TD5 Defender ratio change

[Bauke]

hi i was wondering if anyone has a td5 defender with a disco transfer ratio in it, if so how did it perform as mine is reving very hard at 110kmh and i have 255/85/16 tyres which already gear in up, would the disco transfer be okay when a larger intercooller and chip have been installed, i do tow a bit but you can always change down a gear and use low range for very steep starts
any info would be apreciated

[justinc]

Hi BAuke, yes it is a good thing, BUT you still have to deal with the 2.5litre aspect, even chipped they are basically nowhere near an Isuzu for bottom end:(

Highway running it'll be excellent, but you may need to turf the 255's or you'd be in 4th on every hill. And you have HEAPS of hills out where you are:eek:

Give it a whirl, I reckon it'll be fine, but 1st gear starts when towing up hill, and reversing a trailer etc will need lowrange.

A bit like my 110 will be trying to reverse with a trailer on:(

I have a 90 to do soon, THEY really need the 1.222:1 change over IMO.

JC

[fatman]

Unfortunatly you'll have to use the clutch harder on 1st high and you'll have to use low range more offen.
How i know? I have a disco td5 manual and tuned with 235/85 16 tyres it revs 2180 at 100km/h,i put 255/85 16 on,revs drop to 2080 at 100km/h,at 3200rpm you travel with 150+ km/h! but the clutch takes a lot of "beating" on take offs from traffic lights,especialy on ascents,so i was considering using a transfer box from a def..
You can use this Ashcroft Transmissions - Ratio Calculator (http://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html) to experiment.
Only R/P change will suit your (and my)needs:( ,plus that low range will get lower :D
At this video http://www.youtube.com/watch?v=E9ZaRUCIJfc&feature=player_embedded#! i was in 2nd gear low,i had to slip the clutch real hard... i didn't want to use 1st low(my mistake)..

[grover7488]

do you really need to change Defa gearing when running 255/85/16?

It is only a 4% increase from the stock 235/85/16

I agree with Fatman that R+P is the best way but that would mean a 3.7 and i dont think that anyone makes them.

Fatman is talking Disco and 255/85 are a 15% increase so he would need 4.11

[Bauke]

thanks justin another question does a 1996 v8 disco transfer box fit straight in in regards to speedo sensor etc

[justinc]

thanks justin another question does a 1996 v8 disco transfer box fit straight in in regards to speedo sensor etc

Yes, but you'll need to fit the front output housing, as the low range switch needs to be connected to the system, to allow the engine ECU to know it is in low range, and adjusts the throttle response accordingly.

JC

[geckos]

Bouke,

Ive got what your after.
My car specs just for the record.
2005 Td5 defender. I have the big chip, larger intercooler, larger exhaust, and increase boost. I have fitted the Ashcroft gears 1.22
Ashcroft Transmissions - 1.222 Gear Set (http://www.ashcroft-transmissions.co.uk/index.php?act=viewProd&productId=44) . I did have 255/85R16. I have also fitted 4.11 crown wheel and pinions and now have got 315/75R16. My rpm is back up to 2500, or around that.

The change from 1.41 to 1.22 equals a decrease of 13.47%.

2500rpm - 13.47% = 2163.25rpm

The change from 235/85 to 255/85 equals an increase of 4.43%
(in saying that a friend has an isuzu county, he's now got 33x12.5R15 and this has correctted his speedo).

Going from 235/85 to 315/75 equals to an increase of 9.81%.

To do a 100km/h on the GPS im doing roughly 113km/h on the speedo and roughly 2500rpm like i said above. The clutch is on its way out, and i find it better to reverse in low range than high.

Im looking into 3.8:1 ratio's to bring the speedo closer to true and to bring the benefits of the 1.22:1 gear set to use.


regards geck.

PS the 4.11 crown wheel and pinions are great offroad, even lower than original.