 | Home > Puma (Tdci) > higher gearing |
 
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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11324  
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That depends, to an extent, what your purposes are and how high you think you'd like to raise the gearing:
If you need or want taller tyres then that's an easy way to increasing the gearing, but it affects both high and low range. Depending on how big you go, you may create other problems that need to be engineered out with a suspension lift and castor correction measures. Changing the diff gearing is a much more expensive solution and again affects both high and low range. It may be more practical though if you were already planning to upgrade them with lockers or LSD's, for example. Changing transfer gears is less expensive and can be done so that it only affects high range, leaving low range untouched. Ashcrofts offer a 1.1 gear to replace the standard 1.2, which could be what you're looking for. Tuning the engine won't affect the gearing at all, although I guess it'd make it easier to pull away in second, if that's the issue. Darren 110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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26th Oct 2020 9:34am |
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| 100inch Member Since: 15 May 2012 Location: Brunswick Posts: 411  
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Maybe worth considering 255/85R16 (or similar OD) tyres. To me the perfect size for an everyday Defender including towing. m
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26th Oct 2020 7:15pm |
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| MatLandy Member Since: 11 Sep 2020 Location: Paris Posts: 184  
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I have been running Ashcroft 1.1 ratio in the transfer box with a tuned engine (165BHP tune from BAS) on my 2.4L Puma for 2 years / 20k kms now. I wouldn't change the gearing without a tuned engine though. I wouldn't change the gearing if I was towing also. It does not affect the speedo, does not affect the low range gearing. It is also the opportunity to slot an Ashcroft ATB diff in the transfer box while at it, improving backlash and traction over the standard poor diff while keeping the possibility to manually lock it when necessary. To give you an idea, the 1.1 ratio in high range drops engine rpm by around 9% for achieving the same road speed as a 1.2 ratio. One good way to (slightly) reduce engine noise in the cabin ! And now the 1st gear is not "too" short anymore, oh well, still a bit short but I can live with it now.
Of course this set-up is more costly than just putting taller tyres, but there are much more benefits for me with the 1.1 route. /Mat Last edited by MatLandy on 28th Oct 2020 9:06am. Edited 2 times in total |
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28th Oct 2020 7:47am |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051  
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changing the tyres is the simplest way of doing it. what are you running now? 235.85s? try the above or 255.85s these seem to give a good compromise for most applications.
if it works but you dont want to run big tyres then reverting to 235.85s with a 1.1 T box will give you same (as near as) benefit as 255.85s with a 1.2 box. i am going the other way with my 130 which is heavy and tows dropping to a 1.3 box. Cheers James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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28th Oct 2020 8:09am |
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| NMBRPL8 Member Since: 07 Jul 2015 Location: Australia Posts: 147
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great feedback thanks. can the puma not handle the higher gearing without a tune? i dont have much faith in this modern donk as it is in its detuned state.
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28th Oct 2020 9:29am |
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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11324
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It'll work but it'll obviously be more sluggish. Whilst not an exact comparison, try pulling away in second to get an idea. Nothing to do with any weakness in the engine - it's just the way that it's been set up. Darren
110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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28th Oct 2020 9:33am |
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| Chicken Drumstick Member Since: 17 Aug 2020 Location: Near MK Posts: 751
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Well what are you trying to achieve? Taller gearing will blunt performance. And unless you have the grunt from the engine, you may find it won't hold speed as well or even require you to downshift where you didn't before. Especially on hills and inclines. With the 6 speed in the Puma's, they are already very capable of cruising at decent speeds. I believe the Puma already has the 1.211:1 transfer box as standard. Which on factory sized tyres gives you 70mph @ 2300rpm https://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html |
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28th Oct 2020 10:20am |
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| ashtrans Site Sponsor Member Since: 08 Nov 2008 Location: Harpenden Posts: 258
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 glad you like it, Dave |
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29th Oct 2020 7:11pm |
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