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Series III gearbox rebuild

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Where, exactly do they leak from? My 109 is leaking from the gear selector area, though exactly where I'm not sure as I've not investigated yet.

The output flanges?

The front and rear mainshaft?

The intermediate gear shaft "O" ring?

If there is a bearing with additional sealing then I think it would be a good idea to investigate it.

G.

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Mine is leaking from the selector rail. When I took the spare to AW I mentioned it, yes I changed the seals on the selector shafts, and no, I didnt use any sealant on the top housing....there's no gasket for it, and no instruction anywhere about using RTV, so I didnt! I'll know next time!

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To think that I threw in a Gen Rover low miles recon suffix D with the sale of my last SW as a spare . I must have thought I was Santa Clause :hysterical:

Any one tried a rubber backed bearing as well as the bearing seal, to stop migration? Timken do a version I'm sure.

Does the migration only take place at certain times of year or is it all round...... :D

There's a member of LRUK forum called Daz who runs one - he brought over two bad boxes and we (well, more "I" - he hadn't even bothered to wash them off and I had to spend a day with the pressure washer cleaning them both before stripping) built up one good one with new bearings, including a sealed rear bearing. I didn't like the idea of it being completely sealed, so we pulled the seal out of the side facing the gear box but left the side facing the main seal and transfer box. You could ask him how it's going; the only time I heard from him again was when I chased him up a couple of months after it was refit (he said it was going very well).

However, I would stick to a standard open bearing of good quality (SKF, Timken or NSK). A sealed bearing has only its grease to lubricate it, and if that becomes displaced around the edges of the races or makes its way out of the rear seal, then it'll start running dry. It also will lack the circulation of oil which transfers the heat away and sheds it through contact with the casing. I suspect it's also not great for the main seal to be left to run dry (the oil or grease applied on assembly will eventually migrate).

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Where, exactly do they leak from? My 109 is leaking from the gear selector area, though exactly where I'm not sure as I've not investigated yet.

The output flanges?

The front and rear mainshaft?

The intermediate gear shaft "O" ring?

If there is a bearing with additional sealing then I think it would be a good idea to investigate it.

G.

The main external leaks for a gear box are the selector rod seals, and there is little that can be done about it. The original seals are almost (but not quite) rectangular in section, with a slightly narrower inner diameter on their inboard ends (leaks would be worse if fitted the wrong way around). these do tend to harden with age and heat, so if yours are old and leak significantly, it could be worth replacing them. This can be done with the box still fitted - you need to remove the tunnel cover, gear stick, detents and then the top cover before removing the selector rods complete with forks. The forks are then removed (mark their positions carefully on the rods first) for the seals to be swapped over. The later seals were o-rings with plastic spacer washers, which I have tried to even worse effect. The top cover has no gasket and should not need sealant (it gums up the detents). However, a small amount of sealant around the faces of the side detent seals (the rubber hose lengths that cover the springs under the L plates) can help. Make sure the breather is clear.

The biggest loss of oil is almost invariable through the rear bearing carrier/main casing joint into the transfer box. That's why Series transmissions are notorious for empty gear boxes and over-filled transfer boxes. Use that bearing seating compound and you'll have no more trouble.

The primary shaft seal at the front is rarely a problem.

Use a thick paper gasket to seal the gear box to the transfer box - don't be tempted to use RTV sealant or Hylomar by itself (as done on LT77/LT230 units), as this will result in a transfer box oil leak equivalent to about 1litre/100miles (don't ask me how I know ;)).

The main leak I get from the transfer box assembly is the small o-ring around the plunger controlled by the yellow 4wd lever, but that's just a minor weep whose only significance is to drip every couple of days and mark my driveway :(.

If the drive flange seal lands and seals are in good order, you should not suffer any leaks there. The intermediate cluster shaft's rear o-ring can sweat a little oil if the hole through the casing is scored.

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.

If it don't come out perfect you can easily double de-clutch. :) Mind you.......probably not the point of all synchro box.

Good stuff Gaz..

i always double de clutch. especially when changing down cos it just sounds so cool ;)

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i always double de clutch. especially when changing down cos it just sounds so cool ;)

'tis funny, so do I, even on the eurobox!

Legacy of learning to drive in an old tractor.

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yeah, even in the 09 lacetti estate i occasionally drive.

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However, I would stick to a standard open bearing of good quality (SKF, Timken or NSK). A sealed bearing has only its grease to lubricate it, and if that becomes displaced around the edges of the races or makes its way out of the rear seal, then it'll start running dry. It also will lack the circulation of oil which transfers the heat away and sheds it through contact with the casing. I suspect it's also not great for the main seal to be left to run dry (the oil or grease applied on assembly will eventually migrate).

The rear main bearing of the Fairey OD has a sealed bearing....do you think an open bearing would be better for this too? I'm liking your train of thought on this one

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A sealed bearing has only its grease to lubricate it,

There are bearings available with a seal on one side only. The open side is facing the splash lube. The seal on other side is throwing oil back after lubricating the races. I think this is the idea ?

They are useful also with seals on two sides,as greased swivel bearings to keep water and dirt out where the swivel does not run in oil (Jap)

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There are bearings available with a seal on one side only. The open side is facing the splash lube. The seal on other side is throwing oil back after lubricating the races. I think this is the idea ?

