| JTHOMPSON | -- 08-07-2010 @ 4:46 PM |
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On the way home from a car show today, I noticed that my ammeter was reading zero at road speed or slightly negative if I applied the brakes. On the way to the show, the ammeter did show a positive reading at road speed. Is there a quick way to narrow down the problem? Suspect the generator has given out or the cutout is the issue. I pulled the band off the generator and it looks normal from what you can see with the band off.
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| 37RAGTOPMAN | -- 08-07-2010 @ 5:01 PM |
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Did you smell anything burning, ? while driving,??? if you want take the fan belt off.,RUN A HOT lead to the post on the generator. keep hands away from fan, take the cutout off first. touch the wire from the battery to the post on the generator, see if it revolves, it should if it is working, if it is not you can clean it up and maybe install new brushes of rebuilt it,and test it again, this GENERATOR is a form of DC ELECTRIC MOTOR, I BURNT a generator 2 years ago, and for the time being installed a ALT,[ BITE MY TONGUE ] but I have to say it works flawless,and in the mean time will get a generator rebuilt so I can use it for judging, CERTIFIED AUTO ELECTRIC sells these with the fan adapter , it will install in 20 minutes. GURANTEED,!!!!!!!! use original wire that goes to the cutout, just inlarge a little to install over the alt post, THIS IS IF YOU WANT TO GET THE CAR ON THE ROAD NEXT WEEK, the cost is about $225.00 which it not bad ,this is a outright price. and it is NICE SET UP. only 1 wire,
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| JTHOMPSON | -- 08-07-2010 @ 5:37 PM |
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Ragtopman: I may have. Kind of hard to tell as it was hot out and you get all kinds of smell on a day like today. I don't have a need to get the car on the road 'next week' so I'll do some testing as you suggested. Thanks for the quick response.
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| supereal | -- 08-07-2010 @ 6:55 PM |
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Place the leads of a voltmeter across the battery terminals. With the engine running at a fast idle, you should see about 7 1/2 volts. When you let the engine idle down, the voltage should drop to just over 6 volts if the cutout is working. The original cutouts are just a relay that opens when the system voltage falls below the battery level. This also prevents battery discharge when the engine is off. If you find that the generator is charging, you may find one of the solid state cutouts to be a big improvement. C&G (800/266-0470) has them on page 132 of their on line catalog www.cgforparts.com They also sell rebuilt generators if you find that is necessary.
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| JTHOMPSON | -- 08-14-2010 @ 12:12 PM |
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Found the problem. Years ago, the cutout was converted to use a rectifier. It came unsoldered so I soldered it back together and we're back on the road! Thanks for everyone's help
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| ford38v8 | -- 08-14-2010 @ 1:10 PM |
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jthompson, as I understand the system, when your battery is not up to full charge, you will show a + on your ammeter. This would normally happen during the first few miles after starting your engine, as the starter motor would draw the charge down. When the battery is topped off, your cutout will open to prevent overcharging, and you will show zero. Your ignition requires very little juice, but accessories and lights would draw your battery down, requiring an adjustment of your third brush if you frequently drive at night. With the cover band off the generator, moving the third brush down slightly will raise the voltage to accommodate the requirement. I expect that either Super or Tom will confirm or set me straight? Alan
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| supereal | -- 08-15-2010 @ 1:52 PM |
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Alan is correct. The purpose of the cutout is to disconnect the generator from the battery when the output is is lower than the system, such as when the engine is at slow idle or shut off. Many cutouts were converted to a simple diode to replace the former relay. In most cases, this worked OK as long as the diode held up. Many early diodes couldn't handle the current, and failed. C&G sells a better version on page 132 of their online catalog www.cgfordprats.com
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| MG | -- 08-24-2010 @ 12:03 PM |
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I have this same problem with the gen on my '34. I took the band off and tweaked the 3rd brush a litte bit and it started charging again. It will work OK for a while and then stop charging again until I move the 3rd brush a little bit again. I don't know whats going in there. I tightened all connections I could see in there and the brushes have a lot of meat on them. I did clean the commutator also but to no avail. Any suggestions as to what might be going on in my case and what I should look for?
