Cobber's collected guide to TR-7/8 lighting

[Cobber]

Over the years I've posted many bits of advice on the headlight circuitry of these cars, I decided to extract and collate these posts here in one place, for the convenience of all and to save repeating myself.

"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

80'Triumph TR7, 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
'98 MG-F, 69'Ford F250.

[Cobber]

<u>On the subject of fitting relays:</u>
I wouldn't bother buggerising around trying to clean the contacts in the switch, just replace it. But when you do replace it you must fit some relays on the light circuit it's self!
Yes, I know there are already headlight relays, but they're only for the control of the elevation of the pods not the lights themselves.
You see the switch has to carry the full current demanded by the head lights this over stresses the switch which is a crap design and isn't up to the job.
So if the standard sealed beam rubbish headlights are still fitted you would have about 10 amps of current constantly running through the switch, which when you have a good look at the switch, it's easy to see why it's too flimsy to do the job!
The situation gets worse if you have a quartz- halogen conversion because depending on the globes fitted you could have 16 - 20 amps running through the switch witch really isn't up the demand of the standard lights let alone halogens! But by fitting relays the switch only has to carry enough current to switch the relays (a few milliamps) as the relays will do all the heavy lifting and the now under stressed switch should last forever!

And to hell with the argument: " But then my car will not be original" Your car won't be very original when the lights fail and as a result you ram the car head on into a bloody great tree!

The melted remains of some of the switches I've seen tends to indicate that current draw has a everything to do with switch failure!
You've also got all that current running through the next weakest link, the dip switch!
By fitting relays you will only have a few milliamps running through it too.
All good auto electricians and manufacturers of halogen lights insist that relays must be fitted with any lighting upgrades to all cars!

I might seem a bit paranoid on the subject, but quite a few years ago a good mate and he was also my business partner was killed when the lights failed and he hit a bloody great tree! The investigation revealed that the accident was due to excessive speed and an overloaded lighting circuit (only the day before, he had fitted some driving lights without relays, he had just tapped into the high beam circuit. (Against all advice from his mates present when he did it, I might add)

So, since then nearly every car I've owned has had relays fitted to the lighting circuits (if they're upgraded or not) in fact, like the old rally teams used to do (and still might do, for all I know) I fit separate systems on each side so if one side fails I still have the other. Over the top? Probably, but there's nothing like having your mate killed to focus you on not going the same way!

A couple of years or so ago I fitted a new indicator switch to my TR the bloody thing didn't last an hour before meltdown! So I took it back to the supplier and exchanged it for another. But before I fitted the replacement I relayed the indicator circuit so only a few milliamps would have to pass through the switch, thereby preventing another meltdown!



"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

80'Triumph TR7, 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
'98 MG-F, 69'Ford F250.

[Cobber]

OK, here's the: Idiots guide to fitting headlight relays!

I use New Era brand relays these are made in Japan and are very reliable but Hella, Bosch and Ingram make good relays too, avoid the el-cheapo stuff and Lucas!

Hella Australia has an excellent site with heaps of good imfo:
http://db.hella.com.au/container.html
I am going to refer to various pages of their catalogue to provide the diagrams to help explain. so for the purpose of this exercise we will use Hella relays, but the site should be the same for other brands.

First select the relays you wish to use they come in different current carrying capacities so if in doubt go for the higher capacity unit.
A pair of 30 amp relays should do the trick. 1 relay for high beam the other for low.
So here is the Hella model 3082:

You will need to mount your relays close to the lights so as to simplify the wiring. Intercept the wiring loom close to the each light
For high beam the blue/white wire from the dip switch should go to terminal #86, the terminal #85 should go to ground, a power supply from the battery + terminal should go to terminal #30 of the relay ( some relays have an in built fuse in this case you will need a fuse or circuit breaker between the battery + and the #30 terminal) and you should run a pair of wires from the 2 #87 terminals to the high beam terminals of the headlight globes.
For the low beam do the same except instead of the blue/white wire from the switch connect the blue/red wire from the dip switch to the #89 terminal and the wires from the #87 terminals should be connected one for each side to the low beam terminals of the headlight globes. The remaining head light globe terminal should go to ground.
Note some cars have blue/white on one side and blue/grey on the other for high beam and blue/red and blue/pink for low beam.

You could use a duel relay such as Hella model 3051:


Instructions: http://db.hella.com.au/downloads/911-350-23.pdf

"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

80'Triumph TR7, 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
'98 MG-F, 69'Ford F250.