[DeTomaso] 74 Pantera Amp Gage replacement

[Mike Drew]

> On Jul 16, 2019, at 6:14 PM, Jim Kosloskey <jim.kosloskey at jim-kosloskey.com> wrote:
> 
>   All,
> 
> 
>   My current gage is bypassed due to the potential overheating of the
>   stock gage.

>>>IMHO that’s like removing your tires because of the potential of getting a flat tire. 

There is nothing inherently wrong with the ammeter. There have been numerous failures but I haven’t seen a single one that wasn’t owner-induced. You can do it in two ways:

1). Have loose connections where the two fat wires attach to the ammeter. That causes increased resistance which leads to overheating and potentially a fire. 

2). Have a ridiculous alternator. More is NOT better. A few months ago I was present when a guy with an almost dead battery due to alternator failure, installed a 200-amp (!) alternator. He then drove it only a few miles with the alternator charging the dead battery like crazy, and the ammeter pegged to the charge side. Lori was his passenger and noted smoke pouring out from under the dash. The alternator put out more power than the stock ammeter could handle, and it sizzled it, but good.

If your ammeter is currently in good shape, and you have a reasonable alternator of 100 amps or less, you should be able to connect it properly, make sure the connections are tight, and live happily ever after. 

> 
> >  I am at the point where I am considering replacing this gage. I would
>   like to get one as close to stock but more stable.

>>>If your ammeter got sizzled already by a previous owner, you could replace it with a good original one (I have several spares that I have never needed and could let one go). Hall used to sell a replacement ammeter, but it had a plastic case so the stock illumination circuit no longer works and you have to do a bit of tricky wiring to get it to turn in with the rest of the interior lights. I don’t see it listed anymore. They list a Voltmeter now, which may or may not be a genuine Veglia gauge?

> >  Suggestions?

>>>Personally I would just go for Working As Designed, with proper maintenance (and perhaps a small bypass shunt to route some of the current around the gauge instead of through it). I had a NOS ammeter in the original Ford box, and it came with a brass shunt connecting the two terminals, which the vast majority of Panteras didn’t have originally. The needle will still register charge or discharge, but depending on the size of the shunt, it may not read accurately. But accuracy isn’t really important. If it shows you charging at 45+ when it’s actually 65+, who cares? You just want to ensure the shunt isn’t so large that the gauge barely registers at all because so much current is bypassing it. 

Mike




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-------------- next part --------------
   On Jul 16, 2019, at 6:14 PM, Jim Kosloskey
   <[1]jim.kosloskey at jim-kosloskey.com> wrote:

     All,
     My current gage is bypassed due to the potential overheating of the
     stock gage.

   >>>IMHO that's like removing your tires because of the potential of
   getting a flat tire.

   There is nothing inherently wrong with the ammeter. There have been
   numerous failures but I haven't seen a single one that wasn't
   owner-induced. You can do it in two ways:

   1). Have loose connections where the two fat wires attach to the
   ammeter. That causes increased resistance which leads to overheating
   and potentially a fire.

   2). Have a ridiculous alternator. More is NOT better. A few months ago
   I was present when a guy with an almost dead battery due to alternator
   failure, installed a 200-amp (!) alternator. He then drove it only a
   few miles with the alternator charging the dead battery like crazy, and
   the ammeter pegged to the charge side. Lori was his passenger and noted
   smoke pouring out from under the dash. The alternator put out more
   power than the stock ammeter could handle, and it sizzled it, but good.

   If your ammeter is currently in good shape, and you have a reasonable
   alternator of 100 amps or less, you should be able to connect it
   properly, make sure the connections are tight, and live happily ever
   after.

   >  I am at the point where I am considering replacing this gage. I
   would
     like to get one as close to stock but more stable.

   >>>If your ammeter got sizzled already by a previous owner, you could
   replace it with a good original one (I have several spares that I have
   never needed and could let one go). Hall used to sell a replacement
   ammeter, but it had a plastic case so the stock illumination circuit no
   longer works and you have to do a bit of tricky wiring to get it to
   turn in with the rest of the interior lights. I don't see it listed
   anymore. They list a Voltmeter now, which may or may not be a genuine
   Veglia gauge?

   >  Suggestions?

   >>>Personally I would just go for Working As Designed, with proper
   maintenance (and perhaps a small bypass shunt to route some of the
   current around the gauge instead of through it). I had a NOS ammeter in
   the original Ford box, and it came with a brass shunt connecting the
   two terminals, which the vast majority of Panteras didn't have
   originally. The needle will still register charge or discharge, but
   depending on the size of the shunt, it may not read accurately. But
   accuracy isn't really important. If it shows you charging at 45+ when
   it's actually 65+, who cares? You just want to ensure the shunt isn't
   so large that the gauge barely registers at all because so much current
   is bypassing it.
   Mike
   ________

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   list. They also grant the list owner permission to maintain an archive
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References

   1. mailto:jim.kosloskey at jim-kosloskey.com
   2. mailto:DeTomaso at server.detomasolist.com
   3. http://server.detomasolist.com/mailman/listinfo/detomaso