neels Posted August 30, 2007 Share Posted August 30, 2007 I REPLACE MY 245/70/16 TYRES WITH 265/75/15 STT COOPER TYRES. THE RESULT - AWSOME OFF-ROAD, BUT I LOST A GREAT DEAL OF POWER. WHEN TRAVELLING AT 120KM ON OPEN ROAD AND ACCELERATE- (REVS 3000) THE REVS GOES UP TO 4000 RPM. BUT VEHICLE STAYS AT 120KM. WILL IT HELP TO CHANGE TRANSFER BOX TO DEFENDER TRANSFER BOX AND WILL IT FIT MY DISCO ? NEELS Quote Link to comment Share on other sites More sharing options...
BogMonster Posted August 31, 2007 Share Posted August 31, 2007 Welcome, NO NEED TO SHOUT Is it an auto? Can't see how the revs would increase on a manual... I think the Defender t/box would leave you with gearing below standard, but that may be what you want. You can work out roughly what you need by using the tyre diameters, standard 205R16 are about 29" and your new tyres are 32" so your ideal ratio would be 32/29 x 1.22 which is 1.346, closer to 1.41 Defender ratio than 1.22 Discovery ratio. HTH Quote Link to comment Share on other sites More sharing options...
jules Posted August 31, 2007 Share Posted August 31, 2007 I fitted 275/75/r16 BFG AT's on my Auto D2 and had to change back as it lost so much power. I now run 255/70/r16 and drives and tows as normal check if the High/low diff lock stick will need adapting for manual Difflock with a defender transfer box in a disco 2 Quote Link to comment Share on other sites More sharing options...
RRX Posted August 31, 2007 Share Posted August 31, 2007 Running 265/75/16's on mine and have lost some power campared to normal. Solved by adjusting the pump up and fitting an extra intercooler, as for the revs it sounds like you clutch is worn out escpecially if you doing it in 5th and the revs rise but the speed stays the same Quote Link to comment Share on other sites More sharing options...
jules Posted August 31, 2007 Share Posted August 31, 2007 Running 265/75/16's on mine and have lost some power campared to normal. Solved by adjusting the pump up and fitting an extra intercooler, as for the revs it sounds like you clutch is worn out escpecially if you doing it in 5th and the revs rise but the speed stays the same It could well be a dodgy clutch but my auto sufferd loads with the bigger boots Quote Link to comment Share on other sites More sharing options...
neels Posted August 31, 2007 Author Share Posted August 31, 2007 Thanks for the reply. what do you mean by adjusting the pump up and do you mean a bigger intercooler? (what kind) Neels Quote Link to comment Share on other sites More sharing options...
Bush65 Posted August 31, 2007 Share Posted August 31, 2007 You can change the high range gearing with a defender t/case, but low range is still the same. Another gearing option is 4.11 to 1 ring and pinion in both diffs. I'm happy with Ashcroft 4.11:1 in my disco with 265/75R16 and 33"x15" tyres. The speedo is out - reads about 10% high ie speedo reads 110km/h, actual speed is about 100km/h. Quote Link to comment Share on other sites More sharing options...
neels Posted August 31, 2007 Author Share Posted August 31, 2007 Thanks for the suggestions. what do mean with adjusting the pump up and do you mean a bigger intercooler or can you add another intercooler? my knowledge regarding this is limited. (What Type) sorry for shouting neels Quote Link to comment Share on other sites More sharing options...
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