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Triumph TR3 - Generator Rebuild?

Hi folks: I have a charging system question. When I run my car at night w/ the lights on, the amp gauge reads 0 as it should. But when I put on the high beams (into to which the driving lights are wired) the gauge dives drastically to the negative side, sometimes actually getting mechanically "stuck" at the stop pin. Then I have to tap it on it's side, after which it comes back to read slightly negative.
This makes me think that the generator is not keeping up with the electrical draw, thereby depleting the battery charge. Does that sound right?
I am going to review the mauals for trouble shooting this, but if anyone else woould like to chime in, the more the merrier...
Thanks in advance,
Mike G. '56 TR3
Mike Gambordella

Hi Mike,

I'm not experienced enough to field your question, but I did float it by some folks who probably are. Here's what I got:

> This makes me think that the generator is not keeping up with the electrical draw, thereby depleting the battery charge. Does that sound right?"

Yup, that's right. All except the ammeter shouldn't get stuck just from being bounced off the pin. Now you know why alternator conversions are so popular.
Randall


Sounds as though you might have two issues working together, Mike. I would question why your generator isn't keeping up. I'm running plain-Jane halogen headlights, and the stock generator seems to doing fine. I did pull my generator apart and replace the almost-completely worn brushes with new ones, and I cleaned up the armature and lubricated. Seems to be working just fine. It's not like you're trying to run a hairdyer from a cigarette lighter. Right?

Good luck !

Bill
Bill Stagg

In the daytime, my ammeter reads about 2 amps charge. When I turn on the headlights, it reads 2 amps discharge. If the wire or wires coming out the generator are not secure, check them first. That's easy. I had the big one slip off 3 times on the way to Colorado. The ammeter went to mius 30 - but the red light came on as well. Once the engine was cool, I crimped the slip-on connectors a bit tighter with my long-nose pliers. Problem solved.

You don't say if the red light comes on when your meter goes "tilt".

What is it that you tapped ? The generator or the ammeter ?

Once I had a dead click to minus 30 amps and it was the directional flasher unit that was smoking. I disconnected these 3 wires and taped the ends and got home the last 100 miles - no problem. I replaced the unit and that solved that problem.

When I bought my TR3A (46 years ago - ye-gad!), the battery was spitting acid up all over the inside of my hood and on the battery box. 30 years later during my restoration, (new battery box etc.) I re-set the voltage regulator. All that time it had been factory set to stop charging at about 15 volts instead of 13.6 volts. The ammeter always read 5 amps in the daytime and 2 amps charge at night. That boiled the water/acid and I had to add a lot of new D.I. water. In 1989, after re-setting the control box as per the manual, it has been fine. I rarely add any water.

Check the control box. Inside there are a couple of coils with "contact points" at the top of each coil. Take a tiny flat file and slide the file between the tips of these points. Oxide can build up here. Don't use sandpaper. We don't want sand (silica) to get embedded in the points. It is an insulator.

Somtimes when a problem like yours happens, you pull the black cover off the control cox and with your finger push on these points and that sometimes cures a problem. I don't know why, but it does. There will be a couple of sparks but no damage.

The brushes in a generator need to be replaced about every 50,000 miles or earlier. That's my experience.

If you pull the generator, clean out any dirt between the commutator segments with a sharp tool or the corner of a small screwdriver. Some new or re-built generators actually lose one or more of the copper secments around the commutator. It looks like the basic bakelite was not good enough. It happened to a friend with a new one. It happened to mine. It had been re-built so many times and the O.D. of the commutator had been turned so many times on a lathe that there was almost no copper left and some segments "peeled" away like copper foil.

I have two generators. I carry the second one (re-built) as a spare. It fits nicely next to the spare tire. This, according to the "Lucas Laws of Probability" means that the one in the car will never, ever break down.

It's simpler to me to fix the present system than to go "non-original" and switch to an alternator.

Don Elliott, 1958 TR3A
Don Elliott

Mike-Your comment that the ammeter needle comes back to near zero after you tap the gauge might mean that the ammeter is the problem. Try checking with another gauge.
Berry

Thanks guys.
Just as I thought. Once it gets a little warmer out (like above 0!) I'll get around to working on the 'ol buggy. We've been re-finishing the upstairs of our 1855 farmhouse this winter, (yikes!) so there hasn't been much time available to spend on the car.
(where the heck are my priorities?)

Bill: I too have plain jane halogens, but I also have auxillry driving lights which come up w/ the "brights".
I don't recall this happening prior to installing the halogens. This little extra may be causing the generator to show it's age. Thank goodness Nan doesn't use a hairdryer!

Don: My ignition light does not come on when the gauge gets pegged. It's as though the gauge over-reacts from the large increase in electrical draw by bringing up both the brights and the driving lights at the same time. (although I do like the amount of light provided) The needle bounces around on the spring, and sometimes gets stuck up at the top of negative. Once it's been "encouraged" to return,(it's the actual side of the gauge that I tap)it's fine, just reads slightly to the negative side. I forget how much so from last season, but I don't think it's more than 5 amps.

Berry: I don't have an extra gauge, so I think I'll run the car, and check the output at each location right through the entire circut. Make sense? I have yet to check the manuals as well - short on time.


My philosophy seems to be developing into one of buying brand new parts when they are on sale -needed or not- then I can rebuild originals and always have a brand new extra on hand for that "rainy day".

Thanks guys, for your help - I'll keep you posted.
Mike G. '56 TR3
Mike Gambordella

Mike-My thinking was that the ammeters are very excitable and a small surge of current sends the needle wildly swinging. Probably old age weakens whatever spring dampens them.
Berry

Good thinking Berry, because that's exactly what's happening. As far as I know, they are the original gauges.
Thanks again,
Mike G.
Mike Gambordella

Mine are all original and they only act up like that if something is causing it to happen.

I found a place in Minn that can repair gauges.

Check out these guys. They say it will cost about $25.00 to $85.00 to repair a gauge.

http://www.gaugeguys.com/

Don Elliott, 1958 TR3A
Don Elliott

Mike - Disconnect the flamethrowers and see what happens to the gauge.

Don
Don Elliott

I have had that same thing happen, plain halogens and no driving lights. Just happens occasionally, not always at night either. Always a relief to see the guage come back to center after tapping. For a daily driver, it seems to be prudent to go with an alternator and high tech starter. But I'm stubborn. And I've changed control boxes and starters 3 times in as many years. I really like the quirks, I guess.
Tom

This thread was discussed between 12/02/2004 and 22/03/2004

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