In a message dated 97-07-12 01:13:54 EDT, davepage@intergate.bc.ca (Dave
Page) writes:
> I've been toying with the idea of converting the 4A from a generator-based
> to alternator-based charging system.
Dave:
I can't help you with the mechanicals aspects of the swap, but I can help
with the electrical changes. The instructions below should prove helpful,
should you choose to use a GM alternator. These units are readily available
at any parts store, and are cheap. I paid less than $30 for mine, plus the
core charge of about $10.
I don't recomend using the one-wire alternator for two reason:
1) they are more expensive, and
2) the alternator charge indicating lamp will not work with these.
The primary advantage of the one-wire is simplicity of installation. This is
helpful if you are wiring a car from scratch, but the changes required to add
it to a TR4A negate the one-wire advantage. Even though it takes only one
wire to install, you still have to redo the wires from the old unit.
If your browser makes the following instructions hard to read, let me know
and I can send you a *.txt version of the instructions.
ELECTRICAL INSTRUCTIONS FOR REPLACING THE GENERATOR WITH A GM ALTERNATOR IN A
TR4A
METHOD ONE:
-----------------------------
AT THE CONTROL BOX:
Look for the following wires:
Black: Remove and discard.
---------------------------------------------
Brown/Yellow (2): Disconnect and tie together, with an insulated
connector.
----------------------------------------------------------------------------
Brown/Green:
Brown/White:
Brown/Blue (2): Using a large, solder type butt connector, connect
all 4 of these wires together, and insulate with heat shrink tubing. Be aware
- this connection carries ALL of the current for the car, so it must be a
good connection. You do not want a high resistance here. You may have to go
to an electrical supply house for this type connector, rather than an auto
supply store, to get one large enough to hold all 4 wires. Run two wires into
one end of the connector, and the other two into the other end.
------------------------------------------------------------------------------
------------------
Remove the control box and, please, save for a friend who is a purist!
AT THE OLD GENERATOR:
You will find two wires, Brown/Green and Brown/Yellow. Disconnect them from
the generator and leave in place. Remove and save the generator.
AT THE NEW ALTERNATOR:
On the side of the case, you will find two spade lugs recessed into the body.
The lugs are identified on the body of the alternator as 1 & 2. You will need
a plug (connector) for these. These plugs are readily available at an auto
supply store, usually in a package hanging on the pegboard display rack in
the electrical section, and usually identified as an alternator extension
connector, or something similar. If not, the counter man will know what you
are looking for. There will be two short wires already connected to the plug.
On the back of the case, you will find an insulated screw terminal.
Connect the Brown/Yellow wire to the plug wire going to the # 1 terminal,
using a butt connector, or splice, solder, and insulate with heat shrink
tubing. The plug is keyed, and will only go in one way. Connect the other
lead from the plug (#2) to the screw terminal on the back of the alternator
case, along with the Brown/Green lead from the original harness, using ring
terminals. Both the Brown/Green wire and the wire from terminal #2 connect to
the screw terminal.
You are finished!
There are two things, however, to be aware of:
1) Triumph did funny things when they built these cars, so your car might not
match the configuration above, and it may well have been modified by a
previous owner.
2) You now have an alternator capable of more than twice the output of your
old generator, but the wiring capacity has not changed. If you add heavy
loads, driving lights, high power stereo, etc, you can exceed the capacity of
the wires. Also, If you let the battery discharge completely, the alternator
can possibly recharge with enough current to overload the wires. If your
battery is completely discharged, recharge it with a charger rather than push
starting the car and letting the alternator recharge it. If you must do this,
keep a close watch on the ammeter, checking for overcharging. Under all other
usages, the wiring should not present a problem. The main advantage of the
higher output is the ability to provide a higher charge rate at low RPM and
idle. The standard loads on the TR4A does not require a higher charge current
at normal engine speeds, so the alternator will not be called on to provide
enough current to overload the wires.
METHOD TWO:
--------------------------------------------
AS ABOVE, EXCEPT:
Cut off both ends of the Brown/Green wire - at the old generator and at the
control box - as close to the wire harness wrapping as possible (or, unwrap
the harness, and remove the wire all-together).Connect the two Brown/Blue,
and the Brown /White, wires together at the control box.
Instead of connecting the Brown/Green wire to the new alternator, add a new
wire of at least 10 Ga (8 Ga preferred). Connect one end to the screw
terminal at the alternator, and the other end to the terminal on the starter
solenoid where the main cable from the battery, and the Brown/White wire, are
now connected. Leave the existing wires at the solenoid connected. Very
carefully route this new wire alongside the existing wiring harness, and use
cable ties liberally for support.
Now, the alternator can provide full charging current without worrying about
burning up the wiring.
There is one downside to this approach: The charge indicating light will work
as before, but the ammeter will only read discharge. It will register the
current being drawn by the various loads on the car, but will not indicate if
the alternator is charging.
If you wish to add extra loads, such as a high power sound system, connect
them directly to the battery, properly fused, of course. Loads connected
directly to the battery will not be indicated on the ammeter.
OPTIONS:
--------------------------
There are several other ways to do the replacement. For example, you may wish
to use a larger range ammeter, or you may wish to replace the ammeter with a
voltmeter. If so, contact me with your preferences, and I will try to provide
the appropriate instructions.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/
'74 MGBGT---3000mile/year driver, original condition
'68 MGBGT---organ donor for the '74
|