Tranny gauge installation

[Lance Andrus]

I'm finally taking the smart route and installing a tranny temp gauge when I cahnge the filter and fluid before my big trip the end of June. Can anyone help me with some particulars as to where the best location for the sensor. I've heard welded in the pan, but I've also heard about adaptors that fit on the return line from the cooler.

Thanks for the help.

[Maineah]

The best place would be the pan. You will have to have it off the change the filter any way just make sure it has room where you want to put it before you start drilling!

[Bodybagger]

I'm finally taking the smart route and installing a tranny temp gauge when I cahnge the filter and fluid before my big trip the end of June. Can anyone help me with some particulars as to where the best location for the sensor. I've heard welded in the pan, but I've also heard about adaptors that fit on the return line from the cooler.

The return line from the cooler is a terrible place for it. It's like cooking a turkey with the thermometer outside the oven. By the time an excessive temperature registers outside the oven, your turkey has already been burnt for an hour.

The line TO the radiator will register the actual temperature of the transmission fluid. The pan is a very good place for it as well. Here's how I did mine:

Here's the sensor, the pan, and the fitting I used. I used a 3/8" FPT air hose fitting because it was steel and had the right threads.

After careful consideration, I decided to locate the sensor on the front face, passenger side, of the oil pan, due to adequate clearance and the protection provided by a frame crossmember in front of it. I drilled it out with a step drill. A step drill is the best way to drill a round hole in sheet metal.

This is the hole as drilled.

This shows the fitup between the fitting and the hole. The edge of the hole just touches the edge of the fitting, which allows for complete penetration of the weld.

I cut the air hose detail off of the fitting. I could have just used a pipe fitting, but I wanted steel, not iron, so I selected the air hose fitting.

Here is the fitting after TIG welding. I ran a 3/8 NPT pipe tap down the thread to clean up any distortion and weld bead encroachment into the threads.

And here's what it looks like with the sensor installed. I removed it before installing the pan onto the transmission because this was done during a rebuild and I didn't want a jack to break the sensor in half.

However, there are no worries about the fitting itself. Steel on steel TIG welded with ER70S-2 and with full penetration. It will never leak and will never break. Make certain all the galvanizing has been removed before welding. Brazing will work well, too.

[Gulfstream Greg]

Bodybagger - Great pics and that fitting looks sweet! I agree the pan is the best place if you have the ability to do that. What transmission is that pan for? 4 cyl or V6?

If you do put in the line consider that any fittings you use will have a smaller diameter inside than your hose such as the barb fittings etc. You can drill them out and get some more inside diameter. Also the cooling line only is a small amount of the oil that is tapped off the transmission but still should be a close reflection on actual temp. The closer to the transmission the better. Another thing is get a digital readout gauge. The analogs are hard to get an accurate reading when the temp is high because of the way the numbers are spaced on the dial. And if you are getting up in years as I am, a digital will be easier to see at a glance. Also consider a pillar pod for the gauges instead of under the dash.

Here is something else. When we owned the turbo if the trans temp was running high and I could get it up around 55 plus, putting it into overdrive would cool down the trans temp. I could actually watch the needle moving as the temp dropped

[Lance Andrus]

A great explaination and pics. This is for a 22RE with an A43D tranny. Maybe if I can get my gas tank done today I'll get the oil drained from the tranny today. Guess I'll have to look for someone to do the brazing for me since I'm not equipped to do the job. I assume that a brass fitting would work as well.

[Bodybagger]

What transmission is that pan for? 4 cyl or V6?

It's the 4cyl 22RE with A43D tranny.

I also replaced the small stock tranny cooler with a much larger Hayden. Not sure what the model is but it's about 60% of the area of the AC condenser. Much better flow rate through the cooler as well. Idle fluid temp went down from 165F to 135F and I expect higher transmission temperatures to result in better cooling due to higher dT between fluid and ambient combined with higher air flow at speed. I'll let you know how it does when I take it out in the mountains during hot weather.

Guess I'll have to look for someone to do the brazing for me since I'm not equipped to do the job. I assume that a brass fitting would work as well.

If you're going to braze it instead of welding, you can use iron or steel, but brass melts around the same temperature as the bronze oxyacetylene brazing alloy. You'd have to use either 45 or 56% silver brazing alloy such as Radnor Stay-Silv, and the mechanical strength will not be as high as a bronze rod.

A welding shop should be able to TIG weld the fitting for 20 bucks, but silver brazing may cost more since a single short stick of Stay-Silv costs 10-15 dollars (at HVAC wholsalers).

[Derek up North]

I don't see there being much difference between installing the temperature gauge sensor in the pan or the line to the cooler. There will be minimal difference between the two, probably undetactable with the type of gauge you're likely to buy anyway. To me, the important thing will be the ability to detect a difference/increase in temperature, rather than an absolute value.

For a cooler, you could consider a Hayden #404:-

http://www.summitracing.com/parts/HDA-404/

For a gauge, B&M 80212:-

http://www.summitracing.com/parts/BMM-80212?part=BMM-80212

If you really wanted to get fancy, you could add a manifold, some temperature sensors and relays to inhibit the O/D and switch on an electric fan as the ATF temperature rises, but not 'K.I.S.S.! Or perhaps just 1 sensor and a big red warning light on the dash!

[Derek up North]

Don't shoot the messenger, but here's another opinion:-

Locate the oil return line to the transmission. On

Chrysler and most Ford transmissions, this is the line to the

rear of the transmission case. On GM TH-350, TH-400, TH-

700R4, and Powerglide transmissions, this is the upper oil

line to the transmission case. On GM TH-200, TH-200R4,

4L80E and Ford AOD transmissions, this is the lower oil line

to the transmission case. Note: This location is recommended

to monitor the true transmission temperature

going in, as well as checking the oil cooler efficiency.

http://www.bmracing.com/bmracing/installation_instruction/9500048-08.pdf

[Maineah]

Don't shoot the messenger, but here's another opinion:-

http://www.bmracing.com/bmracing/installation_instruction/9500048-08.pdf

That's why the pan is the best place for the sensor the fluid is just back from the cooler and it is what is about to be pumped into the workings. Here are some neat gauges: http://www.tradervar.com/Digital-Automotive-Gauges-C9312.htm