Having had 2 mechanics give me totally opposing advice, I thought I'd put this topic out here to see if I can get a general concensus that will help me save my gearbox.
When towing a caravan, do you have the "overdrive " function engaged or not ? One mechanic said you only use it on hilly tows : the other said you only use it when towing on level roads. It can wreck your gearbox using it wrongly, so I'm asking you all for the RIGHT advice as to when to use it.
Hopefully someone can advise me properly on this ?? Thanx in advance.....
I only use overdrive when running downhill or on the level with the wind behind me, in overdrive I always keep watch on the engine revs and change down soon as the revs begin to rise. I like to keep the torque converter locked as much as possible when towing as this prevents heat buildup in the auto.
If you do use overdrive when towing the damage may not show up till much later, perhaps after say 150,000k,s when you will have premature failure.
In many vehicles economy is worse when using overdrive all the time as the engine is working much harder to maintain speed.
If not sure, go and chat to an auto specialist and see what they advise for your vehicle.
My "Tow-Ed"course manual says "electronic overdrive should only be used when travelling on flat ground; disengage when in hilly terrain or in windy conditions.
Hi Terry, It all depends what type of auto trans, 3 or 4 speed auto in drive is top gear,some have a switch on the tee bar for o drive, some like ford falcons have the switch on the console ,which depends on the model could be power /econ, as the new 6 speed autos, asi have heard switch is on tee bar for o drive.....The best way is to refer to owners hand book,Hope this is helpfull ASH
-- Edited by Ash on Thursday 9th of August 2012 05:50:55 PM
I asked an auto transmission expert where I have mine serviced some years ago and their advice was to drive in fourth as it is a one to one ratio and does not put strain on the transmission like overdrive does he also said would be more economical, only problem was in the early days I occasionally forgot to change gear when pulling away from lights as my car is automatic and you need to be thinking about it or you look like a dill with your engine revving like mad.
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I would suggest to never, EVER take your car to that mechanic(?) that said to only use overdrive in hilly conditions. Just the oposite, as David (Duchy) said, use it on downhill or flat/tailwind roads. He made a typo though I think (hope) saying "change down when the revs rise". In fact you change down if the revs decrease or you need to put your foot down some to maintain revs/speed.
Modern engined create much more torque than modern overdrive units in most cars can handle without damage.
Put simplisticly, remember riding your 10 speed bicycle? Remember coming to a hill in high gear and trying to pedal up the hill still in high gear? Bloody hard work wasn't it? Much easier when you dropped a gear or two. No different in your car.
Cheers Neil
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Hi Neil No that wasn't a typo, the increased revs are just an indication, that the torque converter has unlocked, to supply increased torque, because the load has increased, my aim is to keep the torque converter locked as much as possible. Cheers David
For everyone's info an article has appeared in this month's copy of Horizon, the RAC's magazine.
In it a reader asks the question whether he should tow in 5th or 4th gear as he had heard stories of serious damage to the transmission when towing in 5th.
The reply is as follows:
The fifth gear is an overdrive, which means the final gear ratio is less than 1:1.
Using this ratio when driving the vehicle under load places tremendous pressure on the gears and other components within the transmission. Your manufacturer's handbook may advise you not to use fifth gear for towing, however sometimes the wording is vague. The guidline is fifth gear is okay for cruising and higher speeds with a light engine load.
As soon as you have to start depressing the accelerator pedal to keep the vehicle speed up, change down to forth gear to prevent wear and damage.
-- Edited by Grahame Readwin on Thursday 9th of August 2012 08:18:23 PM
After all these years you would think they would come up with an Automatic Transmission that wold change gears when it needs to. Instead of all of us trying to work out the best gear to use .
Gday...
They have - Land Rover Discovery 3 and 4, Range Rover Sport have the ZF 6-speed auto. This trans is also in other vehicles such as Jaguar, Audi, Ford Falcon and Terrritory.
I cannot comment with experience on the other vehicles, but the Land Rover and Range Rover vehicles are recommended to leave in D and the computer/s will decide which gear is required for the road speed and load to maintain the engine in the best, most suitable rev range (read torque range).
Interestingly, fourth gear is an intermediate gear (ie greater than 1:1), fifth gear is a 'slight' overdrive and sixth gear is a full overdrive. There is no 1:1 gear in the Discovery's auto box.
Manual, and dealer, both recommend leaving the vehicle in D when towing (leaving the vehicle to determine which gear is required) or if in hilly country to move the gear lever to Sports Mode which holds the revs a bit longer in each gear and will delay engagement of sixth gear.
I have now towed my 2600kg 23ft van for about 55,000km in predominantly D. The box decides to remain usually in fifth on the highway occasionally dropping back to fourth (or third if really hilly). It sometimes chooses sixth along those flat outback roads or if there is a good tailwind.
Cheers - John
-- Edited by rockylizard on Thursday 9th of August 2012 08:44:35 PM
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Thank you all for the replies.... I guess I should have been a bit more specific as to vehicle... 2002 Hyundai Terracan .. auto trans... with overdrive button on gearstick ... don't have an owners manual ... I'm getting the idea only to use it on flat road or with the wind behind me (?) ... Only 1 question remins.. is it really needed to use at ALL ?? Ty all for your input.
I don't have overdrive on my auto campervan, but I do drop mine down a gear when fully laden going through the burbs or up hills etc, only use top when on the flat in good conditions.
When I did have an auto tug with overdrive and van I always took it off when pulling in the same conditions especially in the burbs because of the up and down of hills, bumps, pot holes etc, etc which I understand can damage the gearbox if in overdrive.
Like someone has said, read what you tug booklet says for towing, also contact the manufacturers, selling agents for their advice also on your particular make/model.
After all these years you would think they would come up with an Automatic Transmission that wold change gears when it needs to. Instead of all of us trying to work out the best gear to use .
H Garrie, I have been a auto tec for 40 years,never heared of using overdrive in hilly conditions,have had to repair lots of auto trans due to misuse of elect shift overdrive.Only correct use of overdrive is on flat roads when speeds of 70k and up. I have been doing this up until I changed to a manual campervan. hope tis helps..... ASH
Ash is Drive on an Automatic Transmission classed has overdrive or do some car have an overdrive , And are there any auto transmission that has a brain and select the right gear for the load on the car
I asked an auto transmission expert where I have mine serviced some years ago and their advice was to drive in fourth as it is a one to one ratio and does not put strain on the transmission like overdrive does he also said would be more economical, only problem was in the early days I occasionally forgot to change gear when pulling away from lights as my car is automatic and you need to be thinking about it or you look like a dill with your engine revving like mad.
