bulbs and the beam pattern is more even now with more light out at the cut off. Apparently Koito had a bad run of H4 bulbs, similar to the occasional bent 9004 Nighthawk bulbs a while back.

 

[John_Galt]

That's an interestingly misshapen filament, for sure. Glad you have found the root of your issue.