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Thread: TR3 with Ground Conversion

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    Question TR3 with Ground Conversion

    Hi Folks:

    New here, so kindly direct me to the appropriate discussion if needed. I understand that a popular topic may be negative ground conversion

    I just purchased a 1960 TR3A that has been converted to negative ground. I restore old Brit bikes also, and always remain positive there!

    Some folks in the local Triumph club have mentioned that there are feelings that a negative ground conversion is a good thing on a TR3. I am having electrical ailments on this one however that appear grounding related. It starts and runs great, wipers work fine, ammeter appears to work, but headlights and signals appear to have grounding issues, horns don't work. Headlights have the red wire in the main harness connected to the red/blue, high beams non-functional, park lamps not working except for signals. This doesn't seem like a correct ground conversion? It also has the original generator and a Pertronix ignition installed.

    So, keep the grounding the way it is, or better to convert back?

    Cheers,

    Scot

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    Re: TR3 with Ground Conversion

    Generally to convert to negative ground you just switch the Battery wires and repolarize the generator. That is about it.Many descriptions for doing this on the forum
    Cars of this age do not have a lot of other electrics that need to be changed. Tack is manual, if electric fuel pump then check if it needt to be changed (many work either way)
    Petronix only runs one way. They make units be both pos and neg ground.
    It sounds like you have a general ground corrosion issue with the car or someone just improperly did weird wireing over the years.
    Joe Schlosser
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    60 Bugeye, since 1966
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    Re: TR3 with Ground Conversion

    Yes...these are very easy to convert one way and/or back again! The negative conversion merely makes it much easier if you plan to add a bunch of updates, like an alternator, cooling fan, radio, cell chargers, etc. So it's pretty much what you prefer...assuming you don't already have an alternator??
    John

    1955 TR2

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    Re: TR3 with Ground Conversion

    Quote Originally Posted by CJD View Post
    Yes...these are very easy to convert one way and/or back again! The negative conversion merely makes it much easier if you plan to add a bunch of updates, like an alternator, cooling fan, radio, cell chargers, etc. So it's pretty much what you prefer...assuming you don't already have an alternator??
    An alternator came in the trunk, but the generator is still in the car. Not sure if the generator is for Pos or Neg though. Still in the original box, so sure I can find out!

    Also came with a set of Strombergs in the trunk

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    Re: TR3 with Ground Conversion

    Actually, the generator can be either. It only depends how you jump it on installation. It sounds like the PO had plans to switch to the alternator, which requires the negative ground. The advantage to an alternator is it produces much more power. The original generator is pretty maxed out with the headlights and heater running. If you plan to add fans, radios, or much else, then the alternator conversion is prudent, and therefor, negative ground with it.
    John

    1955 TR2

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    Re: TR3 with Ground Conversion

    Just to amplify what others have said: Your various problems don't appear to have anything to do with the polarity conversion. So whether to take the extra step of switching back, or not, is up to you and what you like. To convert (assuming the car is original otherwise), you just swap connections at the battery, coil and ammeter; then repolarize the generator and you should be good to go. If you should have a factory or dealer radio installed, there will be a switch or plug that you move to change it's polarity. The Pertronix will have to be removed or replaced with a positive ground unit (which also gets wired differently, check the Pertronix instructions for it).

    The headlights and front turn/marker lights should have separate ground wires, that run from the bulb holders back to ground clips just behind the horns on each side. Those clips often break and/or corrode until they no longer function, so that's one of the first places I would check. Remove the screw and make sure there is clean metal underneath, a spot of Vaseline or silicone grease will help prevent future corrosion. Paint does not conduct well!

    Red/blue is not an original color AFAIK; perhaps it is red/green? Normally, one of the red wires would be linked to the RG by an in-line fuse holder, which should be clipped to the inside of the dash just below the instrument panel.

    Likely you've noticed by now, the wiring diagrams given in many places (including the factory workshop manual and Bentley reprint) do not correspond well with the later cars. This is the best diagram I know of, but still has some shortcomings (mostly not showing many of the ground connections)
    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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    Re: TR3 with Ground Conversion

    Quote Originally Posted by CJD View Post
    Actually, the generator can be either. It only depends how you jump it on installation. It sounds like the PO had plans to switch to the alternator, which requires the negative ground. The advantage to an alternator is it produces much more power. The original generator is pretty maxed out with the headlights and heater running. If you plan to add fans, radios, or much else, then the alternator conversion is prudent, and therefor, negative ground with it.
    Sorry, I meant alternator. :-) My understanding is you can buy them in either configuration.

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    Re: TR3 with Ground Conversion

    Good info Randall, thanks. At 20 and 16, you see UR (blue/red) and UW (blue/white). Those are the wires I am referring to. In my car, the UR is currently connected to the R (red) wire going to 37.

