Disco transfer box in Defender 90

[graham2306]

Hi
Seen some previous postings about this, I think I now have a Disco box and I want to know how difficult it is.  Only difference we can think of straight away is the diff lock mechanism.  Anyone done it and know anymore?

Cheers

graham

[extreme90]

not difficult, wen i put 1 into mine its a straight swap, no modding needed
just be care full fitting new box in as u dont nock the oil sealup, and on the mating face of the g/b, cover it in rtv sealent, ull see a little drainage channel cutout into the casing, if you nock the seal up itll p*** oil throught there, but if u silicone it before hand, it wont  
danny

[Miniman]

People have been telling me not to fit a disco transfer box to my 90 they say its over geared but I am not happy with the 90 box....70mph screaming it sod that I want to be going down the motorway at 70mph without all the engine noise. Whats yours like ?

[graham2306]

I can't see why a 90 with a Disco tf box in it would be overgeared, after all the diffs are the same ratio as the Disco and the 90 would weigh a whole lot less.   I've got a box laying on the garage floor now and I am really tempted as I am only getting 20.6 mpg with the 200Tdi in.  Suppose it would be more economical if I drove it like it still had the 2.5NA in it but the 200 Tdi engine doesn't sound right at 55mph in 5th :-) Sounds so much better at 70mph.

Graham

[Xtremeteam]

a 90 with a disco Tbox WILL be over geared if you run anything bigger than 205/16's or 235/70/16's

miniman,u run 750's it WILL be over geared unless u have the pump screwed open & then u run the risk of melting things as ur making it work that much harder

[graham2306]

Thanks for that Mike, I run 235/85s so I guess it will be overgeared in mine then.  Shame really as I now have a Disco tf box on the garage floor.  Don't really fancy smaller tyres, would just get stuck in the ruts.

So what other options do I have for getting better mpg as the 200 Tdi is giving me about 20mpg in the 90 at the moment.  Actually I suppose that may be wrong as my speedo/odo has never been checked/recalibrated for the 235/85s as far as I know, perhaps I'll find a way to check the speedo.  The 235s would make it read under, I think but the calculation of all those bits turning is beyond me.

I've seen people running Disco's on 750s, are they overgeared or do people change the tf box for a defender one?

Cheers

Graham

[paul_humphreys]

GKN overdrive :D

Paul

[graham2306]

Have you seen the price of those Paul.  And the only person I know who has one, Toby Savage, has problems with it after only a few round trips to the Sahara.

 :lol:  :lol:  :lol:

Graham

[smo]

Thanks for that Mike, I run 235/85s so I guess it will be overgeared in mine then.  Shame really as I now have a Disco tf box on the garage floor.  Don't really fancy smaller tyres, would just get stuck in the ruts.

So what other options do I have for getting better mpg as the 200 Tdi is giving me about 20mpg in the 90 at the moment.  Actually I suppose that may be wrong as my speedo/odo has never been checked/recalibrated for the 235/85s as far as I know, perhaps I'll find a way to check the speedo.  The 235s would make it read under, I think but the calculation of all those bits turning is beyond me.

I've seen people running Disco's on 750s, are they overgeared or do people change the tf box for a defender one?

Cheers

Graham

[Edited]? Overgeared on 235/85's??? No chance, in fact when i was running this on my 110, i had ashcroft re-gear it to 1.222Q gears (disco ratio) and if anything wiht the power upgrade i had done after it was still under geared, bags of power but still no top end (or not enough). !.2 is fine on just about any setup under 35" in my opinion and experience.

[Xtremeteam]

Thanks for that Mike, I run 235/85s so I guess it will be overgeared in mine then.  Shame really as I now have a Disco tf box on the garage floor.  Don't really fancy smaller tyres, would just get stuck in the ruts.

So what other options do I have for getting better mpg as the 200 Tdi is giving me about 20mpg in the 90 at the moment.  Actually I suppose that may be wrong as my speedo/odo has never been checked/recalibrated for the 235/85s as far as I know, perhaps I'll find a way to check the speedo.  The 235s would make it read under, I think but the calculation of all those bits turning is beyond me.

I've seen people running Disco's on 750s, are they overgeared or do people change the tf box for a defender one?

Cheers

Graham

[Edited]? Overgeared on 235/85's??? No chance, in fact when i was running this on my 110, i had ashcroft re-gear it to 1.222Q gears (disco ratio) and if anything wiht the power upgrade i had done after it was still under geared, bags of power but still no top end (or not enough). !.2 is fine on just about any setup under 35" in my opinion and experience.

