Improving the cooling on our TJs

TexasTJ2004 said:
if you want to force the lockup earlier, just disable the overdrive. Then the lockup will happen much earlier, in 3rd gear. This is what I do on trails in 4L.
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I do that in 2/4Hi and it’s a bad idea to do in 4Low (4:1).

I manipulate the OD switch multiple times a day…knowing exactly when lockup occurs in 3rd and OD (my target rpm for boost determines when I toggle the switch).

TexasTJ2004 said:
BTW, what gearing do you have? I have 4.56 and running 31 inch tires, I still think that 4:88 would do a better job with 31s and 42RLE do to extremely low overdrive ratio.
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I’m running 5.38s with 35s. I’ll probably get a Rubicrawler at some point for the 2.72:1

4:1 is great in the rocks but not for other trails I like to do.
 
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TexasTJ2004 said:
I did not drive it for at least 3 month, I will start running it and update
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BTW, my temps have been much better since installing the Rubicrawler and having 2.72:1 for faster trails.

Much better than when I was in 1:1 on faster trails bc the 4:1 gearing would rev out too soon.
 
Staying in high gear is not good, for 42RLE. It does not like it. When you go low, the load on the transmission significantly drops, the RPM is higher and general cooling is far more efficient
 
TexasTJ2004 said:
Staying in high gear is not good, for 42RLE. It does not like it. When you go low, the load on the transmission significantly drops, the RPM is higher and general cooling is far more efficient
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That’s why I installed the Rubicrawler.

4hi (1:1) with the RC in low now gives me 2.72:1, and I move to 4low (4:1) only when crawling.

Btw, the grill mount location cools better than the Derale making 1:1 a viable option without needing the Rubicralwer if you have room in your grill for a cooler, but my steering cooler and turbo heat-exchanger take up that space.

Garret was racing around in the Florence trails a few weeks ago in 1:1 with his $50 grill cooler. I was knifing through the dust behind him in 2.72:1 running around the same trans temps as him (180*).

I would have been at 225*+ had I done that run in 1:1 with the Derale and OD off.

I wouldn’t run the Derale unless your grill space is taken up. I run it out of necessity bc I prioritized the turbo intercooler.
 
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MikeE024 said:
That’s why I installed the Rubicrawler.

4hi (1:1) with the RC in low now gives me 2.72:1, and I move to 4low (4:1) only when crawling.

Btw, the grill mount location cools better than the Derale making 1:1 a viable option without needing the Rubicralwer if you have room in your grill for a cooler, but my steering cooler and turbo heat-exchanger take up that space.

Garret was racing around in the Florence trails a few weeks ago in 1:1 with his $50 grill cooler. I was knifing through the dust behind him in 2.72:1 running around the same trans temps as him (180*).

I would have been at 225*+ had I done that run in 1:1 with the Derale and OD off.

I wouldn’t run the Derale unless your grill space is taken up. I run it out of necessity bc I prioritized the turbo intercooler.
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False equivalency. Garret has a transmission that can benefit from a cooler, you have a transmission that it is mandatory to have a great cooler in place.
 
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MikeE024 said:
Btw, the grill mount location cools better than the Derale making 1:1 a viable option without needing the Rubicralwer if you have room in your grill for a cooler, but my steering cooler and turbo heat-exchanger take up that space.
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I am not sure about it. Derale comes with electric fan and is located in the area is not hot.
It is also relatively large.
Grill mount location relies on airflow generated by the main fan, and adds heat load to AC and the main radiator, so it provides better cooling on highway, because it gets far better airflow, which is much better for towing.
But for us wheeling, I think that what we care about is low speed driving, under 15/20 MPH.
 
TexasTJ2004 said:
I am not sure about it. Derale comes with electric fan and is located in the area is not hot.
It is also relatively large.
Grill mount location relies on airflow generated by the main fan, and adds heat load to AC and the main radiator, so it provides better cooling on highway, because it gets far better airflow, which is much better for towing.
But for us wheeling, I think that what we care about is low speed driving, under 15/20 MPH.
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That cooler has a temp controlled electric fan?
 
