'Adding a starter relay' - useful mod in the 75 3.0?

[shiny_car]

I came across this info on alfabb.com and the following link:

http://www.alfamilano.com/Adding_a_Starter_Relay.html

In summary:
*rather than activate the starter solenoid with a high current feed passing through the ignition barrel switch, you add a relay
*the high current feed can ultimately cause failure of the ignition switch and thus problematic starting

The link and alfabb.com references of course refer to LHD US cars (the physical location of the parts in the link are similar but not exactly the same in our RHD cars). So I'm wondering if Aus-spec cars are wired the same (high current feed via the ignition switch) - if so, I'll add a relay. Or whether Aus-spec cars have addressed this issue already with a relay - doubt it, but hoping someone can confirm.

Whilst a relay seems a logical idea, has anyone actually had starting problems as a result of a 'worn' ignition switch? Might be a useful upgrade for anyone with a 75. I presume the TS has similar wiring.

[colcol]

I put a starting relay in my 33 about 20 years ago, after experiencing the starter not kicking over, has not missed a beat since, put one in my brothers Sud when he had the same trouble too, the 33, 75 and 90 have the same starter switch/ignition key, the problem is voltage drop from battery to fusebox to ignition switch to starter motor and Alfa Romeo too thin wires and bad connectors, and fitting relay switches is common to other cars too according to a Auto Electrician i know, particulary Magna's, Colin.

[shiny_car]

Thanks. I'll add a relay.

And if my headlights don't have relays, I'll add them there too. I believe there was a bulletin to add them for headlights, but I can always add additional ones in the engine bay to shorten the powerwires further.

[colcol]

For your headlights you can actually get a proper headlight relay, with proper screw on terminals and chunky magnets and points, the relay is a reasonable size, [about 3 cigarette boxes], so it won't get too hot, here goes this old story i have told before, [yawn], i wasn't fully convinced that the yellow lights were due to voltage drop, so i wired up one side up and left the other side with Alfa Romeo wiring, one side was white, the other side was yellow, convinced i was on to a good thing, i did both sides, Alfa have their headlights through relays, but they are small relays with thin wires and the relays are away from the lights, therefor you get a voltage drop, put the new relay close to the headlights, to avoid voltage drop, Colin.

[shiny_car]

Yeah, thanks Colin, that is exactly my plan. I'll mount relays on the bonnet slam panel (near the factory groundwire brackets), triggered by the exiting headlight wiring. Then a direct feed from the battery wiring. Short distance for minimal voltage drop.

[Duk]

For your headlights you can actually get a proper headlight relay, with proper screw on terminals and chunky magnets and points, the relay is a reasonable size, [about 3 cigarette boxes],

You could also look at using solid state relays. These are well priced on eBay now (make sure you are using DC-DC SSR) and being nothing more than a whopping great big MOSFET transistor with no moving and/or arcing components, should never wear out.

Note they they aren't suitable for inductive loads like solenoids or motors without back EMF diode protection. For resistive loads like headlights, perfectly fine to use without diode protection.

http://autospeed.com.au/cms/A_110574/article.html

[shiny_car]

Good info Duk. I have a bunch of new relays already, so I'll use them for now. SSRs might be new technology, but they aren't as small as a normal relay. 

Thanks for the reminder about back-EMF; I'll add a diode across the 85/86 terminals.