81 Positive Cable & Alternator

[mb4tim]

OK, I need some TR7 Electrics 101.

My 81 has an alternator that doesn't use a big plug on the back. Just a small one, and two threaded lugs - one heavy wire, one thin wire.

One the positive battery cable there's a black block with 4 terminals on it about 16" from the terminal end. There are 2 heavy red wires, one thin red wire, and on thin red wire with a loose fitting black sleeve.

If I pull one of the big or one of the thin red wires, it stops running. If I pull the other thick wire some electrics won't work, but it keeps running. If I pull the thin red one, I can't tell what happens, but it keeps running.

If I pull the positive cable, the engine revs a little higher, life a huge load has been lifted.

IT will run all day - just don't shut it off, because the battery isn't getting charged. I put a 10amp battery charger on it for a few minutes, it will crank over.

I've taken the alternator to Advance and Auto Zone, they both show a battery with a bug plug on the back, and can't test it.

Some further searching on the information super highway shows that this alternator was used on early-to-mid Jaguars. So, I'm guessing by the time my 81 rolled off, the bins with the correct electrics were empty, and they grabbed the next closest thing.

Will someone please tell me how my battery is supposed to be getting charged while it's running, and how c I test it. Pull both battery terminals while it's running and test the voltage across the cable ends?

I'm so ready to start getting it ready for daily driving, but need to sort out the charging system.

Thanks!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!



-Tim
http://www.morSpeedPerformance.com

[jclay (RIP 2018)]

Tim,

The colors on the 81 were probably changed to protect the innocent!, But here are my 1980 DHC wires . . .

Alternator: (P.S. They use alternators that had three different back connector plates!)

* One small Brown/yellow wire goes to the "IGN" light on the dash panel.
* One Large (A) Brown wire goes to said Black connector in the middle of the main Positive lead.
* One Brown wire goes to the starter.

Black Connector Block on main power cable: CLEAN THESE CONNECTIONS REALLY WELL! Look for corrosion at the wires and the ends of the connectors.

* One large Brown Wire, (A), goes to the alternator.
* One large Brown Wire, (B), goes to the Head Light circuit, Ignition Switch, Fuse 5/6, then to the horn, door lights, clock, fog lights, cigar lighter, hazasd flasher and the buzzer.
* One large Brown Wire, (C), goes to the Starter Relay (then one wire goes to Auxiliary Air Valve) and to Fuses 1/2 & 11/12, both of which are used for the A/C circuit and the Electric Radiator fans, when installed.

Starter:

* White/Orange wire goes to Cold Start injector.
* White/Yellow wire goes to Ballast Resistor Assembly.

Battery:

* Extra Brown wire on the Pos side Battery connector goes to a relay then Mixture Monitor.

Two other wires:

* One White wire from Ign switch to Inerta Switch to Air Flow Meter.
* One White/Black wire from Ballast Resistor to ECU.


I found that the Standard Alternator would not pull the electrics on the car. This was before I found the faulty 50 amp fuse for the Heater fan as discussed elsewhere. The Jag alternator is the same one as the TR7 heavy duty alternator installed on A/C cars (69 amps). I installed a Saturn 96 amp unit and have had no problems since. You will have to find a Ford pulley and a bolt and nut to replace the standard bolt.

[url="http://homepage.mac.com/WebObjects/FileSharing.woa/wa/default?user=jclaythompson&templatefn=FileSharing4.html&xmlfn=TKDocument.4.xml&sitefn=RootSite.xml&aff=consumer&cty=US#12296;=en"]Follow this link, Click on "Triumph_Articals", Then download "Alternator.doc"[/url] Also download TR8 wiring diagrams.

Have fun, drive fast & safe, be kewl,

jclay

[mb4tim]

I'll call the pick-n-pull on Monday. Get the alternator, maybe find a pulley, too.

-Tim
http://www.morSpeedPerformance.com

[jclay (RIP 2018)]

Read the article and then go to your fave Auto parts and buy a new one and the connectors!

Have fun, drive fast & safe, be kewl,

jclay

[mb4tim]

I was the alternator. I'm calling about getting it rebuilt locally (right over the hill from work).

If they want more than $50, I'll go the Saturn route.

Thanks guys. Will keep you posted.

-Tim
http://www.morSpeedPerformance.com

[mb4tim]

I talked to the guy, he's getting a new 105 amp Saturn alternator swapping the pulley and tossing in the pig tail for under $100. I should have it Monday or Tuesday.

The Lucus needed too much.

The different model numbers were for different amps ratings.

I guess with 105 amps, I'll have some be able to run a pretty good stereo!

We may have another alternator type to add to the list. I'll also get a part number for the pulley for JClay's list.

