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Normbourne

Series 2A gearbox/transfer case assy.

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Hi guys, I need to change the oil seal between the gear box and transfer case, on my series 2a land rover. The object being to prevent oil flow between same. Any ideas guys....? Is it possible to do without taking the gearbox assy out..? Thank you, Norm.

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A bit oily in the face, but not as hard as taking the whole lot out. Whenever I've done a gearbox repair, I've removed the transfer box from the truck first - and reversed to re-fit. (Makes fitting back into the clutch a lot easier). Best advice I can give is remove the bottom cover and let it drip for 24 hours. Maybe WD40 around the centre gear pin on the outside, (behind the hand brake drum) as well?

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It can be done with the box fitted in the car but it is a bit fiddly and like team Idris says you might need a good shower after to get the oil out of your hair.

Changing the seal might not cure the problem altogether though. The oil also migrates from the gearbox to the transfer case between the steel carrier for the main bearing and the aluminium housing of the gearbox. The bearing carrier has to be glued in the gearbox housing with bearing glue to prefent it from turning in the housing but also to seal it.

Cheers,

Eric.

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If you are going to all that effort I would suggest taking the whole lot out and doing a good overhaul while you are about it. The internal components are cheap, so why not?

Once out and on the bench I fit a little frame to the transfer box to stop it all rolling around and remove the main box from it; everything is reasonable weight if you do it that way. If you get it the correct size you can turn it on its back end so you can fit the bell housing more easily and on its side to get to the bottom.

I would also recommend making yourself a decent lifting attachment that holds the complete box level, much easier for putting it back in the vehicle. Pics here

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the series box is so easy to remove, especially if removed in 2 pieces.

and if you just partially unbolt the front of the seatbox, you can pull it out from underneath (split its really light)

thats how i do it although having a ramp means im not on my back all the time

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It's not "really light", but is manageable by one healthy man when split.

The seal in question can be replaced in situ without removing, splitting or even draining the boxes (unless the transfer box is over-filled, which is common when oil migrates). You need to remove the top inspection panel and the rear bearing carrier, followed by the transfer input gear and oil thrower from the gear box main shaft. With those clear, you can hook out the old seal and fit a new one.

Genuine seals have a steel rim and rubber inner lip, only pattern seals are completely rubber coated. The genuine seals are very difficult to fit in the hole as the steel outer rim is quite delicate and picks up on the rim of its seat. To get around that problem, first file the edge of the steel rim to a bevel to help it enter the aperture, and give a thin smear of RTV silicone sealant to lubricate it as it is pressed in. Be very careful to get the whole nose in before tapping gently home, as if it skews, it'll bend and be wrecked. I'd buy two seals before tackling the job just in case.

As said already, though, this may not cure the migration - the problem is that the carrier unit in which the rear main bearing and this seal are housed should be installed in the casing with bearing seating compound (similar to thread lock), but almost all reconditioners and even LR themselves fitted it dry, so oil migrates through that joint, bypassing the seal.

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It's not "really light", but is manageable by one healthy man when split.

The seal in question can be replaced in situ without removing, splitting or even draining the boxes (unless the transfer box is over-filled, which is common when oil migrates). You need to remove the top inspection panel and the rear bearing carrier, followed by the transfer input gear and oil thrower from the gear box main shaft. With those clear, you can hook out the old seal and fit a new one.

Genuine seals have a steel rim and rubber inner lip, only pattern seals are completely rubber coated. The genuine seals are very difficult to fit in the hole as the steel outer rim is quite delicate and picks up on the rim of its seat. To get around that problem, first file the edge of the steel rim to a bevel to help it enter the aperture, and give a thin smear of RTV silicone sealant to lubricate it as it is pressed in. Be very careful to get the whole nose in before tapping gently home, as if it skews, it'll bend and be wrecked. I'd buy two seals before tackling the job just in case.

As said already, though, this may not cure the migration - the problem is that the carrier unit in which the rear main bearing and this seal are housed should be installed in the casing with bearing seating compound (similar to thread lock), but almost all reconditioners and even LR themselves fitted it dry, so oil migrates through that joint, bypassing the seal.

Thanks guys, I'll give it a go and let you know how I get on.....!

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So I guess guys the answer is to get the output shaft bearing and its metal insert out.

Then perhaps give the insert the Loctite treatment and put sucker backin, followed by the bearing..! The queston here is here do I get the bearing and insert out..? Any ideas guys..?

Thanks,

Norm.

