lekiboy said:
If I ask my mechanic to remove the cover from the box and reapply silicone, will this be a major task? Any recommendation for a very good silcone for this job?
I'm afraid its not a straightforward job and there are some tricky bits you should be aware of.
I would prefer to do it with the transfer box on the bench, but it should be possible to do it in situ, though the extra hassle this causes isn't really worth the saving over removing the box.
Doing it with the box installed:
First:
Drain the oil.
Remove the rear propshaft and the bash plate from the bottom of the transfer box.
This gives you access to the rear output shaft Companion Flange . .
Knock out the 'stake' and undo the nut - it could be very tight, I had to use a 3/4" drive power bar with a scaffold pole over it
With the nut gone, the flange will pull off quite easily as its just splined on.
You now have access to the extension that carries the speedometer drive (the box is upside down on a bench here) . .
Personally, I would remove the speedometer drive before taking the extension cover off.
On my own box this was a ba***rd of a job, but on 'wotdabney's' box shown here it came out easily.
Then its an easy job to remove the extension cover.
The speedometer drive gearing is sandwiched within the cover and is driven by a steel ball bearing sitting in a hole in the output shaft - don't lose that (very small) ball
Now the tricky bit - and the reason I'd prefer to have the box on the bench - The end cover won't come off until the selector fork detent balls and springs have been removed along with the interlock plunger.
First remove both the screwed plugs and extract the spring and ball from each - I used a magnet.
You then have to move one of the selector forks well past its normal position so that the shaft comes out of the end cover (inside - you can't see this) allowing the interlock plunger to be extracted through the hole that held the detent ball and spring. This means removing the Transfer Lever turret and manually (i.e. with a big screwdriver) shifting the selector forward.
Putting it back is worse
You should now have these bits from the detent and interlock mechanism. . .
Next, remove the snap ring from around the output shaft bearing - the bearing won't pull off with the cover I'm afraid as its an interference fit on the shaft.
Almost there now . . . Remove all the 8mm bolts from the rear cover.
The cover will be well stuck down, plus it has to be extracted over the two output shaft bearings.
I heat the covers with a gas torch then use a couple of levers in convenient lever points in the castings to break the seal.
When the cover is off, this is what you see inside.
Note the ends of the two Transfer Selector Shafts - the notches to the outside are for the Detent Balls that 'index' the shafts in their different positions. The notches to the inside are for the interlock plunger. A shaft can only move when the notch in the opposite shaft is aligned with the plunger, thus, one can only move when the other is in a 'safe' position.
Now the faces can be cleaned up properly and new silicone applied before putting it all back together again.
Its tempting to just undo the bolts and try to inject some sealant into the joint, but I don't think that would work without damaging something expensive.
To be honest, if I was this far into the box I'd remove the front propshaft then take out the chain drive to the front.
This gives access to the oil pump filter and magnetic swarf trap - I'd clean them up just to be on the safe side.
Not for the feint-hearted
The very best of luck
Bob.