cborrman · Nov 16, 2018

Any mathematicians / number crunchers / rubber fetishists know / can easily work out what tyre size equivalent would be needed to take a 110 tdi 300 with 265/75/16 tyres at present to the same ratio as doing the disco ratio upgrade that ashcroft offer... and that would fit without it looking like a tonka truck and handling like a greasy weasel?

The ashcroft site says: “This is a very popular gear set, especially for those with a TD5 90/110 or Tdi which revs excessively on the motorway. This gear set will enable you to raise your transfer case gearing by 15%, by replacing the gears in the exising 1.410 ratio transfer box with new 1.222 gears, as used in the Disco”.

Obviously no point if the wheels this size (tbd) need higher suspension which make the extra motoway cruising scary / silly

mick 1986 · Nov 17, 2018

cborrman said:
Any mathematicians / number crunchers / rubber fetishists know / can easily work out what tyre size equivalent would be needed to take a 110 tdi 300 with 265/75/16 tyres at present to the same ratio as doing the disco ratio upgrade that ashcroft offer... and that would fit without it looking like a tonka truck and handling like a greasy weasel?

The ashcroft site says: “This is a very popular gear set, especially for those with a TD5 90/110 or Tdi which revs excessively on the motorway. This gear set will enable you to raise your transfer case gearing by 15%, by replacing the gears in the exising 1.410 ratio transfer box with new 1.222 gears, as used in the Disco”.

Obviously no point if the wheels this size (tbd) need higher suspension which make the extra motoway cruising scary / silly

Assuming you want a 15% increase in circumference of your current tyre, then I couldn’t find a size that is compatible. The best I could get was a 9% increase. This was with 315/75/16 tyres.

Your current tyres are around 31.6” dia, the new ones would be 34.6”, so may need a lift.

bluedog333 · Nov 17, 2018

Have you thought about getting a Disco t-box from another source that may be a bit cheaper than Ashcroft’s offerings? 4/5 new tyres aren’t exactly cheap, plus you won’t affect the suspension or handing ‘qualities’.

Turboman · Nov 17, 2018

bluedog333 said:
Have you thought about getting a Disco t-box from another source that may be a bit cheaper than Ashcroft’s offerings? 4/5 new tyres aren’t exactly cheap, plus you won’t affect the suspension or handing ‘qualities’.

That isn't a bad idea, if cost is the major consideration.

But it is worth remembering that a Disco transfer box only raises overall gearings, an Ashcroft box raises high range ratios, but leaves low range unchanged, with all the off road benefits that that brings.

bluedog333 · Nov 17, 2018

Turboman said:
That isn't a bad idea, if cost is the major consideration.

But it is worth remembering that a Disco transfer box only raises overall gearings, an Ashcroft box raises high range ratios, but leaves low range unchanged, with all the off road benefits that that brings.

Didn’t know that about The Ashcroft box! He’d have the same dilemma with upsizing his tyres only then, wouldn’t he? I.e low range wouldn’t be that low with the increase in tyre size?

Turboman · Nov 17, 2018

bluedog333 said:
Didn’t know that about The Ashcroft box! He’d have the same dilemma with upsizing his tyres only then, wouldn’t he? I.e low range wouldn’t be that low with the increase in tyre size?

Ashcroft trans box increases high range only, I know, I have had several, and they are excellent.

Absolutely right about the tyres as well. But many people have already reduced gearings by fitting 205 0r 225 profile tyres instead of 7.50s on older models.

Rougharse Racing · Nov 18, 2018

The low range ratio is the SAME on all 1.6:1, 1.4:1 and 1.2:1 transfer boxes.
As others have said, fitting a Discovery Transfer box is the simplest and possibly the cheapest way of achieving Discovery ratios.

Turboman · Nov 18, 2018

Rougharse Racing said:
The low range ratio is the SAME on all 1.6:1, 1.4:1 and 1.2:1 transfer boxes.
As others have said, fitting a Discovery Transfer box is the simplest and possibly the cheapest way of achieving Discovery ratios.

Interesting. Didn't know that, apologies to @bluedog333 for that.

bluedog333 · Nov 18, 2018

Turboman said:
Interesting. Didn't know that, apologies to @bluedog333 for that.