This has got to be the ideal solution IMHO, and when I pull mine apart further I will look do do this.

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I've been thinking about this.

The double sealed bearings are out, I think, as they don't last as long as open bearings.

I'm also a bit worried about the single sided ones - what happens if oil does get past? would the oil cause pressure between the bearing and the original seal?

I'm not sure it's the best way. I think for this box I'll pass, but for my lightweight rebuild I'll try it, as an experiment, in one or two places.

G.

PS, for the selector section mating surfaces I have used red grease on a previous rebuild, it hasn't leaked yet, or so I'm told.

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The rear main bearing of the Fairey OD has a sealed bearing....do you think an open bearing would be better for this too? I'm liking your train of thought on this one

Not normally, it doesn't. Yours must have been replaced at some point. Sealing that rear main bearing will just starve the rear main shaft/output shaft thrust bearing of oil. Again, if the seals are in good order, there is absolutely no benefit and plenty of harm in sealed bearings.

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There are bearings available with a seal on one side only. The open side is facing the splash lube. The seal on other side is throwing oil back after lubricating the races. I think this is the idea ?

They are useful also with seals on two sides,as greased swivel bearings to keep water and dirt out where the swivel does not run in oil (Jap)

Like I said, this will prevent the main seal from being lubricated, leading to its failure. It will also reduce the oil flow through the bearing, reducing heat dissipation. There is absolutely no benefit to having a sealed bearing in an oil filled casing - sealed bearings are for use in dry areas, like idler pulleys on fan belts, in alternators or on bicycle wheels and crank shafts, where the seals are present to keep the factory applied grease in and dust out.

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Ah I am with you now, sorry, don't have the box or schematic to hand, but makes sense now... open it is.

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Yes Gaz and Snagger..............quite right. I was forgetting totally about the seal itself and thinking the oil was free to go through races :rtfm:

:D

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Ok, some minor updates:

I've had a look at the layshaft, and whilst I'd be happy enough to stick it back in as is if it was going into my truck I'm not happy that it's up to a V8.

The reason being is the rust on the gears. The customer for this box has specified "silent" so I'm not putting in a rusty layshaft. Also I'd be worried that it would break, so . . . . . . new it is!

The constant gear is fine, so I'm going to go with the speedisleeve on the input pinion.

Anyway, pictures!

23112011478.jpg

23112011479.jpg

23112011481.jpg

G.

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So, shopping list for the mainbox innards:

We've established that it's a Suffix "D" box or later.

Reverse gear assembly FRC1810 (complete)

Reverse gear location pin 591519

Input pinion bearing 55714

Selection of adjustment shims 594021, 594020, 594019, 594018

Circlip 214795

Seal 571059

3/4 syncro clip (three of) RTC1956

Mainshaft roller bearing 6397

Spring clip RTC1957

Shim selection RTC1962, 50702, 50703

3rd gear FRC8179

Bronze bush (singlepiece) 571218

Selection of thrustwashers 267572, 267573, 267574, 267575

mainshaft pin 6405

mainshaft pin RTC1979

1/2 syncro detent spring (3) 503805

1/2 syncro detent ball (3) BLS108L

Circlip (inner) 9960

Mainshaft rear bearing 1645

Circlip (outer) RTC1984

Mainshaft output seal 236305

Layshaft locktab 528683

Layshaft distance piece (selection) 528720, 528721, 528722

Forward layshaft bearing 528701

Layshaft "C" onward FRC2084

Layshaft aft bearing RTC1412

Gaskets set 600603.

Have I missed out anything? Or am I being over cautious? I'm fairly certain that the above list will result in a quiet reliable box.

That's all from me for the next while. I'll be looking at the transfer box next, but it might not be until the week after next.

G.

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The customer for this box has specified "silent" .......

Wow - a silent series gearbox! Now that would be a first!

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I would love it if mine just made less noise, and stayed in first/second on overrun!

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We can dream.

Well actually, the series one box I rebuilt was very quiet, new transferbox shaft and bearings made a HUGE difference.

G.

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That lay shaft is in pretty bad condition, but replacing it with a brand new one will not make for a silent box - these boxes were rumbly and clattery from new, though it's a matter of how noisy; some old gear boxes make a terrible noise. A new or really well reconditioned unit will make a little noise because of the profile of the gear teeth and the tolerances on the various splines and synchro teeth. This is particularly noticeable when you let the engine idle, select neutral on the transfer box and then select each gear and engage the clutch - the higher the gear, the greater the rumble, and there's nothing that you can do about it (other than use much thicker oil, which won't get through the oil ways to lubricate the bushes).

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I've found that sound insulation is the best approach. I lined the underside of my transmission tunnel with asphalt (flashband) and also the engine side of the bulkhead when I fitted the di200. It has made a significant difference to the noise level. I will, at some stage, line the seatbox underside as well. The landrover is much quieter now (inside) with the di200, than with the previous petrol engine.

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That stuff. A relative works in the aerospace industry as an acoustic engineer - his job is to stop the airframes acoustics from killing pilots.

I torched on 3 layers and it has made a difference. Not quiet, by any stretch of the imagination, but a lot quieter.

G>

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his job is to stop the airframes acoustics from killing pilots.

There you go Snagger...........guys are looking after you.

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