Transfer box from Suzuki SJ 41x installation

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The Jimny transfer box (both manual and electronic) are not popular with off road enthusiasts. In both variations the main drive is achieved through the use of a chain and in the electronic version the added complexity of an electronic motor and its controls make it more unreliable. The chain can wear and slip, particularly with those ratio modification kits that change the gearing around the chain. Therefore many people like to change to a gear only driven transfer box, the common (only?) solution is one from an SJ series off-roader.

Despite the similarities between an SJ and Jimny, it is not a straight swap, you require some form of mounting kit. Depending on the kit you use, you will have to change the propshafts as well because the overall mounting position of the box will change. A number of mounting solutions exist:

All of them make mounting kits at various prices. It is also not too difficult to construct your own if you have the ability to weld well. I chose to use the kit from The Off-Road Armory (ORA), this has now been discontinued so although this guide shows the steps in principle, you can no longer purchase this kit.

What is needed

The Off-Road Armory kit comes with a set of mounting brackets, replacement rubber mounts and the Speedo converter. However some other parts are necessary, depending on what you are attempting to do.

In order to fit an SJ transfer box on a Jimny you will also need the following:

  • An SJ min propeller shaft (the small propeller shaft between the gear box and the transfer box).
  • An SJ front propeller shaft.
  • A Jimny front propeller shaft.
  • You will also need some SJ flanges.
    • The Jimny’s original flanges are similar to the very last Suzuki Samurai 4x4s.
    • Therefore, if you are really lucky, using the flanges and propeller shafts from a late Samurai will mean you can bolt it all on.
    • Of course, these parts are like “hens teeth”, so in all likelihood, you will have to mix and match propeller shafts and flanges to suit.
  • The other point to note is that an extended flange is required for the output shaft, which you will not have if you have been working with SJ transfer boxes which have the drum brake fitted to the case.
    • You will have to find a proper SJ output flange, as the shorter input or front flanges can not be used on the rear.
    • There are pictures in the text showing the issues, but make sure you have collected all the parts before you start.
  • Finally, you will need nuts and bolts to affix the propeller shafts.
    • This may seem obvious, but the flanges on the Jimny are threaded whilst the SJ flanges are not.
    • Therefore, you will not have suitable nuts after dismantling the Jimny case.
    • Also, the bolts are too short, as they only have to reach the threads in the Jimny flanges, but they have to go right through the SJ flanges to bolt up.

The work

Reviewing the parts

Figure 01 - ORA kit

  • First you have to get ORA kit.
  • This picture shows the kit as shipped.
  • In the kit you get the speedo adaptor, the mounts and bolts and washers to assemble it all.
  • Not shown in this picture are the replacement mounts which are included in the kit but came separately in my early version.

Figure 02 - ORA mounts

  • This picture shows the mounts in greater detail.
  • My mounts came in plain steel but later versions should be power coated.

Figure 03 - ORA speedo kit
  • This picture shows the speedo kit.

Assembling the SJ transfer case

Figure 04 - SJ flanges
  • The first stage is to assemble the speedo kit onto the SJ Transfer Box.
  • You will have to get a set of SJ flanges to match the prop-shafts you have.
  • If you can not get the correct ones, then you will have some drilling to do.
  • This picture shows SJ flanges with the largest on the left (You want these!!) to the smallest on the right (You want to avoid these).

Figure 05 - the wrong (left) and the correct (right) flange
  • The speedo kit fits on the output flange, which needs to be a proper, extended output flange.
  • You may not have the extended output flange if you have used SJ transfer boxes fitted with the handbrake drum.
  • This picture shows what you need.

Figure 06 - flange with the cup removed
  • Now you need to remove the cup on the end of the flange.
  • This is a friction fit and can be tapped off with a hammer.

Figure 07 - oil seal fitted
  • Now you need to clean up the stem of the flange.
  • The oil seal is going to fit over this and ideally the oil seal should sit on a machined surface.
  • The flange is rough cast and does not make a good oil seal surface.
  • You should clean it up the best you can to smooth the surface as much as possible.
  • Then push the oil seal onto the flange as shown in this picture.

Figure 08 - assembled flange
  • Now the speedo gear needs to be fitted.
  • This friction fit over the end of the flange.
  • ORA recommends that this is pressed on using a press.
  • You can use a vice as it is not too hard.
  • I put the flange in the freezer and the gear in the oven for a short while and then the gear just dropped into place.

Figure 09 - example fitting
  • This picture shows how it fits onto the transfer box.
  • However this is only for demonstration purposes.
  • In reality you need to fit the speedo sensor case first!

Figure 10 - the speedo sensor case in position
  • You need to fit the case and then fit the flange inside.
  • Grease the oil seal with copper grease and push the assembly together.
  • You may need to use a flat piece of metal to push the oil seal into place.

Figure 11 - finished SJ case alongside the old Jimny case
  • You should now end up with this.

Mounting the assembled transfer case on the vehicle

  • Now the assembled SJ transfer case needs to be fitted to a Jimny.
  • Attach the correct flanges for the propeller shaft sizes that you have.
  • Remember - you need an SJ mini propeller shaft (between the gearbox and the transfer box) and an SJ front propeller shaft (to be fitted on the Jimny rear).
  • The original Jimny front propeller shaft stays in place.

Figure 12 - polybush mount
  • The kit comes with replacement bushes made from polyurethane material.
  • These simply replace the existing Suzuki bushes.
  • Also, being slightly thinner, they lower the transfer box slightly.
  • This helps with the clearance under the transmission tunnel and stops the mini propeller shaft from hitting the gearbox remote mechanism.

  • Now before you all write in, I know that the nut and bolt are better off the other way around, so that the nut and end of the bolt do not protrude down below the car.
  • I swapped them over after the picture was taken.

Fitting the transfer box lever

Figure 13 - un-modified lever
  • Now you need to fit the transfer lever.
  • As you can see from this picture, the position of the SJ transfer box means that, un-modified, the lever is jammed against the transmission tunnel.
    • Note that this is with the lever in the fully “back” position – it needs to shift forward from here!
  • I found this to be the hardest bit, as it needs a lot of heat to bend it.
  • It's really not possible to cold bend it and no-one has gas nowadays, only MIG.
    • So its hard to find someone with the right tools.

Figure 14 - lever bent into position
  • However I did find someone eventually.
  • The lever needs to be rotated and bent back.
  • Here is the finished item, in exactly the same ratio (4WD High) as in the previous picture.

Figure 15 - transfer lever showing "rotation" and bend
  • Here is a further picture showing an original level on the right and a modified one on the left.
  • Both lever ends are in exactly the same, correct, position showing how much of a bend is needed.

Finishing assemblies

Figure 16 - flange clamped for drilling
  • So now we are on the home run.
  • You need to replace the rubber boots on the lever and bolt up the propeller shafts.
  • In my case I could only get the medium size SJ flanges and prop.
  • Therefore I needed to drill the rear diff flange to take the prop.
  • This involved clamping the prop to the flange and drilling through.

  • Finally, remember to fill it with oil and connect up the 4WD switch and speedo sensor.
  • Now go and enjoy yourself!!

Page last edited on 21/02/2019 by user Bosanek