Diff ratios

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18 Jun 2019 15:24 - 19 Jun 2019 15:01 #2 by Harry
Harry replied the topic: Diff ratios
My power plant is a 6bt cummins ,5 speed spicer gear box , and np205 transfer case
Chris from Kunnanara
Has also fitted 4:10 like Deano except that Chris has a 6 cylinder Perkins in his Oka
So there are a lot to compare with
Well now I have done some km
I use to get 620 km from my 105 liter fuel tank that is with the 4:88 diffs
AND NOW
With the 4:56 diffs I get 680 km from my 105 liter fuel tank
I ran them both bone dry for the test
I must say the cummins does NOT like running out of fuel
The fuel test was done both times on the same road from Tennant creek via Mataranka springs in and out 2 times and then onto Katherine total 680 km I ran out of fuel as I approached the United service station in Katherine

Jenny and I both enjoy the great outdoors. We try to get away 4 to 5 month a year.
Last Edit: 19 Jun 2019 15:01 by Harry. Reason: Adding
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23 Jun 2019 19:25 #3 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Diff ratios
With the six speed Allison and the 6bt sitting on 1800 rpm at 105kph I'm getting 16L/100k, sometimes up to 18L/100 in hilly country or with a stiff headwind. Can get down to 14L/100 staying under 95kph. Still running 315/75R16 tyres MT pattern and standard diff ratios. Travelling weight is 5.8t full of fuel and water with full camper setup in a bus body.

OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 680w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
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23 Jun 2019 21:14 - 23 Jun 2019 21:15 #4 by Outback Jack
Outback Jack replied the topic: Diff ratios
Interesting all this talk about changing Diff Ratios, when I mentioned it a few years ago, some people ridiculed the idea. At the time I suggested 4.10 would be a good change. How times change...

I have done same run from Tennant to Katherine on one tank in OKA with 6bt. I did not go into Mataranka though. This is with standard spicer and 19.5 tyres that where 265`s. Sitting mostly around 90kph.
Last Edit: 23 Jun 2019 21:15 by Outback Jack.
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25 Jun 2019 09:48 #5 by Harry
Harry replied the topic: Diff ratios
Thank you Peter it is nice to hear from different combinations and therefore people can make up there minds on what options they want to go with if they choose to go that way
My weight is front axle is 2630 kg
Rear axle is 2900 kg
Fully loaded with a spare 19.5 tyres and rim on the roof
And enough food water wine beer for 45 days
I also fitted an aluminum bull-bar on the front
Fuel that I carry is in 2 fuel tanks one 105 lt and the other 165 lt and 100 lt water 32 liters under the bull-bar and 68 lt in the belly of the Oka

Jenny and I both enjoy the great outdoors. We try to get away 4 to 5 month a year.
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25 Jun 2019 09:53 - 25 Jun 2019 10:20 #6 by Harry
Harry replied the topic: Diff ratios
My aluminum bull - bar weight 20 kg thank you Chris and H from Kununurra great work I am as happy as ?

Jenny and I both enjoy the great outdoors. We try to get away 4 to 5 month a year.
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Last Edit: 25 Jun 2019 10:20 by Harry. Reason: Name change
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25 Jun 2019 11:32 #7 by Greg Boyle
Greg Boyle replied the topic: Diff ratios
Bullbar looks great Harry,
is that a painted finish, or annodised.

cheers Greg

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25 Jun 2019 12:42 #8 by Harry
Harry replied the topic: Diff ratios
Painted Greg

Jenny and I both enjoy the great outdoors. We try to get away 4 to 5 month a year.

