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Series III gearbox rebuild

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Following on from a thread started by twodoorgaz (no relation) this thread will cover the topic of rebuilding series III gearboxes.

To start the ball rolling I'm taking one apart in my workshop at the moment and taking photos as I go. I've never rebuilt a series III box before, although I have rebuilt a series I box last winter.

Starting with the complete box on the workbench:








I have a 1/2 dozen of these gearboxes at my old workshop, and I selected this one to rebuild as it seems the most complete, but other than that I know nothing about it.

It is a series 3 box as you can see from the BL logo on the side:


I removed as much of the physical oilmuck as I could with a variety of scrapers, screwdrivers and chisels, mainly in order to avoid filling the partswasher with too much carp.

I then drained whatever fluids remained in the main box and the transfer case.

The drain plug for the main box was a 13/16 spanner (or thereabouts).


I then started to disassemble the lump, mainly as it's too awkward in a complete section!

The manual starts with the main box but covers the splitting of the two boxes later on in the transfer box section:


First off, remove the transfer box inspection plate, otherwise known as the Landrover anti rust drip feed system (patented).


Using a socket of a mystery size (I think it's 7/16 AF).


Slacke n each one of slowly and then remove. I found that the studs came out, rather than the nuts and washers. This is probably better as the studs tend to stick into the workbench.

All removed, but plate still in place:


I cleaned any obvious muck away from the mating surface and then used a stanley knife, aimed away from the casing, to ease the plate away, to reveal:


I quite like the leaf, myself, an autuminal touch, I think.

Next up, the mainshaft rear bearing carrier, also known as the place where the overdrive goes.


Some nuts and studs later the carrier was undone, however it doesn't come away easy, as the goo on the gasket hods it in plase, as do the needle rollers on the end of the mainshaft.


My trusty chisel and I can overcome these difficulties, again, aiming away from the softer metal of the casting a gentle tap with the hammer works wonders.


The intermediate shaft needs to be removed to access the mainshaft to transferbox nuts.

This is it - it just sticks out of the transfer box here-


Remove the bolt holding the retainer.


And then use the expensive special tool to remove the intermediate shaft, holding the big gear cluster with another hand:


It just slides out nice and easy.

Doesn't actually look too bad.


The intermediate gear cluster was happy to stay where it was, so I left it there for a bit:


Then I gently rolled it out of the box.



It has a small trace of surface rust but, at first glance, looks ok. When I'm rebuilding the transferbox I'll inspect in more detail.

Record orientation of the thrust washers on the sides of the tranfer case:



And remove.

Finally! Access to the nuts inside the transferbox:



and the bolts/nuts on the outside:



Unscrew all of these nuts and bolts, using AF and WW sockets (and, no doubt metric as well as BA).


Next I needed to remove the big castle nut that holds the transferbox input gear onto the mainshaft.

I needed to lock the mainshaft in order to prevent the shaft turning as I undid the nut. Here is how I did it:

Engage a gear:


Lock the mainbox input pinion.

I used a tool made from an old clutch plate and a bit of angle, I made this for the series i box last winter and was delighted that I could find it again.


It uses the little access hole where the gear lever frame bolts to.



Undo the tab on the locking washer:


I use a sharpened flat blade screwdriver to do this.



I don't have the special tool to undo the castle nut, but I've found a chisel to be a good substitute. I use a large flat chisel, rather than the traditional cold chisel, as it leave no marks.

From the inspection side of the 'box line up the chisel with the nut, such that the flat of the chisel is against the side of the castleation, then whack the chisel with a heavy hammer.



The nut then just unscrews.


Remove the nut, lockwasher and gear.

Already the gearboxs are coming apart!


They just pull apart!

I found that they can bind unless the main box is supported, so one again the hammer was used:


That's all for now, tomorrow I've to go and find some kero for my parts washer but I'll try and get back to this as soon as possible.



