300tdi 110 overdrive/roamerdrive or disco transfer box.

Hi folks,
Currently driven a 300tdi defender 110, was looking a six gear for better motor way mileage and fuel economy. Was told that i could put a disco gear box into her and I was lookin at the overdive option. Just wondering has anyone had any experience with this? And if the could give advice. I do plan on towing stuff with her, caravans etc.

Conall said:

Hi folks,
Currently driven a 300tdi defender 110, was looking a six gear for better motor way mileage and fuel economy. Was told that i could put a disco gear box into her and I was lookin at the overdive option. Just wondering has anyone had any experience with this? And if the could give advice. I do plan on towing stuff with her, caravans etc.

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disco gear box is the same as the defender box, transfer box ratio changes with defender usually been 1.4 and disco 1.2, you can fit an over drive to defender 1.4 t box but you wouldnt a 1.2 disco box, you can fit a disco t/box to a defender but can be too tall geared for some uses, over drive has more versatility

Thanks James, one that I was lookin at: https://www.flatdoguk.com/defender-roamerdrive-overdrive-unit~2196

Mechanic mentioned they can be bit tough to put in?

Conall said:

Thanks James, one that I was lookin at: https://www.flatdoguk.com/defender-roamerdrive-overdrive-unit~2196

Mechanic mentioned they can be bit tough to put in?

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its fairly straight forward,and if you can afford it a perfect addition to a defender, ive even fitted them to disco 2s after changing t/box to 1.4 and cutting some of the floor to extent the transmission tunnel,for customers that wanted to tow heavy to market but cruise back empty

I tried the 1.2 transfer box on my 200 tdi 90 but I disliked it. Whilst it was good on the motorway it was horrible away from it as it moved 2nd and 3rd gear ratios into the wrong place for driving around town.
The overdrive that I fitted after changing back to a 1.4 box is a far better solution. Your ratios are back where they were but you have that 6th gear for the motorway.
IMHO the overdrive is the way to go albeit the more expensive route.
HTH
Mo

I have a Discovery transfer box on my ex-army 110 with 300tdi on 750x16 tyres. Gearing is about as tall as you would want to go, but it is fine without a trailer. There must be loads of 300tdi Discoverys around on 750's with the same gearing.
I tow a horsebox with mine and hill starts can require a good boot-full of revs to get going, but you can always fall back on low-box if things are really steep. I have never had any problems with hills whilst the Landy was moving.
By comparrison, when I had the 2.5N/A diesel in it and the 1.6:1 transfer-box I found myself in 1st gear low-box when towing a Discovery on a trailer, so the current setup is a huge improvement.
As my 110 started life with an asthmatic 2.5n/a diesel it came with a 1.6:1 transfer-box, so I had to change the transfer box as it was way under geared with the 300tdi and was revving its nuts off at 55mph, by comparison it will now cruse happily at a the motorway limit. I decided to use a 1.2:1 box rather than 1.4:1 as the 1.2:1 box came with the Discovery I broke for the engine.
The TDCi Defenders have he same transfer box ratio as the Discovery, but they use the Ford Transit gear-box that comes with a megga-low first gear.
If money was no object an overdrive is the most flexible option as it keeps a lower 1st gear with the advantage of a higher 5th, although when I had an overdrive on a 4speed Range Rover I always forgot to take it out when I changed down.
If you regularly tow a heavy trailer I suspect that you wouldn't get much use out of an overdrive and you would be better sticking with your 1.4:1 transfer box, in either case I don't think the higher gearing makes much if any difference to economy, although motorway cruising is far more relaxed.

Conall got a romer overdrive on my 110 I wouldn't go back now on one trip recouped one third of cost back in diesel and you can reinstall original parts back with minimum effort so still got originall defender but that extra gear for long hauls

Rimmer Brothers are supplying overdrives for £1620, you can buy one hell of a lot of diesel for that.

I’d love one in my TD5 110 but not at £2,000 including fitting.
I’ll just have to be content to sit at 65mph on the motorway, which seems to be the best speed with regards to noise levels/fuel consumption.

Mine will cruse at higher speeds, but I find that if you go much over 65mph you can hear the wind noise around the windscreen increase dramatically and I suspect that at over 65mph it starts to chew the fuel dramatically irrespective of the final drive gearing. If you need to go fast I suspect that a Defender isn't the most appropriate choice.

I drive a 300tdi discovery with 265/75/16 tyres and happily tow other discos on a tri axle brian james trailer. I'd go for the disco transfer box swap.

Yes you can I admit but you have got to look at the whole picture not just the numbers now I can drive across Europe not worrying if I can make it to the next fuel stop and in relevant comfort

Rougharse Racing said:

Rimmer Brothers are supplying overdrives for £1620, you can buy one hell of a lot of diesel for that.

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Stone56 said:

Conall got a romer overdrive on my 110 I wouldn't go back now on one trip recouped one third of cost back in diesel and you can reinstall original parts back with minimum effort so still got originall defender but that extra gear for long hauls

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Wow that must have been one big road trip to save £500 in diesel, even if you are getting 20% better economy that’s 15,000 miles of driving to save £500 in fuel

When I sold our caravan it was a no brainer to fit the disco box in my 90, it was sitting there in my store waiting and my tranny box was starting to get very noisy.
There was no way I would consider it when wanting to tug big loads about. As it is I really am happy with it, though I only tow a light trailer all-up weight no more than 1 1/2 ton, and at that only locally about once a month.

If you are towing very regularly I can see how the disco box would cause issues and would get through clutches faster, however I have the disco box fitted to m 110 and it quite happily tows a fully laden car trailer as long as you drive it accordingly. I would certainly go for that option, plenty around and much cheaper than an overdrive. Even if you do tow heavy and regularly just start off in low, you will soon learn how to double de-clutch and change ratios on the move.