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Mods feel free to move this if you don't think it's the right section.

According to the original guidelines the LT95 (4 speed manual with integrated transfer box) is recommended to have engine oil (15W40). However I've seen references to GL5 (a newer oil) having better characteristics for a manual transmission.

While we're here does anyone know what the maximum torque spec on the box is? Just in case I want to change the engine in the 6x6 :ph34r:

And one final question, does anyone know if it suffers the same issues like the LT230 where the centre diff can spin oil out if you haven't locked it?

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Modern oils can corrode the bronze components of the gearbox - the correct engine oil works well and the shift is fine - stay with it.

I cannot help with the other questions - my LT95 just works fine.  I lock the CDL when offroad and unlock it on the hard stuff - not sure what you mean spin oil out.

Garry

 

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GL5 is a newer version of EP90 Gear oil, and as above it eats yellow metal over time, GL4 is not supposed to do that.

As the LT95 was designed for Multigrade (engine oil) with an internal oil pump I do not think this would be a good idea but stand to be corrected.

The only weaknesses I know off with this gearbox/transferbox is that it is very slow to change gear and that the tranferbox intermediate gear bearings are held in a plastice cage that will melt if the transfer box overheats (mine did this when the diff end play was too tight). This results in the removable bearing shaft welding to the gears and destroying the gearbox case. There was a metal replacement sold by the 101 spares company but as there are a limited number of 101s around and the use of the gearbox by comp safari racers stopped it was a very linited requirement and is nolonger available.

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In the 1950s and 60s, it was almost universal that engine oil was used in gearboxes and EP90 in rear axles.

These days, if you check out classic car recommendations, a GL4 spec oil will be the one, to whatever viscosity. Do not under any circumstances use a GL5 unless it is specifically for the application. I understand that a lot of modern gearboxes have steel baulk rings and no bronze type bushes or components at all.

I use a millers synthetic in all my manual boxes including the LT85, and a better shift is noticeable !

If you really want to splash out, then Redline MTL 

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7 hours ago, garrycol said:

not sure what you mean spin oil out

One of the known weaknesses of the LT230 is that (I stand to be corrected) if you get one axle spinning madly which results in the little gears inside the diff spinning wildly they can throw all their oil out which means that they dry up and welds the internals of the diff together. Which is why Land Rover recommended and most people lock the diff when traction has the potential to be lost.

Sounds like I'll just stick with shoving engine oil in there then. Why break it if it's not broken.

Still interested if anyone knows the maximum torque it's supposed to handle.

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LT95 was used on perenties behind the Isuzu 3.9 diesel which put out up to 330Nm. It's a pretty sturdy box.

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5 minutes ago, Eightpot said:

LT95 was used on perenties behind the Isuzu 3.9 diesel which put out up to 330Nm. It's a pretty sturdy box.

So an R380 would be stronger in this scenario.

Perhaps I should clarify - if I was going to replace the engine then the three contenders are:

  1. Cummins R2.8 - 310 lb-ft (420Nm)
  2. 3.6 TVD8 - 472 lb-ft (640Nm) :ph34r:
  3. Some silly big petrol engine...

Will see what happens with when I hopefully get it on the road next week and whether the LD28 is gutless / short legged with the current gearing. I don't particularly want to have to change the gearing on the 6x6. I think it's already on 3.54 diffs (but not 100% sure), don't have the option for taller tyres because of the twin rear axles and I think it may already be at the tallest RR gear set in the transfer box. Overdrive might be an option but I'd rather have a PTO on it.

I could live with lower top speed if there's enough guts to pull the 8t GTW so we'll see.

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I think the LT95 is ultimately 'stronger', but given the age and ease of getting fixed, plus 5 gears, I'd pick the R380, though maybe an auto is a better choice?

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We'll see how it handles. Part of me wants it to be a usable practical vehicle but then another bit of me wants to keep it more or less original. Conflicts of the first world!

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Keep it until it's not viable. Then change it.

Focus on your underground lair.

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1 hour ago, Gazzar said:

Focus on your underground lair.

You're fixated on that aren't you.

If I had an underground lair I wouldn't be telling everyone would I?!

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The R380 is considered marginal behind a Thor 4.6 V8, but the LT95 and 4.6 in my 101 handles its torque without any issues.

