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Offroad mainly build for JB43 Jimny - advice
https://www.auszookers.com/forum/viewtopic.php?f=37&t=57520		 Page 1 of 1
Author:  Viktro [ Sun May 21, 2023 9:24 pm ]
Post subject:  Offroad mainly build for JB43 Jimny - advice
Hey everyone,

Firstly a bit of context. We're a family of four living on the road and we travel with a caravan towed by a 2002 Isuzu FSS550 which is a 4x4 truck. Prior to our truck, we had a 2008 GU Patrol which we took offroad regularly - but being our family tow vehicle, we always erred on the more cautious side but still enjoyed getting amongst the medium difficulty tracks.

Here's our old rig:
Image

Part of the reason for getting the truck, was to get a smaller dedicated 4x4 that we could take out on more difficult trails and push things more. We were looking at Sierras, Wranglers and Vitaras (SV420), but couldn't settle on any decent ones that felt like they were a good starting point (i.e. unmodified, felt like they were cared for).

However, in a recent surprise turn, we found a well priced 1999 manual Jimny (we weren't really looking at them) that's done ~140,000kms and is unmodified. So that's what we have now as a starting point.

The new rigs
Image

From a lot of research I've done so far (much of it from these forums), I've come up with a little bit of a game plan and would love feedback/suggestions from people far more experienced that me.

Here it is:

Stage 1
My preference is to stay as low as possible, no body lift and suspension lift if I can help it. I'm not sure whether tradeoff of smaller diameter tyre for no lift is worth it though. I'm happy to cut guards as needed. I'm also keen to keep as light as possible, so avoiding bars front and rear if I can.
  • 7.50R16 or 235/85R16 wheels and tyres, running a mild negative offset, 0 to -10?
  • Reduction gears. It seems the low range reduction isn't much for manual boxes + manual transfer? I found this one: https://lowrangeoffroad.com/suzuki-jimn ... -only.html that might work? But I've also seen people suggest Sierra transfer swaps - what's the recommend approach to greatly increase the reduction?
  • Winch cradle + winch
  • Radius arm protection and bash plates (I see Genuine 4x4 have a range of things that I might get)
  • New shocks

Stage 2
  • Front and rear lockers
  • HD front axles and CVs
  • Something something rear floating axle? I'm not that read up on these, but presumably with the large diameter wheels and rear locker, strengthening the rear will be required

From the little that I've driven the Jimny so far, the power seems reasonable from the G13BB and presumably with the better gearing - that won't be a problem. I'm of the mind of mechanical sympathy and throttle control gets you places - not outright power (though power has its place of course!).

So my questions are mainly around Stage 1, as that's what we're going to do first:
- Does that look like a reasonable approach and is there anything I'm not considering?
- Whilst I'm replacing the shocks, should I be looking for longer shocks with extended bump stops? We're happy to spend a bit more for decent shocks, but would prefer to get it right the first time.
- With the manual box and transfer case I have, will I struggle to get the right reduction?
- Does anybody know of a good company (ideally Zook knowledgeable) up in Darwin that could fit reduction gears and a new clutch for me? (that's where we'll be for Stage 1)

Thanks in advance everyone, love all the knowledge that's on here and I'm looking forward to meeting some of you in the future :)
Author:  sideways [ Mon May 22, 2023 11:51 pm ]
Post subject:  Re: Offroad mainly build for JB43 Jimny - advice
You'll want to drop the high ratio as well as the low ratio. You can convert to a Sierra transfer but IMO that's the old way of doing it before Jimny gears were cheap/available. It depends on how cheap you can source the Sierra parts but I'd say it's cheaper to gear down a jimny case and overall it's a better result. ADD (See business section) sell gears, build transfers and ship them all around the country.

You certainly will want longer shocks than standard, there's quite a lot more travel to be had out of the standard suspension just with longer shocks. You may need to bumpstop space the front for longer shocks, space there is a bit limited. Measure your compressed distance and ask for compressed lengts. The rear has heaps of compressed distance to fit any length of shock that you can make use of, they take an unusually long shock in the back.

235/85 is darn big tyre on a Jimny, you're going to need to cut the guards quite a bit especially if you're trying to stay low. Also, 235/85s are heavy and stiff for their size. There's not much available in the old 750-16s anymore.

Neofitou built a nice low jimny on 33s. Shows the guard cut.

viewtopic.php?f=4&t=46882&start=60

31zook drove a lot of notable tracks in his Jimny, his was 30s then 31s. This was 80mm lift from memory but 3 link front.

viewtopic.php?f=4&t=30877&start=1230

Both those builds are out of date in Jimny world but the concept is still right, there was very little aftermarket support 10 years ago.
Author:  Viktro [ Tue May 23, 2023 9:38 pm ]
Post subject:  Re: Offroad mainly build for JB43 Jimny - advice
Thanks sideways for taking the time to write that response.

I had wondered about the Sierra transfer swap given I had seen some chain and planetary gear reduction options so it's nice to know that's a bit of an older thing. I'll reach out to ADD - I saw they did JB74 reduction gears and they don't have JB43 stuff listed anymore. It would be great to get something local instead of trying to source something from overseas.

That's also good to know about the longer shocks and thanks for the tip on asking for compressed size. Makes sense - get the longest extended I can get for the minimum compressed size.

With regards to the tyres, any other alternative suggestions? My concern with running any smaller tyre is getting hung up on ruts. I imagine it's possible to navigate and straddle the ruts, but this isn't always possible and I've experienced my Patrol diff pumpkin dragging on ruts and would hate to be limited on the trails we want to do. I'm not sure that I can see any way around just getting the larger tyre and cutting? In searching 7.5R16s, I do find BFGoodrich is doing them in their KM3 mud tyre and both Tyroola and Bob Jane T-Marts are showing them in stock.

Thanks for those build links - I've had a look through them and Neofitou's is impressive. Those 33 10.5s are pretty massive though, a bit larger than what I think I would like to do, but gives some sense of the body work that's needed. Being on the road though, that level of modification is going to be hard to achieve without a place to work on it. Cutting with a grinder is one thing, trying to fabricate is another :D. I'm hoping that the significantly narrower tyres like the 7.5R16s would mean just guard cutting without tubbing.
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