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Discomikey's LT77 LT230 into 88" series thread


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Hi all, following a mild explosion of third gear on a somewhat sedate journet home from bowling the other night, i decided it was time to move to a 5 speed. I'm picking up an LT77 later on today, i have an LT230 from my old 200TDI discovery, so shall be using that.

My project spec is as follows:

MUST:

  • fit, function and drive smoothly
  • retain selectable 2WD
  • take as little chassis work as possible, however i am already going to cut off the gearbox crossmember and make it bolt on.
  • retain as many standard off the shelf parts as possible
  • be a serviceable conversion

Should:

  • retain as much series interior as possible
  • retain the yellow lever as difflock and the red as hi/lo lever
  • aim to keep the standard tunnel so as a WOR series mat kit will fit in the future

I am currently waiting on the gearbox, and therefore have not got much i can do, however i have thought of a possible (albeit slightly more expensive) solution to avoiding scalloping the engine crossmember for the front propshaft

a diagram should appear in the post below this as its on my phone at the moment.

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post-13725-0-00762900-1435148589_thumb.jpg

The spline count on the diff and Xfer box IIRC is the same, so i should be able to whack a 3 bolt flange on the front output shaft of the LT230 allowing for a rubber donut (to account for misalignment during engine movement as i am mounting to the chassis) should also reduce NVH. This will be attached to a discovery rear prop cut down and welded to an old diff pinion shaft, making a removable flange from one end, this means i can service the bearing which i will need to support the shaft. If it was solid mounted to the output flange of the LT230 i believe the output bearing would last about 5 minutes.

This support bearing (6) in the BOM will be mounted via an NVH isolating rubber of some sort to the engine crossmember, hopefully retaining the original flange location, and therefore a non modified front propshaft.

That is, if there is enough room to fit all of that.

I dont want to scallop the crossmember, and i am against just whacking an aluminium spacer in there as it will put way too much strain on the front bearing of the LT230.

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I'm not overly excited to scallop the front crossmember either, so I've been wondering if one of the RRC front driveshafts that were made from smaller tube or solid stock could be used instead? .....Just a thought ??

post-194-0-32994400-1435150361_thumb.jpg

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Instead of mounting the bearing to the cross member, how about making up a bracket to fit it to the side of the LT77? Shouldn't be too hard from say 6mm plate.

Then you are in the exact position as if you were running a series t-case, and can do away with the rubber doughnut, and the isolating rubber under the bearing.

*edit* and would probably be able to factor in the bracket making required for the Hi-Lo and 4WD selector.

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Looking at this photo, you could put a longer bolt in the top bellhousing -> gearbox hole and stick a nut on it, there's what looks like a threaded boss near the bottom, and another just behind the output flange.

http://s422.photobucket.com/user/shauniedawn/media/LT77%20Gearbox%20Overhaul/DSC_0899.jpg.html

Could be pretty easy to make is strong enough?

If I've picked out the drain plug as a possible mounting hole then I'm very sorry but I prefer slushboxes :)

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thanks for the input, this may well be the way to go, hopefully i will get everything mocked up tomorrow at some point and update on what i have to work with.

judging by your picture the linkage stuff should be fairly simple, i should just be able to take my time and get things right. i will find a way to mount the hi/lo lever off the bellhousing and keep it in the same place. the difflock one may need slightly more thought but should be reasonably straight forward using a cam and a cross shaft or something of the likes

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Going to be interesting to follow :i-m_so_happy:

I've never been a fan of bearings on props, its just another thing that likes to go bad at the most inconvenient of times. But clearly I see why it would be good here. I would say though, if you don't have a galv'ed chassis, what's the big pain in making a new crossmember/ moving the existing one? A longer front prop wouldn't be bad at all, allowing for less vibrations and better angles. Just a thought

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I had thought about doing similar when planning my conversion as I also wanted to keep the chassis as standard as possible, I have a Freelander 1 sat here and was looking at the centre bearing off that but time and money won out and I went the easy route but I also don't have a galv chassis http://forums.lr4x4.com/index.php?showtopic=94591

In order to keep the Series tunnel I think you'd need to move the engine and box forward slightly as the gear lever is a little further back - this would also help with the handbrake issue, saying that if you're putting the box in from beneath you should be able to get it in place with the standard drum on it anyway.

My box is sat about 1/2" from the gearbox crossmember and the top of the Defender tunnel cover is level with the top of the seatbox, you might have to raise the box from below with the tunnel in place and see how it sits, I believe it is doable.

The diff lock shifter rod clashed with the right hand edge of the seatbox tunnel flange and therefore would clash with the standard tunnel too but if you're doing away with that mechanism you should be alright.

