Last two weekends I have worked on the charging system. First I rebuilt the generator: Good cleaning, bearing, bushing, springs, and brushes. Then I changed out the regulator to an original along with new mounting screws. And then finally today I put a new ammeter gauge in.

Everything seems to work as it should, first time my ammeter actually moves and shows its charging. At night my lights are really bright, hard to believe it's 6 volt.

At idle



And then mid rpm




At night with headlights on the ammeter gauge needle is stable. But during the day with no load it is pretty jumpy. Is that just the nature of the beast or do I need to adjust something?

JB

 

If the wire going thru the loop vibrates, it may make the needle jump? It should be pretty steady at a constant RPM.

 

That's kinda normal for the needle to be a little jumpy if there isn't any electrical load. What you are witnessing is the regulator cutting in and out as required to maintain the 7-8 volt setting. The OEM regulators don't have the "finesse" of today's solid state regulators, they are basically just an on-off switch for the generator. However, if the needle swings very far into the "CHG" then you could have a bad ground or a bad battery.

 

Thank Mixer Man

Using the suggestion from Ross, I took the ammeter wire and aligned it better in the loop and made it more centered. It did settle down quite a bit.

However, one thing I did start to notice was a little dimming and brightening of the dash lights at night, that's a new issue with the voltage regulator change.

The voltage regulator I changed to was an original but not new, so it might have had issues, not sure. I have another NOS regulator still in the box that I am going to install tonight and will see if that corrects the dimming issue.

JB

 

Make sure the belt is tight. Charging system electrical ground and connections need to be resistance free or nearly so, this is also true with alternator systems but they have a lot higher output capacity and can seemingly get away with it. Not so with generators and mechanical regulators. 6 volt systems even more so. Rust and corrosion (or thick layers of paint in restored trucks) wreak havoc. The voltage regulator are often mounted on fender apron or firewall, they need a solid ground reference.

One easy way to check for high resistance is a voltage drop test, with engine running at a high idle, lights and heater blower on, place one end of the voltmeter on the positive battery post (not terminal) and the other on the armature post of the generator.

Since electricity takes the path of least resistance, any voltage drop in the circuit will be displayed as a positive voltage. Circuit needs to be under load for this test. The same test is then performed with the negative battery post and a clean, unpainted portion of the generator case.

The limit for either side should not exceed about 0.2 tenths of a volt. The regulator "sees" corroded or loose connections as a battery that needs charging.

You can measure charging voltage at the battery posts at a high idle RPM (lights on, heater blower) as well. Then connect a jumper cable from negative battery terminal to the Generator case. A marked change in charging voltage shows poor grounding. As a rule battery charging voltages are 1/2 to 2 volts above battery voltage, depending on state of charge and temperature.

Regulators are adjustable for cutout, current, and voltage but they should be pre-set very close to factory settings unless someone has buggered with it. It is adviseable to clean connections including generator to block, replace ground straps etc before any regulator adjustment.

 

In the OEM wire loom there are solid black ground wires from the headlights, voltage regulator, generator, and instrument panel.

 

So I started with a generator rebuild and voltage regulator change out, which brought my ammeter to life. Makes me think for last two years my battery was not being charged properly and maybe one is the reasons for hard starts.

But then my ammeter was jumpy and lights dimmed somewhat, as last few posts suggest.

Popped this bad boy in tonight and everything operates as it should.


Ammeter needle is nice and steady and moves between center position and charge dependent on rpm. I think the original regulator I just took off had been monkeyed with based on the fact it had stainless screws rather than rivets holding the cover on.

JB

 

I've ran a generator in my slick for many years, they work fine but not so much in stop and go/nightime. The truck will always start, but the battery will probably be in less than a full charge. Batteries don't last as long this way. Remember a generator unlike alternator does not charge very well at idle RPM, and consequently the battery is called upon to provide all or nearly all of the juice for ignition, lights, and accessories in stop and go, so it has to have good reserve minute capacity. I keep all my trucks on a battery tender regardless. Classic or antique trucks especially often don't get driven much and this will cause batteries to sulfate and lose performance and capacity. A good charger will pay for itself.

 

So I went back and put a new end plate on the generator, along with a rebuilt armature. When I tightened the pulley nut on the armature shaft, the cooling fins on the pulley are scraping on the front cover in one spot, not all the time but occasionally. I am thinking about cutting a shim to go between the front bearing and the pulley. Thoughts on that? Not sure why it was not rubbing before?

JB

 

"Shouldn't", the obvious question is, are they bent? Suppose not or wouldn't be asking here.

 

Did you stick a screwdriver in the fan to loosen the nut? How bad is the scrape? Just one blade or all of them?

If the armature is not your original, if may be just a little different. Shimming won't hurt except it will move the pulley out too. Grinding off a bit of the blades where they're hitting wouldn't hurt.

 

Ross, I used an impact gun to loosen the nut. I found a metal thrust washer I think will work nicely. It's just 1 or 2 blades. I am going to take it apart again tomorrow and make sure everything is lined up correctly.

Jonathan

 

I will add that I used an impact to tighten it also, maybe a little overkill?

 

It doesn't need to be that tight, it's keyed, right?

 

I took the generator apart again, and everything lines up better now, no scrapes. I seated the brushes while I was in there.

I have two regulators, 8a-10505 rated 30-34 amps and 8m-10505 rated 34-38 amps. Which would be better to install, both are new. The 8a is in the truck now and seems to be fine. Would the 8m give me brighter headlight and tail lights?

JB