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paul connor

Land Rover TUM 110 ..speed

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I have been trying to work a few issues out.

i have a 200tdi defender engine and a Lt77 gearbox, the axles are the original military ones..

 

here is the problem, I can only go 50-60mph. Other owners of the same engine state they can get 80mph with out to much hassle,but mine starts sounding like shuttle re entry at anything over 50mph!

 

I have the transfer box ratio of 1:410 so its a standard defender one. I intend to upgrade to a 1:211 discovery one to upgrade the top end.. But it still seems odd that the top speed seeme limited. I have not tried to get the top end speed but with the noise i get at 50 I do not think its a good idea. I do not want to wreck my engine.

 

Does any one have any ideas where my missing 20mph is? or what could be a miss?

 

I do not want to overgear the engine by adding a new transfer box if there is a problem already I need to address

 

 

So is it

 

1. Salisbury Axle ratios effecting gearing?

2. Transfer box

3. Gear box

 

Does any one else have the same set up and can they advise?

 

PS im not a speed demon, I just get frustrated holding things up. Getting close to the speed limit would be nice

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Hello Paul,

 

I've got a Defender 110 TUM with the 2.5 NA engine, LT77 gearbox, and Salisbury rear axle. Mine will cruise at 60mph no problem and will get up to 80mph after 10 minutes but I never do that unless it's just for a few minutes to clear the engine out.

 

We had a Discovery in Cyprus with the UN that had a 200TDI and that would do 80mph all day no problem and still return over 30mpg.

 

We went up to Donnington and back in a WOLF 110 from Aldershot doing 90mph all the way there and back and it still had plenty left.

 

 

 

 

Has this always done this speed? Have you got a rev counter fitted to see what the RPM is? It sounds to me like the LT77 is too low geared for the 200TDI, having been designed for the 2.5 NA diesel. I've forgotten what transfer box these have but I think it's a LT230. I could be the diffs too. I reckon if you put the disco diffs in, then replace the gearbox with a R380 would that work? What about an Ashcroft box?

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There are two types of LT77

Lt77 was fitted to all 110/90s

Lt77 was fitted to the 200tdi, but only difference is slight higher top gear and syncromesh

 

so it should not make a difference.. I shall have to try being a bit heavier footed and get a friend to follow to make sure its not the speedo thats out!

If not i;ll get MTV to pimp my TUM

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. I shall have to try being a bit heavier footed and get a friend to follow to make sure its not the speedo thats out!

If not i;ll get MTV to pimp my TUM

 

surely if the speedo was out you'd not be holding the trafic back :) ,, a friend has just fitted a discovery rear axle and swaped the front diff , he does not to carry a lot of wieght but does quite a few miles and is better for cruising and MPG , not sure if he changed speedo ,

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ok....

 

Your problem is the transfer box. There is alot of bollox concerning what a Land rover will and will not do. So, here are the facts. Yor landy will do 60, or even 70, IF the NA engine was in good nick BUT.... it will be revving its nuts off and you will be shortening its life. Its a bit different when the vehicle belongs to the army, cause when its broke, you hand it back (I know I do.....).

 

Your 200 tdi is a reworked but essentially the same as the earlier engine, same top speed, just it has got bags more torque due to the turbo, direct injection system and new head design. This is why when fitted to the disco they are able to up the gear ratio in the transfer box, it means its still got the torque to pull it.

 

So to dispell myth here are a few ins and outs.....

 

Defender transfer box gives much better low down power, due to low gearing but will run out of puff at the top end (as you are finding).

 

Disco transfer box will enable much easier cruising as the rev range will be dropped, but will feel less spritley from the lights (not a major difference) and will not give the same pulling power (its not reccomended if you do alot of heavy towing as you will end up breaking it).

 

Axle ratios are the same in defender and disco....

 

Military defender gear box has a shorter 1st and 2nd gear, making it a much better proposition to use with a disco transfer box.

 

Other option.... fit an overdrive. This is best if you do lots of off roading (like serious stuff where absolute control is what you crave) or if you do tow really heavy stuff). They are however expensive and need maintaining.... parts can also somtimes be difficult to get hold of....

