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Defeat? Refitting LT77 disco gearbox


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warning: this post has everything, love, intrigue, horror, technical content, humor and humility.

The release bearing went from annoying hum/whine/whistle to screechy/metally/graunchy on Saturday (good timing, it was supposed to ferry me to Malvern today (Tuesday) ).

So I thought I'd better bite the bullet and change it. Armed with HBOL, RAVE (D2 only it seems) and several other manuals, plus Les' great tech articles I waded in.

All was going well, different than freeagents disco, his was an R380, minor differences on taking the console out, took some pictures, then to the underneath.

off with front exhaust section (flange captive bolts sheared, not a surprise), out with slave cylinder (push rod still has clip, good sign I thought), disconnect fan shroud.

Got the engine crane out, looked in truck, took a few ratchet straps out, then spotted my heavy heavy duty one, bit of overkill, but what the hell, lets use that as the main one and then one of the cheap ones as the rear one.

knock up a lifting point for the PTO cover, fits nicely cool.

Now to the actual gbox removal, well slip back, as all I plan on doing is just replacing the release bearing at first go as the gbox will probably be junk within the next 12 months judging by the clunks and mainshaft debris.

HMMM.... HBOL not too helpful, as piccies don't match and the description seems wrong.

The D1 LT77 has a central cross member with a single mounting. Hmmm, undo the two bolts and have the missus crank the crane, it lifts. hurrah.

Ok, undo all the bottom bolts, and work around undoing all the others, we get a bit of seperation, not enough. hmmm.

FFS, there is a nut up top that is unreachable with the x member in place, the gbox is not low enough, never will be low enough.

I needed the workout, I'm not thin, so it's fine, with my new hernia supporting the chassis, I get the x member out.

At last, the gbox drops enough to get access and she's free. Bits of pushing and pulling and old bearing comes off, looks scabby, sounds scabby, is scabby. New one goes on looks lovely, sounds lovely, is lovely.

So now I start to haul on the box to get it back in position.

"that was quite a loud noise, what was it and why is the handbrake drum crushing my knee?" I ask calmly through the transmission tunnel cover of my wife.

"the strap snapped on the back, are you alright?". This made perfect sense of why I had quite a big weight crushing my knee, which seemed to be getting heavier by the moment, everytime I shifted it got a bit heavier, so i thought I'd just stay still for a moment and let the wife get the axle stand or one of the jacks.

I must say that Gillian, my wife, looked a bit unnerved by this turn of events, and was somewhat flustered as she tried to help. BRRRRAAAAPPP, SCREEEEECH. Ahh good, my neighbours subaru has arrived I think. I can get a little assistance.

"All right mate, still at it, can't get you out from under that thing can we?" he hasn't actually looked underneath, so is unaware that if he had, this would have been a great line, as it was I got the line.

"no, you can't, at least not at the moment, couldn't get the jack for me could you, I'm being crushed by the gearbox at the mo."

His head appears with a grin, which rapidly disappears as he realises that far from my usual sarcasm, I am telling the truth for a change. A few moments later I extracated with just a few creases on my knee thankfully.

Boy was I glad I decided on overkill for the other strap otherwise I think it may been a bit more painful.

Anyway, we crack on and attach 2 of the (in my new opinion) pitifully too weak straps and set about trying to line the box up again. Just wouldn't go.

Decided to sleep on it (plus it was getting late).

New plan of attack, problem is because the box has rotated, so spend the first bit relining it up, a great tip if you take a box off is to put an alignment mark on the bellhousing and flywheel cover, in my case it would have made a real difference and saved a lot of guessing.

Also picked up some m10 rod, cut to size, slotted etc 4 off. fit the studs to the flywheel cover in lowest 4 holes.

We got the box onto the studs and tightened them a bit, box came a bit better together. Kept going, but it was only coming together at the bottom. short version (since not so exciting this bit) is that the box goes almost on, but the top half will not pop onto the studs, worse, it didn't want to come apart either.

Lots of tugging swearing and I managed to get it apart. This time I try a jack under the crank wheel to point the engine back, but the box has rotated again so just can't seem to align it.

Had to give up for a few days as I have to go to Malvern tomorrow, but I am really starting to wonder if I can get it to work, I am sure I am missing something.

So any advice on getting the box back in place, I was thinking:

1) align the box as much as possible.

2) fit a strap to allow someone to rotate a bit more as needed

3) jack front of engine to point downwards

4) put studs on engine

5) try and align and get in place again.

On the other hand if someone wants to earn some beer tokens in the fareham/gosport area I am more than happy to stump up, I really want the car working again for next Monday (31st) as I start my new job in Malvern and want it for commuting daily and back home to Gosport weekly.

