Re:Diffs VVT on Jimny Non VVT

Non VVT M13A pictured, the VVT engines have a "bulge" on the left of the front cam cover.

sniper

Ah pity I thought it was VVTI lol so what do I do now lol

Alter the gearing in the transfer box, a few companies supply gear kits and Redacted Engineering build custom boxes.

Not cheap stuff.....

sniper

Hmmm ok I did read this... by @riccy

Also thinking of a 1.6 SX4 engine lol

You need to read Riccy's post again Wuzie, it is exactly your situation......

A non VVT M13A jimny with a 3.9 diff (your car), will run a 31" tyre if you fit the VVT 4.3 diff, lowering the main gearing to suit the tyre.

This will increase ratio's throughout the box, making your low box higher geared, a negative when off roading.

That is why outfits like Trailgear manufacture gears that make ratio changes, they give you a high box that will handle bigger tyres but also an effective low range box. Sometimes a crawler type low range, lots of possibilities, depends how deep your pockets are.

Have a look at the wiki pages, they explain it well. Redacted boxes appear to be the choice for serious off roaders.

sniper

For example, I Will put VVT diffs (4.3) in my Jimny (M16A non vvt) and 215/75/15 tyres.

Enough?

Maybe in a future I put trail gear planetary (-60% low range reduction) but im scared with the transfer chain.....

Enviado desde mi ONEPLUS A6003 mediante Tapatalk

Lerk wrote: For example, I Will put VVT diffs (4.3) in my Jimny (M16A non vvt) and 215/75/15 tyres.

Enough?

Maybe in a future I put trail gear planetary (-60% low range reduction) but im scared with the transfer chain.....

Enviado desde mi ONEPLUS A6003 mediante Tapatalk

For that tyre size no correction is needed. The 215 tyres are not much larger than standard and the gearing copes nicely with that size. Were you to go to the next size up (235/75r15) you would find it sluggish and it will wear out the clutch much faster (especially if off-roading). Then you need to think about the gearing alterations.

you can look up and compare the actual tyre sizes here:

tiresize.com/tyre-size-calculator/

and the gearing can be calculated properly with this handy website:

www.grimmjeeper.com/gears.html

All the standard gearing specs are listed in the wiki section of this fine site

Wuzie: as mentioned by Sniper, the low box performance wouldnt be good as you are only changing the final drive ratio by doing this. For example; My 07' VVT jimny has a 'rocklobster' transfer box in it (built by a bloke known as 'Rockwatt Engineering'). It has a 1.6 ratio in high box and 5.13 in low-box. Compared to the original with 1.00 in high and 2.00 in low you can see that it has a much greater reduction value for the low ratio gears. This works well with the huge 33" tyres and is the only real way to get it geared properly. Note I am also using the 3.9 diffs and earlier r7me gearbox from the non VVT jimnys to compensate for the rocklobster box (when i tried the rocklobster box in it with the 4.3 diffs and R72 gearbox it was a joke, top speed in high box 5th gear was about 30mph!).

Hopefully this points everyone towards trying to use the grimjeeper site to get the gearing sorted out properly.

sorry to dig up an old thread but im just away to rebuild my diffs and this is still playing on my mind i have added a pic from the Wiki page and from what you guys are saying im confused.

To me if you lower the dif ratio then it works the same in high range or low range.... both will turn the wheel slower as the ratio in the diffs is lower yeah i know the full way to do it is to fit a rocklobster but i aint got my hands on one yet so not an option just now for me.....

Any info would be ace as away to do the VVTI into a 2003 non VVTI manual jimny so the same as the lower box in the pic?

My car is a 2003 Maunal non VVTI Jimny on 31's, and i have diffs from a later VVTI manual Jimny so should be 3.909-4.300 gear change

Regards
Doug

That's exactly what I'm doing with my buggy build... I've replaced the standard 3.9:1 diffs with later 4.3:1 ratio ones, which allows me to fit bigger 29" tyres, so the overall gearing should be close to stock... but as said earlier the low side of the box may still be a bit 'high' as the Jimny has never been much of a rock-crawler, but it should be fine for some greenlaning!

The back diff fitted fine...

The front needed the slots enlarging to fit the bigger crown wheel in though! -