31" for the jimny and regear

hello all!
im new here and owner of 2010 jimny, Auto Transmission
currently got 3" procomp lift and 215/75/15
i can go 31" without re gear the t-case? im using the jimny only for offroad, mostly for rock climbing.
what about the axle, do i have to get stronger shafts?

thanks!

With 31" you will need to think about regearing something. The transfer case, especially if you prefer rock crawling, would be the likely candidate. You wouldn't want to use the trailgear since those are for transfer cases with the standard transmissions and would result in a 1.17:1 high from the original 1.32:1 that you currently have. I think Redacted still makes a kit for the push button transfer with auto. There is also protrack in Greece. If you end up doing the transfer regear, you may want to install an external cooler and temp gauge for your auto at the same time.

I’ve had 3 Jimnys now and all have had 30-31” tyres (235-75-15 and 30-10.50-15) never had problems off-roading with them did manage to do 2 cv’s over a period of about 4 years but the cars were 4 year old and 12year old tho k it was the 12yearold that did the cv’s..both sides at separate times did some small rock climbing sections off-roading at cows and in the lakes ( parkermoor being the most rocky I did) and it was always fine. I found slow and steady was the best method and less bits break

im assuming you talking about this kit that not good?
www.trail-gear.com/product/5323/jimny-electric-t-case-gears
seem like 87% on the low, do i need more than 17% on the high?
if im not installing any t-case gear. it can fail or any damage to the transmission?
i have already cooler installed.
thanks

That kit will not help much on a auto jimny as the gearing is different on manual and auto jimnys. For the kit to work at all you will need the chain from a manual jimny transfer as well..
Will be too much cost for too little down gearing.
Try rocklobster. Try to set up all your different options in the grim jeeper calculator to see what suits your car and tire size best.

That is the kit that I was commenting on. It is supposed to be very good quality (no personal experience) but is not appropriate for your Jimny.

Yakusa's points are on the money. The transfer case for the manual transmission is a 1:1 high and 2.002:1 low. The automatic is 1.32:1 high and 2.643:1 low. The point that Yakusa and I are making is that if you use the kit for a manual (17% reduction in high range) you would actually be basing the reduction on 1:1. You would end up with a 1.17:1 high range rather than your original 1.32:1 (obviously not a reduction). The grim jeeper site Yakusa mentioned is an extremely useful tool. It is here:
Gear Calculator
Using the site you can play a lot with the gearing to find what best suits you. It should be noted that the gearing of the differentials are different as well. Most market areas should have a 4.090 differential for manuals and a 4.300 for automatics.

The last point that Yakusa makes would depend on your preference. The Rocklobster is a rock solid way to go. If you would rather stay with the push-button, you can try these:
Redacted Reduction Gears
Or for a wider selection, try here:
Protrack Reduction Gears

Thanks to zookbob, all above correct. I was on my phone so did not find the links and stuff to post in my reply

Also one option is to change the diffs from your 4.09 to diffs from a manual VVT jimny at 4.3

zukebob wrote: That is the kit that I was commenting on. It is supposed to be very good quality (no personal experience) but is not appropriate for your Jimny.
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well the quality is not completely great in my opinion. As an engineer working with gearboxes for ships I have some experience with gear sets and these make a lot of noise. there was plenty more when they where new and this shows that the gears had not been grind to fit and i suspect there to be some scuffing between the gears inside and some noise from the chain drive. could be my chain was worn of course but the noise is way beyond what i would send out of our factory. But it works, and the gear ratio is spot on for my 235 wheels.
Could even be ok for bigger wheels but i lik to go low.
But i guess the quality is no worse than other brands as a ground and polished gear set probably is way too pricy for a after market kit

you guys are awesome and super professional!!
zukebob, i think my diffs are 4.3,
i think i will stay with the push button, rocklobster mean i need
to buy another t case from samurai? or am i wrong ? do you have a link explaining what is exactly?
i looked on the Redacted kits, the COMP one looks like the one for my needs. i just want to be able to cruise at 90-100 on highways and get nice and slow moves while im on the rocks.
this one can achieve that ?
again, thank you all !

You are correct. The Rocklobster would mean replacing your current transfer case. I never planned to go to a Rocklobster so I never really researched the details of the swap. You could try using the search function of the forum to see what you can find or wait for someone who has done the work to detail the steps.

As far as the COMP set of gears from Redacted are concerned, I put in some of the numbers on the grim jeeper site we mentioned. It certainly seems that the gear ratios wouldn't be terrible for highway. Your 90-100 would be at a little lower RPM (but would likely take you a little longer to get there). The low range is definitely for crawling.

Based on Yakusa's comments, you may want to do a little more research still before making a purchase. I was a little surprised by his experience with gear noise (although Rocklobster has a reputation for the same). Like Yakusa, my career was as a mechanical engineer, although my background was with a company that designs and produces military vehicles for the U.S. Army and Marines. What I learned early on, and I'm sure Yakusa will agree with me, is that experience trumps theory every time. Try to get more info before you make a final decision......unless the gear noise makes no difference to you.

A 'Rocklobster' box is a hybrid SJ box made using parts from a SJ410 and SJ413. There is a conversion some people do called a mini-lobster, which is basically just a SJ413 box stuck into a jimny, but this has no real improvement in low-box.

For a non VVT jimny its pretty straightforward to put a lobster box in, you just need the intermediate prop and front prop from the SJ (use the front prop as a rear on the jimny, existing jimny front is fine as it is). There is also a mounting cradle and speedo ring you need for the box to go into the jimny.

With VVT jimnys I found the intermediate prop was different to the SJ so I had to have a custom one made (shorter than the original jimny one). The spline count on the gearbox output shaft is different to the SJ prop. This also lowered the gearing way too much as the VVTs have different gearbox and diff ratios.

In the end I decided to swap the lot (gearbox, diffs, props) and use the rocklobster box as this was the only way to get it useable on the road. It now sits about 4000 RPM when doing 60mps (100KPH) roughly, which i am happy with. Lowbox is really low as well I think the ratios in my rocklobster are 1.5 in high and 4.13 in low. This is with 31" tyres on.

Almost correct. The mini lobster is when using the 410 transfer box in the Jimny. It's has a slightly lower low ratio that the 413/Jimny.

Haven't read the entire thread. But for anything more than greenlaning I wouldn't hesitate getting a rock lobster transfer box or even lower gearing for 31-32" tyres. It just makes a world of difference.