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Another Series LT77/LT230 conversion


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We've had a couple of threads on the subject, but I thought I might as well start my own, rather than tag onto anyone else's.

Those of us who read Classic Land Rover magazine may recognise my other half's Series III, which was a feature vehicle in the December 2015 issue.


Part of the writeup on it mentions the gearbox that was assembled from a couple of others to make one good one about 6 years ago.
All things considered it's done well for the 20,000 miles or so it's covered in that time, but having started making a bloody awful noise whilst driving along -eventually deduced to be layshaft bearings- it needed something doing with it.

Rebuilding a series box was an option, but the cost of doing a proper job balanced against using the short bellhousing LT77 and 1.222 ratio LT230 I had 'in stock', along with the need to have the thing back on the road fairly quickly saw the decision to go for a 5 speed box.
The aim for the end result is to run permanent four wheel drive, and keep the separate levers for the transfer box as the Mrs like em.

So, decision made the required bits were pulled out of the way.


And with a little swearing etc, it all came out, and ended up looking like this, about this time it started getting dark, so I went into the garage to do some prep work on the box.


Discovery release arm, recycled, and reinforced with a bit of steel welded over the pivot piece.


Back to this afternoon (it was a bit wet for me to want to go out and play first thing) and started by scalloping out the bellhousing crossmember to allow the front prop some clearance.

It needs a bit more widening, and will be getting checked with a propshaft in place before I weld in a closing plate.


Hoofed the box in...


Followed by the transfer box so I could get on with making the mounting brackets.


The idea was to use the standard Series gearbox mounts on the chassis, and adapt the gearbox mounts to suit, whilst I also had a cunning plan for the levers.
A bit of Cardboard Aided Design saw some rough patterns...


Then a bit of 6mm steel (previously liberated from a skip, I mean who throws good steel like that away?) received some attention from a marker pen and the plasma cutter.
Yes I know the bolt holes to mount them to the gearbox are rough as, but first off, I currently only have a battery drill (which would make the job take forever) and dont have a 13mm bit to hand.
For these reasons I decided to blow them out with the Plasma instead.

A bit of welding and a couple of gussets added to the N/S mounting to give it a bit more strength.


After that I gave up for the day as it got dark.
Tomorrows jobs (weather permitting) will see me make some propshafts, finish the bellhousing crossmember, then put the box back in with the clutch in there.

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Very cool. Looks like you've just got room to get the handbrake drum off without resorting to extreme measures once it's all together. A mate of mind has a previously converted 88 with 77 and 230, but whoever put it together obviously didn't really feel that the handbrake shouldn't be a job that requires moving the entire drivetrain! Needless to say, MOT coming up, and the handbrake is totally fubar. I'll be following this with interest! What engine, by the way?

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Nice work, the more I see people removing the seatbox makes me realize how difficult I made it for myself when I didn't remove mine. The cut out in the crossmember, you say that your going to widen it. For reference mine is 10cm wide with the propshaft sitting nicely in the center.

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It's a 2.5 diesel, Wendy (the other half) bought it with 2.25 diesel, and fitted the 2.5 herself after the 2.25 died someone was kind enough to empty a bottle of coke into the fuel tank without her knowledge.

Anyways, today's progress...

To begin, everything came out again, and the hole in the bellhousing crossmember was made wider, out to 120 mm if you like statistics.


Which was then closed off with some 3 mm plate I had handy.

I know some of the welding looks awful, but working outside with the current windy weather meant it was a bit hit and miss.

It is however suitably burned in, and serves it's purpose.


Unfortunately I found that the handbrake assembly would have ended up too close to the middle crossmember to be able to get the drum off without dropping the box, so whilst the plasma cutter was handy I made another hole.


Formed up some steel to fill in the hole with the vice and some brute force.


Then welded it in. See above for notes on welding.


Daylight started to run out again, so I took the transfer box into the garage and started on the levers/linkages.

The plate on the side needs the back hole re drilling to suit when the drill.battery recharges as the cardboard template was off half a hole.


I also decided it would be fun to bolt the mounting plate on, as I'd spent a whole £1.81 on new bolts and washers for them.


The Hi/Lo linkage works fine, and will run nice and close to the main box, whilst the diff lock link needs a pivot and rod making up to move the actuator forward/back with the movement of the yellow lever, although I may wait until it's all in the car to make sure it all fits in as I want it.

If I can pin down my local land rover sage tomorrow then I should have a clutch plate to fit, and can actually put the boxes back in and bolt it all up.

If you're interested, propshafts will be 31" on the front and 16.5" on the rear.

I might manage to do it using the 2 standard props cut and welded, but worst case I can pick up another prop along with the clutch plate to use for the job.

I want to have it done before Christmas, but it hinges on parts.

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Very good reading - keep it coming please.

The Hybrid is about to go into the workshop to have the 2.5 N/A come out and a 200 Tdi to go in after the Seriesbox has been rebuild.

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Still held up by a lack of a clutch plate.

Stripped and cleaned/lubricated the handbrake assembly, finished welding the hi/Lo linkage, and made some propshafts the right length.

As an added bonus the 110 **** a hub bearing earlier, so for now I have two Land Rovers sitting that are going nowhere without parts.

Add that to the C3 that's also sitting waiting for a new turbo to turn up and I'm doing tremendously well.

There's threat of a clutch making an appearance on Monday, so we might see some progress then.

Merry Christmas indeed...

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Well, by good fortune I've gotten a clutch to suit the box, so the project has resumed.

