Towing heavy loads in an automatic

[Spetz]

Hi guys,

Soon enough I will be towing about 1,500kg (3,200lbs I believe that equates to).
Tow car will be a Mitsubishi Diamante so I am towing at its max manufacturer stated towing capacity.

I've added an ATF cooler but wondering what would be the best auto selection?
99% of the road is just highway so I will be towing at around 90km/h I suspect.
The transmission is a 5 speed auto - Am I best to just leave it in D or am I best to leave it in 4th?
The torque converter locks in 4th as well.

 

[Jetronic]

If the torque converter stays locked in 5th, you're good with that. You'll get better mileage in 5th IF the transmission decides to shift up that high; it will depend on how much wind resistance you have.

 

[B320i]

Figure out if fifth gear gets lockup as well. If not, you'd simply be warming the ATF un-necessarily. If there isn't much difference between locked 4th and 5th, just use 4th to save the transmission hunting around. Some can be rather twitchy even on the flat.

 

[demarpaint]

I'd check the owners manual, if you don't have one you can probably download it. Some vehicles have a tow haul mode, others suggest locking the car out of OD, I've even heard some people say towing in OD was OK. When I towed I never used OD, when the slightest incline or head wind forces a downshift that tells me something.

 

[dlundblad]

I am not sure how hilly it is where you are, but see how it behaves. It might constantly be shifting between 4th and 5th if you just put it in drive. Putting it in 4th may be the better bet for the transmission.. not so much the fuel economy.

 

[Spetz]

Thanks guys.
Fuel economy is not a concern of mine rather what is best for the transmission is my main priority.

Both 4th and 5th have TC lockup.
I know that at the speeds I'll be towing the engine will be under 2,000rpm in 5th which might not be enough torque.

 

[Donald]

It's why I have a 3/4 ton pickup. Don't have any considerations in this area.

 

[OPR4H]

Try letting in D, first.

 

[bullwinkle]

Not sure about Mitsubishi (I've never towed anything that heavy with a car that light before), but you'll get better ATF AND coolant flow by towing in 4th and keeping the engine RPMs up. I had a Ford E4OD work van burn the ATF by trying to tow even light loads at 65 MPH/105 KPH without locking out overdrive.

 

[hpb]

If this is towing your Mirage track car, I'd lock it out of 5th. Those Magnas, even with the 3.5, aren't the most torquey things around, you'll need the extra RPM's. I always lock my Falcon out of overdrive (4th gear in my case) if I'm towing anything over about 500kg, as even with the grunty Barra 190, it hunts between 3rd and 4th.

 

[Linctex]

Originally Posted By: Spetz

I know that at the speeds I'll be towing the engine will be under 2,000rpm in 5th which might not be enough torque.


It depends on the truck.

My 2008 F150 with a 4.6 SOHC makes GOBS of torque between 1200-2000 rpm. I tow with it all the time in 5th OD, Often times loads of about 1500KG - 2000Kg usually around 110kmh (1400 rpm)

Downshifting is only a problem with the cruise control on for some reason.

 

[SZR48207]

Keep it out of overdrive and your transmission will thank you.

 

[demarpaint]

Originally Posted By: Reddy45
Keep it out of overdrive and your transmission will thank you.


Exactly!

 

[FastLane]

If your at max load then leave it out of 5th.

 

[simple_gifts]

Quote:
(3,200lbs I believe that equates to).


Actually 3,300; but who is counting? j/k

 

[ammolab]

One gripe with my CR-V is my choices when towing: "Drive" this gives me constant hunting from 5th to 4th or..."3" which locks the transmission in 3rd ( engine screaming close to 5000RPM at highway speed ).

Why oh why can't I select & hold 4th gear for a nice tow down the highway. My friend has a Korean SUV, any gear may be selected and held...NICE!

 

[Alex_V]

Consult the owner's manual, but outside of that the
That's a quirk of the Odyssey/Pilot/Ridgelines I've driven - no way to keep it in its power curve at highway speed, just 3rd which isn't practical above about 45? or 5th which puts the RPM's just as low as it can tolerate.

My '85 GMC 1-ton, tow-haul is called "D".

 

[SoNic67]

Originally Posted By: ammolab
One gripe with my CR-V is my choices when towing: "Drive" this gives me constant hunting from 5th to 4th or..."3" which locks the transmission in 3rd ( engine screaming close to 5000RPM at highway speed ).
Why oh why can't I select & hold 4th gear for a nice tow down the highway. My friend has a Korean SUV, any gear may be selected and held...NICE!

Because US cars have a separate button for "O/D off" - that puts you in what Koreans call the 3rd/4th gear (the one below the last).
Look in the manual.