LAracer

I'm about to do it this weekend. I have the pdf that describes pretty much everything. Just wanted to ask for any last-minute advice that the pdf might leave out. Thanks.

(the pdf I'm talking about is this one: http://www.iluvmyrx7.com/3rdgen/how-...auge%20mod.pdf )

LAracer

Just for the record...

Temp gauge mod is now done. I followed the pdf word-for-word. Only problems I had was pulling some panels off (this was my first time dissassembling the dash). I used alot of force to pull the dashboard end panel and meter hood off, but nothing cracked. I didn't need to remove the steering wheel.

This is a pretty easy mod for newbies (like me), but a word of caution: if you're not very good at soldering try to find someone to solder the jumper wire for you. I had no problems, but I've soldered quite alot before.

The difference in gauge behavior after the mod is incredible. At first I thought I had screwed something up because the gauge didn't move until the car got quite warm (I burned myself pretty bad making sure all the wires were still connected). As I drove in stop and go traffic, the gauge hung close to the middle, but was obviously very sensitive to exactly what the engine was doing. At speed, the gauge went way down to cold. It read so cold that I thought something had come loose, but when I let the car idle in the garage, the gauge went back up until the fan came on just over the halfway mark. So I think it's working fine (the ambient temperature was very cool which I think explains the low reading on the highway).

All in all I am very happy with the "new" gauge. I have much more confidence in the temperature reading, and the dash still looks stock. Oh, and it cost me less that $40.

dubulup

Good work, I recently did this also. The weather outside in ALT is getting colder, so driving around the gauge sits on the normal low marker, and when I kick the fan mod on it moves to the cold reading. Your guage seems to be working perfect! I was surprised how long it takes to get the car up to normal temp also.

James Paventi

iTrader: (34)

Did this mod two weeends ago. I'm very happy with it. The pre-modded stock gauge might as well be a cold, normal, rebuild gauge!

reza

Questions:

Do you need to keep the Radio Shack(potentio meter assembly) box in the engine compartment? Or do you just use it once to adjust, then take it out of the engine bay?

Thanks,
Reza

Lunar7

Once you determine the value of resistance you need you can replace the pot assembly with a fixed resistor at that value.
That makes for a cleaner install.
Use 1 watt resistors if you can get them.

I ended up using a lot lower resistor value than the article sugested.
I set my guage so that the top of the normal range corresponded to the cooling fans turning on with no electrical load (AC, blower and parking lights off).
That should correspond to 220 deg F.

LAracer

Yeah, you could replace the pot with a fixed resistor, but I left it in. It's in a shiny little aluminum box so it doesn't look too bad.

I worry a little about the heat from the engine changing the resitance of a fixed resistor (I guess it could affect the pot too). It's probably a good idea to check the calibration of the temp gauge every now and then (like after an oil change?). Leaving the pot in makes re-calibration much easier.

Has anyone checked to see the affect of heat on the pot or fixed resistor?

Lunar7

I see no change in calibration with heat.
I used 1 watt resistors for better heat resistance.
(compared to 1/2 or 1/4 watt)
I know it's staying in calibration because the top of the normal range corresponds to the electric fans turning on.
It alwyas seems to be dead on.

LAracer

I guess I'm just paranoid.

reza

good info. How long did it take to do it?
Any difficulties experienced during the mods?

James Paventi

iTrader: (34)

Took me a total of about 4 hours … not counting the time to order the parts and read the how to. Everything was easy, except for removing the stock gauge to solder the jumper wire in place. Then again, compared to the rest of this car, pulling the dash apart was a walk in the park. Now that I think about it, I took about 30 minutes (of the 4 hours) and tested every dash light (one was burnt out) while I had the gauge assembly on my workbench. All in all, it wasn’t a hard job … especially considering that the instructions are well though out.

I’d be happy to give anyone pointers, if it’ll get you started …

LAracer

It took me a little longer - 6 hours. I was trying to be really careful not to break any parts of the dash. I also cleaned them up pretty well before I put them back.

HeatTreated

Man, that site link on the How To, isnt working... can someone e-mail me the how to... if you saved it? or paste it on here? thanks alot.

Mahjik

iTrader: (1)

The site works, but it's not an HTML page. It's an Adobe PDF file, so you need to RIGHT-CLICK on the link, and then do SAVE AS.

You'll need Adobe Acrobat Reader to view the file. Don't ask for it in another format, that's the only format it's in...

spurvo

Note that it also takes pdf files an AGE to load from this site, whether the gauge linearization or manual pages. Just be patient.

I did this mod also, and swear I've become a temperature **** because of it. TOTALLY **** about temperature, just like I oughta be

FattyCBR

Anyone know if this would work on temp gauges in other cars?

Thanks

James Paventi

iTrader: (34)

Hmm ... probably a discussion for another forum, but I'll venture an educated guess since I love electronics … almost majored in electrical engineering.

Maybe in another gen of rx7, maybe even another Mazda, but I doubt that it would work in another make. Well, unless the same gauge circuit is used in other cars ... maybe manufactured / sold by say a company other than Mazda.

Now if you were willing to put in the time to reverse engineer the gauge in the other car I'm sure that a solution exists. You're gona need some electronics experience though. I’d venture that a high end hobbyist could do it.

spurvo

Mazda, in it's infinite wisdom, decided that customers would be bothered by seeing large fluctuations in engine temperature, given they were paying $36K for the car. So they set the gauge to come up fast so customers would not be bothered by the long warm up (or be bothered by thinking they were driving around on a cold engine. 'Cause why would THAT be a bad thing?), and not move more or less NO MATTER WHAT the hell was really going on. Unless the car was boiling its coolant out the overflow tank 'cause it just overheated. THEN, said customer that would have been SOOOO inconvienenced by a moving needle (that nearly EVERY other car I've EVER driven has!!!) would dutifully pull right over on the freeway or side road he or she was driving on and shut down the engine and call the friendly local tow truck owner, rather than continue for thirty miles to the nearest gas station run by "a guy I know" and COMPLETELY warp the housings.

Right.

My second gen had a nicely linear gauge. So has every other car I've ever driven.