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6 speed TDi


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I drove my 110 on the road properly for the first time in ages yesterday, its only been used offroad (albeit quite a lot) for the past year so I've never got it out of third gear. My day to day motor is a Mini and I've got a bit used to having 6 gears and getting back in the 110 I kept trying to change from 4th to 6th which got me thinking....Can the newer Defender 6 speed gearbox be persuaded to sit happily behind a TDi engine? Is it something thats being considered by better people than me?

Will :)

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easier to fit a overdrive, then you still have the standard gear plus overdrive on 3rd,4th & 5th high range & you can use it as a splitter box.

to fit the latest box, it would probably need a custom flywheel housing to match the gearbox bell housing to the rear of a 200 or 300tdi block, which wouldn't be a cheap process.

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Transit gear ratios:

Transmission

Gear ratios

1 st ...5.44

2 nd ...2.84

3 rd ...1.72

4 th ...1.22

5 th ...1.00

6 th ...0.79

Reverse 4.94

Defender:

1st: 3.691:1

2nd: 2.132:1

3rd: 1.397:1

4th: 1.000:1

5th: 0.770:1

Reverse: 3.536:1

You'd want to drop the transfer ratio from 1.41 to take advantage of the 6th on the road, if not you'd end up with a free underdrive ... might suit someone!

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Often 6 speed boxes arent really there to give the car longer legs, but simply to make the intervening gears better spaced.

You can see that with the ratios above, the MT82 6th and R380 5th are the same, but the rest of the ratios are closer together on the 6 speed and theres a lower first.

With the landrover, the only real advantage is that fitting the 6speed box gives you a lower first gear, which means in turn you can fit a longer transfer box ratio to improve top end and cruising and still be able to pull off with a heavy load in first.

Unless you do any sort of towing, i'd probably look at just fitting a 1.2 ratio transfer box.

The MT82 box itself has an integrated bellhousing, unlike the R380, so to fit it to anything non-ford would require an adaptor plate, and that might not even be possible depending on how long the input shaft is, and whether it would still be able to reach the flywheel after you've squeezed the adaptor plate in.

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IMHO, a large number of the 6-speed boxes out there are not just to give better spaced ratios or in this case crawler firsts, but to make up for the fact that an awful lot of modern diesels have very very very narrow power bands (VWs 150BHP 1.9TDI for example) so to make any real progress you need to be swapping cogs all the time to keep it in the power band.

Bit of a band-aid solution if you ask me.

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I dont think they're powerbands are any narrower than a landrover TDi or any other turbo diesel tbh.

Some visual examples:

VW PD engine, in 130hp and 160hp tune:

GOLF_1.9pd%20130-165.jpg

Landrover 300Tdi:

300tdi_power_graph.gif

As you can see, the graph shape isnt all that different, infact if anything the VW engine is actually producing its power earlier and ramping up much quicker than the landrover engine, mainly due to it having a VGT.

Its more that because its a passenger car, its geared to do 130 or 140mph, whereas a landrover/transit or other commercial vehicle is geared to do 90mph.

If you spread the gears out in a 5 speed box by enough to manage 130mph, your gonna have to wind it round to the governor in every gear to ensure your still in the powerband when you select the next one.

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If you spread the gears out in a 5 speed box by enough to manage 130mph, your gonna have to wind it round to the governor in every gear to ensure your still in the powerband when you select the next one.

You kind of confirm what I was saying (or trying to say) with this TBH ;)

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Hi it is certainly an interesting conversion and as you would expect we have looked at it a couple of times, the front end is relatively simple, new flywheel housing etc, BUT the back end and ensuing length is a major problem, this makes too long to fit a 90. My opinion was 'a hell of a lot of work' for very little gain, all you get is a lower first gear??. No doubt someone will do it just for the hell of it. Regards Ian Ashcroft

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I wonder about the reliability/robustness of the 6 speed.

Defender sales are small in Aus, but the 2007 on models seem to experience an awful lot of drive train problems. Diffs and clutches mostly, but also transfer cases and the 6 speed gearbox, all at low km's.

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The box is used extensively in ford transits in the UK, and while i've heard of DMF/Clutch issues, i've not heard of anything with the transmission itself. I've also heard the MT82 is fitted to some mustangs?

Transfer case is the same LT230 thats always been used afaik?

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Hi it is certainly an interesting conversion and as you would expect we have looked at it a couple of times, the front end is relatively simple, new flywheel housing etc, BUT the back end and ensuing length is a major problem, this makes too long to fit a 90. My opinion was 'a hell of a lot of work' for very little gain, all you get is a lower first gear??. No doubt someone will do it just for the hell of it. Regards Ian Ashcroft

Pity there isn't a higher gearing to get the engine revs down when road driving,..£1000 for an overdrive isn't appealing

Looking at the LT77 and the R380 configurations and the way the reverse gear on the R380 is on the mainshaft instead of using an idler engagement like the LT77 I am surprised that someone hasn't come up with a 6 speed gearbox out of the 2 LT gearboxes...???

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