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Diffs vs Transfer

Posted: Mon Nov 12, 2007 4:18 am
by Geqz
Hello guys! Nice meeting you. I have a 2001 Jimny 1.3 16V SOHC with a 4" lift kit and 30's. I have researched a lot about this subject but I still need some help!. I decided to go with the R&P due to some facts I came across. The point is that in my case it's easier to swap R&P's than get a whole new transfer case. I found a place with R&P's 4.88 and I was wondering if this reduction would be enough to regain some power I lost with my 30's? I plan to run 31 muddies in the near future but not bigger than that. I want to know if 4.88:1 would be enough knowing that the standard Jimny has 3.909:1 diffs. How much reduction will I obtain from these diffs in %? will I be too rev on road? I'm not into rockcrawling, I just want to regain my lost torque in Hi and Lo (on and off road) and have a decent reduction to go outside and play tough ;)

These guys at the store told me that the front diff is "high pinion" type and I should change my front case for a "standard" one :?: is this true? I haven't read anything about the jimny's front diff being high pinion. I don't even know what that means. If you also know something about this would be great!

So: 1) Will 4.88:1 be enough to run 30 and 31" tall tires?
2) How much reduction would I obtain?
3) Is the Jimny front diff "high pinion"?
4) Do I need to change the front case?
5) and last but not least: Is it strong and tough enough to handle mild off-roading? I'm not comparing with a new transfer!

By the way, I live on a hilly area and I forgot were my 5th gear was :D Highway just once in a while. That's why I need my lost power in Hi range too.

Thanks a lot.

Posted: Mon Nov 12, 2007 12:12 pm
by muppet_man67
yes the jimny front end is high pinion. Im pretty sure you cannot simply change it to low pinion as the tie rod runs under it. I would be surprised if you could get the diff gears your talking about for a high pinion setup. Both options are a little harder on a jimny then a sierra however you can get reduction transfer gears for a jimny. otherwise its possible to put a sierra transfer case in.

Posted: Mon Nov 12, 2007 6:55 pm
by zookstir
Changing from 26.5" tyres to 30" tyres increases your gearing by around 13%. Changing your R&P from 3.909 to 4.880 reduces your gearing by 24.8%. Therefore your final gearing in both high and low will be approx. 12% lower. Your speedometer will indicate faster than you're actually going ie. at indicated 112KMH you will be doing 100KMH.

Posted: Mon Nov 12, 2007 8:42 pm
by Gwagensteve
Please make sure that your source for 4.88 r&p's knows that you have a JIMNY not a SAMURAI. SAMURAI were known as jimny or Sierra in world markets up until 1999 and there are 4.88 r&p available for these diffs.

The actual Jimny (post 1999) has a high pinion front end and to the best of my knowledge there are no ratios lower than 4.3 available for the front.

It is not possible to change to a "regular" r&p as the steering gear woudl interfere. (tie rod)

Anything is possible, but I believe changing the transfer case is a better option.

Steve.