Headlight Upgrade for 86 XJ6 III

I recently purchased the 7" outer headlamp bezel conversion kit to replace the original US spec. 5". I did’nt purchase the offered headlight itself because I wanted all four units to be compatible.
What are my best options going forward and do I need to upgrade the wiring in some instances ?

Good looking flat (for the S3, looks odd but they went to flat because of the optional headlamp wipers; you can get convex ones of course) H4 7“ halogens. I have ones from a Lada but you want better. Lucas or cibie or hella etc. and good H4 are as good if not better than xenon (that’s my opinion).

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Something in a tri-bar always looks good.

A fresh set of H4’s does wonders.


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Is there such a thing as a 5" (H4) type headlight to replace the 5" sealed beam ?

A 5 ¾ H1, or a halogen sealed beam, but to be honest the standard high beam lamps are pretty decent.

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Really? What standard high beam lamps are you talking about? Because the DOT-approved ones sold in the US are only good for stumbling around in the dark.

My s3 with h4 outers and original inners had the best high beams I’ve ever seen on a car. I went to gm sealed halogens that I imported from a junkyard in Colorado (out of a Mercedes actually!) and no difference. S1 is good but the outers are not as good. The inners are.

There are a few things you can do to tart up your headlights (I tart up everything):

You can fit 5 1/2 inch driving lights at the inner location. Use outers only on the headlight switch, but switch on driving lights separately for long range.

Conversely, you can fit hi/lo halogen 5 3/4 inch inners, and run both lights both low and high beam

IMO a good idea is to fit relays for both high and lo–take the load off of the Hella relay (S3) or the switch (S1).

You have that right. Starting in 1996, I ran our series 3 XJ6’s with 7 inch flat headlamps. In 2007, went to visit my father in New York and drove his 1986 XJ6 with ‘standard’ US 5 inch headlamps. On the way home, in the evening, got caught in a downpour. Until this day, I’m amazed we made it home in one piece for me to tell the story. After 7 inch light’s, you’ll want to take the old 5 inchers and throw them away or use them on a golf cart.

Aftermarket 7" outers and 5" 3/4 inner “crystal” H4 headlights, the glass is clear and the pattern is on the reflectors. Inexpensive, very nice look, good cut-out pattern and plenty of light.
But, more important, I have installed relays and thicker cables as well.

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Osram nightbreaker lamps and thicker wiring are the best upgrades, but I didn’t need either.

Aye, A fresh set in my car did wonders.

Relays do have their merits if the old wiring just has too much internal resistance. In many cases though, the wiring is good and it’s just the last contacts that spoil the show: measure voltage at the final connector. If you see less than 12.5 V I’d do something about it: sand the spades of the bulb and spray some lubricant into the three prong connector. Then search for the next connector usually hidden inside the front wing on its way from the inner headlight to the rubber grommet where the wire enters the engine bay. It is a Lucas bullet connector and it is not built to stand decades of use inside a front wing.

Apart from that: as David says - any quality H4 7" outer (Hella, Bosch, Cibie) and H1 5 3/4" inner headlights will work pretty well. I wouldn’t be as enthousiastic as David on this one - in fact technical development was significant even before the advent of XID and LED -, but still there is a huge leap forward from 5 3/4" US sealed beam units.

Good luck


75 XJ6L 4.2 auto (UK spec)

Just a footnote. The Series 3 cars already have a relay, the pricey special purpose Hella which is designed to permit use of the “flasher” stalk on the steering column to emulate a proper latching switch. Additional relays unload the somewhat feeble contacts of the Hella, particularly in the daytime “flash” mode.

Also, modern US “sealed beam” headlights are similar to non-sealed beams. They contain a halogen bulb (which must have a quartz enclosure of very small size by design) that is similar to the stand alone H-series bulbs. But the reflector/lens assembly is also sealed to keep the reflector from corroding and, I believe, to meet US DOT laws that require “sealed” beams.

The idea is to have a thick wire going to 4 (fused!) relays near the lamps, and just use the adequate-but-not-great wiring to switch the relays. A volt does a lot to the light output.

I have those halogen sealed beams but I really am enthusiastic about the normal incandescent ones. Mind that I‘m only talking about the spot lamps. Better is always possible but signs will be blinding anyways.

Indeed it does. If you consider the physics, not only are you getting more radiation because there is more power, but the filament is getting hotter, shifting the Planck’s Law distribution of the radiation towards shorter wavelengths–more light, less IR heat.

All the nightbreaker lamps do, like a projector lamp of old days, is to burn very hot (so, like a 10v bulb on 13v, in layman’s terms).

That way they don’t last as long despite being halogens that like to burn hot, but that’s not really a problem anyways.

So they are whiter, brighter and the wiring can be kept.

It’s really the voltage difference between battery and the terminals that shows the loss in the wiring, Jochen. Without current flowing there is no voltage loss…

xj6 85 Sov Europe (UK/NZ)

Yes there is. I used 5 3/4 H4 outers and 5 3/4 H1 inners I had leftover from another car project. If you don’t want to drop the coin on the 7" conversion, this will get you the same results, beam-wise.


Hella make a rounded glass and a flat glass, the above kit is the flat glass. Couple this with H1 inners and you’ll wonder why you didn’t do it sooner.