Smo,what engine were you running ?

if its a TD5 then thats fine but graham has a TDi,i found with my tdi on 750's to be just fine almost to the point that an overdrive wouldve been better than the high ratio gears,
im planning on fitting a 1.2 Tbox to mine simply for the fact i run small tyres day to day & the big uns come out at the weekends,if its over geared on the 33's then ill have to live with that or tune it some more

[smo]

I admit Mike, its a TD5 - however doesnt every TDi owner out there claim their engine is every bit as good if not better than any TD5 ever made??? ;)

[Miniman]

Well I was told that I should not fit 90 diffs in my series with a 2.25D because it would be over geared and under powered but it was not. On the flat I got 85mph out of it but it was short lived as i was on the motorway and I could not keep it in one lane....lol....

Mike have you used a disco transfer box ?  Where you live are there loads of hills. How fast is max yours will go before its screwing the engine.
If I get on the motorway and i get upto speed with all the traffic at 70mph I am screaming the poor engine. I dont want that and even if it was over geared it would only be over geared in 5th , 4th would be fine that is the only gear I would have probs with if any. Maybe your truck is under powered mike...lol  

Anyhow its dont matter I am going to go for a change at some point because I will be damed if I am going to scream the engine to bits just to come to drumclog. Anyhow before the 90 I only had 4 gears...lmao.

Not sure what tyke has on his discovery but they are big tyres and he dont have any problems. I will get me new tyres on first and see if they make any difference they are 31" so will see......if I not impressed i will change the Tfer box.

[Xtremeteam]

wi the pump screwed open on 205s i was pulling 80/85 flat out & it was after another gear,fit my 33's n speedo is readin 65 ish & it doesnt want to go much faster unless i feel like burning shed loads o fuel

[Miniman]

wi the pump screwed open on 205s i was pulling 80/85 flat out & it was after another gear,fit my 33's n speedo is readin 65 ish & it doesnt want to go much faster unless i feel like burning shed loads o fuel

There ya go you just said it....

wi the pump screwed open on 205s i was pulling 80/85 flat out

So you was redlinemiking the balls off the engine. Mine is 4500rpm at 70mph Its a diesel for gods sake not a petrol, Oh and that is 70mph GPS time not landy time...lol

Now to drive a diesel 200tdi down the motorway like that is just asking for trouble and I dont want it. Trouble that is...he he....I just fit the dam thing...

[Miniman]

Hey my landy is in both avatars...lol

I want one like yours mike....OH I HAVE, Humm looks like drumclog to me...lmao....

[paul_humphreys]

Have you seen the price of those Paul.  And the only person I know who has one, Toby Savage, has problems with it after only a few round trips to the Sahara.

 :lol:  :lol:  :lol:

Graham

Lots, but you did not say cost matters :shock:  :D .

Paul

[Litch]

I've got a 300TDi 90 fitted with Disco transfer-box and 265/75x16's and the gearing is perfect. The engine is completly standard (just very low mileage being a genuine parts repower unit) and having lived with it for over 2-years I can't imagine having the standard Defender transfer box again.
I don't need to play the gears to hold a decent speed and when I drop it into top (usually at about 60-65MPH) it just keeps on pulling. Hill climbing or towing doesn't affect it at all and I still return 30MPG when driven normally but at the moment I am trying a bit of sedate driving and hope to return a regular 35MPG (speedo readings checked against a GPS).


Like I have said many times before, if anyone wants to try it before they do the job themselves they are welcome to PM me and we can sort something out.

[Budgie]

Well, I went the other way. I've put a 1.410:1 ratio T-box in the Disco because it was overgeared on the 1.22:1 standard box running 33" tyres and that wasn't just in 5th either!!
To maintain 30mph I was in 3rd, if I put it into 4th then it struggled, and at 40mph I was in 4th and couldn't go into 5th.

Whenever it saw a hill it started backing off and coming home from the Belgium National in 2004 I was on the M6 climbing a long hill with a head wind and at one point I was in 3rd with foot to the floor and still only doing 40!!  :shock:

After fitting the 1.410:1 T-box it was like driving a standard Disco on 205's, even the speedo was only reading 2mph slow. I could overtake, climb hills and cruise at 30mph in 5th again!!  \:D/

The 1.22:1 T-box was fine running 31" tyres but anything larger then I wouldn't bother with it.  

Oh, and that's all with a 300 TDI using a larger intercooler and tweeked injector pump!

