Ask Mr. Bentwrench©

October 21, 2017

Dear Mr. Bentwrench – I’ve got a ‘Sylvania’ sealed beam in one side and some odd looking old ‘Lucas’ headlamp in the other. I can’t see at night for squat and OMG, if it’s raining? Maybe adding some fog lights would help? I know I really need to completely update my lighting just for safety but would like to at least try and keep everything reasonably ‘correct’ as I am planning on showing for the first time at the next Bash. Help! It’s dark out there! – Driving in the Dark



Dear Driving in the Dark -


In general, all twin headlamps are all designed for either LHD or RHD low beam light patterns. Early sealed beams were rated at just a measly 35w/55w but after the use of halogen headlights was finally US approved in 1978, sealed halogens went to today’s at least a ‘drivable’ 55w/60w.  Everything but the sealed beams will use the standard 55w/60w H4 bulb. Sure, conventional 100w H4 bulbs are both available and popular, but they can really tax some small wire gauges and have been known to completely melt down some bulb holders and plug sockets!  High output LED headlamp bulbs are developing quickly and run way cooler and draw about nothing. However, I don’t think we’re quite all there yet. So, let’s get into our correct & specific LUCAS lighting!



Lucas headlight buckets are known to run a bit shallow so we’ll only address genuine Lucas headlamps. Also, for some added vintage competition sparkle, dress them up with some chrome, wire mesh stone guards!


Semi-Sealed Beams – The simple, early Lucas 7-inch, pre ’68 H4 headlamps are usually identified with a square ‘LUCAS’ cast into the center of the glass. These are becoming more rare now and are not currently even being reproduced to my knowledge. Crap!  


Sealed Beams – Plain vanilla Lucas OEM 7-inch sealed beam headlamps. US DOT required and common to all post ’68 export models. Identified with either a round and later oval ‘LUCAS’ in the center of the glass. However, most all ‘correct’ replacements today are set up for only right-hand-drive cars, that is, they dip to the left on the low beam. OK, technically not legal for driving on the right-hand side of the road, but the odds of us blinding an oncoming motorist with a tungsten lamp like these, powered by the generator or alternator of a thirty-plus-year-old British car are probably pretty remote.


‘Euro’ Headlamps – An early 700 series Lucas 7-inch, ‘European only’ H4 bulb design but with a clever, supplemental, 5w ‘pilot light’ in the reflector. Commonly called a ‘city light’ configuration but I’ve run mine more as a poor man’s ‘daytime running light’ (DRL) for some increased visibility without taxing my already marginal generator output. I would also score them as ‘correct’ on older cars.

Halogen H4 – All post ’68, 7-inch round are all marked in various combinations of “Lucas/Halogen/H4” on the lens. Also found with that real novel looking flat lens too. Modern convex replacements now come with the new halogen Lucas P43 (55w/60w) bulbs. Then, there are high-output xenon bulbs (same wattage but 30% brighter) available for only $10-12/pr more.  Looks like winning replacements for any driven class car!


PF-770 – The very first Lucas Tribar 700 series with an H4 bulb design. Common only to like the very early full fender XK-120 era cars. Typically identified with the tribar’s plain black center dot. Know why they are called ‘TRIBARS’? Simply because earlier headlamps had only TWO bars supporting the center reflector. The ‘tripod’ term has since just become a common misnomer. 







P-700 – The next generation Lucas 7” Tribar H4 headlamps. Widely used in many higher end British cars of the 1950s and 1960s. However, I find the older original P700 series had just “LUCAS” on the tripod but many of the current reproductions are for some reason displaying an incorrect “P700”?









They will retrofit just about any car with twin round 7-inch Lucas headlamp buckets. OEM spec H4 bulbs may also be upgraded to both the new generation halogen and advanced xenon bulbs.

PL-700 – The top-of-the-line for the Lucas Tribar headlights and carry a unique ‘LUCAS PL’ badge style design on the center of the tribars. OEM only for all the high-end cars such as Rolls, Bentley, Aston-Martin and the like but (IMHO) an out-of-character anacronym when retrofitted to more common cars such as later BL production MGs and Triumphs… even if they are flat gorgeous. Also, reproduction quality has been reported on many forums as a BIG disappointment and are not currently considered very good reproductions at all. However, finding any decent, show worthy originals has become prohibitively expensive today.





Below is just a sample of what were the most popular lamps and what we will usually see fitted up at shows.


FT/LR Series – Long running series. Round, FT for ‘Flat Throw’ (fog) and LR for ’Long Range’ (driving)

  • FT6 – Lucas ‘PATHFINDER’ lamps are all glass, sealed beams with full fluted lenses. Slightly smaller than the SFTs and ‘period correct’ accessory lamps. Really good-looking set of lamps too.






  • FT10 – Lucas ‘NOVA’ foglamps are slightly more affordable than the nearly identical 576 series but more importantly, a little slimmer which makes them ideal for mounting in front of the grille


    or where clearance in limited. Also, these were the original lights fitted to all the famous Works rally Minis, and are judged ‘period correct’ for all cars of that period.

  • FT11 – Later 1970’s model Lucas ‘SILVER SPEAR’ with perhaps now a slightly less fluted clear fog on the FT11 but the same typical clear, unfluted lens on the ‘long range’ driving lamp LR11. Both just later models of the 10’s from the early 60’s through mid-70’s but now with “searing white halogen beams”. Wow! 


SFT Series - Round, fluted/fog lens (‘Flat Throw’ pattern), H4 bulbs, pedestal mount

  • SFT 576 (5.76”) in Amber or Clear color lens

  • WFT 576 (5.76”) is facia mount in clear lens (as fitted to the REAR of all the rally cars!)

  • SFT 700 (7”) in Amber or Clear color lens… and just as big as your damn headlamps!




SLR Series - Round, clear/long range lens (LR=‘pencil beam’ pattern), H4 bulbs, pedestal mount

  • SLR 576 (5.76”) in clear only (rated at 80,000 candle power)

  • SLR 700 (7”) in clear only and still just as big as your damn headlamps!


LR8 - Rectangular, fluted Amber (‘fog’) or fluted Clear (‘driving’) lens… but yet identical lens design.

  • Lucas LR8 or ‘SQUARE 8’, modern CAD design fluted lens available in either amber or clear.

  • Fitted to everything from the late 60’s and all through the 70’s. OEM on Shelby Mustangs, Rolls-Royce, Bentley, Aston Martins, Rover & Jaguar. They fit perfectly and are deemed ‘correct’ options on cars like MGB and Midget and Triumph TR4, TR250 and TR6. However, now becoming harder to find at affordable prices for us as they are also highly prized by Shelby Mustangs collectors. Damnit!




Now, for some obtuse history, folklore or maybe just outright lies. Amber was the ONLY color early on for fog lamps due to its alleged anti-dazzle effect in dense fog. However, with the advent of the very first CAD computers, all lens designs advanced by leaps and bounds since light output pattern could then be better controlled with much more precise cut-offs. After that, amber color lenses became just a nostalgic ‘vintage look’ carry over. Next, everyone always speaks reverently about the famous Lucas ‘Flame Throwers’. In truth, there was never such an ‘official’ Lucas model and it simply became the accepted slang for the quite impressive, clear lens, 7”, 700 series tribar headlamps when fitted with the 100w H4 bulb set! Jeez! I bet you could light a cigarette off then just within minutes at rest! So, Driving in the Dark, now ‘ya know!


If I don’t know the answer… I just make one up! ™






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