Using relays

[Stephen]

(I've split these posts out of the Wiring Tips article, since they are capable of supporting a thread of their own and weren't lending much to rooster's article submission. - Mike)

Very well written article but I doubt many here could actually use it to wire up their t bucket (how many people here have relays in their t bucket wiring? I wasn't planning any in mine). The only way an article like that would be useful to me is if it was accompanied by a wiring diagram. Remember... a pictures worth a thousand words. I should do a search and find any wiring diagrams on this forum that would be useful. That article wakes up your brain but some of us need a little more help.

 

[butch27]

I have 3 relays in my bucket. Horn- Fan and brake lights. I trust them and may have to put one for Headlights soon.

 

[SCCustomRides]

Very well written article but I doubt many here could actually use it to wire up their t bucket (how many people here have relays in their t bucket wiring? I wasn't planning any in mine). The only way an article like that would be useful to me is if it was accompanied by a wiring diagram. Remember... a pictures worth a thousand words. I should do a search and find any wiring diagrams on this forum that would be useful. That article wakes up your brain but some of us need a little more help.

If it is help you need just ask, I have never built a vehicle without at least 2 relays, The 68 camaro you see on my site actually has 26 relays and what seemed like 1000 miles of wiring, the 55 chevy pickup you see has 15 relays, 2 computers and 2seperate control harness's. try hiding that crap on a 55 pickup.
If you are not going to run any relays in your harness then may I suggest you keep it parked outside, (wouldn't want your house to burn down with it when you start it up), I had a customer bring me his cobra kit car about 10 years ago after he wired it and had a malfunction, this of course was after the harness melted to everything, fried gauges, destroyed paint etc... It ended up being a complete frame off job (guess he thought he did not need any relays as well) but I couldn't tell what anything was with all the melted plastic and burnt cooper.
Get where I am going with this? Basics first-diagram later.

 

[Francis Blake]

I thought I could get by without relays but started blowing fuses right away so installed one for the horn and one for the fan and thinking about one for the electric fuel pump. I had to install a relay for the elec fuel pump on my sons truck.

 

[SCCustomRides]

I thought I could get by without relays but started blowing fuses right away so installed one for the horn and one for the fan and thinking about one for the electric fuel pump. I had to install a relay for the elec fuel pump on my sons truck.

I always run one for the headlights as well, just in case.

 

[Stephen]

So I'm getting the feeling some use relays and some don't. My brains kinda rusty... did relays come on 57, 58 etc Chevy and Ford, other?

 

[Mike]

You mean like that starter solenoid on the Tri-5 Chevrolet? Or the horn relays? Yes, earlier model cars used relays.

The use of relays just makes sense. Control high amperage circuits with lighter gauge wiring/switches and keep those higher amperage accessories from overloading the rest of the system.

 

[T-Test]

So I'm getting the feeling some use relays and some don't. My brains kinda rusty... did relays come on 57, 58 etc Chevy and Ford, other?

Yes, on some things, but most used fuse link wire at the starter or ignition switch.

 

[grazza]

Mike, as an old dude I remember being told to always put a relay into any heavy load circuit. I also remember being told the relay should be as close to the user unit as well. Like the headlight relay should be next to the headlight and so on. Is that your take on it as well? I notice a lot of Hot Rod and Kit Car wiring jobs place the relays under the dash or seats.
Your views?

 

[Mike]

Since we're using a relay to do the 'heavy work', that means it should be wired to the accessory it controls with adequately heavy wiring. When we add length to a wire, we add resistance to that wire. So I agree, wholeheartedly, get the relay close to whatever it is controlling, to reduce the resistance in the high amperage circuit. There are going to be times when we might make exceptions in light of aesthetics, but, in my not-so-humble opinion, those instances need to be the exception and not the rule.

 

[Lee_in_KC]

I have four 30-amp relays in my set-up... horn, radiator fan, fuel pump, headlights.

 

[madmike8]

If your battery is under your seat or behind you, you might as well put the relay there too for your headlights/radiator fan. Your still going to be running heavy cable to the front, but it saves you from running another long run for the relay's coil.

I don't know why you would wire a car without relays in the higher amperage circuits, but if you do remember the entire circuit needs to be capable of handling the load including whatever switch you use.

 

[rbsWELDER]

I have four 30-amp relays in my set-up... horn, radiator fan, fuel pump, headlights.

Lee,

Where is each located on your T?

Mark

 

[T-Test]

I try to put all I can under the dash, and the rest under the seat. Buckets are not all that long, and as long as you use something bigger than 16/18ga wire, I think you would be O/K.

 

[Lee_in_KC]

Lee, where is each located on your T?Mark

They are all under the driver's seat, next to my fuse panel. I know the preference is to have them close to their loads, but I didn't want them out in the weather. I have the appropriate-sized feeder wires from the relays to the loads, with dedicated grounds coming back to a common ground post.

 

[ellis8500]

Here is a link to a chart that will help you determine necessary wire size.

http://www.offroaders.com/tech/12-volt-wire-gauge-amps.htm

 

[WEDRVIT]

I hope I'm not the only one out there that's using one on my GM direct drive starter. Sure cures those hot start blues (click , click , click)

 

[donsrods]

I always use relays. My 27 has four of them......electric fuel pump, fan, high beam, low beam. My 23 had eight of them, electric fuel pump, fan, high beam , low beam, and 4 relays for the Ron Francis (or Painless, I forget which) turn signal setup.

Relays simply give better current to the accessory with less load on the switches.

Here is the setup I used on my 23......

Don

 

[sstock]

Hi Don, here is a pic of no fewer than five relays -all of which are used to control the " Hot Dot" ignition button.
Crazy but cool.

 

[grazza]

Don, just wondering if you could come over to Australia and wire up my '27 please. Oh yea, sorry, but I don't work at 4am (or any other time after about dark LOL). That sure is a neat wire job.