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V8 90 - Manual gearbox options


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Hi folks,

I'm building a V8 90 over the winter, using a serp 3.9 or larger rover unit. I want to have a manual box behind the V8, not auto.

What options do I have regarding gearboxes? Can the Lt77 90 box be converted to mate to the v8? Or is there other boxes I can use?

Thanks

Chris

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I've a ZF4HP22 behind my 3.9 and so i've effectively got the same usable power as a slightly tweaked tdi but with rubbish fuel economy:

:ph34r::ph34r::ph34r:

definitely go manual, why put a powerful engine up front and soak up all those horses with a porridge box.

lt85 was what they put behind the v8 originally, so makes sense to use that if ones easily available. Although an r380 is theoretically strong enough (copes behind tweaked td5's) and is a much nicer gearbox to live with.

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nicks90 shares my sentiments regarding slushboxes!

R380.

You can use a TDi one, with a 300 series Disco V8 bellhousing, and it more or less bolts up. You will need to modify the spigot bearing in the crank though, as the TDi input shaft has a larger diameter.

Alternatively you can fit a 300series Disco V8 input shaft and bellhousing to a TDi or even better a TD5 box (they're stronger), but this requires stripping and rebuilding the box.

Last option would be to simply use a 300series Disco V8 box complete, but the shifters will end up in the wrong place.

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LT85 is stronger than R380, but, the R380 is a nicer Gearbox, smoother gearchanges

and Generally quieter, as it has taper rollers for the main bearing, the LT85 does not

R380 runs on far more expensive oil as well MTF93 or something - its NOT cheap

where as the Santana LT85 runs on 20/50 Grade mineral oil :D and is cheap, worth

factoring in ?

The LT85 was designed for the V8 90, and I belive 110 V8s so is up there as a top contender

Lastly the LT85 was made in 2 stylees - "Split Case" and "Solid Case" - the Solid case is defo the one to go for,

HTH

Nige

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I've had an R380 behind my V8 in the 90" for three years now, the first two behind a 3.9 and for the last 10 months behind the new megasquirt 4.6 We properly abused it on the Transilvania trophy this year and it's not making any funny noises or anything yet :P It originally was a 300 tdi box which had the input shaft changed for the v8 one and a disco v8 bellhousing.

One day i might consider swapping to an auto box - If i wake up one morning and can't be bothered to use my left leg to operate a clutch that is :rofl:

Steve

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Last option would be to simply use a 300series Disco V8 box complete, but the shifters will end up in the wrong place.

There's also the option I did, which is to phone Mr Ashcroft and ask for a nice strong R380 (all the latest/greatest internals) with a V8 bellhousing/input and a Defender tailcasting/shifter. Then it miraculously just all fits nicely with everything in the right place, with a proper V8 clutch and no mods to fit anything. Yes it costs more money, but it cuts out a hell of a lot of pratting around both at build time and when servicing.

MTF94 is not overly expensive, and TBH I wouldn't class that as a deciding factor in gearbox selection.

My R380 has done many thousands of miles (very few of them "easy") in the years since the truck was built, behind the 4.6, and seems fine so far.

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There's also the option I did, which is to phone Mr Ashcroft and ask for a nice strong R380 (all the latest/greatest internals) with a V8 bellhousing/input and a Defender tailcasting/shifter. Then it miraculously just all fits nicely with everything in the right place, with a proper V8 clutch and no mods to fit anything. Yes it costs more money, but it cuts out a hell of a lot of pratting around both at build time and when servicing.

MTF94 is not overly expensive, and TBH I wouldn't class that as a deciding factor in gearbox selection.

My R380 has done many thousands of miles (very few of them "easy") in the years since the truck was built, behind the 4.6, and seems fine so far.

Well thats more or less option two out of my list. Whether you rebuild it yourself or get ashcroft to do it is just a case of money/time/skill/tools etc.

The end result is going to be the same, assuming you do it properly!

I'm glad there are plenty R380s being used in anger behind big V8's, gives me hope mine will actually stay in one piece. Might even have to tempt fate and run it up santa pod :P

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The Disco box has a different selector housing, with the gear stick coming out in the wrong place, so you really want a defender box.

You'll need a bellhousing from a 300 Series (1994-1998) Disco V8.

You can get away with using a standard Defender 300 TDi gearbox, by modifying the spigot bearing in the end of the crank, and thats probably the simplest option, although the spigot bearing ends up a bit thin.

