[greenzook89]

I've been doing some research about a possible diff swap for my SJ80. After a few quick measurements the front diff of the Jimny looks like it would go into the coily fairly well. I would need to mod my top buckets and run Jimny front suspension. (that would fix my gay front strut problem and also allow a locker). Where i'm stuck is on ratios. I've been referencing the diff ratio thread and see that a SJ80 runs a 3.909 ratio, whereas as Jimny can be 4.09 or 4.3 depending on engine. So that leads to putting Jimny diffs front and rear. What i'm wondering has anyone done this or played around with both diffs enough to know how hard/easy it would be to do?

Keen to hear your thoughts/research.

Cheers.

[sideways]

So you're planning to use coily radius arms with a Jimny diff?

You could import a 3.909 Jimny front diff 3rd member from overseas if you want to keep the higher ratio. Expensive, but probably the best way (short of putting a WT diff in).

If you want me to measure up anything on my Jimny, let me know.

[greenzook89]

sideways wrote:

So you're planning to use coily radius arms with a Jimny diff?

You could import a 3.909 Jimny front diff 3rd member from overseas if you want to keep the higher ratio. Expensive, but probably the best way (short of putting a WT diff in).

If you want me to measure up anything on my Jimny, let me know.

Cheers for the offer. Yeah coily radius arms (at least the front, there's almost no difference. not sure on the back yet)

Was the 3.9 Jimny front diff a JDM model or Euro Diesel?

[sideways]

Petrol pre VVT euro(UK spec?) manuals I think.

(Very) roughly there's 145mm between the radius arm holes and 890mm between the arms at the diff end.

[greenzook89]

sideways wrote:

Petrol pre VVT euro(UK spec?) manuals I think.

(Very) roughly there's 145mm between the radius arm holes and890mm between the arms at the diff end.

Mine measures the same 145mm but measuring from the inside of the radius arm bracket i got 570mm

I've read about people putting Jimny rear centres in WT diffs, so (disregarding ratios for a moment) theoretically would a Jimny rear centre with a matching ratio to the front fit the coily rear diff housing?

Edit: Linky for Jimny centre in WT viewtopic.php?f=5&t=47885&p=846499&hilit=jimny+rear+diff+centre#p846499

[sideways]

That was the spacing on the rear diff?

Yeah, Jimny rear, 1.3l Sierra F+R, coily R and Vitara F 3rd members are all basically the same thing and will bolt into each other (disregarding ratios, spline counts and tailshaft bolt patterns).

[greenzook89]

Yeah I realised that just before sorry. Measuring from the inside edges of the radius arm mounts on the diff, the coily measures bang on 800mm, Front is 570mm measured the same method.

[alien]

going from 3.9 to a 4.09 is only a 5% increase, and to 4.3 is a 10% increase in reduction..

a 215/75r15 tyre is roughly a 6% increase in size over the factory 205/70r15 - so changing that diff gearing will cater for a slight tyre size increase (215/75) up to a 235/75r15.

IMO that's well worth doing!

[Joe]

There's one kid on here i know has swapped a jimny front diff into his coily but i cant remember his user name i go search now

[Joe]

Found it viewtopic.php?f=4&t=10041&start=210

[Skippy]

^ Thanks joe, have read through it a handfull of times to make sure i hadn't missed anything.

Greenzook and myself will be doing this, when... well that will depend

From previous conversations we have had i think 30's will be his max tyre size intentions but i think we will base this all off 235's for the moment.

Going off measurements Sideways has supplied on the rear radius arms, i'm suspecting we will be using coily arms as the jim ones are way to long and castor correction will be need but we won't know untill we sit the arms side by side and check over them both. (lucky for greenzook i have a jim)

I've PMed tuffcoily for his knowledge and will also consult the almighty goat builder

[Angus Martin]

Decisions, decisions hey Josh?
Are you going to be going the Jimny front diff or the WT front diff now?
I've probably made this a harder decision for you haha
Angus

[greenzook89]

Bahaha. At this point I'm going to sit back and see what options pop up. The Jimny swap will end up being hella expensive and then just opens the door for me to spend even more money. (Locker, chromos, power steer etc.)

[Angus Martin]

Yeah fair enough, Darren's doimg good work me thinks!
Be keen to see where it all goes!