KevinK2

stock 1st kick-on point is 221F at low and 226F at med. Gage doesn't budge.

I use parking lights and fan switch to keep temps well below about 210F for normal driving. I wanted to know when it hit 220-225 at track events, and stock gage needs 240F to move from normal. by adding 245 ohm resistor, parallel from ground to the temp sensor near oil filter. Test was to let fans come on naturally at 221F, and be sure there was an obvious shift in needle reading.

Not as elegant as recalibration or 2nd gage, but much easier and simpler. I'd try a simple 150 and 100 ohm resistor pair for 250 ohm start point. add female tab to one wire end, with an extra male tab, and fit this to sensor. oem connector goes on this exra male tab (must squeeze plastic body of oem wire connector to get it to relase from the sensor). Just carefully ground other end of the resistor lead.

works well for me. only rises up at hot track events(220F) and I back off a lap.

also, will give a false 'quick warm-up', so allow a bit more time before full warm up is assumed.

roadsterdoc

Thanks for the tip. I tried the linearization on my 94VR and was not satisfied with the results. I'll try this on my silver 94.

245 ohm resistor in parallel from the sender, huh? Is 1 watt sufficient? No gauge modification necessary?

KevinK2

yup, that's it. I used 1/2 or 1/4 watt ... very little current there. Gauge is not touched.

I initially used a pot to dial it in, then used several resistors to get 245.

allenhah

iTrader: (4)

This is going to sound pretty stupid considering I was a physics major in college, but what do the wattage values mean for resistors? Was it power handling?

This sounds like a great idea...definitely going to try this before my track event.

KevinK2

watts imply the continuous current rating for the resistors.

w = v x i

at 13V, 1/4 watt allows 19 milliamps (ma). 1/2 w 39 ma.

I just measured 28 ma thru the resistor, engine cold. I would think ma through this resistor would drop quickly as temp increases. I'll test hot ma's later, but 1/2 watt R's would be safest choice. I think I used 1/4 watt, which have worked fine.

allenhah

iTrader: (4)

Ahh that's right...now I remember. Thanks for the very helpful information Kevin...I'm gonna pick up some 1/2 watt resistors this weekend, some male/female tabs, and have some fun with the soldering iron.

I also didn't realize until recently that I could hook up the autometer water temp gauge to the bleed vale hole on the top of the thermostat housing, so I think I'll install that temporarily while I fiddle with the resistors.

DamonB

Be sure to remind everyone those resistors need to be in series to get 250 ohms. If they parallel them they'll only get 60 ohms.

allenhah

iTrader: (4)

Good reminder Damon...

Just for clarification, this mod basically "shifts" the stock gauge behavior down a certain number of degrees, correct? So instead of budging from the middle at ~240 degrees, it budges from the middle at ~220 using a 240ohm resistor for you?

That sounds exactly like what I'm looking for...