Or as above, have the defender box rebuilt with the appropriate input shaft and bellhousing.

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The Disco box has a different selector housing, with the gear stick coming out in the wrong place, so you really want a defender box.

You'll need a bellhousing from a 300 Series (1994-1998) Disco V8.

You can get away with using a standard Defender 300 TDi gearbox, by modifying the spigot bearing in the end of the crank, and thats probably the simplest option, although the spigot bearing ends up a bit thin.

Or as above, have the defender box rebuilt with the appropriate input shaft and bellhousing.

So the input shaft length is the same in defender and disco r380 boxes?

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I've a ZF4HP22 behind my 3.9 and so i've effectively got the same usable power as a slightly tweaked tdi but with rubbish fuel economy

To some extent you're right (I have both, a 110 300tdi w/ manual trans and a 3.9V8 auto. The tdi is more fuel efficient but the V8 has much better performance). But what I like on auto boxes is that you can change gears without any interruption in traction. You can go up steep slopes and shift gears easy. You can go very slow on steep slopes or in mud w/o burning the clutch and so on. There are many advantages of manual boxes over auto ones.

Anyhow, the question was about manual boxes. I'd go for an R380. It is good to cover up to 450Nm so you shouldn't have any problem there. How to attach it to the V8 was already discussed...

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So the input shaft length is the same in defender and disco r380 boxes?

I've got a defender TDi box in the garage with a Disco 300series V8 bellhousing attached, and the input shaft protudes by the same distance as a real V8 box, so yes, as far as i can see the shafts are the same length.

The length of the spigot bearing area on the V8 box was longer, however the witness marks from the spigot bush show that it will comfortably fit onto a TDi shaft, and theres plenty of clutch spline too.

The only issue i can see from using a TDi box is the spigot bearing. The hole in the V8 crank is something like 24.5mm, and the TDi input shaft is 22mm, meaning you end up with a bush with a very thin wall. It should work fine though, as plenty of folk fit V8's to series boxes (which have the same 22mm shaft) and simply bore the spigot bearing out to the correct size.

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  • 8 years later...

Hi, All, recently returned to the Land rover Fold having had to sell my 95Discovery300Tdi,  am 80% of the way thru redoing my 1996 110 CSW 300Tdi,  the plan is to replace the engine with a 3.9 using Carbs, so am collecting parts over winter, the above topic was extremely useful answering anumber of questions i had regarding Gearboxes etc

I have one query,

i read up on the gearbox history LT77/85/R380 Santana solid/split cases etc vey interesting, i didnt realise the Rover SD1 used a 2WD version of the LT77 (or are they all classes as 2WD before the transfer box is added?? is the low gear selection part of the transfer box or inside the main gearbox meaning 2wd and 4wd 'boxes are different?

 

The question i hope someone can answer is regarding LT77/R380 bellhousing for the V8 there as appear to be a number of different shapes/part numbers.

Will the readily available Rover SD1 2wd? LT77 bellhousing fit on a Defender/Discovery 300tdi R380 box to allow a Rover 3.5/3.9 to bolt up?

Rimmer Bros list new bellhousings @ £354 :-Part no-  FRC133 they say this fits the LT77 /R380 /SD1/TR8/MG etc

i have seen a few others listed on ebay several using part number HRC1288  listed for use in/as  Land Rover V8/LT77 SD1 TR8 / MG conversion bellhousing.  but is a physically different external shape to the new ones and second FRC133 plus the starter and clutch arm appear to be in different positions in the bellhousing?

Is there a difference between early Defender V8 / TDI V8 Discovery bellhousing and the later TD5 / V8 ones/ are they interchangable/All use the same gearbox casing 6bolt pattern? 

Any info much appreciated thanks.

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The gearbox end of the bellhousing for LT77 and R380 are the same, so they all fit the boxes, however different engines have different patterns at the clutch end.

Tdi and Td5 are different, so no interchangeability with each other or the V8.

The V8 bellhousings for LT77 and R380 are the same except the LT77 one is an inch longer along with the input shaft. This means that they are not interchangeable as while you can physically fit an LT77 bellhousing between an R380 and a V8 the input shaft will not reach the back of the crank properly. 

2WD gearboxes for car applications are different as they have a differerent output shaft on the back.

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