jackeroo TD 01 auto overdrive on or off?

Submitted: Sunday, May 21, 2006 at 05:42
ThreadID: 34082 Views:2632 Replies:6 FollowUps:1
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would like to know whether it is better to have o/d on or off for normal around town driving and what is best for towing c/t (1000kg) off is when the light on the dash comes on ? seems arse about to me. would appreciate your thoughts.
thanks tony
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Reply By: Member - Doug T (QLD) - Sunday, May 21, 2006 at 07:12

Sunday, May 21, 2006 at 07:12
I don't own one but I feel that under 80kph I would turn it off, As i do with 5th gear in my ToyotaI drop to 4th , so It should be ok with a small van , depends on if it seems to be struggling to keep up the pace or not ,Though I reackon just 5th would be better , as for the light being on check your owners manual to see what is the norm' , Many years ago I drove trucks with 2 speed diffs and got used to the button being down for low and up for high which is logical but when the Japs introduced the CK40 UD with 2 speed diff down was high and up was low so i ask someone and the answer was that it was done like that to get around copy-rights, but being electrical I just changed the wires over and it was like normal .

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AnswerID: 173736

Reply By: wbsl - Sunday, May 21, 2006 at 07:58

Sunday, May 21, 2006 at 07:58
I believe that the power switch on the Jackaroo auto doesn't turn the over drive on or off just increases the rev range where the transmission changes gear.

When the dash light is on, power setting, the transmission holds the lower gear longer to allow the engine to rev higher and make better power, then changes back earlier for the same reason.

I use this setting on my petrol jackaroo and it gives better performance and increase fuel economy for both towing and normal driving.

I have found with it on the economy setting I use much bigger throttle opennings on hills etc and use more fuel.

Regards Wayne
AnswerID: 173740

Follow Up By: disco driver - Sunday, May 21, 2006 at 13:45

Sunday, May 21, 2006 at 13:45
Years ago I was the "lucky" owner of a 89 Holden Appollo (Toyota Camry) which had the same system.
All the switch does is to alter the shift points in the transmission and, as you say, allow the motor to develop more revs and hence more power.

As a matter of interest my current vehicle (99 L-Rover TD5 Auto) has exactly the same system. I turn it on when towing the van till I reach cruising speed then turn it off.
Also gets turned on when towing up long hills, stops the transmission from shifting/hunting between "gears".

FollowupID: 429737

Reply By: Outbacktourer - Sunday, May 21, 2006 at 13:31

Sunday, May 21, 2006 at 13:31
If I remember correctly (sold the Jack in '02) you need to select "3" on the stick and not "D" in order to keep out of O/D. You can overheat these boxes relatively easilly if you are towing in O/D but with such a load that the converter has not locked (ask me how I know!) This can occur if you have a decent load on, have headwind or are on an uphill stretch. With this box and the one I now have in the Patrol (button activated O/D) I don't use O/D below 80 KPH in town or out, and under 100KPH when towing. When towing if I come to a hill and it drops out of lock in O/D I go back to 3rd immediately. Not sure about the Jack (can't remember) but in the Patrol it will lock the converter immediatey if you are over 80 KPH. If you can keep the converter locked as much as you can this will be the best for wear and tear on the box (less heat) and fuel economy.
AnswerID: 173778

Reply By: Gerhardp1 - Sunday, May 21, 2006 at 20:54

Sunday, May 21, 2006 at 20:54
The Jackaroo has a power switch as mentioned earlier, changing the shift points higher.

I always have mine in power mode as it is nicer round town. On the highway it doesn't really matter as at 100k you are in 4th with the torque converter locked anyway. When using the cruise control it's best in economy mode as the shift program from 3rd to 4th is not good when in power mode, hanging on to 3rd way too long after the crest of the hill.

The torque converter locks up in 2nd, 3rd, and 4th gears in either power or economy setting.
AnswerID: 173843

Reply By: Chaz - Monday, May 22, 2006 at 06:29

Monday, May 22, 2006 at 06:29
Hi Tony,
While driving around town, you should leave your overdrive switched off for two reasons. Firstly you will notice that there is no engine braking in 4th gear as with all 4 speed autos and secondly your transmission will run cooler in 3rd because you'll reduce the load.
Autos tend to chew through brakes more than manuals, so if you use the gears to slow down, you'll find your brakes will last longer. Leaving it in 4th, you'll go through brakes much faster.
Towing a 1 tonn camper is no drama if your doing the speed in overdrive, but if the converter unlocks, then drop it back to 3rd.

AnswerID: 173891

Reply By: Athol - Monday, May 22, 2006 at 16:15

Monday, May 22, 2006 at 16:15
I have a 2002 3.0lTD auto and I always use normal Drive position with OD switched ON.
Any overheating of the auto trans firstly results in the transmission deleting the torque convertor clutch operation, and secondly deleting 4th gear operation from its operating menu untill such time as the temperature is reduced, when all comes good again. The convertor clutch operation is deleted from the programme at approximately 130 deg c, the oerheat light does not operate untill 145 deg c.

Should the vehicle be operated using cruise control when the transmission gets hot and commences deleting the upper gears/convertor clutch from its menu then the resultant increase in engine revs can result in the engine temperature increase and overheating may result.

I tow a Coromal PC511 pop top caravan, including a trip from the Brisbane area via the coast to Perth and return via the Great Central Highway (yes including Warburton WA) and return to Brisbane via Three Ways. I first experienced this overheating problem 80km east of Three Ways when we encountered strong head winds, and it continued untill the winds subsided. Each time the transmission was allowed to cool it then performed faultlessly untill getting hot.

An additional transmission cooler had rectified the problem.

The operation of the power/economy switch ONLY changes the shift points whilst using less than 3/4 throttle, once heavy throttle positions are used the transmission automatically uses the power mode for shift points.

Hope this is of some assistance.

AnswerID: 173994

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