Correct gear for towing???

[Woolyback79 Lurker Find all posts View Profile Close Woolyback79]

Hi all, just went for a pre Christmas trip trip to see how the fuel economy would go among other things.
I have a 4 speed auto towing the missus, baby, some gear in the back and a pop top caravan. No heavy mods on the car.

My mate who worked at Toyota mentioned that the start of the torque range was about 2800 revs so keep just below that should be ok. i did not ask to many other questions and went on my way.
the car pulled the van no worries at all, for pretty much all of the 400km trip i was towing in 3rd at just under 2800 rpm @ 100kmh which i though was the thing to do, road was flat.

When i did try 4th the revs went to 2000rpm but on the odd occasion they would go up to 2400rpm but not actually jump back into 3rd. ended up with fuel cons of 19.5/100km. had a head wind on the way back so it isn't worth mentioning.

Now with my story out the way. what gear should i be towing in under the various conditions and what speed/rpm have people found best?? when i told my mate the story he said that 4th was ok for flat no head wind but i still had the surging rpm which he though would be the torque converter??? any idea's?? do not want to do a gearbox over Christmas.


Thanks

[frederick Member Find all posts View Profile Close frederick]

best gear for towing

Gidday, with my 2006 D4D 5 speed auto i always tow in drive and never lock in a gear unless going down a steep hill. The reason for not locking in a gear with an auto is that you will overheat the gearbox and ending up costing you big bucks ( see toyota handbook about locking in lower gear for long periods).

I tow a 2.2 tonne Jayco discovery outback poptop caravan and try to sit on around 2000rpm whenever possible and travel speed of around 90 clicks which returns fuel econony of around 14 litres per 100ks.

If i travel at 100+ kph then economy suffers to around 18 litres per 100ks.

Thats why all caravanners seem to be travelling slow when you past them on the highway, obviously if retired you are not in a hurry and they are after the best fuel economy as well.

I have a rear mounted camera on my caravan and a monitor on my dash so i can see if any traffic is building up behind me and i will let them past as soon as safe to do so.

Good luck and all the best

Wazza (Frederick)

[Corigator Avid PP Poster! Find all posts View Profile Close Corigator]

Wazza,

Correct me if I am wrong, but my understanding is that placing a 5 speed auto in 4th only stops it going up to 5th. It can change down at any time.

[frederick Member Find all posts View Profile Close frederick]

Yes you are correct. However have said that if it is locked in 3rd it is unlikely to change down at all therefore as the book states is locked.

Wazza

[Sunshine Member Find all posts View Profile Close Sunshine]

I have a 2004 Auto diesel 4 speed and try to leave the car in top gear if possible and can use the Cruise Control most of the time at 90kph. We tow a 1.2T Jayco Camper Trailer and get 13.5L/Km at that speed. As soon as we try and go faster the use of fuel climbs quickly and probably ends up at the figure you stated. The other thing is that if you come upon a slight rise in the road we try and stop the cruise from kicking down into 3rd; we tap it out of cruise and drive with the accelerator and can go quite a long way before the gearbox will kick itself down into 3rd. That will then give the best fuel economy that you can get but still maintain a good speed.
The surging revs sound like you might have a torque converter problem; I'm sure mine doesn't do that even into the wind. The only time the revs go up is when the gears go up for 4th to 3rd.

[D4D Addicted PP Member Find all posts View Profile Close D4D]

For a 5 speed D4D my experience is the towing sweet spot is about 1T. I could tow my 700kg Tambo perfectly in D, whereas I need to use 4th for my 1.2T Goldstream otherwise the gearbox is always dropping down.

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

If it is an auto just leave it in D, the auto will select the gear best suted, just knock it down a gear manually if you come to a hill, if the hill is a fairly large one you may have to knock it down another gear manually to assist the auto. This also applies to going down a hill (even without towing).

If it is a manual, 4th gear is best, unless your on a highway/motorway, then use 5th.

[Woolyback79 Lurker Find all posts View Profile Close Woolyback79]

thanks guys, will see how we go.

[pinko351 Member Find all posts View Profile Close pinko351]

Hi Woolyback79

After reading this string of posts I think the non mechanically trained person could be confused. For MY mind some of the information is born from a lack of understanding of the workings of an auto and its torque convertor. Your mechanic friend seems to be giving you the best information while trying not trying to confuse you. Could I suggest you read your owners manual with regards to towing as Toyota explains it well.

In sort, by all means tow in drive when conditions permit (flat roads) this will return ok fuel consumption, but when you get to the hills change down gears and keep the rev's up (for my 5 speed auto 2500rpm) to ensure the convertor is locked. If you allow the rev's to drop, the convertor will slip (it's designed to do so) and create heat, which is no good for an auto box. Hills are a time to look after your auto not worry about fuel use.

You stated that when you towed in drive, the rev's surged from 2000rpm to 2400rpm without changing down gears. This is normal as it is the convertor unlocking as you accelerate for the change in conditions. But when unlocked the convertor is slipping and heat starts to build. Either accelerate and get the rev's over 2500 or change down to get the rev's up.

Please note I speak for the D4D 5 speed auto and the 4 speed may have different convertor lock points. Your owners manual should point you in the right direction.

Hope I have helped and non caused more confusion, not sure I have written a post that explains it all that well. Maybe read the 150 section on overheating autos - could help.

Pinko

[chester ver 2.0 Member Find all posts View Profile Close chester ver 2.0]

On the 4 speed auto the tourque converter in 4th will lock up at about 85 to 90kph depending on load. I tow a 1.3 tonne wind up Goldstream and find 95 is the sweet spot in 4th gear as said above i will turn the cruise control off for hills put the foot down to 100 and let speed reduce back to about 90 and this does form most hills or give it a decent kick and get it back into 3rd for the long climbs and then just chug away at 80 or so up the hills. This was derived from 19,000 k of towing on a recent half lap around australia with and average fuel economy of 17l per 100k for the whole trip this is all based on a diesel engine