DIY - How to install 1:1.925 low range gears

1) transfer box input gear.

It is held in the front of the transfer box face plate by a circlip and has a bearing on it:

You need the complete gear + bearing (which is pressed onto it) it will have 16 teeth

 

2) Low range side (idler) gear

These sit on a side shaft in the front of the transfer box - are a single gear with two gears cut into it

21 teeth on one end and 15 teeth on the other

 

The gears I have were generously given to me by "M1s3ry" on the pajero club of victoria forum.

Check the condition of the input gear bearing - if it needs replacing you will need a new bearing as the io bearing will not fit onto the Gen2 gearshaft - luckily mine was OK to re-use.

Removing the Gearbox
Follow the steps in the manual to remove the gearbox - if you have a manual gearbox you can ignore the step to disconnect the exhaust as this was not necessary with my manual gearbox. Manual 22D is the main file to reference for manual transmissions - it also shows how to strip the Gen2 box to find gears.

The gearbox / transfer box balances on the transmission mounts - put your trolley jack underneath there and it will be a lot easier.
Both shifters need to come off - both of mine needed a tap with a screwdriver from underneath to break the silicon seal and get them loose.
Both tailshafts can come off as well - if you have chosen not to drain the oil leave the tailshafts in the box to maintain the oilseals.

You can get onto all of the bellhousing bolts with a good 14mm socket, a heap of 1/2" drive extension bars and uni-joint except one. It is located under the starter motor bolt and faces the engine mount outrigger. I found a socket and ratchet could be slipped onto the bolt once the front tailshaft was removed and with some timber packing around the rachet head stopped it slipping off the bolt head. Pass a piece of timber down next to the strut tower next to the inlet manifold and press onto the end of the ratchet handle to loosen. Others have used articulated ratchet ring spanners.

IF ANY BOLTS ARE TOO TIGHT TO UNDO - USE A HEAT GUN TO WARM THAT POINT ON THE BELHOUSING - DO NOT USE AN OXY FLAME.

Many of my bolts were siezed and needed a heat gun to warm up the alloy housing for them to release - be careful of melting wiring/clutch hoses etc.

With the box out you might want to replace your clutch and rear main seal while you have the chance.

I have put the shifters back on as I was about to wash the box down.

Seperate the transfer box
Now that the gearbox is out you need to seperate the transfer box.

Carefuly drive out the roll pin that secures the gearshift locator, you will likely want to re-use this so don't damage the pin - I used a 5.5mm punch to get it out. Placing a rag underneath it as you punch will prevent the pin popping out and disapearing down into your gearbox.

now unbolt the transfer box from the gearbox - there are some lugs that allow a large screwdriver or crowbar to help ease the boxes appart - never lever off the actual machined mounting faces in case you damage them.

Once the dowel pins are clear you can carefuly pull the boxes apart - the gearshift rod will remain attached to the gearbox and passes through the transfer box via a small O-seal, be gentle and ensure no excessive side load is placed on the shifter rod.

Strip down the transfer box

with the boxes seperated unbolt the 5 bolts that secure the front cover to the transfer case. As before lever only on the lugs and not on the actual machined mounting faces. 

Due to the transfer box shift interlock being held in the front cover you will need to attach the transfer shifter and shift gently from 2H through to 4Low and back to 2H to allow the cover to come off - it needed some tapping and gentle levering to break the silicon seal with mine.

DO NOT ATTEMPT TO REMOVE FRONT COVER WITHOUT REFITTING THE SHIFT LEVER FIRST
if you pull the front cover off without the lever in place the shift rods can pull out of the shift area and damage (ruin) the interlock pegs and springs - i've just done this and it is bad :(

The gears will need to turn slightly to seperate so the cover may become jammed about 30mm out. The laygear shaft needs to detach from the front cover - it is only sitting in a socket so you may need to wiggle and tilt the cover to allow the shaft to detach.

Once free you should have a cover that looks like this

Now the fun begins!

Start with the front cover:

To remove the input gear use a set of heavy duto 90deg circlip pliers and remove the circlip. The circlip might not come all the way off but it needs to be removed from the groove it is locked in. You can now gently tap the input spline with a piece of wood etc to ease the bearing clear of the front cover and seperate the gear assembly fully - Do not force and be careful with the oil seal.

