200tdi Defender 90 - Can I fit a disco transfer box?

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herby1985

Member
Posts
12
Location
Smalley, Derbyshire
Hi There,

a couple of things I would like clearing up,

  • Can I simply fit a 200tdi disco transfer box to my 200tdi 90 as I believe the gearing is different and allows for a better drive?
  • Can I swap axles on from a 200tdi disco which will allow me to have discs al round?
  • Is there anything else I can do to the drive train to improve the drive/performance by swapping parts over from a disco?
Any halp much appreciated

:cool:
 
yes - better drive.. depends
yes, i believe so
improve?

you need to say what you want. offroad, pulling heavy loads, huge wheels... 1.2 lt230 isn't ideal

you mainly drive on the road and want to drop the revs, increase top end a bit for motorways.. 1.2 lt230 is fine
 
search and you will find
1.4:1defender
1.6:1mod spec
1.22:1disco

pre disco 2 td5 manual will have diff lock and speedo drive
 
Cracking, Thanks fanatic & trax

It was more for a better top end, dropping the engine revs and noise, don't do a deal of towing but will be doing a spot of greenlaning soon.

I was aware of the ratios and was under the impression that the 1.22 disco lt230 would be the one thta best suits my needs, has anyone ever fitted one and how bad are they to fit?

Cheers
 
I have a 1.22 transfer case fitted to my 90. It took a full three years for me to realise why my 90 was so slow to accelerate compared to similar vehicles and why it never ran out of puff :). I like it but I don't think it would be too happy if I were to change tyre size to 33".
 
herby1985 said:
Hi There,

a couple of things I would like clearing up,

  • Can I simply fit a 200tdi disco transfer box to my 200tdi 90 as I believe the gearing is different and allows for a better drive?
  • Can I swap axles on from a 200tdi disco which will allow me to have discs al round?
  • Is there anything else I can do to the drive train to improve the drive/performance by swapping parts over from a disco?
Any halp much appreciated

:cool:
Click to expand...

Seriously, why not buy a Disco? :whoosh:


Fitting the 1.2:1 transfer box will pretty much kill the performance of the Defender, unless you are running 205 tyres.

Remember a 7.50 or 235 standard tyre for a 90 is larger than the tyres fitted to a Disco. This means the mph/1000rpm in a Disco and 90 are pretty similar when on their standard tyres, so you get similar performance (slightly better in a 90 due to less weight and better aero with the Discovery).

Yes a 1.2:1 transfer box will allow you to cruise at higher speed. But in most cases it's a negative modification.
 
300bhp/ton said:
Seriously, why not buy a Disco? :whoosh:


Fitting the 1.2:1 transfer box will pretty much kill the performance of the Defender, unless you are running 205 tyres.

Remember a 7.50 or 235 standard tyre for a 90 is larger than the tyres fitted to a Disco. This means the mph/1000rpm in a Disco and 90 are pretty similar when on their standard tyres, so you get similar performance (slightly better in a 90 due to less weight and better aero with the Discovery).

Yes a 1.2:1 transfer box will allow you to cruise at higher speed. But in most cases it's a negative modification.
Click to expand...

Depends on what is powering it
 
I have had a disco t/box fitted to my 300tdi for 6 months now.

Haven't noticed any loss of acceleration, but it doesn't cruise as happily on the motorway now and even the slightest of hills needs me to change down to 4th, even when I'm doing 70mph. If you are on the flat or going downhill it is fine, and seems to rev lots less, but I am not sure it is worth the effort as 4th on a motorway is just wrong!
 
But in terms of fitting ease it is just a case of taking one t/box off and putting the other on. I got a refurbished one from syncro gearboxes when I did mine
 
james6546 said:
I have had a disco t/box fitted to my 300tdi for 6 months now.

Haven't noticed any loss of acceleration, but it doesn't cruise as happily on the motorway now and even the slightest of hills needs me to change down to 4th, even when I'm doing 70mph. If you are on the flat or going downhill it is fine, and seems to rev lots less, but I am not sure it is worth the effort as 4th on a motorway is just wrong!
Click to expand...

Yep it's now pretty much over geared for the power. Acceleration will have taken a dive too, even if you say you don't notice it. But getting up to speed will be worse.

