Skids and transmission temps

Has anyone had issues with engine or transmission tempts with skids? I know some have airflow whereas many don't. Curious if its even an issue to think of as I've only seen it brought up maybe once?

 

A question I’ve thought of myself. But most skidplates cover less frontal area than the factory tins do, so airflow changes for skidplates by themselves is probably not a huge deal on most designs. Some have very good coverage though, with little airventing, so I’d wonder on those.


There was a guy on here that had a full bumper that was pretty sealed tight, and he had skidplates, and he ended up having problems with trans temps. So it’s possible…but that may have been mostly due to the bumper covering up the majority of the radiator.

 

Maybe my RCI full skids + 2 small spot lights effect cooling, mine hit 200F transmission temp when outside is 45F ish. Almost stock weight (other than aluminum skids and hrew sliders), stock tires. Not towing as well.

 

This is certainly my concern. I was about to actually pull the trigger on some skids until I started thinking about temps.

I am curious with RCIs design if it’s preventing airflow. Their KDSS version has no holes in the front other than the logo itself.

right now I’m leaning towards RGS but their rear skid is as solid as can be. Maybe I can drill out some vents…

 

No change with full skids. I'm still adding an AUX cooler and larger pan though.

 

My Rival skids have quite a few vent holes. I don’t know if they make a difference. I guess I should check the trans temp sometime.

 

Sounds like an answer looking for a problem. I think we would have heard a lot more about it if it really was a issue IMO.

 

Factory "under cover" doesn't offer much of opening other than that mash covered little window. Are you planning to drive across country for hours non-stop? You might be overthinking it.

 

There are definitely some makers that do a good job with the front, rival being one. It is the rear I would question since it basically puts a solid metal shield around the transmission. Atleast yours has some vents though!

This was my thought as well, the platform has been out for so long and we're only hearing small anecdotes about it here and there.

I think most manufactures do a good job with the front skid. Some have no ventilation, but many don't have sufficient ventilation IMO. Even if its just two mesh covered windows, theyre huge in comparison to a cutout logo. Like RCI skid for KDSS for example... (non-kdss version has 4 additional vents, which is fantastic)



Honestly, its really the transmission that id be concerned about. The transmission doesnt have a factory skid. Its completely open, but once you add a skid...it becomes very enclosed. So if the front isnt getting adequate airflow, you know for sure the transmission is just going to be baking.

Funny enough, driving cross country non-stop would give me less concern since airflow is constant. Its when youre idling, crawling slowly, or towing where theres less airflow/more load that I would be concerned of temperature rises.

 

It's also interesting that the RCI website shows their KDSS front skid on a non-KDSS 4R...

 

lol yeah, not sure why. i actually called them to confirm too

 

My Non KDSS RCI for comparison

 

I've wondered about ventilation on the skids. Both the TRD skid plate and the regular skid plate have vent holes in very specific places. If you look at them from the front you can see they are the in same location on both. They could have put holes anywhere, but there seems to be a reason why the engineers chose those locations. Then @kmeeg posted a pic of the limited with it's duct leading to one of those holes, which reinforced the idea that the designers wanted airflow there. Maybe not a big deal, but it makes me want to stick with one of the Toyota versions...

 

I remember trying to trace out where the air goes from the stock vents. Seem to remember the air is directed to the bottom of the front diff., not sure where else.

 

time for auxiliary transmission cooler with electric fan and 180F switch

 

Good find! There definitely seems to be reasoning there. I'm currently leaning towards RSGs plates because of it. An abundance of airflow here. Maybe atleast start with the front first then maybe drill/vent out the rear skid

 

Fast forward to 9:45 to see a description of where the engine oil cooler is. I imagine that this is probably the reason for at least one of the vent holes in the skid plate.

