Saturday, September 18, 2010

Headlight Relays

I wrote this blog entry a month or so ago but I was so busy preparing for the Round Britain Reliability Run I never got a chance to post it. So, finally, here it is...

I've had a couple of problems in the past few days with the dip / flash stalk on the steering column. My uprated Halogen headlamps seem to have been putting much more strain on the switchgear than the old sealed beam units. Last year I had to take the stalk off and repair it because the full beam terminal seemed to have heated up and melted into the nylon body of the stalk causing it to smoke and spark quite dramatically! After it failed again on the same dark country road as before I decided it was probably time to fit some headlight relays!

I'm not the greatest electrical engineer in the world so I decided to do my research first. After a bit of searching I found an excellent thread on the Club Triumph forum. Once I understood what I was doing I made up a circuit diagram.

Basically, instead of going direct to the lights the wires from the switchgear go to a relay instead. When the light switch is pressed the relay circuit activates the secondary circuit which connects the lights directly to the battery. So that's the theory! You also need to do a bit of maths to make sure the cable can support the current it needs to be carrying. All you really need to know is Power = Current x Voltage. Most headlamp bulbs are 55/60 Watt so the current will be around 5 amps. Because there are 2 headlamps we need cable and relays that can take at least 10 amps. I decided to go a bit bigger on the battery supply cable to give me more capacity for upgrades in the future. The relays required are the common as muck 30A type.

I first thought about where I was going to mount the relays themselves. It's easiest if they're up front with the rest of the wiring for the lights. On the CT forum, James mentioned that he'd seen the relays P clipped to the bonnet tubes. Initially I thought this would be a great idea but when I looked into it a bit more I discounted it on the grounds that the cables would eventually get weakened by the movement of repeatedly opening the bonnet. I decided on a custon bracket bolted behind the quater valance. I made this up out of 3mm alloy and test fitted it. Perfect! Now to start the wiring...

I started by fitting the brown relay supply cable. This attaches to the battery positive terminal with a ring terminal and goes straight to an inline fuse holder before joining the rest of the loom running to the front of the car.

At the front of the car I crimped it into a butt connector along with another two short lenghts to supply both of the relays. The brown wire attaches to the '30' terminal on the relay. On the picture below you can see a left over length of the brown wire is being used to temporarily hold the relays in place!

You can then start attaching the other wires. The low and high beam cables can be found by tracing the cabling from the headlamps to the connectors in the centre of the bonnet. There should be a number of 4-way connectors, each with 3 wires connected to it. The low beam is the blue wire with a pink trace. Remove the supply wire from the connector (the others go to the headlamps), shorten it, crimp a terminal and attach it to the relay. Now you just need to repeat that with the high beam wire (blue with white trace) and connect it to the other relay.

All you then need to do is connect up both the '87' terminals on each relay to the connectors by the headlamps. There we go - all done!

Wednesday, September 01, 2010

Electronic Ignition

I've been meaning to change to electronic ignition for ages. I was hoping to go straight to Megajolt but with the RBRR coming up fast I decided it was time to get something sorted! I've heard good things about the kits sold by 'SimonBBC' so I got one of eBay. BBC stands for 'Best British Classics' in case you're wondering and they have a website ( as well as selling on eBay.

The kit contains a red module to put in the distributor, special rotor arm, a magnetic 'collar', grease, cable tie and various other bits. The fitting goes a little like this...

Firstly, you need to whip off the distributor cap to expose its innards. You no longer need the condenser or the points so they can both be removed by removing the two screws. You need to reuse the screws so keep them safe! There is also a braid connecting the baseplate to the distributor body. It doesn't say anything in the instructions about it but I removed it and it worked so I guess it either needs to be removed or makes no difference!

Once you've stripped the guts out you can install the ignition module. This needs to have the base coated in silicon grease before fitting. I think the reasoning behind this is to dissipate heat into the baseplate and prevent overheating. The module has a circle cut out of the bottom that matches up with a lump on the baseplate so the module 'locates' very easily. The instructions tell you to put the screws in loosely so you can adjust the proximity of the module to the collar on the distributor shaft. I actually found that with the locating bump and the two screws there wasn't really any potential for moving it and just did up the screws.

Now you need to fit the rotor arm and collar. The kit gives you a couple of different ways of doing this. Firstly, you can use the supplied rotor arm which comes with a collar built into the bottom to activate the ignition module or, secondly, you can fit a separate collar and use your own rotor arm. I'd just bought a new top quality 'red' rotor arm so I went with the latter option.

Then all you need to do it pass the wires out through the distributor body and connect the red one to the plus side of the coil and the black one to the negative. It's really important to leave enough free cable inside the distributor to allow the plate to advance and retard. I checked mine by sucking on the vacuum pipe! The cables in the kit were a little strange. One was too long and the other too short! I sorted this with a little spare cable and a few crimp connectors.

I then threw it all back together and reconnected the battery. It was time for a test drive! I turned the key and the engine span over but nothing happened. Something was wrong and it wouldn't fire. I suspected my connections at first but everything seemed to be in order when I tested them with my multimeter. There isn't much in this kit that can actually go wrong so my suspicions turned towards the stuff in the diff! I fitted the rotor arm with the built in collar just to see if that made any difference and it did! The engine fired up straight away. Comparing the position of the collar on the rotor arm with it built in and where I had it with my normal rotor arm revealed the problem. Basically, I'd just pushed the collar too far down the shaft for its motion to be picked up by the ignition module. All I did was refit the normal rotor arm and pull the collar up to the bottom of it. Job done!

I haven't driven the car since doing it but just at idle it sounds much smoother and I'm sure it's going to make a huge difference to how the engine feels. I'm really glad I did it and I can't believe I didn't do it sooner!