MN diff ratio change

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MN diff ratio change

Postby Bikebear on Sun May 15, 2016 4:14 pm

I feel the MN 2.5 diesel is a little overgeared and I'd like to change the final drive ratios from 3.917:1 to 4.3:1, as used in the 3.5L petrol ML. I'm well aware that the engine will rev higher for the same speed and it may affect the fuel economy, that doesn't worry me greatly.
Does anyone know if the 4.3 gears from an ML will go into a 2013 MN 2.5 diesel?
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Re: MN diff ratio change

Postby Cowboy Dave on Sun May 15, 2016 5:32 pm

yes, provided you have the 9.5" diff
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Re: MN diff ratio change

Postby triton_guru on Sun May 15, 2016 5:36 pm

Could you just buy the whole diff assembly and just bolt it in? Or are the pinons different lengths? Might need the 3.5l tailshafts also :)
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Re: MN diff ratio change

Postby 4wd26 on Sun May 15, 2016 5:44 pm

Yeah just easier to swap out whole rear diff
Too much effort swapping out centre axles and ratios even though it can be done if the housing is different
Front diff is the same between models
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Re: MN diff ratio change

Postby snakesoup on Tue Jun 28, 2016 1:30 pm

ok what about putting ml 4.1s into a manual mn with 3.9s in it, if I change the diffs over how much difference will this make, would have to help running 33inch tyres I would think ? sure there would be a formula hey ?
didn't SRB do this to his clubby??
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Re: MN diff ratio change

Postby L200Shogun on Tue Jun 28, 2016 3:10 pm

60mph 29.5" tyres 3.917 give 2141 revs

60 mph 30.6" tyres 4.1 give 2161 revs

so with 4.1 and 31s you will have same gearing as standard

60mph 32.6" tyres 4.33 gives 2142 revs

so with 33s you want 4.3 to have standard gearing

http://www.differentials.com/technical- ... calculator

or

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Re: MN diff ratio change

Postby snakesoup on Tue Jun 28, 2016 6:28 pm

excellent work there little shogun!!
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Re: MN diff ratio change

Postby Maxiy on Wed Mar 13, 2019 12:01 pm

Quick Question

What size diff would a 2014 MN have? 9.5 inch ?

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Re: MN diff ratio change

Postby aids84 on Wed Mar 13, 2019 3:30 pm

Yes more than likely a 9.5" they have 12 bolts holding the centre into the housing. The 9" only had 10 bolts.
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Re: MN diff ratio change

Postby Maxiy on Thu Mar 14, 2019 5:46 am

aids84 wrote:Yes more than likely a 9.5" they have 12 bolts holding the centre into the housing. The 9" only had 10 bolts.


Cheers.

Next question.
If i get new 4.3 centres, will they just bolt in, or will i have to change the gears on the ends of the drive shafts (please excuse my ignorance)
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Re: MN diff ratio change

Postby aids84 on Thu Mar 14, 2019 6:17 am

The rear diff centre will swap straight over.

You could swap the entire front diff assembly out of a V6 ML into your car and run a vacuum line to the actuator to keep it locked in. Or takes the gears out and get a diff specialist to install the gears into your housing and do away with the actuator setup.
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