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Triumph TR6 - Wiring questions

Another project, another set of questions...

I am fitting an electric fan. I have removed the original, so this will be my only fan and as a result I want to make sure that the wiring is done properly. Electrickery scares me, so I am hoping for some advice.

I want to use a two position switch (auto on and manual on), rather than the three position one mentioned in Dan Master's book - I don't want to give myself the option of switching the fan off, it would only end in tears. The switch has three connectors - Marked power, load and ground. Ground is obvious, but I am confused about the other two. My fan came with a relay and such, and it suggests that the wire from the AC sensor is used with a switch when no AC is fitted. My guess is that this is used so when the AC pump is on the fan runs. Does this go to the load or power contact on the switch? What goes to the other? A line from the + terminal of the battery?

I am supposed to connect to an unswitched fused 12v supply. This is a purple wire, I think (75 car if it makes a difference). The problem is that the two connectors on my fusebox for purple wires are used, so I need to tap into one somewhere. What's the best way to do this? Cut the wire and use a tube type crimp connector? Use one of those Quick splice connectors? Something else?

Any thoughts on the best location for the relay? My original plan was to put it close to the original relays, but that is very inconvenient since my thermostatic sensor is in the solid water pipe (from the bottom radiator hose to the water pump) and I plan to get my 12v supply for the fan from the starter, though I have enough 12 gauge wire to route around the engine bay if need be.

I am a bit confused about what is needed for a ground. Looking at the ground connections which have served so adequately for 30 years I wonder whether I really need a big grounding block. Can't I just put a connector around pretty much any bolt going into the chassis or body? I know that everyone who posts pictures online shows their super duper grounding block with lots of connections screwed in, but is that really necessary? Is that just another example of the "I must use grade 8 hardware to attach my cup holder" mentality which many of us (myself included, I admit) are guilty of?

Crimp or solder? Any way to check my crimping, other than a tug on the wire?

Sorry about all the questions. Any advice welcome, as usual!

Thanks
Alistair
A Hewitt

Alistair

You will already have a power supply to the thermostatically controlled fan. The switch to be added should be simply connected across the thermostat contacts - i.e. in parallel so that it can replicate the thermostat's function when you feel additonal cooling is required. NO ADDITIONAL CONNECTION is required to the 12v supply.
I would check your switch - you probably only need the "power" and "load" connectors but a check with an ohmmeter will confirm.

Good luck.

Barry
75 TR6
BJ Quartermaine

Alistair

If I understand correctly, here is what should work

Power should be for the 12V power from the battery. Pulling it off the main power lead to the starter should not be a problem.

To connect to teh fuse box, you can buy or make a "y" connector. This is a connector that you can put on the fuse box power spade connector and it splits into 2 spade conenctors for your fan relay and for the purple wire.

Load is the signal from the thermostat sensor. When the sensor closes (completes the circuit), it triggers the relay which starts the fan. When the sensor opens, the fan power is disconnected.

You need unswtiched power so the fan will run after the car is off and if it still needs to cool. If it is in a switched circuit, the fan will not run when the switch is off.

As far as ground goes- I don't know if your fan is in a plastic suppoort. If it is, it probably needs a dedicated wire from the ground connection to a location on the car. In my book it does not matter where you ground it- to a bolt or grounding block. My opinion is a block looks more professional but that is about it.

I solder as a rule. Crimping I have found eventually oxidizes and you get a poorer connection. But crimping will work. A gentle tug on the wire is the best way to test a crimp. If it pulls out, it isn't good enough.

Hope this is somewaht clear and helps.
Michael Petryschuk

Thanks for the help. I got the fan wired up yesterday and then installed my new battery cables so I could test it. As an aside, did you know that the negative battery cable has two possible orientations for the conectors for the block and body, and apparently was not standard from the factory - some connect to the block first, some to the body. I found this out after calling Dave at TRF to complain that my new cable was wrong. Well, I found it interesting.

I searched and searched for my soldering iron, but could not find it, so everything was crimped. Not my first choice, but I really wanted to get the fan in. Of course, I have questions...

While looking for a location for my switch, I realised that the courtesy light switch just in front of the gear lever was not being used, so I connected to that. So, I now have three ways to turn the fan on - the switch, the probe that goes into the radiator fins, as supplied with the fan, and a sensor in the stainless steel pipe from the bottom radiator connection from Revington TR. All in parallel, so hopefully that will make sure the fan comes on when it is needed.

