towing with TD5 auto

[vbrab]

Have to take about 3/4 ton max (including trailer) 3600k's and am wondering if trans would handle that load running in top/4th?.
I usually lock my trans into 3rd with sports/power button for towing, but that is when I am towing LOAD, but lucky to sit on 80kph.
Only two real hills on the trip and I would be doing those in 3rd.
Anybody know what might be safe towing weight limit for 4th?

[pop058]

I use my D2 to tow my loaded box trailer in D. Anything heavier I usually use 3rd lockup.

[PhilipA]

I use 4 lock towing my 1700KG offroad caravan at 95-100Kmh, with no ill effects.

I change down on hills to 3 lock if I fall under 80Kmh.
Regards Philip A

[vbrab]

Didn't now you could lock 4 (use power button).
What I was told that using power button just sets gear change at higher pressure, so that it will stay in 3rd after it reaches 80kph (which seems to be they usually change into top) and also would not then drop into 4th when load was off going down hill.

Thanks, will have to check with my trans man to see if I can just use power button on 4th, and if that helps the box when towing, as not looking forward to a snail pace 3500k's

[PhilipA]

I don't think it changes pressures, just the revs when changes are made. It will lock in 4th at 80 Kmh , helped if you ease off just over 80kmh
until you see the tacho lock at road speed revs..
Regards PhilipA

[shack]

The "sport" button changes a few things, but realistically the only thing most end users would notice is: higher up-shift points, higher down-shift points, and higher TCC minimum lock speeds.

The auto will lock in both 3rd and 4th, but only if in those gears on the shifter (3rd and drive).

If towing a heavy load, 3rd and locked is far and away the best option, unless you have enough power to stay locked in 4th.

[vbrab]

Thanks all, my concern was that somehow 4th gear on the D2 auto box wasn't up to towing (like 5th on a manual box isn't built for towing).
My vehicle will NOT change to 4th unless over 80kph and doing about 2400rpm. Backing off at 80kph doesn't mean it will go to 4th, I also have to be doing 2400rpm.
It has been re-mapped so maybe that makes some difference to how mtr and box work together.

I reckon I have the power to pull the small load in top, and would obviously change to 3rd for hills, so am going to try the trip in 4th where possible.
I have about 12,000 k's of towing to do in next 2 months, so will likely find out if I have it wrong.

[Slunnie]

The big trick is just keeping the heat out of the transmission. You do all that you can when you're driving to keep the torque converter locked otherwise it will generate a lot of heat. If it unlocks in 4th, then pull it back to 3rd and let it lock up rather than staying in 4th unlocked. 4th gear is strong enough for towing, I think the weak link is actually the factory ATF cooler which doesnt cool enough in my opinion.

If your motor is remapped, you will probably find it drives more nicely with the gearbox in S mode.

[PhilipA]

I think this is much ado about nothing. We are talking 750 kg here not 2000+.
I have towed about 1000kg camper trailer for well in excess of 20000ks in the just 8 years and my 1800 kg caravan for about 5000 ks in the last year.
I tried sport and didn’t like it as it delays lock up.
The key preparation issues are new trans filter and the use of Transmax Z, ensure the cooler pipes are Ok and if over 200 kk renew proactively, ensure the front driveshaft is perfect.
My car has towed these weights at 40c through the Kimberley and the trans overheat light has never illuminated.
My car has now done 236kk and the trans operates perfectly.
Just drive manually to maximize the use of lockup.
regards PhilipA
Oh and make sure your fuel manifold at the back is Ok. My only failure was a worn through fuel manifold on the GRR.

[loanrangie]

You don't even need to blink at 750kg.

[johnp38]

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!

[Slunnie]

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.

[shack]

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

[scarry]

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.

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.

[Tombie]

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]

[PhilipA]

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.

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

[Slunnie]

It may also be a blocked ATF cooler.