-Tim
http://www.morSpeedPerformance.com

[bmcecosse]

If the new alternator can really deliver 105 amps - then your drive belt will need to be beefed up to provide the mechanical power - because thats ~ 1400 watts ~ 2 bhp assuming perfect efficiency! The power cables (fat brown wires) should also be re-inforced to carry that current.

[mb4tim]

I asked my alternator guy about the heavier wire, said not a problem.

JCLAY! I need an eye from your machine.

My old unit had a heavy brown wire, brown/yellow with lugs to bolt onto the alternator, and what looks like a black wire that slid into a plug on the back for the idiot light.

On my new harness, the guy told me to take the heavy red lead and connect it to the terminal on the back when I bolt up the heavy brown wire.

I connected the brown/yellow wire to the new brown Saturn pigtail.

There are 4 wires on my pigtail, in this order
<ul><li>Red</li><li>Brown </li><li>Brown/Orange </li><li>Brown/White</li></ul>

Do you know which of these if for the idiot light??

How many wires on your pigtail?

Thanks!

BTW, it's running even better now, doesn't want to stall out anymore. New battery and alternator might help that.

-Tim
http://www.morSpeedPerformance.com

[jclay (RIP 2018)]

Hey, Sorry, the broken foot has kept me from getting around and I just saw your post!

I will look later today and post the information on the wires. I know that one wire on the pig tail is to be cut off. It heck getting old!

Ok, Mine only has three wires on the pig tail. <font color="red"><b>RED on the pigtail</b></font id="red"> goes to the small Brown wire on the harness, <font color="black"><b>BLACK</b> is not used and cut short,</font id="black"> AND <font color="brown"><b>BROWN</b> on the pigtail </font id="brown">is connected to the small<b> <font color="brown">brown</font id="brown">/<font color="orange">yellow</font id="orange"> </b>wire from the harness. <font color="brown"><b>Now, the large brown wire from the harness goes to a stud on the back of the alternator</b></font id="brown"> I hope that helps!

I can only assume that as things like motors get old, they have a tendency to draw more amps to run properly. Now, over here on this side of the pond, new motors are not that readily available as they are in England. So we have to do with what we have.

Have fun, drive fast & safe, be kewl,

jclay

[bmcecosse]

Crazy to think the original cable - designed for maybe 40 amps - will now handle 105 amps. Double it up before you melt something!
So saying - how on earth is the car going to NEED 105 amps !!

[mb4tim]

Well, the older 85 amps were replaced by the newer 105 amps. I'm thinking heated seats fro the winter. And, if I'm not needing the 15 amps, I won't be drawing in, and I won't be stressing my wiring.

I'll check into beefing up that heavy wire front the back of the ne alternator. See where is goes, and make it thicker.

Thanks! I'll have starter checked out over the winter. It's a slow cranker.

-Tim
http://www.morSpeedPerformance.com

[black_1980_tr7]

Actually its not that hard to get such high amp demand from
an alternator.

Head Lamps = 10A (55W each on low beam), 17A with high beams
side, trim and dashboard lamps = 15A
electric radiator fan = 12A (intermittent duty)
interior blower = 10A
A/C clutch = 5A (intermittent duty)
fog or driving lamps = 15A
brake lamps = 6A (intermittent duty)
EFI and fuel pump system = 15A (10A are pulsing injectors)
Ignition = 6A (pulsing)
windscreen wipers = 10A (intermittent duty)
battery recharging = variable amount

these add up to more than 90 Amps

Notice that in this list, the day time current is about 50%
less than night time driving current from all the lamps.

Depending upon your how you use your car, its easy to exceed
65A. Its not so much that one will be using a newer 105A alternator
at it's 105 limit, but when the engine is at idle the newer
alternators put out more current. So when the turn signals flash,
there's more power or reserve capacity at 1000RPM to drive the
in-rush current of the lamps. Thus the dash and headlamps don't
momentarily dim down & up with each turn indicator flash.

As for the 6 or 7 gauge brown wire from the alternator,
it should handle a 500A to 600A surge current.
http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
and an time average DC steady state load of 35A without
getting warm.

[:)]

[black_1980_tr7]

Bosch Alternator installation was on this old thread...
http://www.forum.triumphtr7.com/topic.asp?TOPIC_ID=2023

[Odd]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by black_1980_tr7</i>
Notice that in this list, the day time current is about 50%
less than night time driving current from all the lamps.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

In your country maybe
- but in most countries where safety and sensibility reign there are now laws demanding and/or recommendations on using daytime driving and positioning lights at all times [i.e. to be lit day <u>and</u> night]. So the current draw is just about equal all the time, the difference being if the dipped headlights/driving lights are switched to the non-dipped main beam headlights since they are some 5-10 watts more each...

[FI Spyder]

Despite the fact my 91 Integra has daytime driving lights at 40% and my '88 Tercel wagon doesn't but I put lights on in cloudy and late afternoons (sun glare) you won't see me driving Spider with lights on during day. That just wouldn't be cool.