ericobrave Posted January 3, 2016 Share Posted January 3, 2016 Have been rebuilding a 90 200 tdi since February and just got the Mot so feeling quite pleased. I've never driven a 90 before, only my 110 for the past 25 years. that is also a 200tdi. I am surprised by how low geared the 90 feels, at 60mph the engine seems to be running faster than I am used to on the 110, the boxes are both LT77 and both have 1:1.410 transfer gears - I know because I rebuilt them both so the only difference is the tyre size, 7.50 Rangemasters on the 110 and Michelin 205/80 on the 90. Or is this just my imagination ?? 1 Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 3, 2016 Share Posted January 3, 2016 The difference will be the tyres.... 205/85R16 on the 90 are quite a bit smaller than the 7.5, which are about a 235/85R16. Quote Link to comment Share on other sites More sharing options...
daveturnbull Posted January 3, 2016 Share Posted January 3, 2016 Gearing is the same, must be the tyre size that's doing it. Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted January 3, 2016 Share Posted January 3, 2016 Yep, I bought a 110 that had 205s on it. Drove horribly until I put some 750s on. Quote Link to comment Share on other sites More sharing options...
western Posted January 3, 2016 Share Posted January 3, 2016 as above smaller rolling circumfernce on the 205's means everything works harder to cover the same distance as a 110 on bigger 235's. Quote Link to comment Share on other sites More sharing options...
ericobrave Posted January 3, 2016 Author Share Posted January 3, 2016 Thanks - yes they look significantly smaller but I understand that this is the correct tyre size for that year's model - 1993 so I will stick with it and hope to get used to it. I'm not clever enough to work it out but how much faster is the engine running at say 60 and is this a problem ? Years ago I would have fitted an overdrive !!! 1 Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 3, 2016 Share Posted January 3, 2016 Swapping between those tyre sizes won't be a problem! Quote Link to comment Share on other sites More sharing options...
Snagger Posted January 6, 2016 Share Posted January 6, 2016 It'll be a 10-12% difference in final gearing with those tyres, so it's almost certainly the cause. All 90s will happily run 7.50s or 235/85s, you'll just need to change the speedo drive gear for correct calibration. Quote Link to comment Share on other sites More sharing options...
Kevm Posted January 9, 2016 Share Posted January 9, 2016 It'll be a 10-12% difference in final gearing with those tyres, so it's almost certainly the cause. All 90s will happily run 7.50s or 235/85s, you'll just need to change the speedo drive gear for correct calibration. That is not strictly true as my 2.5NA really struggles with 235/85/16 - way too high geared, I seldom get into 5th gear and I am going to change them for 235/70 section. With more power it would be ok though. Quote Link to comment Share on other sites More sharing options...
Snagger Posted January 9, 2016 Share Posted January 9, 2016 That is not strictly true as my 2.5NA really struggles with 235/85/16 - way too high geared, I seldom get into 5th gear and I am going to change them for 235/70 section. With more power it would be ok though. That's because your engine needs attention. I had a 12J in my very heavy 109 with big roof rack pulling the same size tyres and the overdrive was in use on all the level ground and most hills, and that final gearing isn't much lower than yours. Performance was far from startling, but it'd pull 4th with overdrive with that roof rack even in stiff head winds or up 1:20 slopes. Yours should do the same. Quote Link to comment Share on other sites More sharing options...
deep Posted January 9, 2016 Share Posted January 9, 2016 I actually put 255/85s on my 2.5NA 110 and the gearing is much nicer (and the speedo more accurate!) than it was with 7.50s. I can't imagine how unpleasant a 90 would feel, with the same gearing, on 205s! Quote Link to comment Share on other sites More sharing options...
Pepé le Pew Posted January 9, 2016 Share Posted January 9, 2016 I actually put 255/85s on my 2.5NA 110 and the gearing is much nicer (and the speedo more accurate!) than it was with 7.50s. I can't imagine how unpleasant a 90 would feel, with the same gearing, on 205s! As far as i know the 2.5NA 90 had a 1.4:1 T-box and 205/80/16 tyres and the 2.5NA 110 had a 1.6:1 T-box and 7.50X16 tyres. Eric Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 9, 2016 Share Posted January 9, 2016 I thought all the NAs were 1.6:1? both the 90 and 110. Quote Link to comment Share on other sites More sharing options...
muddy Posted January 9, 2016 Share Posted January 9, 2016 I actually thought only very early 110s with the 2.25 and some with 2.5 were 1.6 with all 90s being 1.4? Anyone got an early 110 to check? Quote Link to comment Share on other sites More sharing options...
