Overdrive for Towing (same, same but different)?

Submitted: Sunday, May 23, 2010 at 12:21
ThreadID: 78692 Views:3449 Replies:5 FollowUps:2
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I know that there have been many threads both written and read on this subject, and I would like to think that I have read most of them, but this one is a little bit different...

My wife and I have a caravan (15' 6" internal) that has an ATM of 1,620kg.

I have always towed it using all the gears available to me, including overdrive, and sometimes I have had trouble understanding what the fuss about overdrive gear usage is.

However, I am about to take delivery of a new employer-provided Hyundai Sante Fe (2.2L manual diesel).

I will be checking with the dealer, of course, but a review of the technical details reveals that the top three gears (4th, 5th and 6th) are all overdrive gears - does this mean that while towing my van I will be forced do it everywhere using only 1st, 2nd and 3rd gears?

Peter F.
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Reply By: Notso - Sunday, May 23, 2010 at 12:46

Sunday, May 23, 2010 at 12:46
Yes, that's an interesting one, a mate just bought a Kia Sorrento, a clone of the Hyundai, and it's the same, although I think fourth is actually an underdrive gear, if that's the correct terminology as it is a bit more that 1 to 1 as opposed to the other way.

Anyhow apparently the hand book doesn't say anything about the issue, he has been towing in 5th, gets great economy and heaps of get up and go.

You might find 6th a bit tall for relaxed towing.

AnswerID: 417781

Reply By: Maîneÿ . . .- Sunday, May 23, 2010 at 12:50

Sunday, May 23, 2010 at 12:50
interesting reading, click on "specifications" then "transmissions"

Santa-Fe gear ratios

Maîneÿ . . .
AnswerID: 417782

Reply By: pop2jocem - Sunday, May 23, 2010 at 14:14

Sunday, May 23, 2010 at 14:14
Peter, I think it gets down to the load you are asking the vehicle to tow, the design of the gearbox(strength) and the amount of torque the engine is capable of generating at lower RPM. The other important factor is the drivers ability to "feel" for the wont of a better term, the difference between the car doing the job easily or struggling because too higher gear is being used and the driver just putting the foot down a bit more and taking advantage of the engines torque rather than shifting down a gear. I would think that in the case of a relatively light van such as you have using up to 5th may be ok but downshifting if the car starts to drop revs on a hill or going into a head wind.
It looks like in your case you do not have the luxury of selecting the vehicle(offset of course by the fact that it is being provided) but looking at the ratios I wonder just how suitable the Sante Fe is for towing anything other than a relatively light load. Just as a matter of interest what is the maximum towing allowance for this car???

Hope this helps a bit

Cheers
Pop
AnswerID: 417793

Follow Up By: fawkesp - Sunday, May 23, 2010 at 14:46

Sunday, May 23, 2010 at 14:46
Pop,

The Sante Fe is rated to 2 tonnes (2,000kg), so I am only ever towing approx 80% of maximum load.

And because it is not 'really' my car, we generally treat it quite gently - I do not want to go to work on Monday and tell the boss I broke his car while using it for (admittedly permitted) private use!


Peter.
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Follow Up By: Tenpounder (SA) - Sunday, May 23, 2010 at 15:01

Sunday, May 23, 2010 at 15:01
I agree with Pop: Frequently, 4th gear is straight through 1:1 using a simple dog clutch (or similar) and 5th is via a lay shaft which is often smaller diameter, weaker bearings etc. I have been told my Prado fiits this description. So the issue has nothing to do with the gearing ratio, and everything to do with the relative strength of the components involved. I suspect we are often dealing with a good old four speed gearbox, and there's just enough room to squeeze in a layshaft to give us a fifth gear. Pity it has to be so puny, but stil
Like Pop says, its a lot to do with "feel", and I have never owned a vehicle that does not have a sweet spot, which, for me, takes care of the gear choice in relation to engine revs. But this issue adds another layer of problem, which can only be answered by reference to the design of the various shafts, bearings and cogs, not by ratios!!
If I am right, then, the only informed answer has to come from the manufacturer.
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Reply By: Gazal Champion - Sunday, May 23, 2010 at 17:43

Sunday, May 23, 2010 at 17:43
Hi fawkesp,

I have taken Roothys advice over the last several years about not towing in overdrive but just occasionally I have gotten curious and slipped the old girl into overdrive. Now my van is a 2 tonner and the tug is a 80 series landcruiser and every time I have used overdrive the rpm slowly decreased for the same accelerator pressure and I could see that fuel economy was suffering over time, and this was on flat going. So I decided that if I was travelling down hill I might occasionally drop it into overdrive but the problem there was that I forgot about it and performance and economy would suffer so I found it best to leave it in 3rd gear all the time, or drive in my, case having an auto box.

Best advice is give it a try and see how it goes. It may be a whole different ball game with your vehicle and towing combo.

As is often said the best rules are no rules. just try it and see.
Cheers Bruce.
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restless and lost on a track that I know. HL.

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AnswerID: 417832

Reply By: Member - Graham H (QLD) - Tuesday, May 25, 2010 at 12:55

Tuesday, May 25, 2010 at 12:55
Read this thread Long but worthwhile.

http://forum.candm.com.au/showthread.php?t=3900

It is all about keeping the car in its torque range.
A 100 ser at 90kph sits on 2400rpm which is just nice and it sings along no probs.

Put it in 5th and it runs hotter and lugs away and hunts up and down on the auto like mad
Why wear out the box for nothing.

O/D is for cruising the vehicle ON ITS OWN not with double the weight on the transmission.

Incidentally over 50,000k the economy didnt suffer at all by using 4th instead of 5th

AnswerID: 418050

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