I bought a cheap set of pliers from Bunnings and really struggled to get the circlip out - spend the money and get a good pair! DON'T USE PLIERS LIKE THIS

With the input gear off clean up the sealing flange on the cover and put it to one side. DO NOT PUT THE NEW GEAR BACK IN.

here are the standard Io input gears and the Gen 2 gears: Io are on the Left

 

You can see that the syncro shift lock on the io is not a full ring, this does not appear to affect the operation - also the input shaft is longer on the io however the oil seal lips appear to be in the same position - time will tell if this is a problem.

The gears I inserted had a worn groove on the oilseal lip - hopefully this does not affect the operation too badly!

Now for the lay gear - this is tricky:

* Shift the box very gently into 4Low - the shift ring will now half come off the main gear - DO NOT LET IT COME OFF FULLY

* Grip the laygear shaft with your fingers and pull the shaft out of the laygear - the laygear will now be loose in the box.

* Gently draw the laygear forward and lean it over so the larger end can clear the shift ring and allow the gear to exit the case

you will have the following items once removed - clean and inspect for wear and replace where required

Take note here- the dimples in the thrust washers ALWAYS face against the laygear, their flat sides are against the case.

The lay gears from the io and gen2 are below: Io on the right - note the larger input side and identical output side - the 1:1.94 gears have a different output side and need the output and shift mechanism to be stripped down - way too much work for 0.02 difference!

 

Re-assemble the transfer box

This is quite tricky as the larger input gear side makes assembly different - you can trial fit the lay gear into the case and sand back any high points on the inside of the case that contacts the gear - I spent about 30minutes cleaning up the area - easiest way is to place the gear in and let it scratch the inside of the case when it rotates - this will identify the areas that need sanding. 

 

* go and place the entire new input gear including bearing and circlip etc in the freezer for a minimum of 30 minutes to shrink it.

* While this is happening scrape all the silicone off the transfer box front cover and clean the mateing surface with some mild sandpapaer and a scotchbrite pad and turps - do not damage the oilseals

* lift and mount the transfer box vertically with the open end facing up and secure firmly - i placed this on my bench and clamped the lug next to the spedo pickup firmly in my vice.

* clean the mating surface of the case as above with the cover.

* Place the lower thrust washer into the bottom of the case - use a slight smear of grease on it's flat site to help it stick to the case - align the flat of the hole with the flat deeper in the box. dimples should be facing you.

* grease the inside lip of the input gear oil seal in the front cover - I used a GP marinegrease

* retrieve the bearing from the freezer and place on your bench.

Now work fast as the bearing will be warming up and expanding!

* using Loctite Blue max or equivalent product run a fine continuous bead around the center of the front cover mating flange making sure you encircle all dowels and all bolt holes

* Lower the laygear halfway into the gearcase and once the smaller gear has cleared the shift fork lean it over away from the shift fork, now with your other hand place the cold input gear into the shift fork and seat it onto the output gears - you can now lean the laygear back upright and lower into the case. make sure the circlip is on the input gear and the two "O" holes are facing the shifter opening

* by looking fown the center of the laygear move the lower thrust washer back into the correct position using a screwdriver tip etc before loading the bearings and spacer back inside the laygear (bearing-spacer-bearing)

* Now slide the laygear shaft back into the laygear and press it down fully ensuring it seats fully and is aligned with the case

* place the front thrust washer onto the laygear shaft with the dimples facing the laygear

* Shift the transfer into 2H

* pick up the front cover and make sure the little interlock peg is sitting in the tunnel between the two holes - it tends to drop down and foul one of the holes fully and will cause the front cover to not close up by about 10mm.

* gently put the front cover onto the box allowing the input gear to gently push through the oil seal and bolt it shut - 25FtLbs torque on the bolts - you may need to wiggle the shift lever to get it in past the interlock. Be careful not to damage the wet silicon seal!

* Quickly swing the transfer case down flat onto the bench so the shifter hole is facing upwards.

* push the input gear fully into the bearing seat and clip the circlip into the retaining ring by putting your pliers through the shift hole - ensure it has fully snapped in place.

That's it!

move the gears by hand and shift down into 4Low to ensure all gears move smoothly and nothing is scraping etc thn shift back to 2H and rotate gears by hand again.

now you only need to re-attach the transfer box to the gearbox ensuring the shift rod passes gently through the oil seals and the shifter locator is attached the correct way around - gently drive the spring roll pin back in (with a rag underneath the pin) and reference the special note in manual 22D regarding the orientation of the spring clip

Job Done!