At least the Ashcroft box will be nice and shiny with a warranty.

Britcyclerider · Nov 18, 2018

I bought a cheap disco 1.2 box and fitted the Ashcroft refurb kit and one piece diff centre. It's quite easy to rebuild and (almost) fun!

cborrman · Nov 19, 2018

Turboman said:
That isn't a bad idea, if cost is the major consideration.

But it is worth remembering that a Disco transfer box only raises overall gearings, an Ashcroft box raises high range ratios, but leaves low range unchanged, with all the off road benefits that that brings.

I am
looking at ashcroft and like it, but its the fitting I see costing more than the parts (ashcroft charge the same as four nice tyres and wheels just to fit) and was looking at new tyres / wheels anyway, but do recognise ashcroft is way to go (also makes it quieter apparently as well...)

cborrman · Nov 19, 2018

Britcyclerider said:
I bought a cheap disco 1.2 box and fitted the Ashcroft refurb kit and one piece diff centre. It's quite easy to rebuild and (almost) fun!

lol.. it looks quite involved, but I suppose you get to see any other issues while doing it!

jamesmartin · Nov 19, 2018

Turboman said:
That isn't a bad idea, if cost is the major consideration.

But it is worth remembering that a Disco transfer box only raises overall gearings, an Ashcroft box raises high range ratios, but leaves low range unchanged, with all the off road benefits that that brings.

thats the series ratio changed boxes not later

cborrman · Nov 19, 2018

mick 1986 said:
Assuming you want a 15% increase in circumference of your current tyre, then I couldn’t find a size that is compatible. The best I could get was a 9% increase. This was with 315/75/16 tyres.

Your current tyres are around 31.6” dia, the new ones would be 34.6”, so may need a lift.

thanks, was wondering if 18” wheels gave more options? possibly going more diameter without going fatter? even putting slimmer tyres to offset need for lift???

cborrman · Nov 19, 2018

bluedog333 said:
Have you thought about getting a Disco t-box from another source that may be a bit cheaper than Ashcroft’s offerings? 4/5 new tyres aren’t exactly cheap, plus you won’t affect the suspension or handing ‘qualities’.

“qualities” lol... I have, is it a lot less work than the ashcroft route?

jamesmartin · Nov 19, 2018

cborrman said:
I am
looking at ashcroft and like it, but its the fitting I see costing more than the parts (ashcroft charge the same as four nice tyres and wheels just to fit) and was looking at new tyres / wheels anyway, but do recognise ashcroft is way to go (also makes it quieter apparently as well...)

fitting a 1.2 ratio aint difficult, id fit a good used one and spend the hundreds saved on other stuff,fitting the one piece diff shaft wont make any difference

cborrman · Nov 19, 2018

jamesmartin said:
fitting a 1.2 ratio aint difficult, id fit a good used one and spend the hundreds saved on other stuff,fitting the one piece diff shaft wont make any difference

yes, if nobody has a genius tyre / wheel based solution that’s the way to go having read here. Thanks all for answers, will let you know!

jamesmartin · Nov 19, 2018

cborrman said:
yes, if nobody has a genius tyre / wheel based solution that’s the way to go having read here. Thanks all for answers, will let you know!

its either bloody tall tyres and issues that gives or a ratio change and if you still want big tyres fit 4.1 diffs

bluedog333 · Nov 19, 2018

cborrman said:
“qualities” lol... I have, is it a lot less work than the ashcroft route?

Same amount of work, the Ashcroft is only a reconditioned unit. Treat a good used one to a drop of fresh oil and away you go. There is the reassurance of a warranty with the Ashcroft box, but to be honest the t-box rarely goes wrong, so you should be ok with a 2nd hand one.

cborrman · Nov 19, 2018

bluedog333 said:
Same amount of work, the Ashcroft is only a reconditioned unit. Treat a good used one to a drop of fresh oil and away you go. There is the reassurance of a warranty with the Ashcroft box, but to be honest the t-box rarely goes wrong, so you should be ok with a 2nd hand one.

I do like the keeping low range with ashcoft though, suppose you could do that yourself with a used one...

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