towing with TD5 auto

vbrab, the sport (mode) button changes upshift downshift points as stated above by others, not forcefully locks the converter.

I tow in D everywhere (never used sport mode for towing or normal driving) and it locks and tugs along nicely on the flat unless there is a very strong head wind/steep hill then it unlocks/downshifts as I need to put the foot down to keep the pace up, at which point I shift into 3rd manually and it will lock again soon after then I will upshift manually back to D as conditions suit.

It always amazes me the resistance difference between towing a small trailer weighing 7 -900 kilos that sits low down behind the car as versus a same weight full height caravan that catches the wind.

Really shows the force of wind power and how those big sailing bath tubs got around the world before steam power.

So sport mode (as I get it anyway) is really for just how spirited you want to drive, as the car will hang in gear longer anyway in standard mode when taking off with a load as you know.

The lockup is completely under the control of the programming unless you have a switch wired in to override the trans computer.

When SHACK really gets his auto programming shack together, I wonder if he will be able to reprogram the box to change and lock straight away in every gear rather like an auto changing manual. Hint hint shack baby!

I use the S mode as it better promotes kick down rather than lugging with an upgraded ECU when you hit hills. It still locks up the TC just as easily with an ECU upgrade, but it doesn't hold on to the locked TC and pull the revs down as speed drops, where a stocker setup uses more throttle and will just kick down. A far better setup, I run it like this when not towing also and it holds speed up the hills better.

Yes, I'm having trouble getting my "shack together" for sure, busy busy busy.

The tunes I have done on the TCU and ECU encourage lockup to be maintained as long as possible before kicking down due to lack of power.

There are a few reasons for this, and they are only MY opinions based on what I've found.

1. better economy.

2. The TD5 runs at best efficiency at about 2k rpm, so if you are in 3rd or 4th unlocked trying to do the speed limit, you are just turning diesel into noise.

3. Heat kills autos, take the 4hp somewhere in summer under load and unlocked, and you basically have a really portable (at least until it dies) heatpump.
If you don't believe me, buy a temp sensor for the auto and watch what goes on, you_will_be_amazed.

4. It's just so much nicer to drive, full stop!

Again, only my opinions...

Cheers
James

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Originally Posted by shack

3. Heat kills autos, take the 4hp somewhere in summer under load and unlocked, and you basically have a really portable (at least until it dies) heatpump.
If you don't believe me, buy a temp sensor for the auto and watch what goes on, you_will_be_amazed.

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A bit off topic,but yes they certainly pump out some heat.

I have an ultraguage on the LC200, that monitors,auto Torque Converter, and pan temp,separately.As well as a heap of other temps and parameters.One could work on the D2? It plugs into the OBD port,and readout sits on the dash,a great bit of kit.

Unlocked,the temps climb surprisingly fast,once locked they cool right down,it doesnt take much to see temps of the fluid well over 100 degrees,if unlocked and working hard.Slow speed hills unlocked really push the temps up.Knocking the gears back one or two in select,or using Low Range,bringing the engine revs up, will often bring auto temps down,even if the auto will not lock up,at the time,for whatever reason.

The LC will actually always lock up when the TC temp reaches 120degrees,then unlock at 110,as sort of self preservation mode,no matter what the gear,usually this only happens if working hard,unlocked.High temp light comes on at 150 degrees,but by then the fluid is cooked.

I had no idea about auto temps either,and have seen the high temp light on on the D2's we had, quite a few times,particularly in soft sand.
And the D4 went into limp mode with an auto error on the dash once or twice as well.
Not using Low Range,when needed, cooks the auto pretty quickly.

Heck. I’d tow my 2,800kg Shark Cat in Drive in 40°c heat with the D2 and not even give it a thought[emoji14]

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I had no idea about auto temps either,and have seen the high temp light on on the D2's we had, quite a few times,particularly in soft sand.

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Scarry, I have to say that if you get a temp light is sand then you are doing it wrong.

IE you are in too high a gear in maybe the wrong transfer case ratio. The auto is dumb enough that it will keep in a higher gear than ideal under several circumstances. You have to drive manually to keep the revs above the TC stall point.

I have never seen a high temp light even towing a 1000KG camper trailer with my RRC in dry sand on Stockton. The only time I have ever seen a light was after fording a river in Litchfield which was 900MM not the 400 I thought and the switch was shorted by water.

The secret is to make sure the revs of the engine are above the torque converter stall point, say 2500 for a V8 and 3000 with a TD5.

That is why on long hills the temp rises , because the TC is below TC stall point (or should I say the point at which it has the same revs in and out). That is why a change down will cool the transmission.

It is the torque converter which generates all the heat when not above it's stall point.

Regards PhilipA

It may also be a blocked ATF cooler.