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KobaltBlau's Avatar
 
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Transmission Temp Stickers - JackOlsen?

Hi Jack, based on the below post, I ordered some non-reversible temperature indicator stickers to see how hot my tranny really is at the track this weekend. I got the ones that look like the image below, but in 200-225-250-275. They have all kinds of different ranges and temperatures.

Question is: Where did you put your sticker? What do people think the hottest place you can put a sticker on the outside of a 915 is? sticker measures 29/32"x1 49/64" or about 23x45mm.

I'll also report my results here after the DE weekend.

Quote:
Originally posted by JackOlsen
Rick, here's an easy way to see if you've got a problem. Clean off a section of the transaxle, and stick one of these on it:



It's a stick-on nonreversible horizontal 4-temp indicating label with a range of 175 F to 250 F degrees. Packs of ten of them sell for US$14 here.

Look for part number 5951K44, and then click on 'catalog page' to see all your options.

With one of these on, you'll at least be able to know if things are getting worse than 225 F, which is where I'd start to be concerned, or 250 F, where I'd start to worry about damage being done.
EDIT: my experience using these added to the end of this thread on 8/31/04

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Last edited by KobaltBlau; 08-31-2004 at 09:42 AM..
Old 08-17-2004, 02:56 PM
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I have some of those, too. But I've never used them. I have an oil-temp gauge on my tranny. The sender on mine goes under the drain plug, I believe.
Old 08-17-2004, 03:48 PM
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does the tranny oil carry the most temp? if so, i would put it on the high tide line of the fluid. that way, convection will drag the hottest oil up to your sticker. (maybe i am overthinking this).
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Old 08-17-2004, 04:05 PM
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I think you should stick em all over and find the hottest exterior place.

One good bet might be where there is not a lot of wind gong past, but there is a lot of hot oil and meshing gears.....
Old 08-17-2004, 04:07 PM
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I guess the real question is how much cooler a good spot like randy described (lots of hot oil and meshing gears) is than the gear oil itself. Hopefully it's within 20F so I can register 200 if it gets to 220F for example. any wild guesses on this?
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Old 08-18-2004, 11:51 PM
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bump
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Old 08-19-2004, 09:19 AM
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"When you measure... you know." Lord Kelvin (aka Wm. Thompson, or Billy to his budds)

YOu can run a fine wire Tcpl down thru the vent hole - you don't want it caught in the meshing gears.....

It would be very complicated to model the thermal profile from inside to outside - 20 oF is just a WAG. I wouldn't hazard a guess on this.

On a camping trip with a bunch of other graduate students years ago (well, actually decades ago) it was very cold and we agreed the wine was too cold. So I decided to put it in a hot springs to warm up despite their claims it woud explode. After a moment the cork blew out, it tilted and sunk. Our only wine.... Back at the office I decided to model what happened (instead of working on my actual PhD project). It was susprisingly difficult, but I just couldn't stop -- and ater a several weeks of non-stop work I realized the answer was.... to give up.
Old 08-19-2004, 09:29 AM
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Randy, thank you for your thoughtful input.

I take the story about the wine directly to heart. Really sounds like something I'd do.

If my 200F (lowest) dot doesn't turn black this weekend, I won't really know much. In retrospect I would have gotten the same stickers that Jack has, starting at 175F. If something turns black I can at least start guessing. Maybe I can coordinate with Jack to put a sticker on the same place that I did, and compare it with his gauge readings. That might actually be useful to others using the stickers.

Well, I'll try it this weekend, the ambient temps are currently forecasted in the low 80s.

stay tuned!
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Old 08-19-2004, 03:22 PM
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Maybe grist for another thread....

Can/should we put these stickes on the body of the oil filters...to "really" see what the oil temps are ???

---Wil
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Old 08-20-2004, 06:00 AM
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Similar heat transfer problem, but would also be interesting. I am planning to stick one to a head somewhere, but since it's not down by the plug it will be a pretty inaccurate CHT. If nothing else, sticking one on a head should show me that they work. you get 10 for $14.XX so it's not massively cheap to stick them all over the place.
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Old 08-20-2004, 06:51 AM
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Wil - no.

A sensor only measure the temperature of the SENSOR. Heat will travel from theoil thru the boundary layer, thru the metal of the can the filter is in and across the glue or subsurface fo the sticker to the sensing part of the sensor -- that is 3 resistances. They are in series so add them up. The temperature of the sensor (at steady state) will be the result of that input plus the exchanges from the surface of the sensor -- convective to air and it could be free, forced or mixed convection. Then there's radiative exchange with everything that is within the view of an ant perched on the sensor. We can neglect evaporation etc. to make it easy.