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i think you pretty much have most covered, in my experience sometimes they jsut go in 2mins sometimes it takes ages, although when you get annoyed with it just walk away and come back 5mins later.

i use strap front and rear - ratchet type with the ratchet still exposed so you can adjust the front to rear height/tilt as your trying to get the box on. crane fwd of final postion so its sort of pulling the box towards the engine.

trolley jack on engine at rear so you can adjust height/angle as required then just lots of pushing/lining up and checking etc.


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ive done one on my own twice in one day (dont ask some fool - read me - put the spilt clutch arm back the first time) with just a trolley jack & the LR bottle jack in the road. yes ive been told im mad before.

first things first get the boxes both in gear & the center diff locked then get it as inline as possible. you'll find it probably goes 1/3" on the studs all round before it stops? means your inline but the splines on the input shaft havent gone in the clutch. apply some pressure forwards on the box, not to much though. i use a crowbar across the back of the tbox & one hand. with your other hand turn a drive flange on the tbox. as you turn the flange it should suddenly move a bit, thats the splines lining up. now it should slide in with a bit of pressure.

that stud at the top you cant reach, you need the socket into a spider into a long extentsion into a spider into a short extentsion into the rachet - fits nicley along one of the ridges in the box.

oh if you drop the back of the engine too much to try & make it easier you'll crush the wiring across the bulkhead.

i dont remove the gbox from the crossmember, its easier just to put the trolley jack under that. then when the crossmember is between the chassis rails it helps hold it all upright as im sure you know how unbalanaced it all is.

if i remember correctly i have the trolley jack under the crossmember & the bottle jack under the rear corner of the tbox to balance it up & align it.

hope something there helps, first time my box went straight back in. 2nd time took ages & when i changed the box cause it blew up i had to go away & have a cuppa before coming back. cant wait till i get the LT77 rebuilt & refit it should take about two days way things are going. currently got a R380 in there & i dont like it.

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If you allow the gerbox to rotate- it then catches on a reinforcing bracket that's spot welded to, and part of the transmission tunnel. If you jack the front of the engine up as far as you can go in order to improve gearbox alignment you can make it just as difficult.

Check that no cables or wires are trapped in the gap between bellhousing and housing.

With the gearbox supported with jacks at the rear - all the weight of it will be concentrated on the tip of the input shaft. You will momentarily have to take all that weight while turning one of the drive flanges with the box in gear and locked. At this point you must have equal gap all the way round the lip of the bell housing.

If you have the angle too steep, the transfer case can catch on the crossmember preventing it from moving forward. Alignment is everything - all the wiggling and twisting you seee/hear about is very dramatic and good exercise, but patience and care will see it in a lot quicker.

Have you had the clutch assembly off? Maybe out of alignment now if it's been removed.

Also a loose clutch plate centre (the splined bit) being loose can prevent a gearbox going back on.

Also make sure the operating fork is located properly - if the thrust bearing moves forward towards the clutch, the slave rod drops inside the lip of the bellhousing casting and then prevents the gearbox being refitted.

Pity you are so far away, I could have made time to have a look.

Les. :)

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thanks all,

Les - no, clutch was left in place, don't believe it will have moved, the splines had engaged, I could no longer move a drive flange (well no more than all the slack).

Good point about the rod, don't think that had got caught.

I think it was the studs at the top just missing the holes, I tightened the bottom ones and hoped that with a bit of jiggling and kicking that they might have popped in.

I also tried to remove the top stud at end of play yesterday, the one on the bottom I did a quick test on did move, the one at the top wouldn't - typical.

Seems the advice is that it can be a b****d and I should just give it another try when I get back.

At least I don't feel such a failure now - everyone always say "oh, yea, just drop the box off and ... " I think those of the words of someone who hasn't done it from my experience so far.

Worst bit is I need to do the defender in the next few months, at least there is more space on the 90 and I won't use such a pathetic strap.

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Sounds like its not going onto the splines. I had this when i did my clutch release lately. Put it in gear and engage diff lock. Jiggle the output flange backwards and forwards whilst applying forward pressure and it'll jiggle into place and line up.

Once Tonk suggested this when we did mine it just popped into place!



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Well, got the box in today, really dirty so still have the trim to put in tomorrow morning.

In the end I made an alignment tool, pictures and explanation follow.

Job on the Discover series 1 is pretty much the same as Les' post for Freeagents motor, but the earlier trim is a bit easier to remove

all the skirts up - you can see the 2 screw holes at the front that have to be removed


close up of those two


rear bit has 4 screws to remove


thought that was all, but a sneaky one is under the electric controls



the controls seem to be able to slide towards the handbrake for removal, no screws on this model AFAIK/can see

This is where it gets more painful.