Edited by Gazzar
Photobucket removal

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nice informative thread i also have my s3 box in bits awaiting some bearings and time.

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Right, I'll remember that, it's one of the things I am hoping to get out of this thread - what wear is acceptable on a gear/bearing/shaft.


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Next instalment - second attempt, the first one disappeared when I hit some key by accident.

I spent the morning successfully looking for some kero for the parts washer, Smiths of the Forest of Dean supplied 3 x 25 litre drums for a tenner, and i filled them up at Hobbs of Gloucester for 46 pounds. The Garage now stinks of kero - which is good as it adds encouragement for the wife to agree to me building a separate workshop.

Anyway, with all that traipsing about the countryside, all I did this afternoon was remove and strip the bell-housing.

Enough prattle, more pictures!



First of, remove the clutch fork and the clutch release bearing shaft.

Owners of those coil sprung landrovers should look carefully at the clutch fork, and note how it isn't made from an old sardine tin. That's a heavy cast lump of steel.


Remove the bolt holding the clip:


Remove the clip:


Fork, clip and bolt all removed.


Next remove the 4 nylocks at the top of the plate with a 13 mm socket:



And then the 3 bottom bolts with a 7/16 AF socket:


The plate just pulls away from the bell-housing.

To reveal the pinion bearing (upper) and the layshaft bearing (lower).


The plate is just a simple casting that holds an oil seal.


MUCH simpler than the series I and series II arrangement.

Next instalment covers removal of the bellhousing itself.

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Right, having saved that bit, onward with the photos.

There are 3 nut and bot sets holding the bellhousing on, and one nut and stud. Two of the nut and bot sets are "special" and must be kept in the correct place, or else the Euro will fail and the Government will put tax on diesel.

There is one nut and bolt on the right side:


And two on the left side:


And the nut and stud is located inside the bellhousing:


There is also the layshaft bearing retaining bolt that has to be removed.


I used a 7/16 WW socket to remove the nylocks and bolts:


And my input pinion holder tool to lock the layshaft to undo the layshaft bolt.



When all of these are removed the bell-housing just slides of the mainbox, usually bringing the layshaft constant gear and the conical distance piece with it.


Incidentally, the first gearbox I rebuilt, which was a previously factory reconditioned box, didn't have the distance piece - the constant gear made a right mess of the layshaft bearing holder! Monday morning in Lode lane?

Anyway - - this is the correct order for the constant gear and distance piece:

I put them all back in the right place, just to keep things neat (I'm a reformed un-neat person).


Next up - final disassembly of the bellhousing.



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The bellhousing also serves to hold the bearings for the input pinion and the layshaft. These are held to the bellhousing in carriers.

Input pinion bearing carrier:


and layshaft bearing carrier:


A few light taps from the plastic mallet soon moves the carrier away from the bell-housing:



Allowing you to see the splines that hold the stud in the carrier - a much better system than the series I approach, but why didn't they weld them?


With both carriers tapped back I then decided to remove the pinion from the bearing.

I unseated the circlip from the shaft;


and lifted it free with the distance piece. This distance piece was stuck to the bearing inner race with surface tension - it took a screwdriver between it and the inner race to shift it.


I was then able to wriggle the whole thing out, and apart.


Why didn't I wait and remove it after removing the carriers? Can't remember - just seemed the easiest way to do it? Perhaps I thought it would be easier to remove the circlip with the pinion held solid in the bellhousing.

Anyway, the manual says the bearing carriers are handed so I took the precaution of marking them "x" and "O" - and putting the corresponding mark on the bell-housing.



Aside from the orientation of the splined bolts I can't see any difference.

Finally, the layshaft (lower) bearing holder.

The holder has three studs welded to it, which protrude through the bellhousing to a collar, sandwiching the bearing into the bellhousing. There are three nuts on the three studs, held in place with a horseshoe shaped locking tab piece.


I unfolded the tabs, undid the nuts and removed the carrier;



and gently drifted out the bearing with a larger socket and a rubber mallet.