Yeh it's easy....

Look for my wine bottle reminiscence posted on a thread here w/in the last coupla days.

Best, - Randy
Old 08-20-2004, 06:07 PM
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I have used temp guages just like that on helicopter transmissions, and if you put 2 of them right next to each other, they can read differently. In my experiences, hey are not too accurate, so if you really want a good idea maybe you could put a few and average them. Just a thought
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Old 08-20-2004, 06:29 PM
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I put them in 3 places on the transmission, and 1 on the thick flange on one of my heat exchanger inlets just to make sure the stickers work (I'm sure they will, just a sanity check I guess). We'll see tomorrow...
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Old 08-20-2004, 10:07 PM
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Here's my report:

I placed stickers in 3 different places that I thought were out of the main airflow, but below the fill line of the transaxle. There are really not that many big flat places to put this kind of sticker. The stickers were placed:

1. on the dip underneath the diff housing, on the engine side to be mostly out of the airflow
2. on the passenger side of the end housing way out on the nose of the transaxle toward the front end of the car, but below the fill line
3. on the driver's side in a recess made for one of the bolts holding the main gear case to the differential, near the big differential thrust plate. I used the recess about on the level of the fill plug.

these descriptions may be hard to visualize but if you look at the 915 it should be pretty obvious.

Here were the conditions:
DE at Second Creek Raceway in Denver
20 minute run sessions
stock 3.0 engine
aluminum case 915
swepco 201 in transaxle
most of the track is run in 2nd and 3rd gears
altitude is approx. 5000 feet, and humidity is very low, so any convection cooling is somewhat less effective than at sea level.
ambient temp ~85F

Results:

all 3 stickers got gray on the 200F dot, they all looked the same. This means that the sticker itself got almost to 200F. In retrospect, I would have used the stickers Jack (Olsen) originally recommended, 175/200/225/250F instead of my 200/225/250/275F stickers. Based on Hayden (of Wevo)'s description in another thread of the fluid inside a splash lube trans being a torrent, this consistency across the stickers makes sense.

The question, of course, is what is the difference between the fluid temperature and the temperature of a sticker stuck to the outside of the aluminum case? I would not be worried about dino gear oil temperatures under 235 or 240 (just my uneducated opinion), and I am making a totally wild uneducated guess that the difference between the sticker temp and the fluid temp is not substantially more than 20F. This is totally unfounded and could be totally wrong. In any case, I am willing to conclude that my gear oil temps are under 240, and I should not be too worried. I plan to try some synthetic gear oil next, which I've done a whole bunch of research on, which according to the expert is fine at temps up in the high 200 range. Stay tuned for a post on that in the next couple of months.
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Last edited by KobaltBlau; 08-31-2004 at 09:41 AM..
Old 08-31-2004, 09:37 AM
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Those results sound credible, to me.

I have heard that unlike motor oil, gear oil begins to break down at around 200 degrees, but I haven't been able to get confirmation of this by experts.

If you're in the 200-225 range in 85 degree ambient with 20-minute sessions, then what's going to happen on hotter days with longer sessions? It would be interesting to see more testing, but it doesn't look like it would take too much to push the trans. temps into the 260 range I saw with my 3.6 and mag-case transaxle.
Old 08-31-2004, 11:15 AM
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Thanks, Jack.

I agree with what you're saying that it wouldn't take much to get the temp higher. In my particular case I don't run much longer than 20 minute sessions, but ambient temps up to 95F or more are certainly possible, and could push the temps into concern zone.

In other words, I think my results are consistent with yours considering the difference in our conditions and cars.

The (very knowledgeable) tech I talked to at red line oils said that he would not be worried about their 75w-90ns in a 915 until the temps were above 285-290F. This probably has no bearing on what temps swepco 2XX are good for, and I have not run the red line stuff.
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Old 08-31-2004, 11:40 AM
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"what is the difference between the fluid temperature and the temperature of a sticker stuck to the outside of the aluminum case?"

- Ther is just no simple way to determine this. It is a very difficult heat transfer problem. Didn't I answer this before? You need to measure the oil temp with a small thermocouple.

Old 08-31-2004, 05:03 PM
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