Overdrive or Transfer box change

[Lorrick]

Hello all

The next thing on the ever growing list of things to do on the 110 TD5 is to sort out a way of getting the engine revs down, as I travel around the UK and do a fair amount of M/Way and Dual Carriageway driving getting to the offending machinery. I have been looking around and see there are Overdrive units that cost half of what I paid for the old girl (Landy not Wife I think the Wife is fractionally cheaper to run but debateable which is the most fun ), and then people that have changed their TF/Box for a Disco one as the gearing is different and some have bought the gear set to go into the existing TF/ box. Has anyone out there in sensible land had any relatively cheap way or common sense way of gearing the box differently to help on motorway running?

Cheers

Richard (PS the wife won’t be reading this)

[chris200100]

I've got a range rover transfer box that I'm hoping to fit soon to my 110. I only paid £30-£40 quid for It so maybe a route to look at.

[Ridgeback]

I have fitted a disco transfer box to my last 90. Was about £80 and all work took about 3-4 hrs.

Well worth it .

My new 90 (td5) came with a gkn overdrive fitted and a second one in the boot. First one had lasted 20k second one lasted 12k . That's £2000 worth of paper weights I now have. It's always going to be better to rebuild your own box with the different gears because you know all the seals and bearings are good but you can get lucky and find a good used one.

[Lorrick]

Thanks for the input, I think I will go the Disco way.

Cheers

[Snagger]

If you do a lot of towing or drive around very hilly areas, then go for an overdrive. If you drive more typical roads and only rarely tow, then the gear swap is cheaper, quieter and more reliable. One thing overlooked in assessing the benefits of overdrives is that by their nature, they will sap some power from the engine - more gears, shafts and bearings to turn, more fiction to overcome and more oil to splash around ... the energy has to come from somewhere. So, while an overdrive's 28% gearing increase looks good on paper, its benefits aren't as big in reality as the 15% gearing difference between fitting 1.22 ratio transfer gears in place of the 1.4 you currently have. The final gearing in 5th with overdrive might be a bit too tall for use other than motorway cruising, too, while 5th with 1.22 gears will be more widely appropriate.

So, it really just depends on whether you need the flexibility of being able to select and deselect the gearing increase for towing and steep hills.

[Snagger]

If you do a lot of towing or drive around very hilly areas, then go for an overdrive (GKNs are now obsolete and were always unreliable, but the Roverdrive is simpler and more robust - still expensive, though). If you drive more typical roads and only rarely tow, then the gear swap is cheaper, quieter and more reliable. One thing overlooked in assessing the benefits of overdrives is that by their nature, they will sap some power from the engine - more gears, shafts and bearings to turn, more fiction to overcome and more oil to splash around ... the energy has to come from somewhere. So, while an overdrive's 28% gearing increase looks good on paper, its benefits aren't as big in reality as the 15% gearing difference between fitting 1.22 ratio transfer gears in place of the 1.4 you currently have. The final gearing in 5th with overdrive might be a bit too tall for use other than motorway cruising, too, while 5th with 1.22 gears will be more widely appropriate.

So, it really just depends on whether you need the flexibility of being able to select and deselect the gearing increase for towing and steep hills.

[Off Road Toad]

I have a Disco Transfer box on my Td5 D90, BUT i have 3.8 Crown wheel and pinions fitted in the Diffs and my 'road' tyres are 285/75 r16's. The reason for the 3.8's is the taller tyres would be a killer for towing with the disco box on. (disco's only have little tyres as standard) by my calculations if you have standard defender size tyres (235/85 r16 etc) a disco 1.2 T/box and 3.8 gears then your Defender will be geared exactly the same as a disco. without the 3.8's its a bit sluggish and difficult to get going when towing (even with a re-map and VNT ) If you've ever been in a disco with bigger tyres on standard gearing they are a bit erm - pedestrian

Steve

[Lorrick]

I have 235/85/16's as you say, and I do tow occasionally, I use the truck as a breakdown wagon, so I am on building sites, farms and all sorts of rough terrain compared to the road. But I do a fair bit of M/way and main road to get to places. So as you say it might be a better option for an overdrive. The only down side is the enormous cost of one compared to the return in fuel and overall savings.

