smo Posted March 9, 2009 Share Posted March 9, 2009 I'm pondering the ratios for my diffs in the d-lander.... She's pretty light by comparison to a 90 TD5 engine (mildly tuned) 4HP22 Autobox with compushift 1.410 Transfer box 37" Maxxis Creepys (to be joined with similar size simex/boggers) Will the standard 3.54 diffs be ok or do i really need to consider 4.11/4.7's?? Quote Link to comment Share on other sites More sharing options...
white90 Posted March 9, 2009 Share Posted March 9, 2009 With the power you have you'll be ok/if a little speedy on descents then there's the option for an Under drive Quote Link to comment Share on other sites More sharing options...
Chicken Drumstick Posted March 9, 2009 Share Posted March 9, 2009 I'm pondering the ratios for my diffs in the d-lander....She's pretty light by comparison to a 90 TD5 engine (mildly tuned) 4HP22 Autobox with compushift 1.410 Transfer box 37" Maxxis Creepys (to be joined with similar size simex/boggers) Will the standard 3.54 diffs be ok or do i really need to consider 4.11/4.7's?? Depends what you want from it. 3.54 will be ok'ish IMO but it won't do any favours for acceleration, probably mpg or crawling ability. If you let me know the gear ratio's I've got a spread sheet to work out speeds, I'll post them up so you see the difference in gear options. Personally if you have the £££ I'd say go for 4.75:1 with those tall tyres. Quote Link to comment Share on other sites More sharing options...
smo Posted March 9, 2009 Author Share Posted March 9, 2009 Gear ratios - 4HP22 1st 2.480 : 1 2nd 1.480 : 1 3rd 1.000 : 1 4th 0.728 : 1 Reverse 2.086 : 1 Transfer box 1.410 as stated and diffs 3.54:1 Quote Link to comment Share on other sites More sharing options...
Adrian Turner Posted March 9, 2009 Share Posted March 9, 2009 I'm pondering the ratios for my diffs in the d-lander....She's pretty light by comparison to a 90 TD5 engine (mildly tuned) 4HP22 Autobox with compushift 1.410 Transfer box 37" Maxxis Creepys (to be joined with similar size simex/boggers) Will the standard 3.54 diffs be ok or do i really need to consider 4.11/4.7's?? I had a Td5 with a tuned ecu, R380 and a 1.410 t/box and a set of Dave Ashcroft 4.75 c/p and low range was just right on 37'' bogger's, high range was a little low for on the road but it did get of the mark well!! Quote Link to comment Share on other sites More sharing options...
bishbosh Posted March 9, 2009 Share Posted March 9, 2009 Autobox = speedy decents regardless of diff ratios!! I would get an underdrive if you want to go downhill slowly with an auto!* *Of course, where there is sufficient traction your brakes can help in this regard! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 9, 2009 Share Posted March 9, 2009 I tend to think that if you've raised the gearing at the wheels by fitting big tyres, you want to correct it as close to the wheels as possible so changing diff ratios puts everything upstream back into its happy place. Lower diff gearing means you can stick a high ratio T box in and have good cruise and a usefully low low box without having to buy an underdrive. Quote Link to comment Share on other sites More sharing options...
SacredDog Posted March 9, 2009 Share Posted March 9, 2009 Autobox = speedy decents regardless of diff ratios!! Doesn't the Compushift allow you to manually lockup the TC irrespective of what gear it's in to give you some decent engine braking? or is it a bit more complicated than that? or was I just dreaming? Colin Quote Link to comment Share on other sites More sharing options...
smo Posted March 10, 2009 Author Share Posted March 10, 2009 Colin - you are correct, compushift does allow you to lock up the TC. I'm still undecided on what to do....lol Quote Link to comment Share on other sites More sharing options...
bishbosh Posted March 10, 2009 Share Posted March 10, 2009 I can't remember the exact details when I asked Dave Ashcroft about the compusihift and locking up, but I do remember that it wont help low range enging braking. I don't think it will lock up in 1st? As I said, I can't remember so we'd better wait for Dave to come along and put me straight! Quote Link to comment Share on other sites More sharing options...
SacredDog Posted March 10, 2009 Share Posted March 10, 2009 I can't remember the exact details when I asked Dave Ashcroft about the compusihift and locking up, but I do remember that it wont help low range enging braking. I don't think it will lock up in 1st?As I said, I can't remember so we'd better wait for Dave to come along and put me straight! Yep, having looked at various websites (including Daves) it looks like it will not lock up in 1st (I guess you don't want it to stall if you have the TC locked up when you have to stop). I would have thought that 2nd Gear Low Box would give enough engine braking for most situations, even our old V8 RRC wouldn't completely run away with me in 2nd Low on fairly steep bits with the standard ZF4 (perhaps I wasn't trying hard enough ) Hopefully Dave can confirm this, or let us know that none of us mere mortals know what we are talking about Colin. Quote Link to comment Share on other sites More sharing options...
Chicken Drumstick Posted March 10, 2009 Share Posted March 10, 2009 Gear ratios - 4HP221st 2.480 : 1 2nd 1.480 : 1 3rd 1.000 : 1 4th 0.728 : 1 Reverse 2.086 : 1 Transfer box 1.410 as stated and diffs 3.54:1 Quote Link to comment Share on other sites More sharing options...
smo Posted March 10, 2009 Author Share Posted March 10, 2009 Ooh, thats cool, thank you mr drumstick Quote Link to comment Share on other sites More sharing options...
Chicken Drumstick Posted March 10, 2009 Share Posted March 10, 2009 Ooh, thats cool, thank you mr drumstick Anytime, sorry it only goes to 5000rpm, I created it for Tdi engines although the Td5 doesn't rev much more (5250rpm I think). Quote Link to comment Share on other sites More sharing options...
smo Posted March 10, 2009 Author Share Posted March 10, 2009 5000 rpm is more than enough for practical use Quote Link to comment Share on other sites More sharing options...
steve_d Posted March 10, 2009 Share Posted March 10, 2009 5000 rpm is more than enough for practical use Didn't you mean 151MPH is more than enough for practical use. Steve Quote Link to comment Share on other sites More sharing options...
will_warne Posted March 11, 2009 Share Posted March 11, 2009 smo, Try the gearing calculator with a 1.66 t.box, underdrive and 3.54 diffs. It worked for me....... 4 distinct ratios in very useful places. Yes, it does mean my propshafts see a little more loading than with lower ratio diffs BUT how often do you see a propshaft broken due to the loading on it and not due to contact with the terrain??? Quote Link to comment Share on other sites More sharing options...
smo Posted March 11, 2009 Author Share Posted March 11, 2009 The low ranges are the same on all boxes aren't they?? An under drive is somthing i would love to have but i'm not sure that i can foot the £1500+vat price!! Quote Link to comment Share on other sites More sharing options...
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