Rickyd said:
That cooler has a temp controlled electric fan?
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Yes. Derale has a sensor (temp switch to be precise) in line, sensing the temperature of oil coming into the cooler. If it is 180F it closes the circuit for the fan and kicks in. If it is 170F it shuts down the fan.
 
TexasTJ2004 said:
I am not sure about it.
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I am sure because I’ve had both while off-roading in southern AZ.

TexasTJ2004 said:
Derale comes with electric fan and is located in the area is not hot.
It is also relatively large.
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Relative to what?

That location does not run cooler than being in front of the grill. If you ever tried both you’d know this.

TexasTJ2004 said:
Grill mount location relies on airflow generated by the main fan, and adds heat load to AC and the main radiator, so it provides better cooling on highway, because it gets far better airflow, which is much better for towing.
But for us wheeling, I think that what we care about is low speed driving, under 15/20 MPH.
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The Derale doesn’t cool nearly as well as the Setrab that Blaine installed in the grill for me…when off-roading or on highway. My temp guage doesn’t lie.

The Setrab worked so well in the grill that I repurposed it to be my intercooler’s heat exchanger.

The Setrab is still installed in the grill and my ECTs are usually around 195-205 when I Offroad…in the southern AZ desert. So it does not hurt my engine cooling and I have a steering cooler above it as well via Blaine.

Tbh, it’s borderline laughable trying to compare the Derale to the Setrab for cooling the transmission. One works extremely well and the other barely helps. There’s a good reason why Blaine installs the Setrab where he does.

Might want to try it for yourself since you like to tinker.
 
MikeE024 said:
Tbh, it’s borderline laughable trying to compare the Derale to the Setrab for cooling the transmission. One works extremely well and the other barely helps. There’s a good reason why Blaine installs the Setrab where he does.

Might want to try it for yourself since you like to tinker.
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You might be right. I never tried setrab one, I have looked at some generic oil coolers (like 50$ units), and read reviews about them.
 
TexasTJ2004 said:
You might be right. I never tried setrab one, I have looked at some generic oil coolers (like 50$ units), and read reviews about them.
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Did you remove your Autozone radiator for the Mopar that you purchased and set on your shelf?
 
TexasTJ2004 said:
I am ashamed to admit that I still did not install the Mopar radiator, and it is still sitting on my shelf.
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You are a smart dude and you know the summer heat is coming, so nothing needs to be said on that that you don’t already know.
 
Rickyd said:
That cooler has a temp controlled electric fan?
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The Derale kit comes with a thermo-switch, but mine energized the e-fan too late and was unreliable (wouldn't turn on sometimes when it really needed to be on).

I ordered a higher-quality switch with a lower temp-rating from a Wisconsin company last summer. The fan comes on earlier now and is reliable. This Derale kit would not have worked for me had I not located a better switch.

I've seen someone say their kit worked just fine for them in conditions similar enough to mine, but that person doesn't have a trans temp gauge so they were making claims that they couldn't support with data.

That's not to say that the Derale kit doesn't work for folks putting less stress on their transmission or operating in cooler ambient temps.

But, if you have tranny over-heat concerns and are going to spend that much on a kit, it's a no brainer to get the Setrab and never look back if you have room in your grill.
 
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TexasTJ2004 said:
I am ashamed to admit that I still did not install the Mopar radiator, and it is still sitting on my shelf.
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I put in my Mopar radiator today haven’t had a chance to properly test it versus the parts store radiator I had in but I can say confidently that the quality is definitely better. It has 55 tubes compared to the 48 on the Parts store and maybe slightly more fin density, basic math shows that as a 13% increase in cooling without accounting for the increased fin density I also noticed the box said made in USA!
 
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