I fitted the Ashcroft part-time kit too, it's very easy to fit and so far is working well although I haven't used the 4wd in anger yet. The kit also included an old style Spider gear not shown in the product listing which was an unexpected bonus especially as I found I needed it having a later model box.

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Update time:

fetched the box, there is a little wear on the output splines, but for the price i can't complain. pulled the series clutch out the way for test fitting and then cut my gearbox crossmember out (hopefully thats the only cutting ill need to do.

with the crossmember out and up on the ramp using a transmission jack it is a dream to pull the gearbox in and out. I find the box slightly touches the seatbox in one place when it is lifted to "operating" position. nothing a hammer won't fix though.

post-13725-0-09261300-1435186616_thumb.jpg

I've managed to come up with a pretty darn simple solution for the gearbox mount, meaning, if you were to leave the crossmember in place all you would need to do is drill 2 holes and fabricate a flat plate. Details below:

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so it turns out all my photo's are too large...

ill resize them in the morning, its late now.

On an interesting note, here is a gearing comparison old to new, at 80mph i will now be doing 100 more RPM, but i doubt that will actually be noticable, and im going to have a more trailer friendly first gear:

post-13725-0-01757900-1435187449_thumb.jpg

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crossmember out the way :(

post-13725-0-78672700-1435227321_thumb.jpg

Gearbox going in nicely:

post-13725-0-84052000-1435227334_thumb.jpg

It touches slighty on the passengers side tunnel flange for the seatbox, nothing a hammering won't sort:

post-13725-0-57596400-1435227342_thumb.jpg

Here's my rather simple way of mounting to the gearbox crossmember:

drill a 10.5mm hole 80mm from passengers side gearbox mount, in the center of the crossmember:

post-13725-0-41533300-1435227352_thumb.jpg

And a socket clearance hole (IIRC 22mm) 210mm from the end of the crossmember lower face, again in the center:

post-13725-0-49788300-1435227363_thumb.jpg

The original series gearbox rubber to crossmember bracket assembly can now be fitted, rubber side down in the hole that was drilled:

post-13725-0-71032400-1435227373_thumb.jpg

The hole from underneath (Sorry not square onto the hole)

post-13725-0-02717900-1435227383_thumb.jpg

post-13725-0-40041500-1435227710_thumb.jpg

And the template for the 6mm thk adaptor plate which bolts onto the gearbox where the original defender mount bolts:

post-13725-0-16777400-1435227718_thumb.jpg

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Gearbox and transfer box mounts and removable gearbox crossmember complete, the lot is back on the floor mated together to make a start on the linkages tomorrow. I have mounted the gearbox as low as possible in order to keep the flywheel housing from touching the bulkhead on torque, this meant i had to notch the gearbox crossmember slightly, but as it was removable it was a dream to do.

I fitted the discovery handbrake assembly and found, to my surprise, that i CAN in fact get the drum on and off with everything in place, you just have to tilt the top shoe with your hand as you slide it on. its really no trouble. maybe that is because i have mounted the transfer box lower though.

Measuring up for my rear propshaft at ride height comes in at 16.5 inches long. does anyone know of a propshaft specialist in the derbyshire area?

Looking at it all in, i am definately going to need a front intermediate propshaft, this is no bad thing however, as i can use this to keep my prop more clear of the engine breather return to sump.

pictures to follow later, off to the pub now!

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Why dont you move the engine crossmember further backwards and avoid the intermediate bearing? I am not a fan of those I must admit.

Daan

I don't really want to start moving the crossmember. already had to hack one out and weld in bolting tabs. i'm not a massive fan of them either, but being as it will be running rear wheel drive, and therefore no torque through the bearing 90% of the time, if i do it right, it shouldn't be an issue.

Following on from the other day, here are the photos:

CAD template turned real plate, gearbox mounted:

post-13725-0-41159200-1435362429_thumb.jpg

Fabricated the bolt on crossmember mounts:

post-13725-0-91416700-1435362437_thumb.jpg

post-13725-0-90597300-1435362444_thumb.jpg

And of course, someone got carried away with the welder and welded the brackets in with a bolt stuck in the wrong end.. Doh:

post-13725-0-04957600-1435362450_thumb.jpg

all welded up, not the prettyest, but i genuinely blame the welder, been having wire feed issues with it since i bought it, (its a known problem with them)

post-13725-0-59307900-1435362457_thumb.jpg

Transfer box went in then and started work on the second mount:

post-13725-0-18804400-1435362464_thumb.jpg

Had to scallop the crossmember for the front output area of the transfer box, to keep it low enough to where i'm satisfied i won't have vibrations through the body.