If you don't like it, your choices are:


- go back to a 1.4:1 transfer box
- fit smaller tyres. Even some 31.10.50's would work better, but 205's much better.
- change your diffs to aftermarket ones with a shorter ratio
- tweak the injector pump if you haven't already done so.


For the record, I used to run a 200Tdi Disco, so the 1.2 transfer box with Simex 33" tyres (they measured about 34" tall). You couldn't use 5th until about 50mph, but with a tweaked 200Tdi it actually pulled them ok. Not the speediest, but acceptable. Long drags up hill (some of the dual carriage ways in Devon/Cornwall way) you'd have to slow up, not that it wouldn't pull the speed, but EGT's and engine temp would rise rapidly.
 
300bhp/ton said:
Yep it's now pretty much over geared for the power. Acceleration will have taken a dive too, even if you say you don't notice it. But getting up to speed will be worse.

If you don't like it, your choices are:


- go back to a 1.4:1 transfer box
- fit smaller tyres. Even some 31.10.50's would work better, but 205's much better.
- change your diffs to aftermarket ones with a shorter ratio
- tweak the injector pump if you haven't already done so.


For the record, I used to run a 200Tdi Disco, so the 1.2 transfer box with Simex 33" tyres (they measured about 34" tall). You couldn't use 5th until about 50mph, but with a tweaked 200Tdi it actually pulled them ok. Not the speediest, but acceptable. Long drags up hill (some of the dual carriage ways in Devon/Cornwall way) you'd have to slow up, not that it wouldn't pull the speed, but EGT's and engine temp would rise rapidly.
Click to expand...

It doesn't bother me enough to change it and keeps up with other tdis that I green lane with and will be better for my upcoming expedition. Though with the roof tent on and a head wind it does seem to struggle to go over 55!

I have fiddled with the injection pump which could be why I don't notice it so much.
 
if you want a disco transfer box ill swap you the one off mine for your defender one ;)

im on 33's in a csw and performance is.... wanting
 
If you just want to up the gearing a bit, why not just fit some larger diameter tyres, I went from 205/80/16 to 235/85/16 (which is the standard size for the current 90) this effectively increased my gearing by c10%. The benefits are a higher top speed, more relaxed cruising, slightly improved fuel consumption and a speedo that is now accurate.
 
james6546 said:
It doesn't bother me enough to change it and keeps up with other tdis that I green lane with and will be better for my upcoming expedition. Though with the roof tent on and a head wind it does seem to struggle to go over 55!

I have fiddled with the injection pump which could be why I don't notice it so much.
Click to expand...

55mph does seem a bit slow. A stock 2.5TD with all it's 89bhp will run at 65-70mph no probs, even on 7.50's/235's.
 
My 90 is a 300tdi edis (bit more power) with an auto box and disco transfer and 265/75 BFG MT s . The auto overcomes the acceleration deficit , and its relaxed at 60/65 on the m/way , the downside is that on 2 lane roads, in traffic you need to be doing 55mph to get TCL in, also not the best for towing as speed is needed again to get TCL so it takes some of the versatility away , but as a m/way commuter its pretty much spot on , so I would say that going to a 1.2 transfer , you need to be pretty specialised in what you want from the vehicle. JMHE
 
Thanks for that, I use it as my main drive for commuting to and from work which is mainly dual carriageway so could do with getting a bit better top end, it has had the pump turned up, I get it in 5th but it just seems to be screaming its nuts off, would it be better to install an R380 with it aswell?
 
herby1985 said:
Thanks for that, I use it as my main drive for commuting to and from work which is mainly dual carriageway so could do with getting a bit better top end, it has had the pump turned up, I get it in 5th but it just seems to be screaming its nuts off, would it be better to install an R380 with it aswell?
Click to expand...


If the gearbox is good then why replace it with an r380? I've just fitted a disco box to mine as part of the rebuild and from my experience I've seen plenty of discos on big tyres which go well so why should it be much different on a 90. We took two discos round Europe last year one on standard tyres the other on 235/85 tyres and over 4500 miles the one on bigger tyres fared the best even in the mountains.
 
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