Bigger 5th or 6th gear for 76 series landcruiser

Submitted: Thursday, Sep 03, 2015 at 16:27
ThreadID: 130178 Views:7353 Replies:8 FollowUps:9
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Hey everyone, Does anyone know of an aftermarket option for the 70 series landcruisers, whether that's a replacement 5th gear or a box with a 6th gear on it.
The big V.8's start to suck it down above 100 km's hr and with all that torque and power it really is a no brainer to somehow harness it, lower some rev's and save some fuel.
I'm surprised that Toyota haven't developed something themselves what with the competitors now using 8 speed autos and I heard 7 speed manuals to greatly increase their fuel efficiency and help reduce emissions.
Anyway let me know.
Cheers
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Reply By: Member - Don / Mandy M - Thursday, Sep 03, 2015 at 16:40

Thursday, Sep 03, 2015 at 16:40
There's a few 6 speed auto options available but I have not heard of a manual option.
Probably easier to change diff ratio,s
Hooroo
Don
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Follow Up By: oetkb - Thursday, Sep 03, 2015 at 16:45

Thursday, Sep 03, 2015 at 16:45
Something that I have thought about but I have no idea what you would swap it with. In the good old days Holden ran the same gear box with 3 different diff ratios, now.... ??? Don't suppose you know the answer for Toyota?
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Reply By: Member - John - Thursday, Sep 03, 2015 at 16:43

Thursday, Sep 03, 2015 at 16:43
G'day, Marks4WD have some listed, not sure if it is what you are seeking or not.
Marks4WD Toyota Overdrive
John and Jan

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Follow Up By: oetkb - Thursday, Sep 03, 2015 at 16:51

Thursday, Sep 03, 2015 at 16:51
Thank you.
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Reply By: Bob Y. - Qld - Thursday, Sep 03, 2015 at 18:40

Thursday, Sep 03, 2015 at 18:40
Funny you posted this today, oetkb. Have just watched a YouTube video of a Mark's Adapters 6 speed auto conversion on the Toyota V8 this arvo. It really gets up and boogies! From memory not cheap.........

Mark's Adapters also market a US made overdrive unit. Bolts onto the rear output shaft of transfer case, and the kit includes a shortened tail shaft. A switch is mounted on the gear stick, to switch on/off.

Hope you're sitting down.........the kit costs $7K plus!

Bob





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Follow Up By: Bob Y. - Qld - Thursday, Sep 03, 2015 at 21:29

Thursday, Sep 03, 2015 at 21:29
Terrain Tamer make, or used to, a replacement t'case gear set that would drop high range gearing by 9%. Also had other option with lower gearing in low range, and combination of the two.

Think they had kits for early HJ45's, 75 & 80 series. Don't know if the 80 series kit will fit these later V8's? Certainly a cheaper alternative if they did.

Also recall that Mark's Adapters did a similar kit, but they had a "better" bearing setup, so needed some machining to fit it.

Bob

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Reply By: Jackolux - Thursday, Sep 03, 2015 at 20:15

Thursday, Sep 03, 2015 at 20:15
Wholesale Autos will drop a 6speed 200 series auto in it for ya , if you have a spare
26 grand .
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Reply By: AlbyNSW - Thursday, Sep 03, 2015 at 20:34

Thursday, Sep 03, 2015 at 20:34
The cost to do it is a big investment which you can buy a lot of fuel with
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Follow Up By: Member - Howard (ACT) - Thursday, Sep 03, 2015 at 21:50

Thursday, Sep 03, 2015 at 21:50
So right Alby,
just did a few rough sums
unit they are offering gives 22% overdrive
it would be unlikely you would ever achieve a 22 % reduction in fuel usage (100% efficiency) but for ease of maths i used 25%
my 2009 VDJ79R has averaged 16llitres/100 for the 200,000km its done
with diesel at $ 1.30 a litre it would take over 150,000 km to break even on a $7900 outlay

if I could even achieve a more realistic 15 % reduction in fuel usage it would take 243,000km to get my money back
thats another 7 years driving so no thanks
cheers
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Follow Up By: AlbyNSW - Thursday, Sep 03, 2015 at 22:03

Thursday, Sep 03, 2015 at 22:03
I don't use mine as a tug but from what I have read from those that do say they get the same consumption towing in 4th as 5th so maybe there are not big fuel savings to be made?