Unless you have deep pockets and know someone who can get a TDV8 to run in isolation away from a body ECU of a RRS then this engine would not really be an option.

 

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2 hours ago, Ed Poore said:
2 hours ago, Eightpot said:

LT95 was used on perenties behind the Isuzu 3.9 diesel which put out up to 330Nm. It's a pretty sturdy box.

So an R380 would be stronger in this scenario.

No, not at all, an R380 wouldn't last at all behind an Isuzu or any large 4 cylinder engine. The torque spikes and torsional vibration would have it destroyed fairly quickly. Many classic Range Rovers were fitted with Chevrolet V8's, Perkins 4 and 6 cylinder engines back in the day with no ill effects to the gearbox. You only have to take them apart to see the huge difference in the size of the components, The R380 is just an updated LT77, the name says it all, 77mm between main shaft and layshaft vs 95mm. Not only are the gears much larger, they're wider too and in a stiffer housing.
They have their weaknesses too as described above but none of that stoped me putting an LQ4 Chev V8 in front of one.

 

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1 hour ago, garrycol said:

know someone who can get a TDV8 to run in isolation away from a body ECU

Um, yours truly :blush: - hence why it's on the cards!

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Why would you change the engine?  You can get a lot more power out of the Isuzu engine than any of those options.

3 hours ago, Ed Poore said:

So an R380 would be stronger in this scenario.

Perhaps I should clarify - if I was going to replace the engine then the three contenders are:

  1. Cummins R2.8 - 310 lb-ft (420Nm)
  2. 3.6 TVD8 - 472 lb-ft (640Nm) :ph34r:
  3. Some silly big petrol engine...

The stock Isuzu 3.9 in the Perentie can do a lot more power than option 1.  You can easily get it up to 200 hp, 400 lb-ft.

2 and 3 will eat Land Rover gearbox and axles.  You would need a real gearbox and axle upgrades.

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It's got a Nissan 2.8 straight six at the moment.

Which is as decent unit, but it's pushing a huge vehicle.

 

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I think a nice rover V8, maybe a 4.6, would work very well.

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1 hour ago, Ed Poore said:

Um, yours truly :blush: - hence why it's on the cards!

If you have this ability, why are you on the internet asking random people what to do? Just go and build it.

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1 minute ago, Red90 said:

If you have this ability, why are you on the internet asking random people what to do? Just go and build it.

If you read the thread I wasn't asking people about what engine to put in it. I was interested in confirming oil levels etc and if anyone knew the maximum torque possible through the box since my delving so far hasn't returned anything apart from it being stronger than most.

But anyway I might as well explain again:

Due to the sightly complicated nature of the 6x6 drivetrain I don't particularly want to change anything downstream of the gearbox substantially, it's also original. But since the engine is no longer a 3.5V8 I reckon that's fair game :D.

I've yet to take it to a weighbridge but according to the brochure from Hotspur unladen weight comes in at at roughly 1640kg (sat outside at the moment so can't be bothered to go indoors). So although slightly unbelievable at the moment, it's not actually (in the scheme of more modern vehicles) that heavy. Shoving in a Isuzu lump or GMC V8 etc doesn't produce much more power or significantly more torque than say a well sorted 300Tdi for example (of which I have most bits lying around in the barns) but come in several hundred pounds more in weight. The standard tune from that Cummins R2.8 is a healthy bit more (and potential for significantly more) but crucially comes in at roughly the same weight as a 300Tdi. The TDV8 is a little heavier but not massively so, but produces a heck of a lot more. And there are plenty of discussions elsewhere that despite putting out more torque and power being V8s they are far smoother so stuff downstream doesn't see the shocks as much. Yes I could probably get silly figures from a 4BT / Isuzu but they're still a 4 pot. Had the R2.8 been a 6 cylinder or V8 I wouldn't have hesitated.

The main issue however is not power / torque but more likely rev range. For the reasons above and in the 6x6 thread I don't particularly want to change the drivetrain and I think (only way for sure is to pull apart bits to see) it's run night running 3.54 diffs and the RR transfer gears as it was originally a Stage 1. So to get a bit more pleasant cruising it means the engine needs to be happier at a higher rev range. I do have a lead on an overdrive but I think I'm going to go down the route of a PTO hydraulic pump so that'll eliminate that.