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| supereal | -- 08-24-2010 @ 3:15 PM |
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MG: It is likely that the commutator needs to have the mica segment separators "under cut". When the commutator wears down to that point, the brushes are held away from the segments. Years ago, every shop could do the job, but today it is likely you will have to spring for a rebuilt generator.
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| MG | -- 08-29-2010 @ 2:27 PM |
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supereal, I've been thinking about my charging problem (or lack thereof) today and decided to do a little experimenting. I took the cover of the generator and then started the engine. Sure enough, no charge on ammeter even when gunning the engine. While the engine was running I sprayed a very small shot of Electrical Grade CRC 2-26 on the brushes and commutator. The ammeter showed a charging condition immediately when I did this. What do you think?
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| supereal | -- 08-29-2010 @ 3:07 PM |
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I suspect my earlier suggestion above will fix the problem. You can also check the brushes to see if they are sticking or badly worn. When the brushes wear, the spring tension that holds them against the commutator lessens, as does their contact. That is probably why the charging improved after you sprayed it, because contact was restored. It is likely the improvement is temporary, however. The three brush generator is obsolete and, as far as I know, an armature is not available. Brushes are, but if the commutator is badly worn, it is probably a better choice to go with a rebuilt. C&G has them for $150 each, exchange.
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| MG | -- 08-29-2010 @ 4:01 PM |
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The brushes have a lot of "meat" on them. I'll let you know how long this "fix" lasts. I don't suspect lack of spring tension in that I didn't touch anthing inside the generator. Also, it wasn't an "improvement" in charging as there was no charging at all prior to this little "shot" of CRC. Even if this turns out to be a temporary fix, I'm tempted to just leave it as it is for awhile as opposed to replacing the generator immediatly. I don't drive the car at night and the ignition circuit doesn't draw an excessive amount of current to cause the battery to deteriorate rapidly.
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| supereal | -- 08-30-2010 @ 9:24 AM |
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Brushes can stick in the mounts, even when there is lots of material left on them, and the connections can also loosen. Be sure to exercise the third brush carrier to keep the connection good. You can burnish the commutator surface with some fine crocus cloth placed over a wooden slat. If the wear isn't down to the separators, it may restore the charging. I have a one wire alternator on my '47, and even though the current requirement of the ignition isn't great, the alternator does kick on after a few minutes of driving to replenish the starter draw, and the accessories such as stop lights. The power to the coil is important, as it runs on only about 3 volts after the resistor. If it drops below that level, you will likely stall.
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| Johns46coupe | -- 09-01-2010 @ 8:21 PM |
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MG, assuming that your generator armature commutators do need to be undercut, you might try this rather than a rebuilt. In a former life, I manually undercut a number of armatures on motors which, for all practical purposes, are the same as generators. It can be done with a cutoff wheel in a Dremel tool. I've even done them with a hacksaw blade and on small armatures, a knife. I would use a Dremel tool with a reinforced cutoff wheel. The trick is to stabilize the armature securely and use the tool to cut the separators between the commutators a 32nd to a 16th of an inch below the commutator surface. Use the Dremel so that the rotation moves the tool AWAY from the windings so that if you get a snag, you won't cut wires. Be sure the undercut area will clear the ends of the brushes. You may even have to wear the cutoff wheel down in order to get a small enough radius to get in close on the end where the windings attach. If the commutators are badly worn, you should get them turned at a machine shop before undercutting. As I said, I've not done a generator armature but see no reason why it can't be done. John
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| supereal | -- 09-02-2010 @ 10:56 AM |
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I've never tried the Dremel tool approach. We always used a hacksaw blade that was ground to the width of the mica. It doesn't take much to get the 1/64 to 1/32 cut. Be sure to repolish the commutator, when the undercutting is done, to remove any burrs that will quickly wear down the carbon brushes. Use sandpaper, not emery cloth, for that purpose, and carefully blow out all particles with compressed air when finished.
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| MG | -- 01-18-2011 @ 4:43 PM |
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I replaced the brushes and this seems to have resolved my problem. Even the horns seem to work better! The new brushes have 3/16 inch more "meat" on them than the ones I replaced - Spring tension means a great deal. Sorry about this late response.......MG
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