Towing

I tow a 1500kg poptop with a D2 TD5 auto, usually at 85-90 km/hr. After a bit of trial and error with various combinations of gear ratio, sport mode and cruise control I tow in 4th only on the flat with no headwind and cc off. I don't want to put a whole lot of torque through 4th for long periods so I use sport mode, which changes down earlier than normal on any slight incline. The only problem with sport mode is that sometimes it doesn't want to change back to 4th, even when it could.

In gently undulating country I use 3rd with sport mode off and usually with cc on. I find that it results in a less stressful trip for car and driver as 3rd can handle moderate hills and you don't have to row the car along on the gear selector. When it gets hilly I turn the cc off and leave it in 3rd. It doesn't use any more fuel in 3rd as I proved on a couple of trips between Adelaide and Echuca.

The fact is that the D2 ideally needs another gear between 3rd and 4th for towing. At 90 km/hr the motor is revving at just under 3000 in 3rd and about 2200 in 4th. Something like 2500-2600 seems about right.

Stephen.

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Originally Posted by Grumpy

Incidently Feral, Did a tow test over 1200km in third and there was very little difference in consumption to what I get in fourth. The whole trip was close on 2200km. In fact, sometimes it was a little better?

Tony :wheelchair: [Grumpy]

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Originally Posted by StephenF10

I tow a 1500kg poptop with a D2 TD5 auto, usually at 85-90 km/hr. After a bit of trial and error with various combinations of gear ratio, sport mode and cruise control I tow in 4th only on the flat with no headwind and cc off. I don't want to put a whole lot of torque through 4th for long periods so I use sport mode, which changes down earlier than normal on any slight incline. The only problem with sport mode is that sometimes it doesn't want to change back to 4th, even when it could.

In gently undulating country I use 3rd with sport mode off and usually with cc on. I find that it results in a less stressful trip for car and driver as 3rd can handle moderate hills and you don't have to row the car along on the gear selector. When it gets hilly I turn the cc off and leave it in 3rd. It doesn't use any more fuel in 3rd as I proved on a couple of trips between Adelaide and Echuca.

The fact is that the D2 ideally needs another gear between 3rd and 4th for towing. At 90 km/hr the motor is revving at just under 3000 in 3rd and about 2200 in 4th. Something like 2500-2600 seems about right.

Stephen.

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Originally Posted by Grumpy

I tow a two tonne van and have just had the gearbox overhauled
214,000 kays. The converter was stuffed!!
Was told by the ZF service blokes in no uncertain terms when going up a steep hill drop back to third and use that lockup. Do not leave it in fourth. Been told that third l/up is in the box and fourth l/up is in the torque converter and it over heats if worked to hard.
My light never came on.
If you listen closely in sport all the four gears and overdrive are being used. At least thats what it sound like.
Don't forget the van is 2 tonne.

Tony :wheelchair::wheelchair:
Jees now there is two of me

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It appears that I may have misled some of you and the thread has turned into a economy drive.

I can assure you that was not my intent.:mad:

The auto oil temperatures that I have collected clearly shows that the transmission is operating normally and is running at a cooler temperature when using 4th gear converter locked. The auto is running cooler and therefore is not under strain. Used sensibly, I also drop into 3rd when approaching a rise because it is all about momentum and keeping the thing rolling.

I cannot see how when anyone can run around all day in 3rd, approaching that big hill at 80 - 90 kph and claim that their auto temps are lower and putting less strain on their transmission because of it.

I have the temperature evidence, it has been back by others here and the opposing view does not make sense.

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Originally Posted by feral

It appears that I may have misled some of you and the thread has turned into a economy drive.

I can assure you that was not my intent.:mad:

The auto oil temperatures that I have collected clearly shows that the transmission is operating normally and is running at a cooler temperature when using 4th gear converter locked. The auto is running cooler and therefore is not under strain. Used sensibly, I also drop into 3rd when approaching a rise because it is all about momentum and keeping the thing rolling.

I cannot see how when anyone can run around all day in 3rd, approaching that big hill at 80 - 90 kph and claim that their auto temps are lower and putting less strain on their transmission because of it.

I have the temperature evidence, it has been back by others here and the opposing view does not make sense.

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You say that the auto is cooler in 4th locked than when unlocked at a slower speed (which makes sense) but why wouldn't that also be the case in 3rd locked? In both cases a major source of heat (slipping torque converter) has been eliminated.

As for strain, the motor has to produce MORE input torque for a given output torque when in overdrive, which is why I am happy to use 3rd more than 4th when towing.

Stephen.

2000rpm is the torque sweet spot.

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Originally Posted by StephenF10

The fact is that the D2 ideally needs another gear between 3rd and 4th for towing. At 90 km/hr the motor is revving at just under 3000 in 3rd and about 2200 in 4th. Something like 2500-2600 seems about right.

Stephen.

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Spot On!!
a 6 speed auto (:wub:)with 6th at the current ratio (.8?)
THEN spread the rest down to the current 1st which is fine when towing.

I wonder if this is possible?:angel:

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Originally Posted by StephenF10

You say that the auto is cooler in 4th locked than when unlocked at a slower speed (which makes sense) but why wouldn't that also be the case in 3rd locked? In both cases a major source of heat (slipping torque converter) has been eliminated.

As for strain, the motor has to produce MORE input torque for a given output torque when in overdrive, which is why I am happy to use 3rd more than 4th when towing.

Stephen.

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Makes sense but it looks like I will have to have a little test session the next time I hookup the van.

Not looking forward to putting around at 90kph. I just wonder how many more times the kids will say 'Are we there yet?' :p

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Originally Posted by feral

Makes sense but it looks like I will have to have a little test session the next time I hookup the van.

Not looking forward to putting around at 90kph. I just wonder how many more times the kids will say 'Are we there yet?' :p

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I would be very interested to see the results, in 3rd and 4th both locked and unlocked.

Stephen.

My D2 revs harder in 4th than it does in 3rd lockup. Pulls about 3000rpm doing 90kph in 4th and drops to about 2800 in 3rd lockup. Common sense tells me which is best for pulling up a hill for both engine and tranny.

If your auto doesn't want to go back to 4th at the top of a climb, hit the button and put it back to normal mode, it'll drop into 4th almost instantly and then put it back in sport.