(Still got the old 1.22:1 T-box in the garage if anyone's looking, £150 and it's yours! I'm also heading down to Glasgow on the 16th so can bring it with me and save postage! :mrgreen:)

[graham2306]

oh no, now I have differing opinions, who shall I belive????  mate suggested this evening that I put the tf box in and then I will know if it is overgeared and if I keep the old one I can swap it again.  Sounds like all the hard work I was trying to avoid is the only way to find out.

I am always amazed at how mch info people post on a thread on here.. Thanks guys.

Graham

[Litch]

Graham.

Whereabouts in Oxfordshire are you?
Like I said, I am willing to let anyone have a drive of my vehicle so they can decide for themselves. I am in Oxford today but that is probably too short notice for you, drop me a PM and we can sort something out as I visit family there every week.

Alan

[Miniman]

It sounds to me that we all have some very different engine power figures. I think its like graham2306 says I am with you fit it and see what I think. Better get me tyres first tho....lol

[tiltboy]

I have a 200tdi with 149,000 miles on the clock, running 235/85 BFG muds and in my opinion it's horribly overgeared!

As Smo stated, in a TD5 with upgrades a disco T box is great. I run a TD5 with work occasionally which pushes out well over 200bhp and has both a disco box and a GKN overdrive! But with that power output it's great. I've seen WELL over 100mph (Bruntingthorpe Airfield before you all start shouting!) and acceleration is still fantastic. However it eats 5th gears. Hey ho.

In a 200 tdi that's anything like miley, then I prefer a Defender T box. Tdi Defenders aren't meant to be motorway cruisers. When you start playing with boost/fuel pumps surely you're openning Pandoras box? I have a friend with a 300tdi 90 on Simex's with monstrous boost and tweaked pump. He trawls Ebay for replacement turbos at the rate of one every two months (along with diffs, u.j.'s etc).

In short my 90 wont pull 5th at all well. With my GPS setup I think that 60 on main roads would be my max. But it's around town where the main difference can be felt, rowing up and down the box all the while because at town speeds third is out of the question most of the time. I have on occasions used low. Think you have as well Litch?

If you go and drive Litch's truck then you can come and have a go in mine for comparison.

Anybody fancy swapping a standard defender tbox in good condition for my very good disco one?

Best of luck.

[Budgie]

It all depends on what ratio T-box you have in now.

I know TD5's have the 1.410:1 but earlier ones were fitted with a 1.668:1 T-box and sometimes going from a 1.6:1 down to a 1.222:1 will give you a 36.4% raise in the gearing (according to Ashcroft's site) and this maybe far too much, causing the gearing to go the other way.

So, before you start thinking about swapping t-boxes then it would be good to find out what you've got in there now so you can work out how much of a change you're looking for.  

To assist there is a final gear ratio calculator on this site but it doesn't include the tyre sizes in the calcualations.  :(

[Xtremeteam]

It all depends on what ratio T-box you have in now.

I know TD5's have the 1.410:1 but earlier ones were fitted with a 1.668:1 T-box and sometimes going from a 1.6:1 down to a 1.222:1 will give you a 36.4% raise in the gearing (according to Ashcroft's site) and this maybe far too much, causing the gearing to go the other way.

So, before you start thinking about swapping t-boxes then it would be good to find out what you've got in there now so you can work out how much of a change you're looking for.  

To assist there is a final gear ratio calculator on this site but it doesn't include the tyre sizes in the calcualations.  :(

AFAIK only the N/As had 1.6,everything else had 1.4 & all TDI discos & rangies had 1.2's,


Now before anyone starts,this is a quick run down,yes the V8s had 1.1..... T boxes & some motors that came out the factory on 205's might have been standard with a 1.6 but the above is a generalisation

[Budgie]

I think you're right Mikee, a full list of the T-box serial numbers and corresponding ratios can be found HERE.  

[Miniman]

So in theory I need to get a 1.410:1 to replace my 1.667:1 then its just a 18% rise..... Not to steep a change...

[JD LWB]

My 110 has had the Disco gears fitted in the T/fer box.  It's great.  It'll pull up to 85 on the motorway (GPS speed not speedo).

I'm running a 200tdi (not tweaked yet) and 235 85 R16 BFG Trac Edges.

I'm planning on having the Allisport full width intercooler fitted next year and the turbo and pump tweaked.  After that, I would need the higher gearing seeingas it pulls well already. :D

[JD LWB]

I've just looked at Ashcroft's website and I see that you have the NA transfer box (1.6) so the disco one would be a big jump (1.2).

But if everything else is the same, the disco box should give you the same results as mine (you've fitted a tdi lump to a NA and mine was a TD, now a 200tdi). :D

[Miniman]

Yer I did mate 200tdi pump tweaked and I got sags which measure in at 31" tread top to road