ricky tango Posted January 8, 2011 Share Posted January 8, 2011 ok here goes , i have rrc with zf auto box and a borg warner transfer box which i am pulling out for a solid lock lt230 as i just don't trust the bw , i know what i need and don't need so thats not a problem my problem is transfer ratios at present with what ever ratios the bw run (i think there all the same) my car cruises on its speedo (which will be out as i run 35" tyres at 60 mph and doesn't really like to go into last gear until around 65-70 but once its in i have to go up to 75 or it keeps dropping back to 3rd gear so what should i really be requesting on purchase of my recon lt230 ? thank you for your knowledge Quote Link to comment Share on other sites More sharing options...
ashtrans Posted January 8, 2011 Share Posted January 8, 2011 ok here goes , i have rrc with zf auto box and a borg warner transfer box which i am pulling out for a solid lock lt230 as i just don't trust the bw , i know what i need and don't need so thats not a problem my problem is transfer ratios at present with what ever ratios the bw run (i think there all the same) my car cruises on its speedo (which will be out as i run 35" tyres at 60 mph and doesn't really like to go into last gear until around 65-70 but once its in i have to go up to 75 or it keeps dropping back to 3rd gear so what should i really be requesting on purchase of my recon lt230 ? thank you for your knowledge Hi, this is exactly what our new ratio calculator is made to help with : ratio calculator lets see what the revs would be as stock and work out whats best from there, select : ZF auto we still need to add the borg warner but you can select 'other' and input high as 1.206 and low as 3.321, 3.54 diffs 31" tyres revs at 70 is 2360 even as stock this is a tad low, ideally you are looking for 2500-2600 @ 70 mph now change the tyres to 35", revs @ 70 are now 2090, way too low, this is what you have at the moment and this is way overgeared, if you change the transfer case to the LT230 type 22D 1.410 the revs are now 2444 @ 70, much closer to stock and close enough to the target of 2500-2600, so thats the answer to your question, you want a 1.410 ratio LT230, Dave Quote Link to comment Share on other sites More sharing options...
elbekko Posted January 8, 2011 Share Posted January 8, 2011 Stock RRC tyres (205/80R16) aren't 31", are they? Stock Tire - 205/80R16 >Search Tires Section Width: 8.07 in 205 mm Rim Diameter: 16 in 406.4 mm Rim Width Range: 5 - 7 in Overall Diameter: 28.91 in 734.31 mm Quote Link to comment Share on other sites More sharing options...
ashtrans Posted January 8, 2011 Share Posted January 8, 2011 Stock RRC tyres (205/80R16) aren't 31", are they? Stock Tire - 205/80R16 >Search Tires Section Width: 8.07 in 205 mm Rim Diameter: 16 in 406.4 mm Rim Width Range: 5 - 7 in Overall Diameter: 28.91 in 734.31 mm OK, that explains why I had the revs come out so low with the stock tyres, Dave Quote Link to comment Share on other sites More sharing options...
ricky tango Posted January 8, 2011 Author Share Posted January 8, 2011 thanks for that guys , i never knew the bw ratios and so me and your ratio calculator weren't getting on dave you have pm too Quote Link to comment Share on other sites More sharing options...
elbekko Posted January 8, 2011 Share Posted January 8, 2011 I must say, I played with the calculator a bit, and either my rpm gauge is way off or the calculator does some strange things For a standard softdash RRC (R380 + BW), it shows it would only be doing 105 km/h at 2500 RPM. That's, erm, very wrong. That's normal cruising RPM at a speed of about 120 km/h, and 150 km/h (on the speedo, so probably 145ish) is 3000 RPM. Or did I enter something incorrectly? Quote Link to comment Share on other sites More sharing options...
ashtrans Posted January 9, 2011 Share Posted January 9, 2011 I must say, I played with the calculator a bit, and either my rpm gauge is way off or the calculator does some strange things For a standard softdash RRC (R380 + BW), it shows it would only be doing 105 km/h at 2500 RPM. That's, erm, very wrong. That's normal cruising RPM at a speed of about 120 km/h, and 150 km/h (on the speedo, so probably 145ish) is 3000 RPM. Or did I enter something incorrectly? Hi Elbekko, this post make me wonder if something in the formulae was wrong so I thought I would do a manual calc to compare, lets look at what the engine RPM will be in 5th at 100KPH, the ratio calculator says 2376, tyre dia is 28.91", 28.91 x 25.4= 734.3mm, 734.3 x pye = 2307.2mm = 2.307m circumferance speed is 100 kph = 100000mph, /60 = 1666.6' meters / minute wheel turns at 1666.6/2.307 = 722 rpm final drive ratio is 5th x transfer case x diff = 0.77 x1.206 x 3.54 = 3.2873, engine rpm = 3.2873 x 722 = 2373.4 thats close enough to the 2376 to say the formulae is correct, in reality the rpm will be higher as we have used a theoetical tyre diameter, ideally you should use 2 x rolling radius to allow for the tyre 'flat spot' Dave Quote Link to comment Share on other sites More sharing options...
elbekko Posted January 9, 2011 Share Posted January 9, 2011 Hmm, guess I shouldn't be surprised my LR doesn't like maths, that would be too logical So... is it normal the RPM gauge is off by 300 RPM+? Quote Link to comment Share on other sites More sharing options...
