D4 auto, towing.

[markorjack]

Hello all,

I am about to tow a tandem enclosed trailer from Tassie to FNQ using my TDV6 Auto D4.

Is there anything to consider?

I know in autos with an overdrive it is recommended not to use the overdrive while towing.

Should I be doing anything special in the D4 like switching to command shift when on the highway?

Cheers.

[discotwinturbo]

How heavy is she ?
We tow a 3.5 tonne trailer, all over, but drive in sport mode, as we find the gearing a touch better. Towing in normal will see it kick in to the top gears sooner....I prefer a few more revs.
It will tow in sixth gear when the speed is right.
On hills you may need to manually kick it down if driving in normal mode...in sport you don't need to worry (on my D4 it's virtually always in the right gear).
D4's like to tow.
Brett.....

[Redback]

Yep sports mode is the recommended mode for towing, I use manual mode and sit in 5th when I'm towing in hilly terrain(1500kg camper) best economy and better response for climbing hills, I only use 6th for flat country.

Baz.

[markorjack]

I'm not sure how heavy it will be but won't be anywhere near 3.5 tonne

Its an 8 x 5 enclosed trailer, only slightly taller than the D4.

At this stage it won't be too heavy.
We are moving back to Queensland and I will only be carrying what we need when we get there until the removalists arrive.
It will more than likely have more in it than I plan which is always the case.

The trailer has brakes but they are only cable over ride so I don't want to load it too much.

Fuel is not a problem as the drive will be paid for as part of a work relocation.

Sports mode may be the go, with occasional command shifting where needed.

[rufusking]

Do have the trailer thoroughly checked, tyre age / condition, wheel bearings etc. that's 4000km loaded and at highway speeds.
D4 will do it easy. There will be times you forget the trailer is even connected.

[101RRS]

Sports mode may be the go, with occasional command shifting where needed.

I agree with towing in Sports mode as the the change points are more suited to towing a load. Why would you need Command Shift - it is an auto and will change gear according the the load on the system so you will always be in the right gear - the system will pick load and adjust accordingly far better than you can.

Garry

[markorjack]

I only just bought the trailer but it had new bearings and the brakes checked before I bought it.
It seems to be in pretty good condition and is only 5 years old.

For some reason it sits 10mm lower in the front right corner and the only thing I can put this down to is very slight spring sag.

As well as I can measure, there is 10mm difference between the wheel spacing on either side as well as 10mm difference from the draw bar to the front tyres.

I have only towed it for about 100k's unloaded but it towed very well with no sway.

Two of the tyres were good, I have replaced two and have two reasonable spares.

[Redback]

I agree with towing in Sports mode as the the change points are more suited to towing a load. Why would you need Command Shift - it is an auto and will change gear according the the load on the system so you will always be in the right gear - the system will pick load and adjust accordingly far better than you can.

Garry

Because if you use cruise control, which I do, it will keep going to 6th, and the slightest hill will keep changing back and forth, it tows fine in 5th at highway speeds, somewhere around 2200rpm at 110kph, fuel economy around 14l to 15l/100k in hilly terrain.

Baz.

[101RRS]

Arh - well we hadn't talked about cruise control until just now - maybe should have been in the initial answers to the OP.

I stand by my comments re not having to use Command Shift on the highway and letting the box do it but you have a point re cruise control.

It shouldn't make a difference but it does - on the highway I don't have the hunting issue that others have mentioned (doesn't seem to happen in Sport as it holds gears longer) but I often get engine manifold pressure faults coming up. Switch off and restart clears.

It seems that the ECU detects unexpected MAP under high load situations in normal drive which seems to be caused by the cruise control making the gearbox hold longer than the ECU expects and detects unusual MAPs. I have heard on here others having similar issues - but is easily corrected when it happens.

So as recommended - tow in Sport (or in Command Shift if you think it necessary - I don't) and do not tow in cruise control.

Cheers

Garry

[Redback]

Arh - well we hadn't talked about cruise control until just now - maybe should have been in the initial answers to the OP.

I stand by my comments re not having to use Command Shift on the highway and letting the box do it but you have a point re cruise control.

It shouldn't make a difference but it does - on the highway I don't have the hunting issue that others have mentioned (doesn't seem to happen in Sport as it holds gears longer) but I often get engine manifold pressure faults coming up. Switch off and restart clears.

It seems that the ECU detects unexpected MAP under high load situations in normal drive which seems to be caused by the cruise control making the gearbox hold longer than the ECU expects and detects unusual MAPs. I have heard on here others having similar issues - but is easily corrected when it happens.

So as recommended - tow in Sport (or in Command Shift if you think it necessary - I don't) and do not tow in cruise control.

Cheers

Garry

If you don't use cruise, it will get to 5th and hold that gear when in sport mode, unless of coarse you back off the throttle and that lets it go to 6th and in flat country I do it that way, but in hilly terrain, it will continuously change up and down the box, that annoys the crap out of me, so I do what the gearbox will do anyway, once you're at cruising speed, if you hold the throttle on it stays in 5th, putting in 5th in command shift and 5th allows you to do the same thing but, have it in cruise control

I then if I need to put the boot in for steep hills I override the cruise and knock it back a gear before it starts to labour.

No matter how good the gearbox is, it won't change before the motor begins to labour, doing it manually keeps the motor in the sweet spot.

Besides I like using the manual mode