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The queston here is here do I get the bearing and insert out..? Any ideas guys..?

Thanks,

Norm.

Take the gearbox out. Remove transferbox. Remove bellhousing.Take top off and remove selector forks. Remove layshaft. Tap mainshaft out of the bearing(a bit of heat helps).

Remove big circlip. Tap bearing carrier out of casing(warm up casing a bit). Remove circlip for bearing. Tap bearing out.

Glue new bearing in carrier. Fit circlip. Glue carrier in casing. Fit big circlip. Put main-and layshaft back in. Fit bellhousing and transferbox.

But if you plan to do all that you might as well overhaul the whole gearbox.

If the gearbox is still doing fine i would just settle for a new seal and accept a little oil migration and check the level in the box every month at least and don't forget to drain the exxess oil out of the transferbox from time to time.

That how i do it anyway. I have another box on the workbench that i'm overhauling and hopefully is going to be oiltight afterwards and then i'll put it on the shelf as a spare box.

Some people fit a hose between the levelplugs of gearbox and transferbox so the migrated oil can run back to the main box.

Cheers,

Eric

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Fitting a hose is pointless - you'd be better off removing the seal instead as either way you're just trying to have a similar level in both units while what is required is a higher level in the gear box than the transfer box. The reason you can't just overfill the transfer box to match the levels is that it will cause the transfer box to leak from its selector levers and shafts, and is also likely to weep through the output seals and fill the hand brake drum.

Monitoring and refilling is the practical approach. A full strip down to refit the bearing carrier correctly with the seating compound is the long-term view. Another thing you can do to make monitoring and refilling easier is to fit the MoD type top fill plug and retainer, which replace the standard breather disc in the top cover and the central detent bung, and fit a Rocky Mountain transfer box dipstick to the gear box, using an MoD tunnel cover or cutting another circular hole in the existing tunnel cover (same size as the one on the left) to access the new filler (the dipstick is accessed via the left side tunnel hole) - this can all be done without removing the box, and a Dremmel could be used to cut the tunnel top hole.

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Okay guys, thank you so much for your advice, I think I will take the easiest route, vis just fit the oil seal, and the oil filler/dip stick arrangement, which is a great idea.

After all said and done, although oil migration past the bearing insert will continue to take place, it shouldn't be that great a flow, compared to that which will take place if the oil seal is crook.

In the 40 odd years I've owned the vehicle, it's never been changed so I can't imagine it being in pristine condition......!

Anyway lads I will advise in due course, in the meantime, thanks again.!

Norm.

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Fitting a hose is pointless - you'd be better off removing the seal instead as either way you're just trying to have a similar level in both units while what is required is a higher level in the gear box than the transfer box. The reason you can't just overfill the transfer box to match the levels is that it will cause the transfer box to leak from its selector levers and shafts, and is also likely to weep through the output seals and fill the hand brake drum.

I agree, thats why i never did that. The level in the main box sit about 6cm higher than the level in the transfer box. so there will be excess oil in the transfer box all the time which is definitely going to come out through the seals.

Cheers,

Eric.

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Curiously early 80's had more oil in the transfer box - and the level was dropped to stop it migrating to the main box!

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Upon further attempts to remove the oil seal, it became apparent that the insert itself was loose in the housing to such an extent that it was possible to spin it readily by hand.

So I might as well fix it once and for all...! after all these years, a remanufactured engine ready to go in, a refurbished firewall, etc. etc.

it would be foolish to just replace the oil seal, there is so much play on the insert interface, oil must be flooding past.....!

I ' m hoping that I can get away with leaving the transfer case in situ and just remove the gear box.

WML

Norm.

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the transfer case will need to be removed in order to split the two boxes anyway. its not a big job to remove at all though.

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Upon further attempts to remove the oil seal, it became apparent that the insert itself was loose in the housing to such an extent that it was possible to spin it readily by hand.

If the carrier is that loose in the housing there is a big chance that the aluminium of the housing has worn away to much by the spinning carrier.

It should be a tight fit.

Cheers,

Eric

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the transfer case will need to be removed in order to split the two boxes anyway. its not a big job to remove at all though.

Despite my reluctance about pulling the gear box out, it turned out to be the best move I ever made...!

When I came to pull out the clutch linkage from the bell housing, it was to discover that one of the pins through the connecting tube, had broken into three parts. I would have been really p......d off, had I put the box back in to then discover that it would have to come out again..!

