Ironhead Sender Unit Part Number

[spiritof67]

I have a #75002-77 cylinder temp gauge...it's the one WITH the light..and I have seen at least three different part's for the sender unit, 75005-77 being one. That part number shows up as an oil temp sender as well. I have also seen 75005-69. Anybody have wisdom on which is correct, or isn't there any difference?

[72 Ironhead XLH]

Why even bother? The only thing you need is the oil pressure light

[IXL2Relax]

It appears that the -69 version is listed (from suppliers) as compatible thru 1976 and the -77 began to be used in 1977 - which seems to make the -77 the proper sender to match the -77 gauge.




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[spiritof67]

72 Ironhead. I'll decide what I "need", thanks.

IXL, thank you for straightening that out. Makes sense now. I'll track one down.

[bustert]

what is happening??
if it is what i am thinking it is, a thermo-resistor. you can test it with an vom and a pot of water on the stove. a thermometer helps to determine scaling.
btw: you can test the gauge with a pot as the sensor, all it does is adjust voltage to ground, start with a high value so as not to over load the gauge and give finer results.

[IXL2Relax]

I suspect that (in 1977) HD changed the supplier/mfr of either the sender (thermistor) or the gauge itself. Often, they are not interchangeable from different mfr, but rather operate as a set. The resistance characteristics of the thermistor are matched up to the operational characteristics of the gauge...

As I understand it, the average 'inexpensive' gauge can have wide tolerances of accuracy and are mostly used as a relative indicator of temperature rather than a scientific instrument, perhaps being set to be near accurate at the most frequent operating temperature.

- Just surmising

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[mikethebike61]

Originally Posted by 72 Ironhead XLH

Why even bother? The only thing you need is the oil pressure light

TOO easy

Anything that is simple MUST be made more complex

Otherwise....you are not making it "BETTER"

Besides, when you know how hot that rear head gets....you can drive yourself slightly insane....kind of like the very inaccurate factory gauges in cars years back....a Ford mechanic in my home town told me in 1965 (he had worked at the dealership since 1919 when he separated from the Army) when I asked why no gauges just idiot lights that a huge % of warranty claims were due to those things giving inaccurate reading and people not know how to interpret the readings..

[spiritof67]

Mike the Bike, thanks for the reply. I guess some of the others here assume everything you do for a motorcycle has to be because something's wrong. Is that why I searched for the red GLASS cylinder head dots for my 'CR, or the "christmas tree" exhaust pipe clamps? Nah.

So to all, here's my thing: I ride an old Harley. I like the old Harley accessories, so I want to fit an HD accessory cylinder head temp gauge. Nota bene that I have ridden this machine in New York City traffic AND on long highway trips (for a 43 year old machine) without a temp gauge. I don't need it; I already have it and I wanted to put it on the machine. And I really didn't think so much "thinking" was going on about "need". None of us "needs" any motorcycle - we all want 'em though!
Now all I have to do is figure out where you can put the gauge on the there's-no-room-for-anything XLCR....because you can't alter the fairing, and there's damn little real estate on the handlebar!

[IronMick]

I had these on my 1980...