 

An R380 will not fit your defender unless..... you change the bellhousing, and output shaft for a short version (really expensive, as the stuff is now rocking horse poo), or unless you cutt of your mounts and weld on 300 tdi stuff (only worth doing iff you are going the whole hog and putting in a 300tdi engine, and box, but also not straight forward).

 

an LT77 for a 2.5 na is the same as an LT77 for a 200tdi.....

 

O, and what age is your defender, as if its pre 1991, you will need to mod the transfer box linkage slightly, not hard but worth remembering.

 

Remember, your engine being healthy and in fine fettle, is also important for you to get the top cruising speeds.....

 

Hope this helps..... I have been down all these routes, as I have been playing with, and modding landies for approx 11 years now, and learnt just a little along the way...... Any more questions, just ask.

 

O, and I have seen loads of wolf engines in workshops with melted pistons, where the drivers have been driving it with the right foot burried through the foot well " cause it was doing it easy", for your engine to last, dont be tempted to "see what it will do", treat it with a little respect, and dont go over 80 ish (not that you would on a UK public road anyway), or else you WILL melt a piston eventually....

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There are two types of LT77

Lt77 was fitted to all 110/90s

Lt77 was fitted to the 200tdi, but only difference is slight higher top gear and syncromesh

 

 

 

Bollox..... all LT77 boxes have syncromesh (or they do out of the factory). The one in a Disco has got a different top assembly and bellhousing. Thats all. The Defender 90 has a different transfer box to a 110. The LT77 in a mili vehicle has a lower 1st and 2nd.... thats about it for LT77 differences, the rest is in the transfer box.....

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Thanks for the replies, I have offered this up on another landrover forum but to be honest I trust the knowledge on here above.

I do offroad but not to the level where I would need anything uprated.So lets hope the new Trans box helps then! I shall keep the old one so if its worse ill switch it back!

 

thank you everyone:)

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whilst your at it, check your turbo. An average high pressure turbo will last approx 60,000 miles before needing a rebuild. A turbo diesel turbo runs at a much lower pressure so will last longer, but not forever. Also due to the low pressure the symptons of a failure are much reduced, but if it fails, the torque wil be down, meaning it will apppear slugish, and will ulitmately impact on top end.....

 

Check your turbo pipes to the intercooler, they all breath heavy so some oil will be evident, but if you can pour a bit of oil out any of the pipes or intercooler, chances are the turbo oil seals have gone. Also grab the impeller and see if you can move it up and down, in and out, if there is any great movement, then the bearings have gone.......

 

Secret of long turbo life, do regular oil changes......, let it idle for a min before booting up the road when first started, and let it idle for a min before switching it off.....

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Thanks for the replies, I have offered this up on another landrover forum but to be honest I trust the knowledge on here above.

 

Paul, my advice to you is to USE the Disco transfer box as the low ratio gearing is the same anyway but have a health-check done on the engine and also the boost put out by your turbo. Another thing to check is the size of the wellies you're running on - if you've got some monster rubbers in each corner (as a LOT of people seem to be doing to increase ground-clearence thesedays) then take a close look at that as bigger tyres will seriously affect your gearing further still.

I've got a 110 Wolf produced for a German Government contract . it's got a HUGE BMW engine and Disco transfer box but was actually pretty gutless on a long motorway hill or when towing anything decent. When I bought it it was running on 255/85R16's which aren't really monster truck size, but not far off the Pinkie's 9x16. After two years of driving on these I spoke to LR Special vehicles and they told me they were never supplied with those tyres. They suggested I go down to a 235/85R16....which I did a month ago. This has totally transformed the truck. It charges uphill towing a heavy trailer on the motorway well in excess of the speed limit and I really have to keep an eye on the speedo needle creeping up on the flat!! I'm in love with this vehicle again.

Paul, other cars might be able to go fast but you can go anywhere in yours, so the Defender isn't really a speed machine (although yours does seem to be a bit of a "lard-arse" by the sounds of it). I've rebuilt, improved and owned ONLY Land Rovers since I got my licence all those years back so my opinions are based on a lot of mistakes and the resulting education.

Get your turbo checked, and a health check on your engine. Use the Disco box definitely and check your wellies!

Let me know what you find out dude,

 

Mike

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