    I like that diagram much better than my Advance Auto Wire version! Can you also share the legend that goes with it?

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    Re: TR3 with Ground Conversion

    Try this link, should give you the owner's manual in PDF. I can post the image later, but can't do it just now
    https://drive.google.com/open?id=0B2...EyZDgxMzUyNzUw

    Positive ground alternators do exist, but tend to be rare and expensive. I'd have to say that seems the least attractive alternative, to me. The stock generator actually isn't all that bad, treated with a bit of understanding and without adding any power-hungry accessories (like electric radiator fan). I drove that way even with an electric fan (and with the earlier 19 amp generator) for several years.

    I did finally do the conversion, after the original generator finally died. This one was $50 at Rockauto
    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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    Re: TR3 with Ground Conversion

    .... and that is the one manual I had NOT been able to find online for free yet. You guys are great!

    Scot

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    Re: TR3 with Ground Conversion

    Your pertronix ignition would have to be negative ground as well if the conversion has been done.

    Edit...I see that Randall has already pointed that out! Doh!

    Cheers
    Tush
    81 Alfa Romeo Spider Veloce, 81 Triumph TR8
    73 Triumph TR6 CF4874UO, 68 Triumph TR250 CD5228LO
    62 Triumph TR4 CT6716LO, 60 Triumph TR3A TS69891LO
    60 Triumph TR3A TS64870LO, 59 Triumph TR3A TS44836LO

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    Re: TR3 with Ground Conversion

    Quote Originally Posted by M_Pied_Lourd View Post
    Your pertronix ignition would have to be negative ground as well if the conversion has been done.

    Edit...I see that Randall has already pointed that out! Doh!

    Cheers
    Tush
    No worries! I see one of your flock is a relatively distant cousin to mine (TS65477)
    Scot Dail
    Raleigh, NC
    1960 Triumph TR3A, TS65477 L

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    Re: TR3 with Ground Conversion

    Quote Originally Posted by scotdail View Post
    .... and that is the one manual I had NOT been able to find online for free yet. You guys are great!

    Scot
    You might want to browse through here, there may be a few others that would be at least entertaining:
    https://drive.google.com/open?id=0B2...U1OWRhNDZhYmRl

    And I still have a huge pile of stuff to scan. Bought another one just yesterday, to add to the pile.

    BTW, I'm still looking for the first page of the June 1964 amendment to the Spare Parts Catalogue. If anyone has it, please let me know.
    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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    Re: TR3 with Ground Conversion

    Update - I have sorted the headlights, and have them working properly now. There are too many black wires coming out of the front end, and one was a power hooked to ground for the headlights. Still trying to sort the front turn signals and horn. Rear signals work, front do not. Getting closer! Breaking out the ohm meter.

    SU carbs are running rough at idle, but good once warmed up. The car came with a rebuild kit. Thinking of rebuilding them or the Strombergs in the boot!

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    Re: TR3 with Ground Conversion

    All those non-working items are grounded to the same little grouding blocks (2) on the lower, inside fenders. I’d start with those grounding blocks...
    John

    1955 TR2

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    Re: TR3 with Ground Conversion

    Yes, the grounds are good, I cleaned them all up. I suspect it just may not be connected properly now...

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    Re: TR3 with Ground Conversion

    I fixed most of the same problems you have by simply tightening up all the plugs under the hood.
    If you want to have a modern radio you will want neg. ground. That and the electronic ignition.
    "Triumph with electrical issues" is a redundant statement as is "Triumph with oil leak".

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    Re: TR3 with Ground Conversion

    Randall
    I see that your float bowl is completely dry and there is a hose on the second tube. (overflow I guess)
    I don't have that hose and my float bowls are always a little moist. Where does that hose go?

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    Re: TR3 with Ground Conversion

    Quote Originally Posted by STeve 1958 View Post
    Randall
    I see that your float bowl is completely dry and there is a hose on the second tube. (overflow I guess)
    I don't have that hose and my float bowls are always a little moist. Where does that hose go?
    That second tube is the float bowl vent. Originally, it had a short length of rubber line and a 90 degree bend in hard line, with the other end of the hard line butted up against the mesh in the air filter.
    Since I'm running paper element air filters from a TR4A (which IMO offer MUCH better filtration than the original wire mesh rock catchers), I just put some long rubber tubes on both bowl vents, and routed them down near the RH frame rail. Hopefully, that is keeping too much dirt from getting into the bowls through the vents, and if I do have a problem with a bowl overflowing, the overflow will get routed down away from the exhaust manifold.

    One of my "back burner" projects is to make some housings to accept modern paper element filters, and add a fitting for the vent (so it gets clean air from inside the filter). So far, I've got a pile of parts in a bin

    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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