A bigger issue is their brick like shape aerodynamics which you cannot overcome

I have increase wheel size to 33 inch and find it a better ratio setup than stock
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Follow Up By: oetkb - Friday, Sep 04, 2015 at 10:13

Friday, Sep 04, 2015 at 10:13
Your dead right, at 7 plus grand it will take forever to recoup my money.
Bigger tyres are something else I've been looking at but now I'm a little nervous on that one too. A guy at work bought the new ford Ranger and was averaging 700kms to a tank, he wanted to improve it so lifted it and stuck 20 inch rims and I believe 33s under it. He's now getting 150 kms less to the tank, Not to mention scrubbing every time he turns and goes over a pothole.
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Reply By: Member - Leigh (Vic) - Thursday, Sep 03, 2015 at 21:25

Thursday, Sep 03, 2015 at 21:25
A set of 33" tyres might give you about 5% benefit. From the pyro my 1HD-FTE prefers a lower gear under towing load whereas overdrive just pushes exhaust temp up and therefore economy suffers. Gearing these things up may not improve economy but perhaps offer a more relaxed higher cruise speed?
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Reply By: tim_c - Friday, Sep 04, 2015 at 12:30

Friday, Sep 04, 2015 at 12:30
I think perhaps you're misunderstanding the purpose of that particular vehicle if you're spending extended periods of time above 100km/h! :-)
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Follow Up By: pop2jocem - Saturday, Sep 05, 2015 at 08:54

Saturday, Sep 05, 2015 at 08:54
Agreed. While that torquey V8 will pull most loads with ease, trying to get good fuel economy at high speeds from a vehicle with the aerodynamics of a house brick, is in my humble opinion akin to trying to make strawberry jam from a wheelbarrow load of pig poo.

Fitting any method to achieve a lower engine RPM will most likely result in a quieter ride but the possibility of getting better fuel consumption is unlikely. In my opinion, and obviously others, the fuel consumption would most likely increase.

Try lifting the right foot a little.

Cheers
Pop
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Follow Up By: oetkb - Saturday, Sep 05, 2015 at 20:13

Saturday, Sep 05, 2015 at 20:13
On the contrary I think your missing the point of this vehicle. If I wanted to plod along at 85 - 90 kms hour when I'm towing then I would have bought something else. when It takes at least 1,500 kms to get anywhere interesting or somewhere I haven't seen a dozen times already then I want to get their at the speed limit and not 20kmh less.
I enjoy hooking up the camper and going pretty much almost anywhere I want with it.
I enjoy loading up the toys on a trailer and following my mates somewhere and turning up the same time they do, and I must admit I like the fact my wife can hook up the horse float and take that nag wherever she wants and she can safely overtake those people that sit on 90, with enough grunt to get around them and back on the right side of the road as soon as possible.
The only thing I sometimes wonder about is the fuel consumption and if there's a feasible way of getting better fuel economy without loosing out on the other benefits.
I did a lot of research before I bought this vehicle and I am more than happy with it, I knew the fuel consumption figures and I was happy to accept it, knowing that horsepower and torque don't come out of thin air (well actually they do, there called turbos and superchargers but eh.)
If I couldn't afford to run it then I wouldn't of bought it, but I can so I do. The question is always worth asking though.
Thanks for your help everyone and happy travels.
Cheers.
:-)
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Follow Up By: pop2jocem - Saturday, Sep 05, 2015 at 23:19

Saturday, Sep 05, 2015 at 23:19
oetkb,

You could try fitting a Hi-Clone. I have heard that they will give you better fuel consumption, an increase in power and wash your shirts whiter than white.

Oh, while you're at it try re-reading your first post.
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Reply By: The Bantam - Sunday, Sep 06, 2015 at 20:14

Sunday, Sep 06, 2015 at 20:14
The question you have to ask ya self is ....... will reducing RPM actually reduce fuel consumption.

If it is a diesel it may not. ....... diesels do not behave like petrol motors ........ there is also a great deal of difference between a light aerodynamic passenger car and a heavy aerodynamicaly poor 4wd like a 70 series.

Toyota are pretty good with selecting gear ratios to mactch engine power curves.

Diesel engines are most fuel efficient in a rev range where the power and torque curves cross and begin to roll over. ........ this is the sweet spot in the engine rev range.

As many have found when fitting larger tyres to various vehicles ....... higher gearing may in fact result in higher fuel consumption.

as for the 6, 7 and 8 speed boxes offered in some diesels ....... this is primarily to compensate for the very narrow peaky power and torque curves that result in all turbo diesels ..... even more so when those turbo diesels are realy pushed for power ........

To get efficiency in a turbo diesel you have to keep the engine operating in that fairly narrow sweet rev range.

If it is a petrol vehicle ........ the limiting factor for economy in a 70 series will be aerodynamic drag ...... so a taller gearing still may not help you.

cheers

cheers
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