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Discussion Starter · #1 ·
Hi guys, going off my compliance plate it says i have 3.5 diff ratios. (4.8 lt auto 2001 GU)
i've got 315x75x16 muddies (35's) and it now stuggles a bit on steep rocky up hills.
I'm looking at going for either 4.1's or 4.3's, i think 4.6's would be to low behind the 4.8lt, maybe.

Have any of you guys with the 4.8 engines changed your diff ratios?
if so what did you put in and did you feel you made the right selection.

i'm not able to afford reduction gears so that option is out.

any comments would be great.

cheers

Pete
 

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Don't have an 4.8, but as standard with 31 tyre, you have 3.54 ratio, so to go to 33" you need 3.9, 35tyre you will need 4.1, 37 tyre - 4.3...

For every 2" increase in tyre diameter, you need about 6% higher ratio to bring it back to factoy standard, the nissan diff ration are 3.54, 3.9, 4.11, 4.375, 4.675, which is also about 6% step. Just nice.
 

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Pete it works something like this.315(new tyre size)x 35(diff ratio)divided by 265(standard tyre)which comes up on the calculater as 41.6,which is a 4.1 ratio.to get it back running factory.hope this makes sense.
 

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Gday all,
I have a question, as I am in the same boat with tyres and diff ratio's, I too have a 4.8 auto and have a set of 4.11 out of my old GQ sitting in the garage.Could I use them in my GU??????
 

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I don't know about that ,as i have 3.9 sitting in shed aswell and want to do same as you .I hope so as i don't want to pay out extra cash for new ratio's
 

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Autos are Superior
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I'm not able to afford reduction gears so that option is out.
reduction gears would be about 1/2 price of diffs if your using new gears. $1000 per end for new nissan gears.

careful using used ones, you can end up with massive diff whine.
 

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Discussion Starter · #8 ·
I've all but convinced a customer at work to sell me his 4.1 complete centres for $400 out od a GU. they have 70 odd thousand km's on them, removed when the patrol was pretty new to fit 4.6's. Seems a pretty good deal if i want to fit 4.1's.
Going from the calcs above" nice work guys" the 4.1's will bring it back to normal, but i was wondering wether to grab 4.3's to give it some more down low grunt.
Was hoping someone may have fitted one of the lower ratios to their 4.8 GU auto and get there opinion.
Thanks to u all for your input so far.

Pete
 

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I can't see any reason why gq stuff won't work in a Gu diff. They seem to work alright the other way Round

It works, just get the diff to the specialist to check the tooth contact, backlash and preload are ok before install. Also GU has a larger flange than GQ on some model.

Transfer case reduction gear is good but it does not change the high range ration unlike suzuki one.
 

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ratios

i have an 02 4.8 with 315/75/16 and had the same problem i got a set of 4;3's and works great, i pull a kimbly with on and off road and it feels like it did back when the car was standerd if not better, next will be a set of trans reduction gears for the tranny cheers locko
 

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yeah i've just got my 4.8 auto today and looked under the bonnet n sure enough its got 3.5 diff gears which are way too tall for 35's. its got a factory rear locker, how hard would it be to swap the locker to a 4.11 diff? is it possible? or should i be looking for a 4.11 factory locker diff?

i have a 4.11 arb locked diff out of a gq so this could work out really well...
 

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i have an 02 4.8 with 315/75/16 and had the same problem i got a set of 4;3's and works great, i pull a kimbly with on and off road and it feels like it did back when the car was standerd if not better, next will be a set of trans reduction gears for the tranny cheers locko
I'm the same as you locko, my 4.5 had 4.1's and I was running 35's which it struggled a little bit with, but the 4.8 manuals have 4.3's so it handles the 35's with ease even when towing my 1.5 ton camper but then the 4.8 has alot more power than all my other mates patrol's I've driven
 

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I recently just bought a GU 4.8 manual and the bloke had dropped 4.6's in it, and it seems fine on 35's
 

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i new you would be happy, one of the best mods ive done to my car cheers locko
 

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Discussion Starter · #18 ·
very happy camper here. What did you guys do about the speedo. On stock wheels at 110 on gps the dash reads 140. At that rate my next service will come round a bit to quick lol. Also learnt that cruise wont activate when the dash reads 140 or above. I dont think my 315's will correct the speedo that much.
 
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