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Alternator questions

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Alternator questions
#1
  This topic is about my 1976 Triumph TR6
72dennis76doug Avatar
72dennis76doug Doug Miller
West Salem, WI, USA   USA
1976 Triumph TR6 "Miss Colleen"
I recently purchased a new replacement Lucas18 ACR alternator (45 amp) for my '76 TR6. I installed it and ran it less than 50 miles before deciding to switch to a GM (63 amp) alternator since I was having an Advanced Auto Wire harness installed. My nephew owns a '72 TR6 with the original wiring harness and most probably the Lucas 17 ACR alternator (36 amp). I would like to give him the 18 ACR as a back-up. I haven't had an opportunity to ask him for any part numbers etc. My questions are these: 1) Will the 18 ACR fit the mounting bracket on the '72. The alternators depicted on plate DW in the TRF geenbook for the 17ACR and 18 ACR look essentially identical. 2) Will there be any problem installing a higher amp alternator (45) in place of the 36 amp alternator.
His car is stock with little, if any, modifications which would require a "beefier" ( is that a word?) alternator. Thanks for any answers you can offer to my novice questions!

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Reddragon Avatar
Reddragon Dale M
Chesapeake, Virginia, USA   USA
1963 Triumph TR4 "Road Runner"
1974 Triumph TR6 "Tweety"
Doug

Recently a friend purchased an alternator for his 74 Tr6, The only one that was listed was for a 75 -76 unit for all model years. The body of the alternator is the same between the 17 & the 18. Having a little more amps doesn't hurt.

Red

dk pony Avatar
dk pony David C
MT Carmel, TN, USA   USA
Just remember that the early 72's had an ammeter and mid-year they switched to a volt meter. The ammeter is only rated to match the stock alternator and using a bigger alternator could burn out the ammeter in some situations.
I don't know if going from a 36 to 45 would cause any trouble but it might be a consideration.

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Reddragon Avatar
Reddragon Dale M
Chesapeake, Virginia, USA   USA
1963 Triumph TR4 "Road Runner"
1974 Triumph TR6 "Tweety"
DK

In Dan Masters book, he addressed your concern.

If the meter was a 60 and not the 30 amp gauge then the update to the 45 amp alternator would not be a problem.

BY using a shunt, a 14 or 16 gauge wire approximately 3 inches in length, would put enough resistance in the circuit to keep the 30 amp gauge from burning and still read close to correct.

For more information google (shunts ).

Red

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
I don't have my information handy; but ISTR that is too small for a TR6 ammeter. You might want to double-check the book. (Earlier versions didn't even mention the possibility of using a shunt; Dan's original recommendation was to wire around the ammeter. Evidently he updated the book after we had some discussions on the topic.)

But given the natures of an 18 ACR and the TR6 ammeter, I doubt it would be a problem. The ammeter won't be overloaded unless the alternator puts more than 30 amps into the battery, which usually won't happen unless the battery is really badly low. And even then, the ammeter probably won't be damaged, just get a little warm. Its internal circuit is just a loop of fairly heavy gauge wire.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

dk pony Avatar
dk pony David C
MT Carmel, TN, USA   USA
As was mentioned it "could" overload the ammeter in certain situations .
It was only mentioned as something to consider.
I am upgrading my alternator to a 60 amp and here is what I did.
http://www.triumphexp.com/journal/dk+pony/15452

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Definitely a good idea with a larger, more modern alternator. I took a somewhat simpler approach and just put the shunt on the back.

This is my old TR3A with a 60 amp Ford alternator (forgot to take a photo of the current TR3 with a 55 amp Denso)





Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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