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25 Jun 2019 17:09 #9 by Peter Davis
Peter Davis replied the topic: Diff ratios
Looks good Harry. What did the steel bulbar weigh?
Are the XT and LT bullbars the same?
Cheers
Peter

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25 Jun 2019 17:27 #10 by Harry
Harry replied the topic: Diff ratios
Hi peter
I think the steel one weighs around the 80 to 85 kg
Yes Chris from Kununurra makes them for both XT and LT
Deano is getting one for his LT tomorrow
You will have to ask Chris for pricing if you are going that way he will be away until the end of July

Jenny and I both enjoy the great outdoors. We try to get away 4 to 5 month a year.

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25 Jun 2019 18:30 #11 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Diff ratios
Harry I forgot to add that 374 weighs 2600 on the front and 2630 on the rear, all loaded up for an extended trip away from supplies, including the two tubbies in the front seats ;-)) We carry 245 litres of fuel in two tanks, one of 105L and the second of 140L. There is also 200 litres of water across three tanks, 2 x 70L and 1 x 60L.

OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 680w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.

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26 Jun 2019 16:02 - 26 Jun 2019 16:07 #12 by Harry
Harry replied the topic: Diff ratios
Weight Peter in your last post you said you are 5.8 ton fully loaded

I am beginning to lose weight as we started off with
44 liters of red wine Jenny loves her wine and one can not buy cask wine up here

60 cans of beer which I had to replenish already feel the difference in heat up here

12 liters of scotch ( thanks Greg brewery)

Should of brang more ...... yer you got it Jenny loves the scotch as well

You know what they say happy wife happy life

176 liters upright evakool fridge / freezer
Now that is a great fridge just bought it before the trip
Had a Waeco before but evakool has more insulation and less running cost or amps I should say
We have only one draw back our Oka is wider and seems to have a lot more room so Jenny does and has filled every nook and cranny with something......... I am sure we will need it along the way
Well Jenny thinks we will

Jenny and I both enjoy the great outdoors. We try to get away 4 to 5 month a year.
Last Edit: 26 Jun 2019 16:07 by Harry. Reason: Spelling check
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26 Jun 2019 16:45 - 26 Jun 2019 16:51 #13 by Harry
Harry replied the topic: Diff ratios
This has nothing to do with diff ratio
But I have upgraded my XT with twin shocks in the front ,wow what a difference it does make . Thank you to Dean ( Oka parts in WA ) for supplying the parts and the fast service that you provided
A very big thank you to Ian Jones for making time for me to get them fitted what a good job you have done Ian .


Any one that has an XT and does not or has not done this upgrade I think you should do it . I highly recommend it ...
a bit firmer on the black stuff ,very very good on corros and the dirt road

Jenny and I both enjoy the great outdoors. We try to get away 4 to 5 month a year.
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Last Edit: 26 Jun 2019 16:51 by Harry. Reason: Spelling
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27 Jun 2019 16:36 #14 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Diff ratios
Yup brain fade Harry, those weights were the tare when it was engineered with the 6bt, the loaded ones haven't been done yet ;-))

OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 680w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.

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30 Jun 2019 06:32 - 30 Jun 2019 06:36 #15 by Holmz
Holmz replied the topic: Diff ratios

Harry wrote: This has nothing to do with diff ratio
But I have upgraded my XT with twin shocks in the front ,wow what a difference it does make . Thank you to Dean ( Oka parts in WA ) for supplying the parts and the fast service that you provided
A very big thank you to Ian Jones for making time for me to get them fitted what a good job you have done Ian .



Any one that has an XT and does not or has not done this upgrade I think you should do it . I highly recommend it ...
a bit firmer on the black stuff ,very very good on corros and the dirt road


How does one tell if it is over damped or under damped?

I bet it is "way better" different on e bitumen.
Can you further describe the feel on the dirt and corregations? And how that translates into "highly recommended".

Note: I believe you... I'm just trying to wrap me head around justifications to have a spend up.
And it Looks like a multi-k$ upgrade...
Last Edit: 30 Jun 2019 06:36 by Holmz.

