MGB Register Forum

I have replaced the original sealed beam headlights with a pair of Wipac lights that have halogen bulbs on my 1973 BGT , bought from Moss.
After using them for only a short time , about half an hour , the reflectors and the inside surface of the lenses on both lights appear misted . The light output is noticeably reduced due to this ‘bloom’ . I took the first pair back to Moss last week , compared them with a new pair and they changed them without quibble.
I’ve just tried out this new pair and with exactly the same result.
Question , has anybody else had a similar experience and , if so , what was the outcome ?. Any help or suggestions welcome.

I've run Wipac Quadoptics for many years with no problem like you describe. I did have the reflector corrode on one after a few years. You don't seem to be able to get them these days without the pilot bulb, so I've got one of each now.
Later MGTFs seem to suffer from the misting you describe, I don't think anybody knows what the cause is but may be to do with the glass material.

I've found the Lucas H4 units have a better beam pattern and with upgraded 60/55 H4 bulbs (Philips Xtreame Vision or Osram Nightbreaker) the light spread and depth is excellent, and these are fitted to my B. Far better than the Wipac units I first tried after buying the car.
Better though for 7in headlight units are Cibie H180s or if you can find some Z180. I used H180s in an Escort for road rallies in the 1980s and if double wired (dip beam stays on with main beam) they verge on fantastic! I also used Hella units but when double wired they last one night and the heat had stripped all the silvering off the reflector. It took my local Hella agent ages to work out they just might (I was using 130/90 bulbs!) have had a bit of abuse!!!

Many thanks Paul and Peter for your replies. I think you may be right , Paul , that it is the lens that is the problem. I think they are plastic of some sort and the heat of the bulb is causing fumes that adhere to the reflector and inside the lens .Hopefully, Moss will change this second pair and l will change over to another make . Probably this time go for Lucas as mentioned by Pete.
Thanks again guys.

I fitted Wipac halogen headlamps to my B a number of years ago. While I did not have the problem you have had (Could it just be damp), I was disappointed until I added relays to the circuit and took the full load away from the light switch and the main loom. The relays were fed from one of the alternator to starter motor cables.

Thanks for your reply , David. I can definitely say that it was not normal condensation inside the light. I have now returned them to Moss. The fitting of a relay is a possibility but , and l am not electrically qualified , l cannot see how that would affect the misty coating on the lens and reflector. It’s a mystery. When l get the chance l will see how this new pair , bought from an auto electrical shop , perform .
All credit to Moss , they refunded the cost of the lights without quibble but saying they had sold many sets of the Wipac lights without complaints .

Hi Ray
I think what David was referring to was the reduced brightness caused by significant voltage drops in the wiring to the headlight units. In the MGB, the headlight wiring takes a circuitous route via the fuse box, light, main/dip switch’s and various bullet connectors before reaching the headlight units. Given the age of the switch gear /wiring, it is not uncommon for electrical resistance to be present in the wiring circuit leading to a significant drop in voltage at the headlight units. When I checked mine I only had around 10 volts with engine running
For example a typical 55watt headlight will draw around 4.5 amps. (55/12) multiply this by 2 for both headlights this give 9 amps.( More if onmain beam) Using Ohms law (V= I x R) you would only need a small resistance of around 0.5 ohm to create a significant volts drop of around 4.5 volts at the headlight unit (9A x0.5R =4.5V) thus reduced brightness.
The relay upgrade is very simple to install and uses the light/main/dip switch gear to power the coil relay ( milliamps rather than amps) then using the main heavy current relay contact to switch power to the headlight units. Hence no volts drop and brighter lights.
You can either purchase the all the parts individually for around 20 pound off from the many auto electrical suppliers on the web or Moss(Sorry) do a kit for around 40 pounds.
Not sure where you are in the country but you are welcome to come and look at my car (I am based in Abingdon) to see what is involved.
Hope this helps
Best regards
Mike Barclay

Michael, thanks for your posting. What l was thinking when l connected the misting of the lens etc with fitting a relay l have no idea!. I have read elsewhere that , because of the old connections in the lighting circuit, the output can be much reduced. It is certainly something l will look into .
I have purchased another pair of headlight units from an auto electrical shop and they seem fine . I did a similar mileage to that when l had the Wipac units fitted and there is no ‘misting’ on either the lenses or reflectors. As you can imagine l am much relieved that l now have good lights , using Xenon White bulbs . Hopefully that is the end of the problem !.
Thanks again to you and the other guys who offered their advice.
To add , thanks for the offer to view your set up . I am in Stockport which is too far to visit you but again , thanks . Ray.

Hi Ray
Glad the new lights are a success. I agree the relay mod has nothing to do with the misting you were experiencing. I think that was down to the general poor quality/fit of components sold by the likes of Moss. The relay mod would help get the best out of your new lights and be kinder to your switch gear.
Shame about the timing, I was up in Stockport 2 weeks ago visiting the Avro heritage Museum.
Best regards
Mike Barclay

Michael. I’ve been away for a week so just seen your latest posting . Pity about being in Stockport area recently when we might have met. Hope you enjoyed the Avro Museum , l went last year but have been previously before the closure of British Aerospace on the site.
If ever in this area again please let me know . Thanks for your helpful comments.
Regards, Ray.