I completely forgot the collar, but it fell out as I tidied up the bellhousing, so I rescued it and put it with the rest of the carrier.

And that's it for today. I suspect I won't get back to this until Tuesday - lots of work on for this weekend.

I hope this makes sense to people - it's hard to remember to take photos of every stage, but I think that if I started skipping bits I'd soon forget to take any! I also think the more photos the better, easier to ignore than to regret the one picture that REALLY helps.


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Hi Gaz

Great to catch up with you here. Looking forward to this.

Do you have a suffix on this box? Maybe a late one as "D" are supposed to be strongest of all.

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Long time etc. Your box doing ok?

I haven't looked for the serial number yet - I was going to look for it after I had cleaned off the castings.

I suspect it is an early series III, though. Although in general it looks much stronger than the series I box - much larger shafts and bearings anyway.


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It won't progress for a bit now - I've a site to prepare for a container coming Monday!

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Long time etc. Your box doing ok?

Box all good. Thinking to pick up and build a late 3 type for any eventuality.

Hows life in England? Hope you are settling in and getting some work and play.

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Box all good. Thinking to pick up and build a late 3 type for any eventuality.

Hows life in England? Hope you are settling in and getting some work and play.

Surviving - what can't be cured, must be endured.

Anyway - next instalment coming up - Gear selectors, mainshaft and reverse gear removal.


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This box came with no gearlevers and some of the studs on the selector mechanism missing.

Note: Top covers are made with the gearbox - I'm fairly certain they aren't supposed to be interchangeable.

Nothing too scary here - just make sure that the ball bearings are recovered, for safety reasons if nothing else!

Top cover:


15mm socket to remove the nuts and also the spring washers


And the top cover:


The various springs and the like:


Little balls:


To remove the selectors requires a bit of work: It is possible to remove them with the selector shafts attached, but I chose to take the shafts off first, then the selector themselves, as it allows space to manoeuvre the selector out of the selector recesses.

Undo the pinch bolts that hold the selectors on the shafts:





and remove all three shafts:



Remove the centre (1st and 2nd) selector first:


Then reverse:


And finally, 3rd and 4th gears, I found that this took a fair bit of moving about to disengage - but it did come out - first one side, then the next.




Next: Mainshaft removal.

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The mainshaft!

Take out the 3rd/4th syncro:


Remove the layshaft - it just comes out:



And you are left with the mainshaft assembly:


and the reverse gear:


The oil catcher and the seal land come away in one piece:


Revealing the Seal, and the circlip:


A circlip pliers dislodges the circlip ready for removal:


The mainshaft is then just tapped forward. I propped the mainbox on the bellhousing in order for the mainshaft to have space to move into.


Rubber hammer time!


And the mainshaft after removing the mainbox.


In all its glory!


I got bored looking at the mucky casing so I spend 30 minutes cleaning it in the partswasher next.


Worth it, I think!

I then removed the lower seal retainer for the selector shafts:


And, I also noticed that they have modified the layshaft bearing holder in the casing, there are now 2 holes in the casting!


Previously the holder for the outer race of the bearing was blind. Good move.

Which brings me on to the topic of layshaft bearing removal.

It's in a (formerly) blind hole, how to remove?

One way would be to tap it out using the two holes, but it could "bind" in the casting, destroying it.

I prefer using . . . . . . . .


I used a propane torch, and played it on the casting, avoiding the holes, in order to heat and expand the casting sufficient for the race to come free.


Which it duly did!




Next section - reverse gear removal.

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Plenty more to come!

So, anyway - reverse gear removal.

The series 3 gearbox seems to have had a number of revisions over the years, so I'm trying to figure out the differences.

One of the characteristics to look for is the Reverse Gear arrangement.

The Suffix "A" boxes had a solid bush for the reverse gear bearing, and all later versions have a roller bearing.

This can be seen without taking the reverse gear out as the roller bearing variant also has a number of thrust washers on the shaft.

