New to towing - jerking / tugging trailer - transmission damage?

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Originally Posted by garrycol

A six speed has the full range in gears in sport mode - it is only the shift points and the time it hangs on in gear that changes and this applies to 5th in Sport mode - it hangs on to 5th for a long time before it goes into 6th.

Try driving on a freeway at a steady 100kph in sport mode - after you have been in 5th for about a minute or so and driving at a steady speed it changes up to 6th - I have seen the specific specs sometime back but it is something like 10o kph and a minute or two.

I have had a 2.7TDV6 with ZF 6 speed for 7 years and 140,000km and I can assure you it goes into 6th in Sport mode and it does it when I am towing my camper in the right conditions.

Garry

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Originally Posted by BobD

I have been towing 2.5t around Australia for the last three months and the car most definitely goes into sixth gear in sports mode. At a constant 100 kph there is no difference between sports and normal. At 90 it usually holds fifth in sports mode unless going down hill, although on steeper down hills it will drop to fifth for a little more engine braking.

I have been towing in sports mode for the last two months but for the last four years have always left it in drive, with no issues. The best thing about sports mode is that it changes down to the lowest possible gear when braking heavily, which is very helpful when towing. With all the hills in NSW it is also good to hold the lower gears much longer on steep hills, as sports mode does.

I know Kevin recommends sports mode for towing heavy caravans but I've never heard him say anything about higher transmission clutch pressures and my car is there quite often lately. We have had lots of chats about trips and Discos in those visits.

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Good feedback, thanks , its possible I haven't been towing my boat ( 2 tonne )over 100 kph , will try it out tomorrow.

So we have hired a van,weighs around 2100KG,and done 600 k so far today.
Vehicle is also loaded.I have never towed more than a small trailer with this vehicle before.

I found that with the vehicle in sports mode it won't change to sixth until at least 100km/hr, and usually only going down hill or on light throttle.

In D it will hunt between 5th and 6 th depending on hills,where in sports mode it will just happily sit in 5th,until a big hill comes along,then it will change back.

Once on the flat,that is west of Inglewood,on cruise,at 90km/hr actual it will sit in 5th all the time whether in sports or normal mode.

Note mine is 2.7l not 3.0l.

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Originally Posted by discorevy

The op has a d3 , unless the d4 six speed has different TCU programming then I will stick with my statement that it will keep 5th in sport mode , I have an sdv6 6 speed coming in tomorrow so I will find out, until then you might want to let us know at which speed / load yours drop into 6th at when in sport mode.





You are right to tow in sport mode , as well as listening to your lr specialist ( especially if it happens to be Kevin from rovertech) I worked with him for a few years a long time ago, I'm by no means a guru on zf ( I've only done one rebuild)

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You can certainly keep your statement if you wish [emoji6]
And I can happily keep mine - we have a D4 and a D3 in the family, and the 6 Speed will Shift up once it’s not labouring (sufficient speed v revs).

We tow above 100 regularly (can tow at 110 where posted in SA) and they both shift up.
The loads are always 1800-2600kg

So , today I managed 12 kilometres (about 7 minutes) at 110 kph in sport mode before having to slow down , car stayed in 5th the whole distance ( no trailer) 2005 tdv6

Could only get 2 minutes with mates 2012 sdv6 at 110 before having to slow down ( it stayed in 5th) so not conclusive, will check later

I'm not sure if there is a difference between tcu's from different year / models, would be good if others could report to add to the collective knowledge.

I assume that the dashboard display is saying S and not 5. If it is saying 5 it will not change as fifth has been selected.

You assumed correct Bob, I also use the gap interface with gear selected , torque converter status ,amongst others, drove to Perth today , managed 28 kilometres at 110 without having to slow down ( not towing ) in sport mode , stayed in 5th , selected normal drive mode after that as it wouldn't be changing up after that distance, trans is in good shape

Discorevy, all I can say is that your car behaves very differently from my car and Tombie's cars as well as my son's D3, which all change to sixth in sports mode but at a higher speed of around 100kph.

Yep - was on the highway today and thought of this thread and tried it - 100kph is the cutoff speed - below 100kph in Sport it stayed in 5th - above it changed to 6th - every time. I confirmed it was in 6th by changing in to normal drive and revs did not drop - if at just above 100kph in 6th drive and changing to sport it changes back to 5th but then straight back to 6th - at 110kph switching between modes may no difference and stayed in 6th.

I might suggest that your box has an issue or in fact you were in 6th in Sport.

Garry

Same. I tried it today. Was in 6th D at @110kph. Switched to sport, no change. Accelerated in sport from standstill. Went into 6th. I wasn't towing anything so not sure if that makes a difference. Gear selection is also load related so I guess if a vehicle is experiencing more load it may stay in 5th.

Thanks for confirmation, I can only think either software issue or maybe the pre updates all do this, anyone with an 05 tried this ?, the only thing mine has different from standard is a bas remap.