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Discussion Starter #1
I was out getting sized and fitted for a winch plate that would go on the stock front bumper and the guy who was test fitting it and measuring said that they had someone with an Xterra kill a transmission cuz of heat soak. The reason they got heat soak was cuz they had skids that ran from frame to frame. I have a set of Hefty Fab skids that I plan to put on tomorrow, I know a lot of folks here run them too but has anyone heard of anything like this? Any issues with yours? I sit in traffic a lot and the truck is also my daily so this definitely got me very paranoid. Also anyone have pix of the hefty fab skids installed up on a lift, would like to see how much they cover under the truck.

Thanks!
 

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I suspect the transmission failure was caused by something else.

Most cooling is accomplished by the ATF cooler in the engine radiator (and supplemental cooler mounted in front of the radiator, if present) - not by air flowing past the transmission itself.

You could completely enclose the transmission in an air-tight box, and it wouldn't overheat - as long as you had a sufficiently large ATF cooler mounted outside the box.
 

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I would bet my truck that skid plates didn't cause the transmission to fail. Heat transmission is negligible via air contact


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It depends on how much the skid plates cover. The ones I've seen are about 1-2 feet wide and run down the middle of the truck. This would leave enough gap for air flow, and should be no problem. In the racecar world, when doing a full flat floor for aerodynamic purposes, the transmission and diff can absolutely overheat, and will always need ducts for airflow. This is a fully sealed floor, and driven at much higher load. I have not heard of truck skids being an issue, and I would imagine it's in fact not an issue.
 

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Currently having the Hefty skids on my truck, I can assure you this isn't a problem, my trans has never run hot, the only possible way I could see this happening is if you parked in a mud pit and ran the engine at high speed digging holes, the mud/muck that would cake around the trans could cause it to overheat, but from normal driving, or trail driving, your trans fluid flows through the radiator and the trans cooler, not to mention allowing for heat to dissipate naturally around it.
 

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In the racecar world, when doing a full flat floor for aerodynamic purposes, the transmission and diff can absolutely overheat
The manual transmissions and differentials used in most racecars don't have several gallons of ATF being pumped through an external cooler.
 

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I would find it most likely that it was an 05 to 08 that someone had done the radiator bypass to save themselves from smod in a very hot climate without adding a separate trans cooler or replacing the rad to get the original cooling back. We have been using the same type of skids since around 2006 and this is the first I have heard anyone with a Frontier or an X say that this happened. Hopoefully the guy fitting your winch mount does not work on transmissions or maybe they are thinking about offering skids and they want to use that as a reason to make them super skinny and thus not cover enough to protect things. The new WAM skids looks too small to me and having that tiny thing for the gas tank that bolts over instead of under the the skid it attaches too is what I am thinking of. I really see them as being intermediate between stock and full skid plates and expect that gas tank bit to be sheared off rather regularly.
 

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The asphalt and concrete is usually hotter than the air, so I would think, but don't know for sure, that a skid plate may help to keep some heat away from the outside of the trans.
 

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People should not make assumptions on a part failure, and blame something unrelated. Plus the newer Frontiers have an external transmission cooler mounted behind the grill.
 

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Discussion Starter #10
Thats what I thought. I wanted to see if anyone knew anything. Looks like the guy was just making it up. Mine does have the trans cooler. Thanks for the added context and additional peace of mind.
 

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Install those skids with confidence. I ran them for 5 years on my Frontier and never had an overheating issue. They have been on my X for 1.5 years w/o an issue.
 

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260k miles on my 2008 and have had hefty skids on it since about 60k miles. No problem yet.

Also...for those saying that the transmission gets cooled by the radiator....not true. That is there to HEAT up the transmission fluid when first starting and driving the truck. Think about it....how hot does your coolant run? 180-200 degrees....that's not going to cool the transmission down, which runs at a much LOWER temperature in normal driving.
 

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for those saying that the transmission gets cooled by the radiator....not true. That is there to HEAT up the transmission fluid when first starting and driving the truck. Think about it....how hot does your coolant run? 180-200 degrees....that's not going to cool the transmission down, which runs at a much LOWER temperature in normal driving.
ATF routinely runs hotter than the engine coolant -



If you're towing something heavy or off-roading in mountainous terrain, it can easily exceed 300 degrees.

The purpose of the in-the-radiator cooler is to bring the ATF down to a temperature that it can handle without breaking down.

180-200 degrees is nothing for ATF.
 

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No sir. If your Frontier trans temp gets up to 300 then you have problems. Do a search on here for Transmission Temp Gauge. Most regar driving trans temps being recorded are in the 140-170 range. The HEAT EXCHANGER (it's not a trans cooler inside the radiator) is meant to get the trans up to operating temp quickly. Research man...research.
 

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Most regar driving trans temps being recorded are in the 140-170 range.
Towing a heavy load or off-roading in mountainous terrain doesn't qualify as "regular driving".

The ATF must be cooled to reasonable temperatures under ALL driving conditions - Not just under "regular driving" conditions. That's what the in-the-radiator ATF cooler accomplishes.

There's a good reason why they don't call it an "in-the-radiator ATF heater".
 
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