Aftermarket gauges with stock senders?

[ForingaMex]

Hey guys,
I'm doing something similar to my 72 as what was discused on this thread by Robroy. http://www.fordification.com/forum/view ... ender+unit
My question is this. Do the stock temperature and oil pressure sending units run in a specific ohm range kind of like the fuel guage? If they do, and I think they do, are they specific to Ford or are they more universal so that they would match with aftermarket gauges? The gauges that I'm planning to buy (Equus) don't come with the sending units. Some of the gauges I looked at come with the sending units and they specify that their sending units must be used for proper operation of the gauges. Is that just for their own protection? I've done some searching around and haven't been able to find anything else related to that.
Any info you can provide will be appreciated.
Jake

[Dragon]

Very specific to Ford and function on 5 volts. Your aftermarket electrical gauges must be matched to their sending units not someone else's. I have the same brand f gauges going in my truck and all of them that need sending units come with them. 6 gauges don't need sending units: Vacuum/Boost, Voltage, Ammeter, Speedo, Tach and Gas. Gas is pretty standard 10 ohms full 73 Ohms empty or visa versa on most cars. Water temp, Oil Pressure, Oil Temp,

Mechanical gauges do not have sending units but Electric gauges do.

[ForingaMex]

Thanks for the come-back Dragon,
I know the gauges function on 5 volts but as dicussed on the link I posted above, (on the last page) that you can put 12 volts to the sending units. The IPVR is there to protect the gauges not the sending units. I'm sure the other sending units function on the same principle as the fuel sending unit? It's basically a variable risistor and have a specific ohm range that they function in? Or am I way of track with this? I'm going with Voltage, Oil Pressure, Water Temp and Fuel gauges and I'm going with electronic gauges because I want to be able to easily remove my gauge cluster.
Do you like your gauges? Are they electronic or mechanical? I asked at the parts store where they have them here in town and they said they don't come with the sending units. I know some of the higher end brand gauges come with the sending unit but at this time I can't afford them. Thanks again for the post Dragon. I'm just trying to properly understand all of this.
Anybody else with something to ad? All info is welcome.
Jake

[Thunderfoot]

The IPVR is there to protect the gauges not the sending units. I'm sure the other sending units function on the same principle as the fuel sending unit? It's basically a variable risistor and have a specific ohm range that they function in?

No and yes....
The IPVR is there to drop the voltage to the range the gauges read in, all the gauges (oil, water, gas, etc) are Voltage meters that are calibrated to the variable resistor range of the sending unit it is connected to. They just read the voltage drop across the sending unit and display it on the gauge accordingly how it was calibrated... The stock Ford gauges are designed to read this voltage change from 0-5Volts, the aftermarket gauges are designed for 12V.
If you can find out the specific resistor range of the stock sending units and the range that the new gauges need they may work... but many make it there own so as to be able to have accurate calibration with there gauges... The fuel gauges are more versatile with stock sending units as they are a bit more standard and for the aftermarket to make sending units for every type of vehicle would be very difficult and cost prohibitive. my there...

Just a couple of ohms difference will throw off the gauge accuracy if not matched to the gauge...

[Dragon]

The IPR sends voltage through the gauge to the ground on the other side of the sending unit. I know that a Ford oil pressure sending unit will quit working on a 12 volt gauge system. It dies inside. Too much current because of the higher voltage.

[ForingaMex]

Thunderfoot wrote:
If you can find out the specific resistor range of the stock sending units and the range that the new gauges need they may work

That is what I'm trying to find out but so far I can't find any info on the stock sender nor the aftermarket gauges but I'll keep looking.

Dragon wrote:
I know that a Ford oil pressure sending unit will quit working on a 12 volt gauge system

So do they function different than the fuel sender? The concensus in the thread I quoted earlier seems to be that 12 volts won't hurt the fuel sender. As you can tell electronics isn't an area that I'm an expert in, atleast not the proper terminology, but it's interesting and I like to learn new things.
Thanks to both: Dragon and Thunderfoot for your posts.
Keep the advise coming tho guide me though the murkiness and confusion.
Jake

[knightfire83]

After about an hour and a half of searching, I found this info on the net about Ford sending units:

Fuel
Source: http://fordification.net/fuel-sending-units.htm
Range: 73 Ohms Empty / 10 Ohms Full

Oil
Source: Rock Auto ACDelco part #F1801
Application: '73-'91 Ford Oil Psi Sending unit w/gauge
Range: 0-4 PSI OPEN CIRCUIT, 4-8 PSI/24-36 OHMS, 90 PSI/8.5-17.5 OHMS

Temp
Source: Rock Auto MOTORCRAFT Part # SW2328
Application: '70-'08 Ford Temperature switch w/gauge
Range: ?????

And this will help from: http://www.broncofix.com/viewtopic.php?t=274976

this is what i got on my gauges...
oil
10 ohms=90 psi
20 ohms=70 psi
30 ohms=40 psi
temp
73 ohms=120*
21 ohms-195*
10 ohms=230*
fuel
empty=73 ohms
1/4 = 33 ohms
1/2 = 25 ohms
3/4 = 21 ohms
full = 10 ohms

Hope this helps

[knightfire83]

And it is very odd that they don't sell the sender with the gauge, as it is useless without it. Perhaps you should try another vendor for your equus gauges such as Summit or Jegs, perhaps the senders will be included when you buy from them.

You can contact equus from their website to see if you can get some information about their ohm ranges for their gauges. http://www.equus.com/index.php and see if their ranges are even close to factory Ford specifications.

Typically you have to use the manufacturers sender with their particular gauge, with the exception of fuel level gauges. It is 98% likely that aftermarket gauges knock down the current they send to their sending units, internally inside the gauge. They usually have a connection for (+) and (-) and (s) if they didn't knock down the voltage, the (-) terminal wouldn't be needed. This would be used for an voltage regulator inside the gauge.

[Dragon]

What gauges is he looking at I got Equus gauges in the 8000 series and the electric ones come with sending units.

I even went into O'Reillys and picked up the oil, temp gauges and they have the sending units in the package. Again those are the white face 8000 series.

http://www.equus.com/downloads/manuals/93-0011.revB.pdf scroll down to #4 where it says to different types of sending units... Blah Blah .

[ForingaMex]

Thanks for finding all that good info for me, knightfire. I was looking on the home-page of the Equus gauges and it says they come with the sending units. So I went back to our parts store here in town an asked again and the guy tells me that he thinks they do come with the sending unit. So I think we're good there.
Thankyou also Dragon. The 8000 series electric are exactly what I'm looking at. The thing is that our parts store has a display board full of dummy gauges and no real gauges in stock to look at. They have to order them in. My experience is that generally our parts stores are not as well stocked as they are in the USA. Too bad. Thanks again for checking that out for me. I'll keep you informed on how I make out... with some picktures to come. I already cut my stock gauge panel appart... too late to turn back now.
Jake