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300vs200 drive ratios


discojmz

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just a quick one. I assume both 200 and 300tdi discoverys use the LT230 transfer box (i know theyre slightly different) and i was under the impression both were 1.2:1

is the r380's output speed for a given engine speed higher than that of the LT77 then? because i borrowed my dad's 300tdi today and engine revs for any given speed are massively lower than my 200tdi

or has some goon fitted a defender transfer gear in my transfer box when it was replaced because of wear about 17000miles ago

cheers

jim

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17k ago it had a rebuilt back axle, new gearbox and new transfer gear. by transfer gear, im led to believe it was just the input gear. I suppose what would be handy to know is what revs peoples engines are at, 200 and 300 alike, for say 60mph in 5th gear or whatever

jim

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Compare revs/speed in 4th as that is a direct gear in the main box as 5th might be slightly different in LT77 and R380. If in 4th the revs/speed are the same then the transfer ratios are the same.

Just a thought are both vehicles running the same size tyres and got the correct speedo gear for the tyres?

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both running 235/70R16, mine on goodyear wranglers, his on general grabbers

it's something to the tune of his at 60mph in 5th is maybe just under 2000rpm and mine is well up probably above 2500

will try 4th and see

as far as i know they have the right speedo gears, theyre both pretty accurate by sat nav

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Not sure on rest of gears but the 300 first gear is much higher than 200 first, as i used to chug away with a trailer quite happily in my old 200 then got a 300 and had to give the clutch some stick just to get going was a nightmare on a hill start with a trailer and a couple of passengers.

Lynall

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  • 2 weeks later...
right, in 4th im at about 2000rpm at 30mph. sorry it's a rubbish figure, its just the only one i can remember from when i was out in it earlier

jim

From memory, my 300tdi running 235 section muddies is only turning about 1500 rpm at 30mph in 4th. I can't hold 30 in 5th as the engine won't pull from that low (about 1200 rpm).

I'll have another look tomorrow.

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As the main boxes are different on 200 & 300 that is why i suggested using 4th as they are both 1:1.

Not really....

Disco LT230s are all 1.2:1

Defenders are all 1.4:1

except: 2.5p and 2.8i BMW Defenders which are 1.6:1 (the first cos it has no go, the second cos it revs high)

1.0:1 boxes were used on some Range Rovers, not sure which ones.

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Makes sense - both are very rare here, although I have driven an ex-SA Army 2.5p but didn't check what transfer box it had. And I've never seen a 2.5 NAD here at all! Quite a few 2.5TDs as the Army bought them (before they discovered their mistake).

The 2.8i 90 goes like a rocket! Though it is considered to be dangerously fast. There was a rumour that the insurance companies would blacklist them as so many were rolled. But it didn't happen, not so far anyway. And now they aren't made any more since Fraud took over.

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Not really....

Disco LT230s are all 1.2:1

Defenders are all 1.4:1

except: 2.5p and 2.8i BMW Defenders which are 1.6:1 (the first cos it has no go, the second cos it revs high)

1.0:1 boxes were used on some Range Rovers, not sure which ones.

Jim what are you smoking, the original question refered to 200 & 300tdi which have different main boxes so the only gear that has the same ratio in both is 4th(direct), so if the two vehicles that are being compared have the same tyre size and speedo drive gear, then by comparing revs/mph in 4th will show up a variation in transfer box ratio's.

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so im running about 500rpm higher at 30 in 4th than comical engineer

does this mean i have a 1.4 transfer box? i dont think i should lol

i have a lucarse alternator (not original) on the disco too. rev pulse from it shouldnt be wrong should it? it certainly seems to rev between the right bounds

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maybe i did! but at only 17k old mine sounds rough in neutral ticking over (a shaft bearing aparently) and after a long run down the motorway it goes incredibly hard to shift. not impressed. time to complain to the garage that had it done and give mr ashcroft a pm i think!

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  • 6 months later...

Ive still not resolved this so ive come back to add some more.

my transfer box is 28D304571E which I believe should be a 28E box. 28E is not listed on ashcroft's website but 28D is, and corresponds aparently to 1.22:1 which should be correct??

Now ive just taken it for another run and at 30 in 4th I see 17-1800rpm and at 40 I see near 2500rpm

I know the vehicle had a replacement lt77 in the past, but if for example a v8 one had been put in by accident I would have taller gears than usual not shorter wouldnt I?

It has had a replacement lucarse alternator at some point, If the pulley were too small on this then I would get incorrect pulse frequency wouldnt I?

I just once warm, nailed the throttle for as long as I dare, and watched the needle swing up past 4500rpm and would have probably kept going had I not let off. This seems very high but I dont know, My tickover is around the 800rpm point which seems right.

Any insight you can give would be much appreciated and would stop me going slowly insane. It's bugging me now, and Im all but guessing

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