I would like to have an indication in the car when the fan runs, and inspired by my use of the courtesy light switch, I figured I would try to use the EGR light (or the fasten belts light, or whatever the other one is). There is a second 12 gauge wire coming from the relay output to the fan. This is intended for a second fan, but could I use it for the light? From what I understand, I would need to fuse this line. The fan wire has an in-line 25 amp fuse, so do I need the same on this wire? If I use smaller diameter wire to feed the light could I just fuse it at 5 amps or something like that? Call me old fashioned, but I don't like the idea of 25 amps to a light on my dash. Maybe I don't understand electrickery (actually there is no maybe about it!) but my limited recollection of A-level physics suggests that the current through the wire will be limited by the demand. So, a small lamp should never need more than 5 amps. Am I wrong?

Thanks again for the advice. What would I do without the BBS?
Alistair
A Hewitt

Alistair, I wired the Perma Cool 16" electric fan to my '72 last year using the Dan Masters drawing and very thing worked well. The only problem I have is that the fan draws so much current the engine will stall when the fan comes on if I don't feather the throttle a little. I am however using Richard Goods GP3 cam and I idle at about 1200. I don't know if that would make any differance though. I am also using his fan shroud and found that even on the hottest days, as long as you are moving the fan won't come on, and when it does, at a stop it's for no more than half a minute or so. It's inconveniant enough that if I can put the stock fan back on without removing the rad, I might do it. It's not easy trying to tune carbs when the engine idles down so much when the fan comes on.

Rob
rw loftus

Rob, Do you have it running thru relays?
What Alt. are you using?
DON KELLY

Don, my car is one of those weird late '72s that used the GM alternator. I've been trying to find out if GM used it in anything else just to make replacement easier in the event I need to replace it. Yes I am using a relay. The one I am using is very common in GM vehicles, according to the parts guy. Itis wired as per Dan Masters diagram. I put a fan switch out of an '80 Aries into the lower rad pipe. It comes on at 180 and shuts of at 165. I used that switch because of the temp. range and also because it has a 1/2" pipe thread which made installation a breeze. The fan if memory serves, draws about 20 amps to start and 8 running. I think it is way more than is needed.

Rob
rw loftus

Rob, are you saying it is a stock Alt.?
DON KELLY

Yep, if you have TRF's green cat. it shows the GM alt. for use in the late '72's, I think, it was a long time ago that I looked at it. They recomend you switch to the Lucas in the event of a GM alt. failure. Maybe they have a replacement GM by now, don't know. I would not go Lucas though, GM again.

Rob
rw loftus

Rob, you need to upgrade that to at least a Bosch unit or a Delco. The one you have is probably about 34 amp at best.
You will see an improvement with the converstion.
DON KELLY

Don, I checked TRF's cat. yesterday. On one page they say the GM alt was used on some cars up to cc75000. on another they say up to cf1, so who knows.

Yes, according to the book it is I think 35 amps.

I wondered about using a bigger alt but my thinking was a 20 amp load is a 20 amp load reguardless of what the alt total potential is. I would think that the load on the engine would be the same, is it not? You are suggesting that a larger alt can generate more amperage with less load on the engine?

I drove around town yesterday with the fan shut off just to see what would happen. It was about 70F. In very busy stop and go traffic the temp guage never went above 3/4, and in less busy traffic it went back down to about where the fan shuts off, 165. So, I am so far inclined to think that I could get away with a fan of a much smaller cfm, therefore less current draw.

Rob
rw loftus

Rob- A lot of us have big fans. We all run a larger alt. too. 55 amp+. It is an easy do just ask for some ideas from some of the other members. There is a Bosch unit that is a direct bolt on and even a Luca one that is about 100 amp but is pricey for about 2 bills. Many have the American 10 SI unit . Can't help you with the install on that as I don't have stock wiring in mine but there are lots of articles on the web for installs.
Hey where are the rest of the folks to help this guy.
Rick, Rod, Doug?????
DON KELLY

Don, I've read lots of stuff about the GM 10si alt. but didn't know if it would make a difference. I guess what I'm thinking is if it takes a certain amount of horsepower from the crankshaft to make 35 amps of current with my alt, wouldn't take the same amount of crankshaft energy to make 35 amps even though I had the potential to make 55 amps, and wouldn't 55 amps take a little more power? Obviously I don't know diddely about alt's, I can wire ok, Dans wiring schematic was not a big challenge for me, I just don't understand why a 35 amp alt won't keep up unless with the fan it is totally overloaded. I knew with quartz lights and a boom box a bigger alt' would be benefitial, I just didn't know it would be required with my fan. Obviously I was wroung.

