Another gauge question

The ammeters on my 49 and 51 have the loop or inductive pickup on them. They are also not as thick as the newer ones. The new ones are about 1 MM bigger round than the original gauges requiring some filing or Dremel work. I bought item # A0NN10670A-BLAC, replaces FAD10850A which I can only assume is the smaller inductive gauge. A0NN*****has screw post terminals and requires enlarging the hole. Is the original style still available? I dont mind enlarging the hole, just asking.

It's sad that that aftermarket gets by with using OEM part numbers for parts that are not at all identical to the original part.

You shouldn't have to enlarge a hole to make a gauge fit!

On the other hand, the OEM's often change a part number when there's a supplier change, even if the part is nearly 100% identical and retire the old part number.

Personally, I'd rather have a decent, functioning used OEM gauge that what is being sold today.

Hey Jim-
No, the OEM LOOP AMMETER is no longer made; only the screw terminal style is made now. Yep, I concur they shouldn't use the original part number as they are NOT the same now. Now sold as p/n 9N-10850-B but that is the original p/n for the 30-AMP LOOP Style Gauge. That's just one of many parts that should be corrected. I'm not quite getting at what you say, ...The new ones are about 1 MM bigger round than the original gauges requiring some filing or Dremel work... What are bigger around? The LOOP? New gauges with the LOOP are no longer made. I think you may have this backwards. You shouldn't need to expand the loop to get wire thru; millions of N's worked just fine as is. The OEM LOOP AMMETER used a thick #12 Yellow wire. FORD TRACTOR N-SERIES TRACTORS all used the 30/30 AMP Induction/LOOP AMMETER after early 1939 beginning with s/n 9N-4000; p/n 9N-10850-B. Prior to then, the first early 1939 9N's used the 20/20 AMP AMMETER, p/n 9N-10850-A and it used screw terminals. After the NAA came out in SEP 1952, p/n was now FAD-10850 and used screw terminals. A gauge using screw terminals shouldn't matter what the wire gauge size is. If you are looking for an original 30 A loop style AMMETER, I have a few and I could part with one. These pop up often on fleabay too. restorers seek them. You didn't ask, but just a FYI, no matter which unit you use, if when tractor is running and the gauge is showing a low or negative charging rate, you probably have the wires reversed on terminals, so try switching them or if using the LOOP style, reverse the direction of the wire.

ORIGINAL FORD 9N-10850-A; 20-AMP, SCREW TERMINAL AMMETER UNIT, USED ONLY ON FIRST 4000 9N'S IN 1939:


ORIGINAL FORD 9N-10850-B, 30-AMP INDUCTION LOOP UNIT, USED '39 THRU '52:


NOTE: LOOP USES A #12 WIRE GAUGE, OEM YELLOW COLOR SCHEME:




OEM LOOP STYLE SHOWN ON LEFT, MODERN AFTERMARKET SCREW TERMINAL STYLE SHOWN ON RIGHT:


Tim Daley(MI)

The body of the new gauge is about 1 or 2 mm diameter larger than the hole in the dash. I read a post from someone who used a dremel and sanding drum attachment as it didnt take much to enlarge the hole. Ive got to paint the tractor anyway so I will take care of that problem later.

OK, gotcha now. I haven't replaced any gauges with aftermarket ones in about twenty years or more but never had a problem with fit. Nowadays, aftermarket parts are all not made equally so it matters where you buy from. One millimeter is .040, two is .080, but either way seems like a pretty major flaw in whoever designed it. I would have tried to whittle down the gauge housing on a belt sander rather than alter the dash opening. Could just rotate it around by hand to dust the OD. Better to just get a different gauge that actually fits right. Only way these suppliers will learn is to start returning junk parts. When you don't say anything and just use it with your own modifications, they will never know. As Americans we should demand quality but too many of us just suck it up and take it in the @$$

Tim Daley(MI)

I think Jim in LA may have nailed the issue. Many new gauges are measured in mm instead of inches, & are not really 2" diameter.

(quoted from post at 06:01:37 03/16/23) I think Jim in LA may have nailed the issue. Many new gauges are measured in mm instead of inches, & are not really 2" diameter.

Click to expand...

Dash gauges have been made in 2'' AND 2-1/16'' sizes for DECADES.

Dunno if ''metric'' explains it or not but it is NOT a new phenomenon.

Not for the N's. 1/16 is a big diff... ALL N's used the same size dash panel holes for the gauges.

Tim Daley(MI)

So is the factory hole in the dash 2" or 2 1/16"?
I know I replaced the ammeter over 20 years ago with one from a parts store and it went right in.

No doubt most all parts now made in Asian countries are metric but even 1mm is big diff. Remember, it matters where you buy from. I once bought a Sediment Bulb from
Cheena supplier that had metric threads on it and it boogered up the guys' tank but was abe to fix it. Like I said, I'd rather alter the cheap part than screw up the
original tractor.


Tim Daley(MI)