Pepé le Pew Posted January 9, 2016 Share Posted January 9, 2016 I actually thought only very early 110s with the 2.25 and some with 2.5 were 1.6 with all 90s being 1.4? Anyone got an early 110 to check? I had a 1986 110 2.5NA for years and that had a 1.6:1 T-box. The first 110 with a 1.4 T-box was the V8 and after that the 200TDi. Al the 90's have an 1.4 T-box except the 90 V8 which has a 1.2:1 T-box. Eric 1 Quote Link to comment Share on other sites More sharing options...
miketomcat Posted January 9, 2016 Share Posted January 9, 2016 Atleast some if not all TD 110s had a 1.41:1 t-box. Mike 1 Quote Link to comment Share on other sites More sharing options...
western Posted January 10, 2016 Share Posted January 10, 2016 my '89 ex-TD 110 has a 1.410:1 trabsfer box, pretty much standard fit on TD/TDi vehicles. Quote Link to comment Share on other sites More sharing options...
robertspark Posted January 10, 2016 Share Posted January 10, 2016 My 89 v8 90 has a 1.222:1 May be of some help: http://www.expeditionlandrover.info/gear_ratio.htm Quote Link to comment Share on other sites More sharing options...
deep Posted January 10, 2016 Share Posted January 10, 2016 My 1987 110 has a 1.6x:1 transfer box. Can't remember what "x" is 'cos the sticker vanished when I water-blasted it! Now I think about it, I seem to remember the 90 having a different ratio to compensate for the bizarrely small tyre diameter. Quote Link to comment Share on other sites More sharing options...
GW8IZR Posted January 10, 2016 Share Posted January 10, 2016 My 89 v8 90 has a 1.222:1 May be of some help: http://www.expeditionlandrover.info/gear_ratio.htm With all data like that on the page quoted you need to treat it with care, some ( I expect all ) 2286 petrol 90's had 1.4 transfer boxes from the factory. Quote Link to comment Share on other sites More sharing options...
Pepé le Pew Posted January 10, 2016 Share Posted January 10, 2016 Atleast some if not all TD 110s had a 1.41:1 t-box. Mike You are right. I did forget the 2.5 TD. I had one of those engines and must have banned it from my memory. Eric Quote Link to comment Share on other sites More sharing options...
robertspark Posted January 10, 2016 Share Posted January 10, 2016 With all data like that on the page quoted you need to treat it with care, some ( I expect all ) 2286 petrol 90's had 1.4 transfer boxes from the factory.Ok..... Alternative source of LR published information.... Page 13/14 (pg no at bottom of page).http://www.landroverweb.com/Pdf-files/Manuals/Defender-90-110-workshop-maunual-1.pdf Now I know that information is wrong for the v8 90 with the lt85 divided case for 1989 (f) model year as I counted the teeth to double check the sticker on the side as mine is 1.222:1 If you are that concerned ... Count the gear teeth.... I have 1.003:1 box that I was going to use (sat in garage), but decided to use the existing 1.222:1 for my conversion application... Working out the numbers via spreadsheet adding in the torque (interpolated curve) to the equation and some racer math CD (coefficient of drag equation) it looks like I may need to use a 1.1923:1.... So I thought I'd try it with what I have before buying another gearset (or sourcing another transfer case) as I can put both boxes in and have resplined the input gears for both boxes (the 1.003:1 uses the thin input gear for suffix A and B boxes). Both 1.222 and 1.003 boxes use 22 teeth input gears. The other manuals are about for the other models with similar information, but all information can be misleading to a degree unless you verify it yourself. Giyf - " defender manuals " Ashcroft transmissions gear ratio calculator has proved a useful aide and I can confirm that for the two unmolested (before I got them) transfer boxes I have the box numbers and ratios were accurate. http://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html Rob Quote Link to comment Share on other sites More sharing options...
GW8IZR Posted January 10, 2016 Share Posted January 10, 2016 What I meant is its very difficult to put a table together that covers all variations. Quote Link to comment Share on other sites More sharing options...
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