I just need to put a cap piece on the front side so things slide up it rather than hit against it. The mount sits no lower than the low face of the crossmember.

post-13725-0-11035500-1435362472_thumb.jpg

The lot mounted:

post-13725-0-44643700-1435362493_thumb.jpg

Back out it came in order to sort the range and difflock linkages. Keeping the series levers i thought it best to pull it out and precisely measure the position of the red lever pivot on a series bellhousing, i then made a bracket to attach the pivot to the LT77 in the same location. I tapped the 2 blind holes in the casing to M12 and used these for mounting. i fabricated up a plate which also later became the mount for the difflock pivot:

post-13725-0-47817400-1435362502_thumb.jpg

here's the plate:

post-13725-0-42659500-1435362511_thumb.jpg

more to come

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Here's a shot of the Hi/Lo linkage, trying to keep it out the way of the LT77 filler/level plug

The two clevis attachments i used came off the original hi/lo lever. i made them a press fit onto some round bar, at roughly the right length, and installed the gearbox and transfer box in the vehicle, along with the floor plates to check the lengths and throw were right:

post-13725-0-05118100-1435363170_thumb.jpg

Of course, having done 4 years at Uni doing engineering i decided to actually try and use maths to locate the new pivot on the lever

for some unknown reason, the maths and also scaled sketches worked, but when i fitted it, the throw was twice i needed and therefore wouldnt engage low range so i winged it and tacked in another eye, this one was perfect:

post-13725-0-58280500-1435363177_thumb.jpg

FYI the series Hi/lo lever normal throw is around 130mm at the top of the lever, this setup has a throw of 125mm

Back in to check it works again... god i love this transmission jack and ramp! I then measured out the tunnel for the main gear lever (the only modification to the series floorpan i have done as of yet) and cut a hole mirroring the standard one, roughly 6" further back. all in all this is the only hint so far that there is a 5 speed in there.

As you can see the redundant standard gear lever hole lends itself to becoming a cup holder area, so i need to do some light fabrication here to make one:

post-13725-0-89520800-1435363185_thumb.jpg

I spent this afternoon sorting the difflock (or 2/4wd) linkage which turned out surprisingly well. both linkages work like a dream, have no slack and don't rattle at all. I have some M10 nylon washers that i will use on the pivot on final reassembly.

post-13725-0-83190100-1435363197_thumb.jpg

another linkage shot:

post-13725-0-38718900-1435363207_thumb.jpg

here's the end result, it took long enough to get the linkages just right, basically the whole of today. but im rather pleased with it all, and it works like a dream.

post-13725-0-13976700-1435363217_thumb.jpg

I'm basically ready for final assembly now. i need to paint the brackets i have made, and treat the chassis and crossmember where i have notched and removed etc. i have a shopping list for a rear crank seal, couple of gaskets, and a clutch. (i also need to get the bolts to counterbore into the flywheel housing as these were drilled through the series bellhousing before)

almost ready for final reassembly this is all i have to do left (unless i have forgotten something)

  • Propshafts
  • handbrake linkage
  • painting brackets
  • final assembly
  • heat shrink to cover the gearlevers
  • Fit the 2WD kit to the LT230

Will be cracking on early in the AM

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Enjoyable thread, good work :)

I would strongly recommend a genuine rear crank seal, and whilst you're at it you should do the flywheel housing to block gasket

I'm already on it ;)

Thanks for the comments guys, onto final assembly now when i manage to get the remnants of the old gasket off the back of the engine block!!

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to be honest, i (At the moment) prefer the idea of a 4 speed and overdrive. but its the second time third gear has gone now, i always thought a good series box was plenty strong enough for a TDI. To be honest, usually they are, but when you are pushing 25PSI of boost and make it work hard towing for a living, you are kind of asking for trouble. lets just hope the LT77 will last better.

Update time,

I have been on a parts run, replaced the block-flywheel housing gasket, and the crank seal, fitted a new clutch, fitted the gearbox, painted all the brackets and fitted them, replaced the gaskets and seals on the transfer box, and fitted my 2WD kit, very easy to fit, thankyou FF for the how to from the tech archive, and ashcrofts for the kit! Transfer box is now in, both boxes filled with oil, handbrake fitted, although my new shoes were wrong, will change them monday. and i have sorted the handbrake linkage

Pictures tomorrow as my phone ran out of battery.

To do:

  • adjust handbrake linkage
  • sort propshafts
  • replace transfer box rear output cover plate (where an overdrive might go) its cracked and i suspect will leak
  • fit newly painted hi/lo/2/4wd linkages.
  • quickly fab up blanking plate for where the range lever was on the gearbox.
  • sort the rest of the truck for MOT

Hopefully i can get the rear prop i have cut down tomorrow to get me going then its gravy

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"

Hopefully i can get the rear prop i have cut down tomorrow to get me going then its gravy

Interesting to see that you went this route. Will you be cutting down both prop's? Any concerns for balancing them? Are they original S3 prop's or from another vehicle in the LR stable?

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