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30 Jun 2019 07:25 #16 by Alister McBride
Alister McBride replied the topic: Diff ratios
After having one on the front and changing to two and experiencing both i would say from my experience two is crap on corrugations and bumps in general but better for 'race performance' around corners! Two just makes it stiffer in my opinion. Maths and engineering would suggest the same!. I haven't taken the second one off yet but will do when i get the time...

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30 Jun 2019 16:22 #17 by outyonda
outyonda replied the topic: Diff ratios

Alister McBride wrote: After having one on the front and changing to two and experiencing both i would say from my experience two is crap on corrugations and bumps in general but better for 'race performance' around corners! Two just makes it stiffer in my opinion. Maths and engineering would suggest the same!. I haven't taken the second one off yet but will do when i get the time...


Then why did the LT & NT have twin shocks on all 4 corners ???
& 50% of XT's have upgraded!!

OKAs 091, 093, 094, 113, 346x6 & 405

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30 Jun 2019 18:41 #18 by Alister McBride
Alister McBride replied the topic: Diff ratios
More is better? i don't know Brett... possibly as single shocks couldn't handle all the heat build up over bumpy roads... honestly just a guess, you'd be best asking the oka engineers. Just my experience in driving the oka with both and a little bit of knowledge about vehicle dynamics. The linear force equation for a damper is F=cv... It's quite simple really, if you have the same damping co-efficient (c) shocks and you double how many there are you get double the force applied by those shocks (F) at any apparent bump velocity (v), hence better handling on-road and stiffer over bumps...

This has been discussed on this forum before, someone had installed double, larger diameter shocks with (i think approx) half the damping co-efficient. (The 'Powerdown shocks' installed above may be this...?) This gave larger area/volume of oil in shock, hence less heat build up (and degradation) and because of the half or so damping co-efficient, the same overall damping co-efficient as single shocks. Overall, giving good ride over bumps and longevity. You can't really have a racing car and be good over bumps... It's just not physics! ;) Thanks for your question Brett!

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30 Jun 2019 20:23 #19 by Holmz
Holmz replied the topic: Diff ratios

Alister McBride wrote: More is better? i don't know Brett... possibly as single shocks couldn't handle all the heat build up over bumpy roads... honestly just a guess, you'd be best asking the oka engineers. Just my experience in driving the oka with both and a little bit of knowledge about vehicle dynamics. The linear force equation for a damper is F=cv... It's quite simple really, if you have the same damping co-efficient (c) shocks and you double how many there are you get double the force applied by those shocks (F) at any apparent bump velocity (v), hence better handling on-road and stiffer over bumps...

This has been discussed on this forum before, someone had installed double, larger diameter shocks with (i think approx) half the damping co-efficient. (The 'Powerdown shocks' installed above may be this...?) This gave larger area/volume of oil in shock, hence less heat build up (and degradation) and because of the half or so damping co-efficient, the same overall damping co-efficient as single shocks. Overall, giving good ride over bumps and longevity. You can't really have a racing car and be good over bumps... It's just not physics! ;) Thanks for your question Brett!


I did a partial differential equation (PDE) course, and dampers were a huge part.
I passed it, with a 35/100... they graded on a curve and I got an A...
It is seemingly akin to black magic

Most of the damper knowledge seems equally arcane to PDEs ...

Hence it seem like dual is better for bitumen and single better for corregations, but it is an interesting think none the less.

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01 Jul 2019 02:31 #20 by outyonda
outyonda replied the topic: Diff ratios
have you felt the temp of shokysafter corrogations, single hot, dual warm.

OKAs 091, 093, 094, 113, 346x6 & 405

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01 Jul 2019 03:33 #21 by Holmz
Holmz replied the topic: Diff ratios

outyonda wrote: have you felt the temp of shokysafter corrogations, single hot, dual warm.


I was thinking more of how it feels in terms of ride, not how the damper feels in temperature??

Does the extra dampening of the duals actually result in a better ride on the cooregations? And then if so, why not three dampers or four?

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