• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Gauge cluster refurbishing

OP
OP
fallingdown

fallingdown

Sponsor/Vendor
Bronco Guru
Joined
Jul 20, 2010
Messages
1,604
19377564083_d3f8f8ad49_h.jpg
 

mburkhart

Newbie
Joined
May 29, 2015
Messages
51
Beautiful work. Can you explain why some folks choose to replace the alt gauge with a voltmeter?
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
I'll go ahead and add my answer to your question in the meantime mb.

Two basic reasons these days. One is that some people prefer a voltmeter for various reasons, and the second is that when you upgrade to a higher output alternator (above about 70 amps) the ammeter becomes less than desirable from a wiring standpoint.

To give some more detail, some people are just used to reading a voltmeter as ammeters have not been in regular use since the early eighties. Others prefer the type of system information a voltmeter gives vs an ammeter. Some of those also don't think an ammeter gives the full story (I'm not one of those however). And still some more are just tired of their finicky ammeters not working at all. EB ammeters are fairly reliable as ammeters go, but in other later applications they hardly ever worked.

From the high-output alternator's standpoint, the gauge itself is fine. It's the wiring that is less than capable of higher current flow.
Some ammeter designs are literally dangerous when used with too high a current flow because the current passes through the wiring inside the gauge. Ours are not designed like those however, and are quite safe with handling excess current flow. They're inductive reading (like a timing light) and have no direct electrical connection.
However, and this is a BIG however, the actual gauge wires themselves are not capable of handling all that new-found current reliably. The size/gauge of wire used by Ford in the original harness, and even those of some aftermarket replacement harnesses, is just not robust enough to handle more than about 70 amps reliably.
The wire can handle the current for a short time, and even quite a long time if it's in perfect shape. But after 38+ years of life, it's rarely in perfect shape. And you really don't want to be the one to test that theory.

So that's a long way of saying that if you upgrade your alternator and don't upgrade the specific wiring to a larger gauge, then an ammeter is not recommended and you might as well change to a voltmeter. Especially handy to do while your gauge cluster is out and being refurbished.

Hope that helps. Quite wordy, but at least gives you some info to digest.

Paul
 
OP
OP
fallingdown

fallingdown

Sponsor/Vendor
Bronco Guru
Joined
Jul 20, 2010
Messages
1,604
I'll go ahead and add my answer to your question in the meantime mb.

Two basic reasons these days. One is that some people prefer a voltmeter for various reasons, and the second is that when you upgrade to a higher output alternator (above about 70 amps) the ammeter becomes less than desirable from a wiring standpoint.

To give some more detail, some people are just used to reading a voltmeter as ammeters have not been in regular use since the early eighties. Others prefer the type of system information a voltmeter gives vs an ammeter. Some of those also don't think an ammeter gives the full story (I'm not one of those however). And still some more are just tired of their finicky ammeters not working at all. EB ammeters are fairly reliable as ammeters go, but in other later applications they hardly ever worked.

From the high-output alternator's standpoint, the gauge itself is fine. It's the wiring that is less than capable of higher current flow.
Some ammeter designs are literally dangerous when used with too high a current flow because the current passes through the wiring inside the gauge. Ours are not designed like those however, and are quite safe with handling excess current flow. They're inductive reading (like a timing light) and have no direct electrical connection.
However, and this is a BIG however, the actual gauge wires themselves are not capable of handling all that new-found current reliably. The size/gauge of wire used by Ford in the original harness, and even those of some aftermarket replacement harnesses, is just not robust enough to handle more than about 70 amps reliably.
The wire can handle the current for a short time, and even quite a long time if it's in perfect shape. But after 38+ years of life, it's rarely in perfect shape. And you really don't want to be the one to test that theory.

So that's a long way of saying that if you upgrade your alternator and don't upgrade the specific wiring to a larger gauge, then an ammeter is not recommended and you might as well change to a voltmeter. Especially handy to do while your gauge cluster is out and being refurbished.

Hope that helps. Quite wordy, but at least gives you some info to digest.

Paul

Paul is absolutely correct in his reasoning. in fact I usually see one or two gauge clusters each year that have been involved in a vehicle fire presumably due to this issue or just poor wiring in general. Its not uncommon to install a voltmeter and then re-run the large diameter Alt wire so that it is forward of the firewall. Should a problem occur It might give you just enough time to put the fire out or at least catch the awful spectacle on video so you can post it here on CB:cry:
 
Top