This is the later type:


So, my gearbox is a "B" variant or later. I still haven't found a serial number.

Removal of the shaft is similar to the layshaft bearing - use of propane.

Heat the end of the casing where the large end of the shaft is sited;


and also the web where the small end is sited:



I used a blunt punch to drift the shaft out - plastic hammer time - It came out really easily; no problem! The punch was mainly to stop my fingers getting burnt from the heat of the case.


The gear stayed behind:




Now that the casing is empty it's time to do a close-up inspection of the wear on the components.

The shaft has a pronounced lip on it - I suspect that this is the way it should be, but if anyone knows contrariwise please let me know.


Likewise the distance piece is bright and shiny, but looks to be fine:


The bronze thrust washer is, again, obviously used, but looks to be reusable:


The reverse gear itself is very shiny, but I'd say it is fine to go back in, it looks no different in shape from the picture of the new one on the Landrover Parts sellers website.


So, that only leaves the bearing to be replaced.

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The Bearing is part number FRC1812, and the whole Reverse Gear assembly is FRC1810. A genuine Gear assembly is about £40 inc vat, and a genuine roller bearing is about half that.

The non genuine parts are about 1/2 to 1/3 of the genuine parts.

Interestingly the Britpart prices are a bit higher then Bearmach for the assembly and a LOT dearer than Bearmach for the roller bearing.

Which to get? Is the Bluebox Company still producing rubbish? Or does anyone know if the bearing is available from a Bearing Stockist?

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Wouldn't touch any Britpart bearings, all of them I have seen/had experience of are shockingly bad.

Really enjoying/am impressed with the write up, didn't expect it to go this fast!

Tech archive for sure :)

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I think you'll find that the shaft is perfectly normal having that larger diameter on, but I'll admit its 2 years since I did mine. Get a new bearing and check it on the shaft, if it rattles, its worn.

You should be able to get all the bearings independantly, for less than BP or BM. I'll give you an exmaple, I looked up the main OD bearing a little while ago, £45+VAT...got the same thing for £6.50+P&P ;)

Unfortunatly, I lost the bit of paper that I wrote some of the bearing numbers on, is it marked?

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You are right, the shaft is correct, the roller doesn't go beyond the lip. Thanks for that.

The reverse needle cage doesn't have any markings (that I can see), but I'm putting together a little notebook of dimensions/prices and I'll visit my local Bearing suppliers and get part numbers.

I do wish these suppliers would specify the bearing manufacturer, it would allow me to buy in confidence.

For the reverse gear roller I have measured the shaft diameter, the gear inner diameter and the cage length.

The dimensions are

Shaft diameter (bearing inner diameter) 25.00mm

Gear inner (bearing outer diameter) 33.02mm

cage length 23.57mm

So, am I measuring this right?

The nearest I can find is

K25x33x24 which has the cage 0.43mm longer


Just for example.

I think this will fit, and the distance pieces between the circlips will "absorb" the extra 0.43mm.

So, that is a heck of a lot cheaper then the LR branded part, with no loss of quality.

I think I'm on the right track.

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Though, to be honest I've just had a good look at the reverse gear - and while it might be okay there is some pitting on the teeth, so I think it's best replace it. It's going behind a V8 so when in doubt.........chuck it out!

Landrover only supply the complete gear with bearings and circlips - part number FRC1810.

- so FRC1810 will be on the shopping list; about £43 including VAT.

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Right - question to those who abuse gearboxes - has the reverse gear shaft EVER broken on you? I'm wondering if I need to replace it. It looks ok - some longitudinal scratches but no ridges and no wear areas.

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Don't know about the RGS. Have had good branded bearings and quick service here. http://stores.ebay.co.uk/shop4autopartsnet

Guy usually gets back to you regarding P/N and what bearings he can get you. I bought NTK and Timken from him mostly. Reasonable money and he trounced my local BSL by a long way on price, like for like.

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