Tranny cooler needed?

I'm using the comanche with an automatic (AW-4 tranny) for occasional residential snow plowing. Blade is a Sno*Bear brand. I understand that tranny is rated light/medium duty. One issue I have read is that tranny likes to get hot. I also understand that you can over cool fluid which could be harmful too.
Would a tranny cooler be needed? If so, what size? I would think the cold weather would help keep tranny cool. (90% of the time jeep is a DD.) When pushing snow, I don't push comanche and I take my time-usually in 4L.
What other modifications/changes has anyone else have done to this type of tranny?
Thanks!

Well, I would put a trans fluid temp gauge on it before I did anything else.

The problem with snowplowing is how hot the engine/coolant/radiator is getting from reduced air flow through the radiator. You could end up adding heat to the trans fluid when it flows through the radiator.

You can "T" into the outflow trans cooler line, or run a gauge off the pressure test port.

FBNEMO said:

What other modifications/changes has anyone else have done to this type of tranny?
Thanks!

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I completely bypass the radiator loop connection (especially in the summer) and run it straight through an aftermkt Hayden HD cooler.

I also have a temp sender/gauge. It gets hot here in the summer 100+ quite often and I do some toy and utility type towing as well as wheeling. Even with the cooler (and without the radiator heat exchanger) the tranny temp can get up to 180-200 on a slow, steep hill. When I'm cruising flat on the highway it rarely gets over 165F (more like 145F) even in 100 degree weather.

If it's really cold (like anywhere below 30) I can easily add in the radiator loop with an addition/re-route of the hoses.

Joe's got it fairly well nailed down.

If you really want to get a handle on the cooling efficiency of the transmission "cooler" - a good idea with the snowplow anyhow! - plumb one gage in with two sensors - one in each transmission cooler line. Use a DPST switch to change over sensors (or DPDT, if you have two-wire sensors) and you can quickly look and subtract the high reading from the low to see if it's really needed.

Alternatively, you can use a 'thermal bypass valve' (the better cooler makers have them - check B&M, Flowkooler, or Hayden first) which short-circuits the fluid back to the transmission when it's cold, and allowed it to flow through the cooler when it's warm. Also not a bad idea (and what I would do after totally removing the OEM "heat exchanger" from the circuit - warmup times are similar, but it takes a thermal load off of your engine coolant loop - heating the air with a cooler in front of the radiator has less impact than using the coolant to "exchange heat" in the transmission fluid directly.)

5-90,You have alot of electrical info out there,thats awsome!One point of mind that comes to me in an application like this is "closed vs open transition"/"shorting vs non-shorting"!What have you foound out with different types of sensors?

RCP Phx said:

5-90,You have alot of electrical info out there,thats awsome!One point of mind that comes to me in an application like this is "closed vs open transition"/"shorting vs non-shorting"!What have you foound out with different types of sensors?

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Most of the sensors I've dealt with are thermistors - variable resistances WRT temperature following a predictable curve (usually published in GM manuals - since that's what they most often are.) So, I've not run into any issues like that - but wouldn't a diode across the terminals (akin to across a relay coil) handle transients like waht you're talking about?

Not the same at all,the diode "shunts" the "field"(relay coil) as its de-energized."Closed vs Open" applys more to things that are either "spike" sensitive or "load" sensitive.

I don't believe you can "overcool" a transmission unless you are in temps less than 20-30* below zero. I have asked this question of a few folks who know transmissions and they all said you can't hurt anything that way at the temps we see in most of the country.

RCP Phx said:

Not the same at all,the diode "shunts" the "field"(relay coil) as its de-energized."Closed vs Open" applys more to things that are either "spike" sensitive or "load" sensitive.

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Which is why I'd asked. How would you handle it? As I said, just about all of the temp sensors I've known are simple thermistors, and the gage usually works as some variety of resistance bridge or responding to voltage changes caused by the variable resistance - but I know far from everything... Edjamacate me, please!

FBNEMO said:

I'm using the comanche with an automatic (AW-4 tranny) for occasional residential snow plowing. Blade is a Sno*Bear brand. I understand that tranny is rated light/medium duty. One issue I have read is that tranny likes to get hot. I also understand that you can over cool fluid which could be harmful too.
Would a tranny cooler be needed? If so, what size? I would think the cold weather would help keep tranny cool. (90% of the time jeep is a DD.) When pushing snow, I don't push comanche and I take my time-usually in 4L.
What other modifications/changes has anyone else have done to this type of tranny?
Thanks!

