[sjf1234]

I am putting 31's on my 09 Jimny and would like to change the diff centers to something a little shorter in ratio to offset any power loss.

Anyone know what model Zook I can harvest from?

[Gwagensteve]

There isn't one.

Only option is 4.3 but these are hard to find. That's not enough reduction to be helpful. Any reason you're trying to do it in the diffs not the transfer?

[sjf1234]

I've read reducing transfer ratios can make on road revs very high... As its also my daily driver I want to make it at least somewhat comfortable on road.

Correct me if I'm wrong though.

[sideways]

If yours is a manual then it has 4.3 diffs, if it's auto it's 4.1. There's 4.5 available aftermarket and 5.xx from Japanese models.

It's much easier and cheaper to do the gearing in the transfer case on these models, there's plenty of options around. How many revs you end up with depends on what option you pick. EG a Sierra transfer case conversion with 4.16 gears provides a massive 58% reduction which would kill on road driveability. There's aftermarket gears for you case that provide a more modest increase in revs.

[sjf1234]

Which japanese models will fit?

[sideways]

All of them, but the 660cc ones have the 5.xx gears. You'l need either the whole 3rd member or the right model of ARB air locker as I believe they have a different number of crown wheel bolts in the front. Pretty sure they also run an alloy carrier.

[Gwagensteve]

I thought 4.3 diffs were rare/sporadic?
5.xx gears will also overhear a car on 31's by a fair margin

[sideways]

Nah 4.3 are quite common, 2005 (VVT) onwards manual. Not worth fitting to a 4.11 car to get like 5% reduction IMO. I agree the 5.xx gears will overgear it, they're going to be a massive PITA to get and fit too. They are an option though.

[vet 180]

sideways wrote:

It's much easier and cheaper to do the gearing in the transfer case on these models, there's plenty of options around. How many revs you end up with depends on what option you pick. EG a Sierra transfer case conversion with 4.16 gears provides a massive 58% reduction which would kill on road driveability. There's aftermarket gears for you case that provide a more modest increase in revs.

I disagree with this as you can get this for the front:
http://4xfourart.com/Product/41/JIMNY-R ... FRONT.aspx

and a vitara front R&P for the rear of the Jim. That will gear it pretty much perfectly for 31's and be cheaper than transfer gears. The positive of transfer gears is the extra reduction in low that is possible.

Although if you have a manual you can fit the auto transfer which might be cheaper. If you have an auto the diff gears will be your best option.

[Gwagensteve]

I say nope.

Swapping to 5.12's in a 4.3 geared Jimny is a 20% increase.
31's are a 16% increase.

Jimny's need more than 20% more low range. Especially with 31's.

Anything for the transfer except the Apio reduction planetary (does this even fit late model jimny's?) that reduces low range also reduces high range. I agree that 5.12's +the apio planetary kit would be ok, but wow, that's an expensive way to do it.

That 350€ gear is AU$515, + freight, plus ~$300 for professional fitting, +~$150 for a front vitara 5.12 +~$300 fitting.

That's a lot of coin for a meh gearing outcome.

It's the same problem as Sierra's running 5.12's. Overgeared on the highway and undergeared in the bush. Owner then corrects low range gearing and then has the car spinning at 5,683,590,684,839 rpm on the highway.

[vet 180]

Gwagensteve wrote:

I say nope.

Swapping to 5.12's in a 4.3 geared Jimny is a 20% increase.
31's are a 16% increase.

Jimny's need more than 20% more low range. Especially with 31's.

Anything for the transfer except the Apio reduction planetary (does this even fit late model jimny's?) that reduces low range also reduces high range. I agree that 5.12's +the apio planetary kit would be ok, but wow, that's an expensive way to do it.

That 350€ gear is AU$515, + freight, plus ~$300 for professional fitting, +~$150 for a front vitara 5.12 +~$300 fitting.

That's a lot of coin for a meh gearing outcome.

It's the same problem as Sierra's running 5.12's. Overgeared on the highway and undergeared in the bush. Owner then corrects low range gearing and then has the car spinning at 5,683,590,684,839 rpm on the highway.

I agree that transfer gears are the better option and you can gear low also, but not the cheapest option. You can also get low range only 4.1 transfer gears to correct low range latter.

Jimny's run a 205/70r15 tire stock which is 26.3 inches. Adding 20% is 5.2 inches which equates to 31.5 inches. Bang on perfect by my calculations?

[Gwagensteve]

But no 31 is 31.5" tall and some are barely 30"

Based on that 51.2's would correct most 33's which would be even more terrible off-road.

I generally agree that slightly overgearing on road to offset big tyres is completely fine to offset the aerodynamic drag and rolling resistance... but when it leaves you with no options for correcting low range (and leaves a poor low range outcome) I can't recommend it.

[vet 180]

Gwagensteve wrote:

But no 31 is 31.5" tall and some are barely 30"

Based on that 51.2's would correct most 33's which would be even more terrible off-road.

I generally agree that slightly overgearing on road to offset big tyres is completely fine to offset the aerodynamic drag and rolling resistance... but when it leaves you with no options for correcting low range (and leaves a poor low range outcome) I can't recommend it.

But the jimny has low range only gears. So you still have options.

[Gwagensteve]

Huh? Is there a reduction gearset for a jimny that only reduces low range?

[pete_79]

Yep!
A few options actually...

I had 77% low range only reduction gears in my Jimny. They where awesome.

[Gwagensteve]

For an 09? Isn't that electric shift?

[vet 180]

yeah there are options for push button stuff.

In saying that last time I looked at gearing options I didn't notice these:

http://www.lowrangeoffroad.com/suzuki-o ... 3-kit.html

To the OP the link attached is the best 1 time solution for 31's for the reasons already mentioned.

I wonder if it really does reduce the auto box by 17% and 87% as the auto has very different ratio's to the manual.

[sideways]

/beaten by minutes!

Yeah, there's quite a number of transfer gearing options these days. Even LROR has them. VVT Jimnys don't run the planetery low range like the older models but there's much more available for these than the planetary ones.

Still, I'd rather do it all in the transfer. Cheaper, easier, much easier to resell and less of a headache if something gets broken.

[Gwagensteve]

vet 180 wrote:

yeah there are options for push button stuff.

In saying that last time I looked at gearing options I didn't notice these:

http://www.lowrangeoffroad.com/suzuki-o ... 3-kit.html

To the OP the link attached is the best 1 time solution for 31's for the reasons already mentioned.

I wonder if it really does reduce the auto box by 17% and 87% as the auto has very different ratio's to the manual.

They look ideal for what the OP wants. Much better outcome than 5.12 diffs.

[sjf1234]

I've also read that the Auto VVT transfer case has shorter ratios. Will this work as an option?

[Gwagensteve]

Apparently auto transfer is 27% lower on high and low, so, like diff gears, too much highway not enough bush.

[shep]

sjf1234 wrote:

I've also read that the Auto VVT transfer case has shorter ratios. Will this work as an option?

It worked for me, 4000rpm @ 100kph with 245/75/16 tyres. Low range was fine as well.

Vvt jimnys have better gearing stock then earlier jimnys so don't need as much to keep it working well.

[vet 180]

sjf1234 wrote:

I've also read that the Auto VVT transfer case has shorter ratios. Will this work as an option?

Ratio's are not perfect for 31's, plus you get a smaller/thinner chain etc

Those gears linked really are the best solution unless you can pick up an auto case cheap

If it was me I would get those gears and run 30x9.5 tires and little to no lift.