front diff overhaul question

[rb30e]

Hi Guys,
Just overhauling the front diff on my GU. Previously there was a leak from the big seal around the steering knuckle.

I have dismantled everything and noticed that on the knuckle around where the seal travels the metal is quite pitted, just from general ware and tare.

Was thinking that with a new seal running on this surface it would still potentially leak.
Just wondering if any one had any ideas of how to clean up this surface to prevent leaking, short of replacing the diff housing.

I ran a thin bead of silastic over it and was thinking if I run a razor over that surface to clean any excess leaving silastic only in the pitted sections it would help it seal better.
Then on second thoughts with all the mud, sand and general crap that gets jammed up in this area the silastic wouldn’t last that long.

I was thinking maybe applying kwiksteel over the same area then sanding it back to leave only the pitted areas covered. Will probably last longer but was worried if fragments break off and jam in the seal it would start leaking again.

All of the above probably sounds a bit dodgy but if I can get by without replacing the diff housing then that would be the way to go.

Ideas anyone?

[nissannewby]

The oil doesnt actually leak from there. There is a seal that seals the diff from your knuckle (inner axle seal) this will be the seal that is leaking. If that seal is in good working order there should be no oil in the knuckle at all. Those wiper seals are made to keep stuff out mre efficiently than they keep stuff in. Replace your inner axle seal and they will fix the leak :)

[rb30e]

Nissannewby,

Thanks for that, I removed the NS axle, which was leaking the most, the hub was filled with gear oil and it was because that seal was leaking. I have got both the axel seals and going to replace them.

Was just concerned that mud or water especially when the hub is submerged will enter the joint and foul the components inside the hub. When I undid the OS knuckle water was sitting in the bottom around the bottom swivel joint.

[threedogs]

Hot diffs, cold river, bog holes etc, better check diff oil as well

[nissannewby]

Yeah water can also get in from your king pin bearings so make sure you slap some silastic on them before refitting. They arent the greatest seal but you can put grease in the gap between your ball and knuckle this will also help to keep water out. Also give the balls a nice sand up with some emery paper see if that helps a little.

[rb30e]

There was water entering from the king pin bearings also, there is actually no gasket on the flange that bolts to the hub, its just a shim so a bit of slazo is crucial. There is a seal on the bottom of the king pin bearing but water still seemed to get past it. Changing all that anyway.

Those shims, there are 5 different sizes and must dictate the correct preload on the kingpin bearings. not sure what the specs are and how to check it as I dont have a W/S manual. All of mine were .5mm, bar one which was missing?!?! I just bougt another .5mm shim, changed the king pin bearings slazo on the flanges and slazo on the cup that separates the king pin bearing grease from mixing with the CV grease and she'll be right!

I went over the joints with scotch bright they are pretty clean but they are still pitted. was thinking I could try and smoth it off by filling the pitted areas with something and sanding it back. Bogging it up basically but using kwicksteel which is pretty tough.

Just wanted to know if anyone has tried similar

[Finly Owner]

Yeah water can also get in from your king pin bearings so make sure you slap some silastic on them before refitting. They arent the greatest seal but you can put grease in the gap between your ball and knuckle this will also help to keep water out. Also give the balls a nice sand up with some emery paper see if that helps a little.
Hey Mate, sounds like I coulddo with you to learn a thing or two over at Big Rigs on 28th of this month. Reckon you can make it, and maybe lend a hand at Make Overing an old deisel MK?


Tim

[nissannewby]

Yeah mate I have informed scotty i will be there so I will certainly be able to lend a hand.

[rb30e]

thanks guys for the info all sorted now

[rb30e]

oh yeah one more question, filling the front diff, the owners manual does not have the filling capacity it is just blank next to front diff oil capacities.

I just filled it til it was level with the fill plug hole, is the correct? seems like a lot of oil

[rb30e]

just managed to download the service manual, thats the correct method, fill until level with fill plug.

Anyone know where the front diff breather ends up? want to check its not blocked after fitting all new seals. Having trouble finding it being in a wheelchair.

[nissannewby]

Yeah mate thats the correct method. Im pretty sure it goes up into the engine bay somewhere i dont know where exactly if you have some compressed air just remove from diff end and blow some air up it. Hopefully someone can give you exact location.