Lucas relays

[Mr Spigot]

I am considering fitting a second Lucas Windtone horn to my 1960 car (negative earth with alternator) and reading various posts here, a relay is a sensible addition. There are a plethora of them available, mostly little black plastic boxes, and while making the horns work safely is the main goal, I would like to keep the relay relatively period looking. I have carried out some research and there are various Lucas relays available but I am not sure which one is appropriate. I have found plenty of 6RA, some SRB111 and a couple of SB40 which may do the trick, but don't know what the difference is between them.

Could somebody educate me please!

[oliver90owner]

I think the srb111 is a make and break relay - not what you really need for a horn.

[Bill_qaz]

A 4 pin 40amp would do the job.
Sample https://www.ebay.co.uk/itm/324561466319 ... media=COPY
Or a genuine lucas if you prefer

[Mr Spigot]

A 4 pin 40amp would do the job.
Sample https://www.ebay.co.uk/itm/324561466319 ... media=COPY
Or a genuine lucas if you prefer

Thanks, yes there are plenty of little plastic boxes that will do the trick, but I wanted to get something which looked more ‘period’ like the silver Lucas ones.

[Bill_qaz]

Do you mean this type?
https://www.ebay.co.uk/itm/183998683984 ... media=COPY

[JOWETTJAVELIN]

SB 40 three terminal relay is what you want.

[svenedin]

SB 40 three terminal relay is what you want.

That relay is/was used as a horn relay. Rather expensive to buy now!

[Mr Spigot]

Thanks. Yes, that is what I am looking for. I will keep an eye out for cheaper options!

[geoberni]

Thanks. Yes, that is what I am looking for. I will keep an eye out for cheaper options!

They are to be found, like this listing of Lucas 6RA for £10
https://www.ebay.co.uk/itm/266076200354
But note the seller seems to have both single and double pole ones on the photographs. Probably doesn't know the difference.....
Don't forget the 6RA was the generic model/style of relay, the actual contact arrangement and even voltage differed.They certainly came in 12v and 24v, I'm not sure if there were 6v ones.

Lucas still make the 6RA, but only in the one version I believe.

Update to say I found this list on the MGAGuru website. It lists many of the different arrangements of vintage Lucas Relays.
https://mgaguru.com/mgtech/accessories/ ... ucas_1.gif

Here's a radical thought though, ....get any old relay from a boot sale or autojumble, anything you can pick up for a couple of ££, remove the insides and just use the cover to hide a modern relay.....

[Mr Spigot]

Many thanks. That list is really useful and the idea of using the cover to hide a modern one is a very cunning plan.