Vehicle & Technical > Defender

High Range Gearing

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drum:
Fit bigger tyres  :D

nosnibod:

--- Quote from: "Bush Tucker Man" ---
So, I suppose the options are;
1. Replacement high-range gearing (Ian Ashcroft, or similar?)
2. GKN Overdrive (expensive, but flexible, but also read a couple of bad stories)
3. 'Rover-Drive' (Canadian?/American?, not very common over here?)


4. 'Go with the flow & just take it easy, well I usually do, it was extremely rare the Discovery went above 60mph
--- End quote ---


Hi,

I have a 2004 110 and found the same as you (lots of revs and noise above 60-ish).

I looked at an overdrive first - the GKN ones were reported by several people to be unreliable so that put me off them altogether. I did have a test drive of a 110 fitted with one, and it did make quite a considerable difference.

I then looked at raising the gearing (your 110 almost certainly has the 1.4:1 transfer box) and although this was a cheaper and more reliable solution it did raise another problem - the fact that the standard tune of Defender TD5 isn't really up to it.

This is especially important if you do any towing of course.

In the end I decided on the 1.2:1 transfer gearing coupled with a remapped ECU and larger intercooler.

The result is superb. It's no rocket-ship, but it simply drives so much better and feels so much more relaxed that it's almost a different vehicle.

Of course the other much cheaper alternative is to simply take it easy, and if I didn't use motorways much then I don't think I'd have bothered changing anything.

Bush Tucker Man:
Thanks for that insight Dave.
I'd have thought that a bog-stock Td5 would cope with the 1.2:1 box, or is the low gearing masking the standard situation?  

I've been out this morning, but only to Otley & it was a perfectly relaxing drive there (mainly A-roads)

nosnibod:

--- Quote from: "Bush Tucker Man" ---Thanks for that insight Dave.
I'd have thought that a bog-stock Td5 would cope with the 1.2:1 box, or is the low gearing masking the standard situation?  

I've been out this morning, but only to Otley & it was a perfectly relaxing drive there (mainly A-roads)
--- End quote ---


The Defender TD5 is (or was) slightly less tuned than the Discovery, and in my opinion I wouldn't want to try the 15% higher 1st gear like that. It will be fine unladen, but when towing...

What JE have done is take into account the higher gearing when remapping the ECU (they even take into account the type of exhaust fitted). The anti-stall still works beautifully - you can pull away on tickover even when towing as long as you're not too sudden with the clutch.

It seems that re-mapping the ECU across the entire range is the "correct" way to go about these things, rather than just squirting in more fuel at a certain point. JE prepare the TD5s for Bowler and apparently they are perfectly reliable tuned to 250BHP, so my 195BHP should be okay for a while yet. Apparently exhaust gas temperature is the thing to be careful of, and the correct "pattern" of fuel delivery into the cylinder is critical - just dumping fuel in leads to all sorts of problems.

I'm drifting off topic here though...

If the GKN or other overdrives prove to be reliable now then I might well go that route if I was in the same position as you.  The TD5 in the Defender is perfectly capable of handling everything you throw at it with the standard gearing, but raising the gearing, especially in 1st, is asking a bit more than I would feel comfortable with.

The downside of the "cope with everything" low gearing is of course the high revs and noise at motorway speeds. Adding an overdrive will sort that out  :)

Bush Tucker Man:
The subject is also under discussion on 'LandRovernet.com'


http://www.overdrives.co.uk/landr.htm

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