Anyway, the whole point of this thread was confirming oils. I'm going to run as is for a while since it's no work involved and see how it fares with the current setup. Who knows I might be surprised? 

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Posted (edited)
10 minutes ago, Ed Poore said:

.... and if anyone knew the maximum torque possible through the box .....

Okay.  How do you think that anyone on the internet is going to be able to provide a factually based answer to this question?  All you will get is a bunch of random opinion.  It is not the best way to make decisions. I'm pretty sure that the engineering team that designed the LT95 is not about to pop up here and give you real numbers.

Anywho...  Why are you not considering the Cummin 6BT?  There are hundreds of those conversions in the UK with off the shelf conversion parts.

Your biggest issue with keeping the LT95 is the bellhousing is quite far forward and this will make space a limiting factor.

As to the oil question.  It does not matter really.  But most people today would use a modern manual transmission fluid instead of the engine oils for the gearbox side. The friction modifiers in them make the synchros work a little better. Continue to use engine oil in the transfer case.

 

Edited by Red90

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1 minute ago, Red90 said:

Okay.  How do you think that anyone on the internet is going to be able to provide a factually based answer

Did I say it needed to be factual? The R380 has it in the name. I have not seen, even a clue or guess work as to what the maximum torque may be, hence a rumour may lead to something. All I've seen reference to is it's "one of the strongest" yeah compared to what?

I'd be happy with someone with real world experience saying its as strong as or stronger than say a standard R380. Then I've got at least something to base it off.

My real world experience is with an R380, a 4 speed Series 3, and a ZF6HP28X so not as many as some people on here. And I've not broken one of those. If Nige came along and said I've not managed to break one then that's good enough for me because I'm not a hooligan like him :P

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1 hour ago, Ed Poore said:

All I've seen reference to is it's "one of the strongest" yeah compared to what?

Compared to the other Land Rover manual boxes.  The LT77/R380 have a 77mm main to layshaft spacing.  The LT95 is 95mm. This allows you to use stronger gears and reduces bearing loads.

That all said, there is no way to have a fact based comparison on strength.  The only time that the 95 was in production alongside the smaller boxes with the same engines was the early V8s.  That time period is what caused the belief they were stronger and why early 90/110/130 did not use the LT77 with the V8.  But this was with 3.5 V8s and the early LT77 (which had design issues that have been since addressed). The LT95 also had design issues, which were addressed.

The only real way to get strength comparisons is to look at statistics on failures over a large number of boxes and look at the failure modes.  There is a lot of data on the R380 but anything on the LT95 will be hearsay that I would not rely on. They only came with two engines and neither were near the power levels you are talking about.

 

 

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3 hours ago, Red90 said:

Your biggest issue with keeping the LT95 is the bellhousing is quite far forward and this will make space a limiting factor.

Not true, the LT95 was first used in the 101 with both a straight 6 and a V8 for production. The 101 Bellhousing and Input shaft are 4 inches shorter than the RRC one.

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3 hours ago, Red90 said:

Why are you not considering the Cummin 6BT? 

Half tonne, admittedly more power, but as said above gearing. Dug out the spreadsheet - assuming ~0.9 RR ratios in the transfer box then 2750 RPM for 71mph, quick search shows 6BT governor is set to 3000 or 3200 RPM. TDV8 and R2.8 are 4000+

3 hours ago, Red90 said:

Your biggest issue with keeping the LT95 is the bellhousing is quite far forward and this will make space a limiting factor.

If you had a look at the 6x6 thread then there's a substantial gap between the front of the LD28 and the radiator pack (which has, I think, a V8 disco radiator - it's certainly damn chunky). There's loads of space down the sides even considering there's as turbo stuck in there.

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So I take it you have a 3.5 V8 with LT95 at the mo?   Assuming it's not a daily driver then my own thoughts would be go with a 3.9/4.6V8 just for quick low cost/simplicity and enjoy the extra poke.

The best combo I ever had in a LR was the Isuzu 2.8 4JBT1 intercooled with an LT95 in a Rangie - ultimately 'upgraded' to 300TDi and R380 but I mourn the loss, it's not as good.  loved the wall of torque from the Isuzu and the impregnable feel of the LT95, especially off the beaten track, off road and gunning it through sand and mud.   But I always think it's better to enjoy the car in whatever form than have it garaged and out of order while going through a lengthy re-engineering project that sometimes never happens.

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