VDJ7# Overdrive

Submitted: Monday, Jun 15, 2015 at 00:34
ThreadID: 119184 Views:5137 Replies:6 FollowUps:5
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what are peoples thoughts on these over drive kits for the landcruiser vdj?

landcruiser overdrive

I read about them in a magazine a few months ago, my cruiser gets a good 100km's less to a tank sitting on 110 than it does around town, i think purely because it revs so much.

says it drops the revs from 2,430 rpm to 1890rpm at 100km/h which would be great.

only thing is you could buy alot of fuel for the price tag of one.
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Reply By: wholehog- Monday, Jun 15, 2015 at 07:32

Monday, Jun 15, 2015 at 07:32
Have you heard of wind resistance...

Lower revs does not necessarily equate to less fuel consumption.

Overdrive gearing is a form of engine torgue division...where gearing above 1 to 1 ratio-direct drive is torque multiplication.

Put it simply...have you ridden say a 10 speed pushbike...do you always try to ride it in 10th gear when just cruising on it..? Is it comfortably..plenty of torque straight to the back wheel..sucks in the inclines and wind factor easily ?
AnswerID: 555975

Follow Up By: Daale - Monday, Jun 15, 2015 at 10:32

Monday, Jun 15, 2015 at 10:32
thanks for the reply but i understand gearing mate. wouldnt be looking at this if i didnt
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Reply By: Member - Alastair D (NSW) - Monday, Jun 15, 2015 at 08:02

Monday, Jun 15, 2015 at 08:02
Dale,
Wholehog is correct, resistance factors are the cause. Wind resistance goes up by approximately the square of the speed, so if you double your speed your resistance goes up by 4 times. The other factors like engine friction, tyre rolling resistance etc also increase faster than just the speed.

If you drive long distances on relatively flat highway then you will see some benefit from the o/d but otherwise little, certainly not enough to justify the expense. I am quite surprised at the revs that you quote as in my 100 series td auto the revs at cruising peed are much lower. Yes it does have a slightly overdrive top gear but not major. Also it drops from the o/d gear on hills and any acceleration. I know the V8 has more torque but I doubt that you would find you would stay in o/d other than hwy cruising.

Try and see if the company has a demo vehicle you can drive and see for real how it performs.
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Reply By: AlbyNSW - Monday, Jun 15, 2015 at 09:12

Monday, Jun 15, 2015 at 09:12
Even if it improves your fuel economy, it will never pay for itself, I have heard people say also that their fuel economy when towing in 4th is no worse than 5th

The vehicle is not an ideal highway tourer, you are basically trying to push a brick shape object through the air
Off road is a different story being the most economical vehicle doing the Simpson crossing this season according to Mt Dare staff

Are you running standard wheels? I found that 33's are a better all round size on the 70's
AnswerID: 555982

Follow Up By: Daale - Monday, Jun 15, 2015 at 10:34

Monday, Jun 15, 2015 at 10:34
yea well that makes sense to me cuz i get about 650 to a tank around town and 550 on the open road.

the fuel economy probably isnt improved in 4th because theres only a few hundred revs in difference between 4th and 5th.

i think toyota have made the 5th gear to be a towing gear.

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Follow Up By: Bob Y. - Qld - Monday, Jun 15, 2015 at 17:57

Monday, Jun 15, 2015 at 17:57
If you get 550 kms out of a 90L tank on the open road, Daale, you're doing very well I'd say!

Like Alby said, anything with the aerodynamics of a house brick will never get exceptional fuel consumption, without adding head winds, towing etc. We've got a Falcon sedan 4 litre, that exhibits inverse consumption to your V8; down to 8.2L/100 on highway, but abysmal consumption around town, if one gets a bit heavy on the load pedal.

Mark used to make an overdrive gear for the L/C transfer case, as did Terrain Tamer, but you had the overdrive all the time. These new units would be good if one did a lot of heavy towing, say on highways like the New England. Another 3-4 gears and the possibility to "split" at least the top 3 gears.

As for Toyota making 5th gear for towing, I'd disagree there. The 75's and 6 cyl 79's were/are very weak in 5th, and I'd say the increased torque of the V8's would soon find a weakness in the VDJ79's. A Toyota parts supplier once advised me never to use 5th under 80 clicks, but I wonder how many adhere to this criteria?

Hope your V8 gives you many years trouble free service,

Bob

Seen it all, Done it all.
Can't remember most of it.

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Follow Up By: Daale - Monday, Jun 15, 2015 at 18:16

Monday, Jun 15, 2015 at 18:16
Hi bob.

yea most of the cars i've owned were normally better on fuel on the open road. i really just put it down to the revs. it does have the aero dynamics of a brick but when you drive it at 110 it has plenty of power spare power -> there fore i think it could be reving less and saving fuel.

if the fifth gears are too weak to tow with (which i think i have also heard) not sure why toyota made 5th gear so low. maybe they never bothered to change the rations from back in the day when people didnt really go over eighty?

i always drove my nissan around in 5th under 80 never gave it any dramas, not sure bout the yota's.
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Reply By: Daale - Monday, Jun 15, 2015 at 10:39

Monday, Jun 15, 2015 at 10:39
i reckon its great idea that marks have done this, anyone whos driven a vdj at a 110 would know how much torque they have at 1800 revs (more than enough to push the car along at 110 - head wind or not) although i do agree would take along time to pay itself off.

i reckon reducing the revs to this 1890 at 110kmh would definately improve fuel economy in the vdj, i would be interested to know what figures people will get out of it.

apparently the marks 6 spd auto conversion was a hit, does a similiar thing with the revs at 110. anybody know anyone whos done this conversion?
AnswerID: 555989

Follow Up By: Member - Stinger2 - Thursday, Jun 18, 2015 at 20:55

Thursday, Jun 18, 2015 at 20:55
Hi Daale, I think a couple of guys over on Lcool.org have done this conversion...check it out
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Reply By: pop2jocem - Monday, Jun 15, 2015 at 20:46

Monday, Jun 15, 2015 at 20:46
It doesn't make a lot of difference whether you use 4th or 5th with the newer/stronger 5 speed H150F series gearbox in the Toyota from a reliability point of view, as long as you don't let the revs drop too low and make the whole thing struggle.

Fuel consumption?

Try a little experiment. Make sure plod isn't behind you when you try it though.

When you are cruising along at your chosen 80, 90, 100 kph, CAREFULLY stick your hand out the window into the air stream.

That's what your vehicle is battling against, plus the gradient of the road and whatever load you may be towing or carrying.

You may reduce your engine RPM by using some sort of overdrive but drop below a certain "sweet spot" for your engine and the result is the engine starts to struggle and most likely use more fuel.

Cheers
Pop
AnswerID: 556009

Reply By: Batt's - Tuesday, Jun 16, 2015 at 11:19

Tuesday, Jun 16, 2015 at 11:19
Sounds good but expensive what about changing the diff ratios if there is something available I know it will make all of the gears taller which should make it more pleasant to drive not revving out as quick as you go up the gears and the torque of the V8 will handle it easy your low range will still be pretty good . Also if you run stock tyres and are planning on going larger later on you have to take that into account.
AnswerID: 556028

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