I'd already made the new propshafts:


I'm sure we all know what a clutch looks like, so we'll skip to the box having been put back in.


Sat on the mountings.



And put the front prop on before I ran out of daylight.


Back at it tomorrow and should see it all finished and back on the road again.

About bloody time too.

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So,it's been back together and running for 3 days now, here's the last part of the story.

Rear propshaft on first thing, followed by making up a link rod between the handbrake pivot and the drum, then adjusting it up.

next job was to sort out the tunnel, which started off with a fairly small hole, which ended up with a somewhat larger one by the time it all fitted with clearance.


Seatbox went back in, followed by the handbrake lever which all adjusted up, and it now holds on a decent incline with 3 clicks on the lever. The LT230 transmission brake is a massive step up over the Series item.

The Series III speedo cable was cut down slightly (about half an inch off the end) and filed smaller to fit the drive gear in the transfer box, with a tab of steel made up to hold it in.


The linkage for the red lever needed extending a little more to have it sit where I wanted it (my fault for making it on the bench and guesstimating where it should be) whilst a pivot and link rod made from some angle in found under the bench sorted out the diff lock linkage.

All under the floor/tunnel, and nice and close to the side of the box, whilst the transfer box will all come off by dropping the props, one bolt from the handbrake rod, 6 bolts from the mount and the six holding it onto the gearbox.

Success. I think.


As we'd been without a car since Christmas eve and needed it to go for supplies and we're running out of daylight, trimming the tunnel wasn't seen as a particular priority.

A scrap of carpet found in the back of the garage was cut roughly to size, had some holes added, and went over the tunnel to keep the elements out.


The first run out was relatively successful, although was punctuated by some loss of drive which was cured by sticking the diff lock in, but then invited some less than encouraging noises from the transfer box.

Next morning the problem was cured by taking the one remaining freewheeling hub off of the front axle (the other had a damaged end and was chucked a while back as it was pissing oil everywhere) and replacing it with a solid flange.

A short test run saw me taking in a 200 yard run through some 2 foot deep flood water (the road out of our village has done it a few time in the past year or so) and the now solid drive setup in the front axle worked perfectly.

Another trip of 110 miles went down fine, and I'd worked it out after 30 miles or so.

It pulls along well at 65 - 70 mph in 5th, whilst seems quite happy at 60mph.

The permenant 4WD setup suits it fine, the steering doesn't feel much different to how it did before, asides some mild feedback when doing full lock turns at low speed.

Fuel economy seems unchanged, woth some rough sums seeing it returning high twenties for the run out, which is the same as it was giving with the old box.

As another added bonus the speedo now reads accurately, woth about 2 mph difference between the GPS and the clock on the dash.

All in all, great success!!!

Some engine mods to come in the next few months should hopefully make it a little more lively, and even better as a daily driver.

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Very Nice - well Done !!

The Hybrid's chassis is galvanized so a bit reluctant to start cutting etc. like what you did but could be tempted as you mention the front axle not really giving problems.... Parabolics, Koni's, Powersteering, 4 x Zeus disc brakes, 200 Tdi Series with a LT77.....


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Very Nice - well Done !!

The Hybrid's chassis is galvanized so a bit reluctant to start cutting etc. like what you did but could be tempted as you mention the front axle not really giving problems.... Parabolics, Koni's, Powersteering, 4 x Zeus disc brakes, 200 Tdi Series with a LT77.....


I have a 109 on a galvanised chassis that I'd prefer not to cut. Like you, I have a 200Tdi in it, but with standard transmission (+ overdrive). I fancy an LT77 or short R380, and have a Borg Warner RRC transfer box to go on it. Rather than cut the cross members about, I will move the engine a little forward on modified brackets to allow space for transmission brake servicing. It'd help keep the transmission tunnel closer to standard anyway, which would allow the continued use of the not inexpensive Wright Off Road matting. I prefer the handling of the BW unit to the LT230 in winter as the viscous unit keeps the 4wd from spinning up one wheel on ice but prevents wind up as you get off the icy patches without messing about with levers. It does mean slightly increased tyre wear. The biggest cost to me is that it is likely to require an IVA check and loss of the original VIN (I'm on historic status with no road tax). Still, it'll be years before I'm home to do it, and planning now is futile as the rules could change.

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Does anyone know how much the vertical and lateral distances from the gear box main shaft to transfer box output shaft vary between the Series and LT230 units? The engine and gearbox are mounted higher in Defenders, but I'm curious if the transfer box output shaft line is also higher.

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That's an interesting question. I mounted my LT230 high to avoid taking a chunk out of the crossmember for the front prop, but this required modifying the bulkhead and making a new tunnel. My crankshaft and gearbox mainshaft line is roughly 3" higher than standard series placement. My feeling is that the drop is about the same on the series and lt230 boxes, but interested in confirmation.

Well done with your conversion!

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  • 3 years later...

You may or may not be interested to know that Tubs used to be my every day driver, and I have missed the old girl ever since I sold her a million years ago. Here she is, waaaay back in around 2003. I added the pointless inclinometer and the Scooby Doo bobble head, a CD player and makeshift speaker system (PC speakers suspended from the cab roof) and a Bungie sticker on the bumper. Sold her on maybe around 2003-2004ish I think when something broke and she died in the middle of the road ( I think a diff broke). 

It's nice to see that she went on to have more life and even appeared in a magazine? Wow. Would love to have seen that.  I hope she is still going!



Edited by GuruFoxx
spelling & general sloppy typing
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