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MG TD TF 1500 - Head lamp brightness

The adventure continues.........OK, I am thinking that if I change the headlamps on the '53 to halogins I will get more light. Do they draw more current from the already marginal system? Are there other tradeoffs? Thanks, Tom
Thomas McNamara

Don't have any experience here but the original QI really draw the current. With high beams on you have to be running about 2k rpm to break even.

Chris Couper


The original tungston bulbs were 45/36 watts. US tungston sealed beams were quite often 50/40 watts but I've got one that says 60/50. You can find quartz sealed lamps at 55/40 or 60/50. I am using a set of GE halogens which are labeleded 65W/35 watts. The additional 40 watts consumption requires an extra 2.9 amps if the voltage regulator is set correctly. If your charging system is working correctly there's no reason why you can't change to halogens. But, you may not be able to use twin fogs or twin driving lamps at the same time. One maybe, but not two. I've checked the calculations many times over the years and if your 53 has the later 19 amp dynamo, I'd put in the halogens.


My 52 has halogens and I've never noticed any problems. The night time illumination is by far better.
Robert Dougherty

Dear Thomas,

An interesting subject indeed.

About 10 years ago, I attended a seminar on english car electrics. One of the topics discussed was what at that time was called "yellow lights" which can be interpreted as dim lights. As one drives down the road at night, notice the range of intensities of the low beams. They range from super bright (probably the latest ion discharge kind) to almost totally yellow (here in Qubec sometimes - none!).

They put a car on the lift and using a VERY sharp stylus of a voltmater, pierced that plastic jacket of the main cable, and grounded the other side to the chassis if a 1953 Triumph Mayflower. With absolutely no load (even the clock had beed disconnected), there was a measuarble drain of 1 to 2 volts to the chassis. It was explained that under a high lighting load of say, above 3 amps, that the voltage getting to the headlamps can be as low as 7 volts, hence the yellow lights. Halogen or incandescent - it makes no differecnce except at some point, the halogens will fail to excite.

The probable cause for this problem is/are a) corroded battery posts, b) possible breaking of some of the strands in the wires inside their (plastic) jackets, c) poor connections on the dynamo, in fact poor connections everywhere, d) poor grounds, e) a weak dynamo and f) a poorly adjusted V/R. It goes without saying, that this is the least expensive first solution - clean and re-tighten every connection including every connection under the dash! Put on new brass or copper star washers, where none presently exist. In desparation, replace the wiring harness!

I know of another instance where a friend of mine with a TC experience "yellow lights" (does this carry the same stigma as "bad breath"?). He replaced the wiring harness ONLY, making sure that all the re-connections were clean and tight, added new battery cables and voila! Problem solved.

After scortching the 'PL' on my tripods, I installed a pr of JC Whitney "7" off-road" lamps 13BS9302W for $46/pr They are great, and great value! They use H4 bulbs and you can have your choice of 60/65, 100/55 (my choice), 100/80 and 130/90 watts and in all the flavours and colours imaginable!. With a fresh dynamo, on high beam, I have no trouble keeping the needle in the middle of my voltmeter in my TF at above 2500 RPM, but can't use my heater. So it boils down to seeing or keeping warm and driving slowly.


Gord Clark
Rockburn, Qu.
Gordon Clark


I switched my TD over to halogens last summer as well. No problems overtaxing the electrical system and quite noticeably better light.

Scott McCoy

My 50 td suffered from yellow low beams for years. Never did figure out what the problem was. High beams were fine, but lows were yellow. Changing sealed beams did not help.

Last year I installed a set of halogen bulb type lamps and all is now great.

Bruce Cunha
Bruce Cunha

This is so far down the line it probably will not be seen, but here goes. The usual reason that headlights are very bright and very dim is due to the ground wir being attached to the wrong side of the sealed ;beam bulb. Looking into the bulb facing the rear of the car one can seen that the groung in aon the right side. It is usually crossed with te/he dim from the other side. Swapping the two wired will correct the problem. It is not from low voltage or other cause. The ground causea many problems and never get credit for same. Try this, those of you who have the bright and dim problem
Ellis Carlton

This thread was discussed between 09/02/2003 and 18/02/2003

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