The disco 1 has a central gearbox mount


As far as I can see you will have remove the cross member to allow the box to drop to get to that top nut on the bell housing. I jacked the box up with the crane after undoing the nylock centre of that picture, one at the rear too. This is a central bar doofer for holding the mount to the cross member.

I then undid the 5 (!) bolts on each side holding the cross member and moved it out.

After lowering I could get the top nut undone, I went through the tunnel from inside, it was V tight, and this was the only place I could get enough turn on it. If you have good quality UJs for your sockets then you might fare better, but most of my rotation space was gone after the slack was took up.

I then moved the box away and put a new release bearing in. I wasn't changing anything else as I think the box is a bit end of life and everything else appears fine. I may regret it in a few months, but who knows, I bought the car for £500 with the bearing whine and aim to run it till end of MoT and then see where it is going.

Had the rear strap not snapped it probably would have been an 'easy' job to realign the box and bolt back up, but because it did I had a real problem sorting out the rotation of the box, the transfer box as noted causing the bugger to rotate badly.

I came up with this:



It is just a bit shorter than the cross member which meant is sits easily between the chassis legs and did a VERY good job of aligning the box, it almost jumped on this morning (well that is probably a bit of an exaggeration!).

It cost about £15 to make, buying a decent box section from B&Q and some thick bar.

If I made another I would:

1) make the end pieces longer - they were only just the right length

2) make the bottom bits non existant - I realised as I was working that if another strap snapped I was looking at a real injury!

3) make it a bit stronger, it flexed, but that could be my pants welder(ing)

4) try and get some plates for the end rather that bit of bar as it would have helped alignment in two planes then.

I'd suggest making one of these if you have a D1 box to do, Looking at the 90 the side mounts on the LT77 on that look like they do a similar job if you have them on the box when putting it into position.

Thanks for the positive comments, really thought this one had me beat and was getting close to throwing my toys from the pram, along with lots of stress of new job monday, away from home etc etc I was close to a matchbox and rag solution :)

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Bad form replying back to my own post - but got all the trim back in today and the beast still fights me. :(

Battery dead.:(

Nasty jump leads means it takes ages to jump start.:(

Try to engage a gear and it won't go in.:(

Try reverse and it grates badly.:( :( :(

Looks like the slave has gone now :-# . FFS! I only took it out and put it to one side and for this it thanks me by not going the full distance so it won't fully disengage the clutch.

Can put it in 1st while transfer is in neutral, then drop transfer into low or high and it will creep forward. Standing in front it can be stopped, so the plate may just be touching..

So a quick trip to brooklyn4x4 in the morning for a slave and see if it will finally get back on the road, only about 2 hours before I really need it.

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pump the clutch loads of times nice & slowly. they self bleed & it could have just got air in it while sat in a strange position during all your fun with the box.

i always leave the box on the crossmember, that aligns the box quite well enough i find. plus its flat to put a trolley jack under.

plus if you lower the back of the engine/box for access to those studs too far you'll crush the wiring behind the head, i ended up rewiring the temp guage to cure a problem this caused. to get to the studs you need two extentsion bars & two UJs for them.

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should have said, carried out a full on bleeding of it, nothing doing. Pedal is firm but still not disengaging the clutch enough. Doesn't help that it seems the disco resevoir is tiny.

X member would be best solution, but I had to beat mine in and out with hammer and jack, hence why my aligner was a few mil shy of the width of the x member size.

Thought the wiring had been stoofed as you said, I have just been introduced to disco bulkhead wiring sockets - phew!



changed both the slave and master today, clutch was still dragging. Got peed off with it so dropped it into high box while in first and dragging and drove round the block giving it a bit of abuse. Got onto the decent length of road and gave the b*tch a good bit of clutch slip, I figures I might wear off the excess :) and it went to totally fine.

Quick discussion in work has me thinking that the plate had stuck onto the flywheel, and all it needed was a bit of abuse and it would have been fine.

Master cylinder on a disco is a PITA as well, stupid no access, wrong side resevoir, elongating of holes for feul filter, clevis pin with nut not clip arse.

However to top that off, my CC has been scammed so I had to cancel it and now can't go up because I can't pay any bills while I am away.... life sucks

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yeah i always have to move my crossmember with a hammer too, if your really daring (& not under it) mine will hold the box up with no bolts in while i move the jacks about.

yep slave is a pain, & the replacement isnt the same as the original so the cap rubs on the fuel filter. ive got a 'special' 13mm spanner with a 20-30degree bend in it for the top bolt. you forgot to mention that the bolt through the pedal arm adjusts the height of the pedal as you turn it - no i didnt notice for ages either.

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