Manual/Auto Gearboxes/Tcases

Just some assistance for a future purchase.

I think I have access to an Auto 99 G13bb Jimny.

I plan to lift a 2" suspension from the jimnybits store and maybe later a body lift. Tyre size will most likely stay 215/75/15 or if possible closer to a 29" 235/75.

It's not for any hardcore stuff. Mainly on road with a few trails every other weekend or so.

What should I do?
Just keep the Auto as it is? Will it cope well with those sizes and survive? Or will it break eventually somehow?

I read about Transfer cases and that the auto has better? What about replacing the auto tranny with a gearbox and using the auto transfer case?

Will that bolt straight together with no extras?

Also, If I can't find a manual jimny. Any other gearboxes fit? Maybe from a samurai? Or must it be a jimny.

My understanding of the Jimny Auto boxes is that they suffer from over heating and that an uprated oil cooler is required for them to do any more than the road use with stock tyre size they were designed for.

I don't know how good they are or how hardy they are once they have the improved oil cooling sored out.

Rhino Ray has built a few off road Auto Jimny's with big tyres. He may be worth a phone call for advice. He's a nice guy who doesn't seem to mind sharing his knowledge.

I did ask on here once before how an auto box would work with a Rocklobster transfer box but I cannot remember the answer. I think it was of the negative though.

I am not sure how the auto box works. I think it has an ECU and that tells it when to change gear at pre-determined settings that are rev/speed determined. So how bigger tyres and reduced transfer box ratios would effect that I'm not sure.

I would like an auto Jimny though I think. I would make it a little bit expedition like with sensible sized tyres though (215/70/15) and a small 2" lift, hidden winch and a cool roof rack to hold my waffle boards.

Can anyone answer the auto box questions?

As for a manual Jimny - they are ten a penny and the root to better ratios with them is a well trodden path of the rocklobster from Rockwatt on here. That is changing the transfer box, not the gearbox on a manual though.

So I think you need to decide what you want. If it's an auto for it being an auto, get it and leave the gearing alone with that size tyre but improve the gearbox oil cooling or if it's a manual - save a load of hassle and buy a manual car in the first place.

Kirkynut

Think Rays own trials jimny is auto with 31s and yota axels.

I have auto and up to now have had no issues at all.

I have been talking with Rockwatt about fitting a Rocklobster and he assures me it will be fine with an auto.

I'm pretty sure transfer cases are the same on autos and manuals. The diff ratios are slightly different- the auto being very slightly lower geared.

I'd stick with the auto. I doubt you will have problems with 215/75 R15s. However 235/75 R15s are on the limit for standard gearing with a manual, so you'd be looking at changing the transfer case anyway. As Kirky says, no point swapping an auto to manual when you could just buy a manual in the first place.