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Thread: generator doesn't appear to be working

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  1. #1
    Senior Member 2billydavies's Avatar
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    Question generator doesn't appear to be working

    hi guys... me again. another quick question for ya'll. You might remember, my generator wasn't charging my batter after installing new belt.

    Well, I took the generator out and opened her up. There doesn't appear to be anything wrong with it on the inside (not that I would know what i'm looking at it, but everything appears to be in great shape). So I'm starting to wonder a few different things.

    The battery started going dead and not charging the moment I put a new belt on. So here's a few questions about the belt:

    1. I understand the belt should only have about 1/2" of "play" in it. But let me ask you.... when the belt is on, should I be able to very easily grab the generator pulley and easily spin it? Not rotate the entire engine or anything... i simply mean be able to turn the generator pulley very easily by hand while the belt is on? I can do this to the water pump pulley as well. It very very easily spins. Which is really starting to make me wonder do I even have this belt on tight enough?? I'm thinking maybe the belt just isn't tight enough and its just slipping very easily.

    If you remember, my father had a lawnmower belt on this thing for probably 20 years. After it broke last month, I went to Napa and simply had the guys there size one out for me. It's much skinnier than the lawnmower belt..... but for the life of me I can't remember if I could easily spin the pulley's by hand. I don't think I could.... which leads me to think the belt simply isn't tight enough.

    2.: in regards to the generator... how "freely" should this pulley spin? there is no resistance at all when I spin the wheel in either direction. Again, I can't remember if there was any resistance at all before I had the issue. I don't think there was.... but this thing spins very easily. Thoughts on this?

    Before I go out and buy a new generator, please let me know what ya'll think. Maybe I should just really tighten this belt up a bit more? What i'm thinking is 1/2" play in the slack of the belt might be close to an inch or something.

    thanks a ton!
    Billy

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    Jedi Trainee Merlin63Tr4's Avatar
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    Re: generator doesn't appear to be working

    Sounds like your belt is way too loose or you are using the wrong belt (too narrow) for the pulleys on the car.

    If your TR still has the wide belt pulleys (uses a 3/4” wide belt) you should tighten the belt until it has between 3/4” to 1” of slack at the middle of it’s longest run (between the crank pulley and the water pump pulley).

    The Gates P/N for a cogged wide belt is: Gates 695


    If your TR has been modified by replacing the pulleys to use a thin belt (uses a 1/2” wide belt) you should tighten the belt until it has between 1/2” to 3/4” of slack at the middle of it’s longest run (between the crank pulley and the water pump pulley).

    The Carquest (Gates) P/N for the thin belt is: Gates 7380 XL


    M.
    Merlin the '63 Tr4.... it grows younger !

    "A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools." -- Douglas Noel Adams (1952-2001)

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    Senior Member SASSAMON's Avatar
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    Re: generator doesn't appear to be working

    Billy,

    You wrote: "it's much skinnier than the lawnmower belt"

    The standard TR3 belt is about 3/4 inches wide at the widest part. V-belts come in several standard widths and are to be used with a corresponding width pulley groove. If a belt is too wide it may come off the pulley. If it is too narrow there will not be enough surface in contact with the pulley to transmit the required power to / from the pulley.

    Sounds like you might have too narrow a belt and just the inside of the belt is touching the pulley and not providing enough friction.

    NAPA can look up the proper belt for your TR3 and if not in stock get it for you in a day.

    Good luck,

    Roger
    1957 TR3 TS21383L "Bettie"
    1957 Triumph TR3 TS21383L "Bettie"

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    Great Pumpkin TR3driver's Avatar
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    Re: generator doesn't appear to be working

    That's my thought too, your new belt is too narrow and is bottoming in the groove. For a V belt to work, it has to only contact the sloped sides of the pulley. Take the belt off and look at the bottom of the groove. If it is polished, the belt is too narrow.

    And in case it's not obvious, there should be considerable resistance to turning the pulley with the belt installed. However, it should turn freely without the belt to stop it, for as fast as you can spin it with your fingers. It doesn't really present any resistance unless it both has field current and is spinning fast enough to generate power (over 1000 rpm).

    Finally, since the generator and control box are so intimately linked; I wouldn't replace either one of them without running through the tests to show which one (or both) is bad. A bad or misadjusted control box can cause the generator to fail in short order; and also can keep it from working at all.
    https://drive.google.com/open?id=0B2...Y5ZjQxZTA2NGFm
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Senior Member 2billydavies's Avatar
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    Re: generator doesn't appear to be working

    oh wow. i'll bet that's it. this belt is totally bottoming on the each of the 3 pulley's. i don't think the sloped sides of the belt are even touching the sides of the pulley's at all.
    thanks everyone. I should have stuck with the 15 year old lawnmower belt. lol

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    Obi Wan
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    Re: generator doesn't appear to be working

    How wide is your belt at its widest point? How wide are the pulleys?

    David

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    Jedi Knight
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    Re: generator doesn't appear to be working

    Quote Originally Posted by 2billydavies View Post
    oh wow. i'll bet that's it. this belt is totally bottoming on the each of the 3 pulley's. i don't think the sloped sides of the belt are even touching the sides of the pulley's at all.
    thanks everyone. I should have stuck with the 15 year old lawnmower belt. lol
    Its only a lawnmower belt when its on a lawnmower.
    Good you seem to have figured it out.
    Tom

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    Jedi Knight
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    Re: generator doesn't appear to be working

    Quote Originally Posted by TFB View Post
    Its only a lawnmower belt when its on a lawnmower.
    But it's still a Tractor Belt when it's installed on a Triumph.
    59 TR3A "Butter"

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