Anyway it turned out all oil seals need replacement and the seal on the main shaft, was approaching 5 on the moh scale it was that hard, not surprising really considering that I've never changed it and I've had the vehicle 40 years. But no wonder the oil was flooding past.

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Another thing I meant to mention is that oil had been leaking past one of the stud bolts also.

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I've heard that in Europe, that there is an argument that goes that the oil is actually coming from the chamber at the rear of the gearbox selector shafts and from there down the machined groove on the transfer box face into the gearbox. Thus bypassing the output drive seal completely.*

I've heard of a bloke, who installed a brand new virgin box and sure enough, oil migration took place, which seems to point to an inherent fault in the design.

The fact remains, there is a clear unimpeded access between the gearbox and the transfer case, via the chamber at the rear of the selector shafts.

After further deliberation I believe that what is happening with reference to oil migration is that the gear selector rods, act as pumps, transferring oil every time a gear is selected, to the chamber at the rear end of the selector rods, which of course is then drained into the transfer case...!

I think I am on the right track in drilling a drain into the gear box and blocking off the channel drain into the transfer case.

Further I cannot see any ramifications in doing so, it isnt as though the flow from this drain is meant to lubricate anything within the transfer case. (or is it....??)

I've been racking my brains, trying to work out why rover would provide this channel, could it be that it was meant to be simply a means to relieve any pressure which may build up, due to the action of the selector rods....???

Anyway, for me my mind is made up, I intend to go ahead with the mod. I will advise in due course, unless lads, any of you, can see any reason why I shouldn't proceed.

Norm.

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The selector rods are quite a close fit between case and lid , last few boxes I have stripped have not had much trace of oil in that area!

Mind my current fitted box is leaking oil from front selector seals so must be able to pass some [suspect incorrect pairing of lid and case they are machined as pairs]

Is the groove in transfer cas not a vent for transfer case?

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That channel is indeed the transfer case breather, which vents through a plastic cap on the top of the square pedestal of the rear of the gear box top cover. If you block that off, you need to make a new breather for the transfer box, and I'd suggest a brake bleed nipple and length of silicone hose screwed into the upper inspection plate of the transfer box for that. However, any oil migration through there will be immeasurably small - my LR factory rebuilt transmission also suffered significant migration, as is the norm, and a later rebuild showed it was the factory's failure to use the seating compound between the gear box casing and the rear bearing carrier, as I mentioned earlier. I will stop just short of guaranteeing that is the cause of your migration problem, because there are exceptions to every rule, but will assure you that you are barking up the wrong tree worrying about the transfer box breather channel. ;)

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That channel is the breather for the transfer box as Snagger states and should not be closed off.

I have a recon box here and they fitted a length of hose inside the channel and sealed the channel with silicone gasket. The end of the hose is high in the chamber. Frankly I don't see the point in doing it like this. If there was oil coming past the selector shafts it would just accumulate there untill the level reached the top of the hose.

On top of that,I have never found any oil in that chamber in all the boxes I have had and I am convinced that is oil is migrating only via the main bearing carrier and the thread of the bottom bolts that hold the transferbox to the main gearbox.

Eric.

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Yes I now see how that channel is a breather, I have only just noted the small hole in the inspection plate.

This of course makes nonsense of my contention that it may be a pressure relief, what a round about method for a breather...!

As regards oil being evident in the chamber upon gear box strip downs, I wouldn't expect to see oil there because as soon as any oil collects there it would drain straight through to the transfer case.

As regards oil flow into that chamber, if that is what is happening (?) it could only be a minimal but the same could be said for oil flow past the output bearing insert.

The mod I'm considering entails as I say, blocking the channel, and drilling a hole to ensure drainage into the gearbox, but of course I had Intended to revise and install breathers to both GB & TC as part of the overhaul.

The installation of breathers makes the channel obsolete.

It seems to me to remove doubt regarding all possible reasons for oil migration is the thing to do.

But having said that, in view of your comments, I intend to give the matter further consideration.

Thanks guys,

Norm.

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There's no problem with what you plan, Norm, as long as that new breather is added to the TC. Make sure you fit a splash plate underneath the breather as the gears will be flinging oil at it. The breather holes in the top cover of a Fairey overdrive is a good example of what to do, but I would also extend it with some plastic or silicone hose,as drilled holes allow some oil out and any water and dirt in.

The essential thing is to get that bearing seat compound, like Locktite "Lock 'n Seal", to seat that bearing carrier in the casing - that causes casing wear and the carrier will eventually spin, but is where the migration is happening - promise!

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