Alistair, a thousand apologies for high jacking your thread, but when I get this fixed I will be very happy and this is helpful.

I'll start looking for alt. convertion info.

Thank You very much Dan

Rob
rw loftus

Don, sorry, I'm embarassed.
rw loftus

Rob - hijack away! Always interesting to see where things go.

In this case I am very interested - I am confused by all things electrical but place great confidence in Dan Masters' book. He has a table of "typical" loads (i.e. loads which might be on while driving)which comes out at 21 amps. That doesn't include the ignition system, though - no idea what that draws.

My new fan has a running rating of 11.5 amps, so I have to guess that's over 20 amps on start-up. Now Dan's 21 amp typical load includes things like wipers and heater - since my heater motor isn't even hooked up from the last time I was looking for a short circuit, I reckon I have a 15 amp load without the fan. So if the fan kicks on that takes me to 35 amps or so. My alternator is rated to 43 amps (original but rebuilt 18ACR), but that is only at the ideal revs - about 3000 rpm as I recall. If the fan kicks on at idle (and that seems to be the most likely time) then I think I may have a problem. In theory the battery should handle the short term load as the fan starts, but as I understand it the voltage will drop from 14.6V from the alternator to 12 volts from the battery.

My alternator is not that old, and I have just spent far more than I planned on an engine rebuild, so I would rather not buy an upgraded alternator right now. I guess time will tell whether I need one or not. I think if I had an older alternator rated at 35 amps or less I would be more concerned, but even my rebuilt Lucas unit is probably underperforming at its age - I am a bit older than the car and I certainly don't perform as well as I once did!

Does anyone have any idea what the ignition system draws?

Assuming I need a new alternator, any ideas on part numbers, prices etc. for the Bosch unit? I would much rather have a direct replacement rather than cutting wires.

Cheers
Alistair
A Hewitt

Running rate of 11.5 but probably a lot more on start up.
Alister I'll look up the info for the Bosch which is the easiest to do and get back unless others can help out.

Rob-Don't be embarrassed. I remember when I was you and Rick and others were setting me straight.Not that long ago.
DON KELLY

I had an alt guy recommened to me yesterday. Then I got thinking, being as I already have a Delco alt., maybe there is one with a larger capacity that has exactly the same wiring as the Delco Remy Delcotron model DN460 that is in my car now. Worth a shot, will let you how I make out.

Once again, many thanks.

Rob
rw loftus

The Delco Remy you have id different than the Delco that GM uses I believe.
DON KELLY

It would seem Don you are right. The guy I went to was recomended because of his knowledge of Lucas, therefore Brit cars. I explained my problem, and what alt I had, and he said that the GM alt was probably the most cost effective. He did recognise my alt and thought maybe the only other vehicles it was used on was tractors. He thought maybe it could have been rewound, but wouldn't have been worth it compared to going the GM route, so that is what I did. He also ageed that parts are probably next to impossible to get. Made the decision real easy. I now have a 65 amp alt to install. The guy marked the wires on the plug for me and even gave me a bracket that will work.

Thanks again

Rob
rw loftus

That is a shop that should get your business for a while. Nice customer service!
DON KELLY

Don, I just finished the wiring and fired up about 1/2 an hour ago. All is right in the universe again. No drop in rev's when the fan comes on.

Alistair, I put my relay right on top of the original one on the inner left fender by the wiper motor. Put the inline fuses there as well. I left them long enough to pull out to make replacement easy but they tuck in between the fuse box and the relay real nice. I did run the fan wiring all the way around the engine bay, I thought with the heavy wire it wouldn't matter much. I took the time to pull it through a length of 1/4" heat shrink, it was real tight. The up side though is that it wrinkled the crap out of the heat shrink. With it tucked under the original harness running along the fender and along the front, if you didn't know these cars you would think it was original wiring!

Good luck and thanks again.

Rob
rw loftus

This thread was discussed between 02/05/2008 and 17/05/2008

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