TR2/3/3A generator to alternator

I am restoring a 1954 TR-2 Long Door. The body, chassis, suspension, engine work is complete. I am now installing the starter, finishing the wiring, bleeding the brake system and installing the new alternator that I purchased from Rimmer. It is the one that looks just like the generator but, puts out twice the amps and is quite a bit lighter.

I plan to keep the voltage regulator, gut it and make the wire connections inside. Does anyone have some hints on how to make this transition easier?

Dick

Check with Rimmer. Some parts vendors have started selling the Powerlite brand of alternator that looks like a generator. Powerlite already makes a dummy version of the control box that can be used as a junction box. BP Northwest also sells these dummy boxes if you are looking for one in the U.S.

If you want to make your own converted junction box, see the Mini Mania tech article linked below. The dummy box conversion is discussed in paragraph 3.

Mini Mania Dummy Control Box Link.

On a TR2/3, I would suggest not installing a jumper between F and E as the Minimania page suggests. That lets you continue to use E as a ground tie point (it originally had two wires, one goes through the harness to the back of the instrument panel, the other to the body nearby), and F as the tie between the lamp output from the generator and the harness wire that runs to the indicator on the dash. I actually linked A, A1 and F (instead of A/A1/D) so it was a straight shot across the back of the terminals; then used D as the tie point for the dash lamp. That also matches the original wiring better.

For the jumper, I just used a short length of 8 AWG wire, stripped of insulation long enough to cover the back of all 3 terminals (about 1-1/2" IIRC) and soldered directly to the terminals. After soldering, I cut away the excess length. Sorry, didn't take any photos. Years ago, I did an alternator conversion that relied on the original jumper between A and A1 and the connection between the terminal and the flat conductor eventually opened up. So this time I wanted to get a connection directly to the brass block that forms the terminal (on TR2, 3 and early 3A).

It's worth trying without it at first; but with both of my alternator conversions (closer to 60 amps than 40), I found that the ammeter needle would hit the stop on the charge side at every cold start. After a few weeks of that happening every day, the needle started visibly sticking against the peg, which I took as a sign that the movement was being damaged by the banging. So, I installed a shunt on the back of the ammeter, in effect converting it to a 60-0-60 rather than 30-0-30, but otherwise keeping it fully functional.


Of course, this also depends on having the alternator connected through the ammeter and not directly to the starter solenoid as some instructions suggest. (I have no idea what the Rimmers instructions say.) Some claim the original harness won't handle the extra current, but I had no problem in 20 years service on the 3A and about 5 years service on the TR3 (so far). However, if you add more electrical loads, I feel it's best to get power for them directly from the A/A1/D junction. I added a Lucas fuse block there, as well as the feed to the headlight circuit breakers (hidden under the dash). My plan was to eventually use a more period-correct fuse block, but I'll probably never get around to changing it.

Thanks Randall,

Dick

+1 to what Randall said— I’ve got the powerlite unit, dummy control box (which I made myself from an old box, and installed a hi current fuze), and the ammeter shunt. I don’t know if you bought your harness yet, but British Wiring will make up a harness using an alternator.

Randall,

I am at the point where I have installed the Rimmer Powerlite alternator and have talked to BNW about their installation instructions, re-using the existing regulator. It almost sounds to simple?? Their teck said that they hadn't gotten any complaints from using these instructions.

1- Remove Field Lead (marked F) and the warning light lead(small wire on the D terminal) and attach wires together.
2- Remove generator lead (large D wire) from the regulator and move to terminal A to create a battery feed. Insure this wiring is rated for 40AMPS minimum.

I assume he is referring to the large D wire?

Connect two wires to the alternator.

Do you see any holes in these instructions, or "Randall Hints"?

Dick