Transfer Case Neutral
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vicpick58
New member
I am new to Toyota, but in most 4x4 vehicles the neutral in the transfer case allows for flat towing like behind a motorhome.
I used it when I had a Chevy S10 pickup years ago, dragged that thing around behind my motorhome by simply putting the case in N and leaving the steering unlocked. Of course I had a tow bar and tail lights.
I read somewhere in the Toyota owners manual that the 4Runner cannot be towed behind a motorhome, but I do not really understand why not if it has a true neutral position in the transfer case.
Prevent burning up the transmission
Quick answer: the oil pump in an automatic transmission only pumps oil when the engine is running. A transmissions spinning output shaft requires lubricant to prevent overheating. The transfer case when placed in neutral separates turning/spinning wheels from the transmission output shaft. The transfer case is lubriated by gear oil slinging around.
There's probably more to it when you get vehicle specific.
Quick answer: the oil pump in an automatic transmission only pumps oil when the engine is running. A transmissions spinning output shaft requires lubricant to prevent overheating. The transfer case when placed in neutral separates turning/spinning wheels from the transmission output shaft. The transfer case is lubriated by gear oil slinging around.
There's probably more to it when you get vehicle specific.
Flat towing a 1999 toyota 4runner 4x4 with auto tranny
I tow my 1999 toyota behind my motor home and do not have any problems.
Here is the trick and pay close attention.
1.Vehicle must be in Park engine OFF. DO NOT RESTART ENGINE.
2. SHIFT TRANSFER CASE INTO NEUTRAL. TURN IGNITION 1 CLICK TO UNLOCK STEERING. YOU WILL HAVE TO LEAVE KEY IN THE IGNITION.
The reason the engine must be off is the automatic hubs are vacuum actuated
and will engage the front hubs causing the front drive shaft to turn the transfer case gears.
I tow my 1999 toyota behind my motor home and do not have any problems.
Here is the trick and pay close attention.
1.Vehicle must be in Park engine OFF. DO NOT RESTART ENGINE.
2. SHIFT TRANSFER CASE INTO NEUTRAL. TURN IGNITION 1 CLICK TO UNLOCK STEERING. YOU WILL HAVE TO LEAVE KEY IN THE IGNITION.
The reason the engine must be off is the automatic hubs are vacuum actuated
and will engage the front hubs causing the front drive shaft to turn the transfer case gears.
Jetboy
New member
FWIW - the neutral position does disconnect both front and rear shafts from the in put shaft. However, the rear output shaft and bearing assembly will still spin. The rear output shaft is higher than the oil level in the transfer case and the oil pump assembly will not spin. Therefore there is no mechanism that will move the oil from the bottom of the transfer case housing up to lubricate that bearing. You can probably get away with flat towing for some distance based on residual oil in the bearing and low load. But you have to recognize that you are spinning a potentially un-lubricated shaft.
I *think* that if you put the transfer case in N and had the front ADD connected (so you were engaging the front diff to drive the transfer case output to the front axle) you would then spin the chain and it would probably move enough gear lube up to lubricate the rear output shaft. Without putting a window in one and running it to see how the fluid flows - I can't be sure of this.
In a perfect world you could install a baffle to hold oil in the rear output bearing area to lubricate during flat towing. Otherwise - it's not designed for that and you may end up burning up the bearings and seizing the transfer case. You might not have an issue and residual oil is enough. I might roll the dice on my own junk - I wouldn't recommend someone else doing it.
Hopefully this will make some sense. In the image I put a yellow line at the level the normal oil fill level is. The oil pump is driven by the input shaft on the front (left side in this image). That is not driven or pumping in Neutral if the transmission is in park or neutral during flat towing. I've also added a pink/purple sort of color circle to highlight the rear output shaft area that will be spinning during flat towing and not lubricated. To flat tow - you need to get the oil from below the yellow line up to the bearing in that area. I don't think you can over-fill the oil enough to do that, but I don't know for sure.
I *think* that if you put the transfer case in N and had the front ADD connected (so you were engaging the front diff to drive the transfer case output to the front axle) you would then spin the chain and it would probably move enough gear lube up to lubricate the rear output shaft. Without putting a window in one and running it to see how the fluid flows - I can't be sure of this.
In a perfect world you could install a baffle to hold oil in the rear output bearing area to lubricate during flat towing. Otherwise - it's not designed for that and you may end up burning up the bearings and seizing the transfer case. You might not have an issue and residual oil is enough. I might roll the dice on my own junk - I wouldn't recommend someone else doing it.
Hopefully this will make some sense. In the image I put a yellow line at the level the normal oil fill level is. The oil pump is driven by the input shaft on the front (left side in this image). That is not driven or pumping in Neutral if the transmission is in park or neutral during flat towing. I've also added a pink/purple sort of color circle to highlight the rear output shaft area that will be spinning during flat towing and not lubricated. To flat tow - you need to get the oil from below the yellow line up to the bearing in that area. I don't think you can over-fill the oil enough to do that, but I don't know for sure.
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mxcannondale
New member
Sorry in advance, resurrecting a 2+ year old thread.
I have been asking myself this same question why the 4runner owners manual for a 5th gen trail says no flat towing.
I myself have owned a 2016 4runner trail with the manual tcase shifter with neutral position.
Also I am almost certain that the 5th gen does not have a front axle disconnect, although i cannot check since I own a full time 4wd v8 4th gen now.
With that being said, if the front driveshaft/diff is always engaged that would turn the front shaft, and also in turn the chain in the transfer case. in theory you should be able to put tcase in neutral, transmission in park, and flat tow to your hearts content, in THEORY. I have a feeling that toyota printed the same owners manual for every model 5th gen and there is some overlap there. I think every other 4wd model besides trail has the electric shift, which does not have a neutral option.
I'm asking myself this question because i'm planning to get a motorhome, and would like to get another 5th gen to town behind it. another option that is really popular that I do not want, is a jeep wrangler, so i'm trying to avoid that at all costs if possible.
Anyone have any other thoughts on this?
I have been asking myself this same question why the 4runner owners manual for a 5th gen trail says no flat towing.
I myself have owned a 2016 4runner trail with the manual tcase shifter with neutral position.
Also I am almost certain that the 5th gen does not have a front axle disconnect, although i cannot check since I own a full time 4wd v8 4th gen now.
With that being said, if the front driveshaft/diff is always engaged that would turn the front shaft, and also in turn the chain in the transfer case. in theory you should be able to put tcase in neutral, transmission in park, and flat tow to your hearts content, in THEORY. I have a feeling that toyota printed the same owners manual for every model 5th gen and there is some overlap there. I think every other 4wd model besides trail has the electric shift, which does not have a neutral option.
I'm asking myself this question because i'm planning to get a motorhome, and would like to get another 5th gen to town behind it. another option that is really popular that I do not want, is a jeep wrangler, so i'm trying to avoid that at all costs if possible.
Anyone have any other thoughts on this?
1. My 2018 SR has a front axle disconnect that is run by an electric motor.
2. The oil pump for the transfer case is on the input shaft. Even with the transfer case in neutral, the output shaft rotates (driven by the rear wheels). Thus you cannot flat tow it because the output shaft has no lubrication.
Whippersnapper02
Senior Member
Toyota advises not to flat tow the 4Runner for the reasons stated above.
mxcannondale
New member
This answers the question then, if it's driven from the input shaft, it would never work, the trans would be in park. I was never successful in finding an exploded diagram of a transfer case, but I'll take your word for it.
Thanks.
