Towing Question

[robbocop]

I have a question regarding towing with the 4Runner. I just traded my 1998 Durango for a 2004 4Runner Limited, with all the bells and whistles. I am a little confused from the manual regarding towing.

I have a 17' bassboat w/40HP motor - total weight 2700lbs. With the Durango, i had to drive with overdrive "off" so it wouldn't shift into the high gear. It appears that with the 4Runner I can tow in 5th gear and just go with it, no special rules for driving. Just the same as if Iwasn't towing.

Is this right?

I have 800 miles on the 4Runner and I know I have to break in for at least 2000 miles. That is no problem, as here in Massachusetts, the ice won't be out til April or May anyway.

Thanks for the help in advance, this is a great resource for me as a new and happy 4Runner owner.

 

[HuntRunner]

I believe with an automatic transmission, as long as it is not shifting back and forth a lot, (from 4th to 5th) you are probably fine to tow in fifth. When I tow, I use fourth gear until I get it to the highway, then I bump it up into fifth.
I don't know what the terrain is like in your area, but fourth is good in the hills too. I don't know if you have noticed yet, but the trtansmission will actually downshift if you are trying to slow down going down hill. It will hold this lower gear until you touch the gas again.
My 4Runner has about 12K miles on it and I tow a boat with it almost every weekend, does great!

 

[khaug]

I tow a Porsche 911 on an aluminum open trailer (~4,000 #). When the terrain is level, I tow in "D" (5th gear is enabled). But I keep a close watch on the tach.

If you see a sudden 200 rpm rise, it indicates the tranny torque convertor has unlocked. If this continues for more than a minute, I manually shift to "4", as running with the torque convertor unlocked will cause the tranny temp to rise rapidly - not something you want to have happen.

 

[HuntRunner]

So that's what is happenning? I wondered why it seemed like it was able to downshift again after I thought it automatically went from 5th to 4th. When I notice this I would manual downshift into 4th; thinking it was already there it would still downshift.
What do you mean by the converter is open? What is happening?

 

[khaug]

The torque converter is a fluid coupling between the engine and the transmission gears. Think of two fans facing each other, with the airstream from the powered one turning the blades of the other.

The torque converter can multiply engine torque as long as the speed of the drive element (engine side) exceeds the speed of the driven element (gearbox side). Some slippage occurs when this is happening, with loss of efficiency. This churning of the tranny/torque converter fluid generates heat.

Modern auto transmissions mechanically lock the drive and driven elements of the converter together when the torque multiplication isn't necessary, such as in steady-speed cruising. If torque requirements increase, however, such as climbing a hill, the transmission's first response is to unlock the two elements and let the engine speed up for torque multiplication. If this isn't enough help, the tranny will downshift into a lower gear as well.

Sounds like you've intuitively been doing the right thing. The rpm jump when a downshift occurs is way more than the modest increase when the converter unlocks. The important thing is to avoid running for long periods in 5th gear with the converter unlocked.

 

[HuntRunner]

Thanks for that explanation! It always helps to know how things work......