Click to expand...

I got an Explorer Trans-Cooler from the junk yard , some brass compression fittings from Ace and Trans-cooler line from carquest and had an independent cooler in front of both the radiator and condenser for about $25 and I have to say it's been one of my favorite mods on the drive-train yet. My transmission shifts smooth at all times no matter what the conditions, weather I'm in stop and go, 100 degree FL summer with two dirtbikes and gear on a trailer or in 4-Hi blasting through sand trails in the Ocala forest or just regular around town driving it's always shifting great and doesn't fade at all. I used to notice that when ambient temp was very high and I was pushing the heep the trans shift would fade and slip or get rough jerky but all of that has been eliminated by the cooler.


I cut the steel lines at the front of the oil pan


I've since replaced these with stainless clamps, they started to oxidize quickly


And there is a specific tubing for trans coolers


I didn't take any pics of the mounted cooler but if you want I will take some to give you an idea of how I did it.

5-90 said:

Joe's got it fairly well nailed down.

If you really want to get a handle on the cooling efficiency of the transmission "cooler" - a good idea with the snowplow anyhow! - plumb one gage in with two sensors - one in each transmission cooler line. Use a DPST switch to change over sensors (or DPDT, if you have two-wire sensors) and you can quickly look and subtract the high reading from the low to see if it's really needed.

Alternatively, you can use a 'thermal bypass valve' (the better cooler makers have them - check B&M, Flowkooler, or Hayden first) which short-circuits the fluid back to the transmission when it's cold, and allowed it to flow through the cooler when it's warm. Also not a bad idea (and what I would do after totally removing the OEM "heat exchanger" from the circuit - warmup times are similar, but it takes a thermal load off of your engine coolant loop - heating the air with a cooler in front of the radiator has less impact than using the coolant to "exchange heat" in the transmission fluid directly.)

Click to expand...

Minor nitpick - SPDT switch, not DPST.

RCP - it's just a thermistor, there aren't going to be any spikes really; the current flow is on the order of a few milliamps and generally the circuit is wired like so: thermistor from ADC input to ground, fixed resistor from +voltage reference (usually 5 or 4.096 volts) to ADC input. Forms an adjustable voltage divider. This only applies to thermistors feeding the ECU of course, if it's feeding the gauge directly usually it's just inline - ground to thermistor, thermistor to gauge, gauge to +12V. In either case there are no real transients to worry about.

5-90 said:

Joe's got it fairly well nailed down.

If you really want to get a handle on the cooling efficiency of the transmission "cooler" - a good idea with the snowplow anyhow! - plumb one gage in with two sensors - one in each transmission cooler line. Use a DPST switch to change over sensors (or DPDT, if you have two-wire sensors) and you can quickly look and subtract the high reading from the low to see if it's really needed.

Alternatively, you can use a 'thermal bypass valve' (the better cooler makers have them - check B&M, Flowkooler, or Hayden first) which short-circuits the fluid back to the transmission when it's cold, and allowed it to flow through the cooler when it's warm. Also not a bad idea (and what I would do after totally removing the OEM "heat exchanger" from the circuit - warmup times are similar, but it takes a thermal load off of your engine coolant loop - heating the air with a cooler in front of the radiator has less impact than using the coolant to "exchange heat" in the transmission fluid directly.)

Click to expand...

Just a side note, I recently replaced my ground wires with a set modeled after the kits your sell and I just wanted to say that it has made a huge difference in the starting and charging parameters on the heep. I was planning on ordering a set of your 4g kit but I was at the junk yard last week and came across a Dodge 1500 with about 30' of 4g wire in it so I lucked out and got it for $5. But to anyone who is thinking of it, DO IT! My dash volt meter guage reads just over the 14v mark now and it starts right up where as before it would take a few seconds of cranking to fire up, my lights are brighter and the engine just seems to runs smoother overall. Also my amps don't whine anymore, the ground loop whine has finally disappeared.

I compared the cost of materials to the cost that you sell your kits for and they were so close I didn't see the point in going through the labor pains myself when for $20 more I could get them pre-assembled. It was just dumb luck I came across the cable at the junk yard. Also your site has so much valuable information and you have contributed so much to the forum.

Thank you

Kelvin