Edit: I realize that it's a water-cooled oil cooler, but those typically come with some sort of ventilation as well, no?

https://m.youtube.com/watch?v=wDeLFAAJCyk

 

Bringing back this thread for some direction.
Installed my RCI Transmission skid plate with the TRD transition skid plate in order to keep the OEM TRD Engine skid plate.
I recently found out about possible transmission overheating with the RCI plates. . My 4Runner is my daily driver and no towing. The main reason I went with RCI is for the CAT protection.
Am I overthinking it or should I worry? I Do not want to instal an external cooler.

 

Never heard of this issue with any skids. The trans still has a cooler and I don't think there's much airflow across the transmission body itself anyway because of the way air flows under a vehicle. Also many other vehicles have full paneling without issues.

 

This is a great point, really how much heat does the case of the trans actually dissipate? Seems it'd be finned if cooling through the case had much effect.

 

I think in the majority of vehicle it's only dissipated through the fluid. In the owner's manuals I have read it states to stop but leave the engine running in a transmission overheat situation.

 

Surprised that more people don't monitor transmission temps with all the other high dollar mods being done. Curious if covering the trans and exhaust would increase heat noticeably.

 

On long trips I’ve monitored my trans temps. Observations I recall (based on my setup)…after enough time at interstate speeds on flat-ish ground, everything heat soaks and the trans fluid assumes the same temp as the coolant. In other words, the transmission cannot get any cooler than coolant temp. In my case, this was at about 190F on a warm day with heavy skids that completely cover the transmission.

My front bumper has cutouts that might improve airflow compared to the stock bumper. But my skids are 3/8 in thick under the trans, so the steel mass is might be acting as a heat sink that makes it warmer in the dead space below the transmission.



Once I was heat soaked, any amount of torque converter slip on uphills/acceleration, made pan temps climb to around 225 in pretty short order. It took a while to cool it below 200 because the water temp did not give the fluid much of a temp differential to cool it down.

So knowing that, it’s worth making an effort to manage the temps by downshifting to 4th whenever you need to accelerate/climb, in order to keep torque converter slip to a minimum.

Based on a fast food drive-thru experience (lol), I’ll add that it needs to be in park as well. If you just hold the brakes, temps will continue to climb, because the torque converter is slipping

Also, Once you are in park, if you raise the rpms to 1500, the increased radiator fan speed will cool down the trans pretty quick.

 

Lots of great information. I wonder how the MillerCat Shields compare with the heat. They box out the area, but the company goes hard promoting "No Overheating".
https://millercat.com/blogs/news/the-answer-to-the-overheating-question

But, only talks about the CAT overheating and no mention about the Transmission.

Thoughts??

 

I’ll stick with my stock skids which haven’t failed me yet.

 

That was an interesting read, shows they put some level of thought into this. As an amateur enthusiast-level aerodynamicist (that just means I read a thing once lol), it makes sense that a well designed belly pan or louvers under a car can end up drawing air out, where it would have otherwise stayed trapped.

I think if somebody in stock form would monitor their transmission temps under similar circumstances as I described, the temps wouldn’t be that different. I think 4runners trans temps are fine in almost all situations, but being heavy, fast, or climbing for extended periods, you really should take some care to need to manage temps. Stock or not.

I suspect that since my belly pan-type skids essentially are flat/maybe even approaching wing-shaped on the whole, that air is being drawn out of the area pretty effectively (at least matching stock airflow).

Feeling the floorboards is probably a good way to tell if things seem hotter. Oddly enough, there was one long interstate stretch on a previous road trip where I did notice abnormal heat radiating from the transfer shifter console area. It lasted a good half hour, but then I never noticed it being hot since then. I think it may have been due by strong crosswinds that messed up the airflow underneath. At least that’s my guess, because a) it didn’t catch fire lol, and b) that was the only time I noticed that heat.

 

Awesome. I appreciate the great information and piece of mind. My wife thinks I'm overthinking it.

 

Well show her my post and ask who she thinks is over-thiking now! Lol