Escape Posted January 10, 2011 Share Posted January 10, 2011 Elbekko, we had this discussion before, with your RRC apparently doing about the same revs as my P38a, despite my bigger tyres. I'd say your speedometer is way off, but GPS data seems to dismiss that idea, right? So it can only be the revcounter. Quote Link to comment Share on other sites More sharing options...
elbekko Posted January 10, 2011 Share Posted January 10, 2011 Must be, still strange though. 50 km/h on the speedo is about 48 km/h on the GPS, and the RPM gauge tells me 1000 RPM, while it should be 1188 according to the calculator (well, slightly different now as my tyres now are a tad larger than standard, but there isn't a whole lot of difference). Quote Link to comment Share on other sites More sharing options...
trulyalya Posted August 9, 2011 Share Posted August 9, 2011 What do those 'overdrive' graphs mean, I wonder? Quote Link to comment Share on other sites More sharing options...
trulyalya Posted August 23, 2011 Share Posted August 23, 2011 anyone, please? Quote Link to comment Share on other sites More sharing options...
G4FUJ Posted August 23, 2011 Share Posted August 23, 2011 What you'd get if you had an overdrive fitted... You can select type from a drop down list, or even mnaually enter the ratios if your overdrive is not listed. Cheers, Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 23, 2011 Share Posted August 23, 2011 They are for if you have an overdrive fitted. Raises the overall gearing ~28% Quote Link to comment Share on other sites More sharing options...
trulyalya Posted August 24, 2011 Share Posted August 24, 2011 thanks for the answers! what's that overdrive and how do I fit it on my old RRC? (manual box) sounds very interesting, but never heard of it before... so, if I don't have an overdrive (btw, how do I check?), i should use ratio 1,0? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 24, 2011 Share Posted August 24, 2011 Elbekko, we had this discussion before, with your RRC apparently doing about the same revs as my P38a, despite my bigger tyres. I'd say your speedometer is way off, but GPS data seems to dismiss that idea, right? So it can only be the revcounter. My RRC's tacho is ~ 300rpm out (too low)compared to the data displayed in MegaTune, which can only really be correct. Speedo is pretty accurate now I have 33" tyres on it For 35" tyres and an autobox I would be going for a 1.66 ratio transfer box, it's really quite important that an auto has the correct gearing to get the changes and lockup in the right place for on-road driving, 1.4 is just about perfect on 33s, 1.6 on 35s would be the same by my reckoning. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 24, 2011 Share Posted August 24, 2011 what's that overdrive and how do I fit it on my old RRC? (manual box) sounds very interesting, but never heard of it before... so, if I don't have an overdrive (btw, how do I check?), i should use ratio 1,0? It's an extra box that bolts onto the transfer case, splits the path of the drive and ups the gearing by ~28% on demand. Depending on the vehicle there are a few types for Land Rovers, there are 2 for the LT230, one is GKN, one is made by Rocky Mountain. Using the "search" function should turn up plenty of info. Some basics are here: http://www.ep90.com/index.php?id=70 Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted August 24, 2011 Share Posted August 24, 2011 PERSONALLY Look at the CWP Ratios, If you change the TBOX ratios, then you'll sort out the gearing for ON road, but the gearing is also off the mark for OFF road too.. Change the CWPs and you can sort both High and Low ratios My 2p worth nig Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 24, 2011 Share Posted August 24, 2011 Look at the CWP Ratios, If you change the TBOX ratios, then you'll sort out the gearing for ON road, but the gearing is also off the mark for OFF road too.. Agreed, but with a V8, and an autobox, off road low ratio is far less important than a stinky diesel and a manual box -IMHO. Quote Link to comment Share on other sites More sharing options...
zardos Posted August 24, 2011 Share Posted August 24, 2011 Hmmm the tool could do with a option to set the step increments, or adapt it's scaling for certain combinations. e.g. My Low with underdrive gives:- Which does not show first or second gear as they are both below 10mph Quote Link to comment Share on other sites More sharing options...
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