[steve b]

I've had a Disco t/box in mine for 8 yrs and imo its fine . I'm running 235/85-16 tyres and with full tanks a hyd. winch and tank and the full cage it goes a little over2.5t . Running solo its perfectly usable and I tow fully loaded 3.5t trailers too . Once fully warm it will hold 5th with the trailer at 55mph fine and if I need lower gearing for pulling away on uphill junctions etc there is low range , with careful practice and some double declutching on the move changes to high range are quiet and quick enough

I took a fully loaded 3.5t Ifor to S.France a few years back for a mate - 700miles and had no issues

Land Rovers are not speedy anyway so for me its a good set up - that and a pto hyd pump on the t/box and the cost of OD's make the decision easy

Engine is a std 200Tdi

cheers

Steveb

[Lorrick]

Thanks Steve

I do pretty much the same and mine is around 2.5 ton. So I think I will definately go for the box, as the ODrive are to pricy. So now to find a good one

Cheers Richard

[RustyNissanPrairie]

Just fitted a 1.2 to mine and hate it, gearbox is a 56A (200tdi) but 1st is too high for towing-it requires more clutch slipping than my mechanical sympathy will allow, reverse is also way too quick, have just bought a recon 1.4 to replace it with.

[Lorrick]

What sort of gear box will I have on a 2002 TD5 Defender ? and what type of Box off a Disco will go straight on ?

Cheers

Richard

[RustyNissanPrairie]

You have a R380 - see link below for ratio's

http://www.expeditio.../gear_ratio.htm

any fransfer box off a Discovery Series1 or 2 will fit

[Lorrick]

Thanks Rusty

[vulcan bomber]

Just fitted a 1.2 to mine and hate it, gearbox is a 56A (200tdi) but 1st is too high for towing-it requires more clutch slipping than my mechanical sympathy will allow, reverse is also way too quick, have just bought a recon 1.4 to replace it with.

thats what i found with a 1.2 box, had it on for a week before bodging repairs to my 1.4 box and stickkng it back in.

[RTF]

I fitted a RM overdrive to my 2003 110 and well worth it just like haveing a 6 speed box

I leave mine in high most of the time as it can start of in 1st high overdrive no problem but when towing use low overdrive when starting of

So my vote is for the overdrive

[Simon B]

I deliberated long and hard about going from my V8 Tbox 1.14 to the disco one when I went from the V8 to an Isuzu2.8, in the end I left as is and did not regret it first time towig a heavy trailer I realised first would have been to high on the disco box. I'm planning to go the RM Overdrive route when funds allow. There seem to be 2 units on the market looking very similar; Rocky Mountain branded Roverdrive and Devon 4x4 "Roamerdrive" not sure what that is all about.

[western]

Devon 4x4 "Roamerdrive" not sure what that is all about

http://www.devon4x4....10107&Itemid=14

it's the rocky mountain unit, just found this

GLOBAL ROAMER CORPORATION (formerly Roverdrive Gear Corporation)

http://roamerdrive.com/

[TSD]

Just personal opinion, but with 33" tyres and a 1.2 box, I always felt that in traffic I was shuffling between gears much more than I did with a 1.4 box. Not that the 2.8 couldn't pull the gears at very low rpm, but it never felt very kind to the gearbox. Not bad enough that I changed the box again, the 1.2 stayed for several years and probably close to 100k.

When the 1.2 started to make very unpleasant noises, I took the opportunity to switch back to a 1.4.

[Simon B]

http://www.devon4x4....10107&Itemid=14

it's the rocky mountain unit, just found this

http://roamerdrive.com/

I see, explains name change.

[Lorrick]

Does a Disco Transfer box have a PTO Take off as I drive my winch off of mine, or would it be easier to go the 1.222 Gear Set from Ashcroft's.

And change the gears rather than the box?

[western]

Discovery LT230 same as any other Defender LT230 transfer box IIRC.

[RustyNissanPrairie]

The discovery transfer box has a different cover plate where the input gear is fitted, the Defender one has a small 'core' plug that can be removed, the disco one is a solid aluminium plate with no centre core plug. Either plate fits either box though.

A friend went the Ashcrofts gear route as his transfer box was a known item with low miles and no towing use. A local mechanic swopped them over.

The main problem is finding a transfer box with a cross drilled input gear so it dosnt end up buggering the splines on your gearbox output shaft, you can fit a cross drilled gear to an earlier box but you have to faff around with the clearances that are set by selectable shim washers ( I went this route with my 1.2 box).

[Lorrick]

Thanks Western

I will have a lookout for a Disco Box then, so thanks to all you out there that gave me exactly what I needed advice wise, and if anyone has a 1.2 transfer box or knows of one let me know.

Cheers

R