Transfer case rebuild

A brand new transfer case!

(T-Cap partner article)

Here's another practical article for Toyota home mechanics. This time we are going to work on the transfer case. Tired gaskets, leaks, worn bearings, slack chain? It's time to give your pride & joy a new lease of life.

Summary:

A. Transfer case (Series 9)

B. Transfer case rebuild - Dismantling

C. Transfer case rebuild - Reassembly

A. Transfer case (series 9)

1. Difficulty

Be aware that rebuilding a transfer case is not a project to be undertaken lightly. In addition to your basic set of tools a methodical approach and plenty of space you'll also need a big bearing extractor. Make sure you have all you need before starting.

2. Price

The transfer case rebuild kit is of course supplied by Euro4x4parts. For 450 € the kit includes all the necessary gaskets, seals and bearings to rebuild the transfer case as new.

3. Removal

Start off inside the vehicle by removing the two gearstick knobs and the boot cover.

Undo the waterproof seal.

Whilst you doing this empty the transfer case by unscrewing the drain plug.

Watch out drain into the funnel not the wheelbarrow :)

Now uncouple the drive shafts. Loosen the nuts the bolts remain in place because they are splined. Tap with a mallet to push them out.

Undo the sensor on the right-hand side of the transfer case.

Now it's time to deal with the chassis cross member that needs to be removed. Use a hydraulic jack to support it and by all means use an impact spanner if you have one. Things can get really seized up in down here!

Now head back inside the vehicle to remove the transfer gear selector lever (otherwise it won't come out believe me, I tried!) Undo the 4 bolts

and the lever comes off together with its joint. Block off the hole to stop anything falling in - even though it's not vital at this stage given that we're going to open up the transfer case!!!

Don't loose the spring!!!

Last step, support the transfer case from below using a jack or even better make up a plate holder using a flat section of iron with two holes predrilled to take two bolts through to the free threads on the housing.

By placing an axle stand at each end of the plate it is much easier to support the weight of the case. Having placed a strap across the front of the transfer case to balance everything all that remains is to unbolt it from the gearbox. Undo the bolts between the gearbox and the transfer case and tap the housing using a mallet.

By pulling towards the rear the case should come out without any difficulty.

It really is a two-man job to support the weight of the unit properly.

That's it the transfer case is now out. Take this opportunity to give it a power hosing so you can continue the job in optimum, clean conditions. Be careful to only clean the outside of the case block off any openings with rags wrapped in plastic bags.

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B. Transfer case rebuild - Dismantling

Now you're ready to get down to work. Once again, remember to proceed carefully with precision and method throughout this stage. Always note the position of gaskets, seals and bearings during dismantling to ensure correct reassembly.

1. Gearbox side

Start off by replacing the radial shaft seal that is still on the vehicle that way you won't forget it during reassembly. Take this opportunity to clean the housing as well.

2. Transfer case

Set your transfer case on a clean table or bench around which you can move this will save you extra work. A few blocks help to keep the unit in place.

Now undo the front of the case.

At the other end unblock then unscrew the output nut. An impact spanner will really help. Be sure to block the shaft to prevent rotation.

Now unscrew the front of the case.

Before pulling off, remove the sensor screwed into the side.

For this step you will definitely need a bearing extractor.

Use the same method for the front drive shaft that is on the side of the case.

Now it's time to open the case.

Unscrew it,

Using a small screwdriver remove the clip that holds the bearing.

Tap gently on the edges of the housing to break the seal

Gently pull on the part.

The half housing will come off with the planetary gear train and the transfer chain... Be careful not to drop anything.

Now the case is in half, catch your breath for 5 minutes before heading onto the next part...

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Let's continue stripping down the case. Now split in two, things should look like this. :

Remove the oil pump by removing the bolts on the pump side,

then on the flange.

You can now remove the gear set leaving you with an empty case.

Be careful when disassembling, there's a fair chance that the brass synchronizer ring, these two clips and two split needle bearings fall into the housing. Don't panic retrieve them and put them to one side ready for reassembly.

3. Planetary gear train and transfer chain

Now it's time to move to the other half of the case. In the previous section you have already checked the tension of the transfer chain. Now check for wear and also that it hasn't scored the housing. Remove it. If the chain is too slack there's no miracle solution it will need changing. Link.

Also check that there's no abnormal play in the planetary gear train. If necessary, it might need changing as well. Link

All that remains is to drive out the bearing and seals, clean thoroughly and reassemble. To make matters easier remove the parts to be replaced one by one, clean then position the new part. Working by elimination all the elements of the kit will find their right place and you'll have no doubts regarding where to put them during reassembly.

Also clean the surface of the case gasket seating with a flat blade being careful not to pit the metal. Use acetone to remove the remains of the joint.

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C. Transfer case rebuild - Reassembly

Reassembly is really just repeating the steps in reverse order. However we're going to look at some points in detail.

1. Gears

Gear set: Start by removing the clip.

Then lift the gears.

Remove the flat bearing,

then extract the bottom bearing.

Reassemble in reverse order fitting the new bearings.

Replace the big bearing on the housing

and refit the gear set in position.

Refit the large ring clip into its groove,

the bronze ring,

and the 3 segments. These parts are very fragile be careful not to damage them during reassembly.

2. Main shaft

Start by unscrewing the small cover and extract the bearing that will allow you to remove the two forks from the housing.

Now it's time to change the bearings be sure to use nice big extractor.

You can now remove the big gear

and change the two split needle bearings.

Reassemble in reverse order checking for any abnormal play

3. Front transmission shaft

To the front, there's only one big bearing to change on each side.

Use your bearing extractor x2

Having changed the radial shaft seal, you can now put it back in place.

4. Final reassembly

Now it's time to refit the shaft, the forks and the brass synchronizer into position. This isn't a complicated job but you do need to work carefully to ensure that everything seats correctly. You can tape or tie the two forks to hold all in place. Align the synchronizer and slide the whole assembly into the housing.

All that remains is to refit the chain and the last of the radial shaft seals,

and refit the position sensors

before closing the housing. Prepare the gasket using the paste supplied in the kit. No need to heap on kilos because once reassembled the joint only covers faults in the metal but don't skip this part otherwise you'll be sure to have leaks.

Close the front of the housing using the same technique.

Now the job's done, check that all the gaskets, seals and bearings have been changed and that the transfer case works correctly by temporarily refitting the transfer lever.

You can now refit the transfer case to the vehicle by following the removal steps in reverse order. Don't forget to refill with oil once everything is back in place.

Your transfer case should now feel as smooth as it did when new!

If you have any questions or problems feel free to call on the collective know-how in the forum La préparation des véhicules (in french only)

Happy mechanics.

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