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Axle ratios for 'classic' LT's |
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Jam-Man 
Yardie 
Joined: 19 Aug 09 Location: Wales Status: Offline Points: 289 |
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 Topic: Axle ratios for 'classic' LT'sPosted: 19 Sep 09 at 13:51 |
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Does anyone know the full range of options for rear axle ratios for the LT range from 1975 to 1996, and do the diffs and axles from the later 'sprinter' shaped vans fit the old 'classic' LT'S?
In all the publications I can find it seems they vary from 4.08:1 to 5.4:1. Is this true or are there some in the ''3 range? I could do with something in the '3' range now I've fitted a different engine, but don't seem to be able to find any info. How do you tell the ratio you've got without physically checking the teeth or the distance travelled per revolution? Is there meant to be a tag on the casing? Thanks.
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paulr
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Joined: 20 Sep 09 Location: Staffs Status: Offline Points: 322 |
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Posted: 23 Sep 09 at 18:16 |
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Hi Jam-Man
There's a section in the '5 speed gearbox 008 and final drive' manual (downloadable off this site) which covers it. Looking at what's on offer I think the lowest you can go is 4.1
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www.flexiblesanders.co.uk
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Jam-Man
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Joined: 19 Aug 09 Location: Wales Status: Offline Points: 289 |
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Posted: 24 Sep 09 at 00:15 |
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Thanks Paul. I'll have alook. I guess 4.1 will have to do...
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BeJay
Vanorak 
Joined: 03 Jun 09 Location: Leicester Status: Offline Points: 1325 |
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Posted: 24 Sep 09 at 03:12 |
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don't forget the option of putting bigger wheels and tyres on, it'll have the same effect of raising the gearing.
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NIL ILLIGITIMUS CARBORUNDUM
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Jam-Man
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Joined: 19 Aug 09 Location: Wales Status: Offline Points: 289 |
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Posted: 25 Sep 09 at 00:00 |
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Hi BeJay, Thanks for that. As you'll see on the thread about v6 Ford into Lt, I've factored for that. I've just countersunk a set of 16" Trannie steel wheels. And as soon as I can get a spare set of rear halfshafts, drums and front hubs, I'll be re-drilling them to suit a Range Rover PCD so I can get my Rangie alloys on! I reckon with my Trannie steels and 205x16 tyres it'll give me an effective ratio of approx 3.7:1. That will help a lot. Cheers.
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paulr
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Posted: 25 Sep 09 at 09:22 |
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Why not fit 215's or even 225's?
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www.flexiblesanders.co.uk
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BeJay
Vanorak
Joined: 03 Jun 09 Location: Leicester Status: Offline Points: 1325 |
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Posted: 25 Sep 09 at 11:23 |
yep, sorry Jam-Man, forgot you'd already mentioned the 16" wheels, just gone back and re read it, I make it very slightly different to you at a 7.5% increase (either in speed for the same revs, or drop in revs for the same speed) which gives an effective 3.8 ratio, but I'm assuming in my calcs that the tyres on it are 205 x 14 (standard aspect ratio of 80 for both sizes of tyre), course if you still find it too low geared you could always put the same size tyres on that I've got on the Disco, 235x85x16, take the rolling diameter from 26.9" to 31.7" gives you an effective 3.5 diff ratio and 18% increase in speed, reckon that might be just a tad on the overkill side though and you'd probably have to start chopping boywork/arches about as well
 although the LT might just be low geared enough to pull it, at least you'd get to use 1st gear a lot more often  , let us know how it alters the feel of cruising 'cos I don't use 1st unless I'm pulling away on an incline so could probably get away with the 7.5% increase even with my n/a diesel, just have to use 1st gear a bit more often, but would make motorway cruising more relaxed. cheers, Jack. Edited by BeJay - 25 Sep 09 at 11:26 |
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NIL ILLIGITIMUS CARBORUNDUM
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Jam-Man
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Joined: 19 Aug 09 Location: Wales Status: Offline Points: 289 |
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Posted: 26 Sep 09 at 00:56 |
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Hi Jack, Thanks for that. I think you're right about the axle ratio... I'll try the 205x16's and if it's still not overdriven enough I'll do as you say. I think it's only the bottom of the front wing corner that would need 'massaging!' I think the trorque of the v6 will still pull it ok even on the tyres you suggest. On the LT gearbox first is a crawler gear, and 5th is only 1:1 and not overdriven at all. However, on the Scimitar box, first is normal, and the '5th' overdrive gear is 0.77:1 with the Jaguar internals, and 0.82:1 as it is. |
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Jam-Man
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Joined: 19 Aug 09 Location: Wales Status: Offline Points: 289 |
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Posted: 26 Sep 09 at 01:01 |
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Hi Paul, If I fit 215's or 225's they all have a lower profile than the regular 80 profile. 205x16's give a rolling diameter of 28.92". 215/75x16'2s give 28.70" and 225/75x16 do give 29.30" but they are a very hard size to get at reasonable money, and the more common 225/70x16 give 28.40"
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ZUB
Vanorak
early morning troll Joined: 30 Nov 08 Location: NORTH WALES Status: Offline Points: 2536 |
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Posted: 26 Sep 09 at 01:13 |
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Dave I've had no luck at all with finding an LT through the so called 900 contacts (scrap yards) they got back to me saying they have contacted only 19 of them
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I'm a bell end
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Jam-Man
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Posted: 26 Sep 09 at 01:51 |
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That's a shame. Well if anything comes up, I'm there all the time so keep trying...
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BeJay
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Joined: 03 Jun 09 Location: Leicester Status: Offline Points: 1325 |
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Posted: 26 Sep 09 at 19:49 |
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Jam-Man, you mentioning the overdrive ratio got me thinking, just checked the ratio's in my volvo 940 TDi owners manual, (the mobile spare engine in case the n/a one in the LT ever goes tits up) and the box that's in the volvo, M46 (4 speed with overdrive 5th on the button) has a 1 to 1 4th gear and 0.79 to 1 on overdrive 5th Mmmmmmmm food for thought, might change more than just the engine if I ever do need to take this one out.
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NIL ILLIGITIMUS CARBORUNDUM
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Jam-Man
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Joined: 19 Aug 09 Location: Wales Status: Offline Points: 289 |
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Posted: 26 Sep 09 at 23:57 |
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Hi BeJay. It sounds like a plan. Unfortunately just changing the engine is never going to work on it's own due to the fact that everything needs to work in harmony. A more powerful engine still constrained by the same ratios in the gearbox and axle that were specifically targetted for the existing engine will only hamper your shiny new engine. As I have found with the 3 litre to an extent even with the box changed, even the final drive on it's own can ruin the full performance of the engine. All 3 things need to be altered in unison to meet the requiremants you have for the van. Decide what you need at the start, i.e performance, economy, pulling power, etc and design it in by choosing the right engine and box. We can't do much about the axle ratio except play with wheel size, but we can work wonders by playing with the wheels and changing the engine and box! Anything with an overdriven gear will do it, but if it's too overdriven your engine won't pull it as I found out with my 4 cylinder LT. Good luck with it, but it's well worth it...
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Jam-Man wrote: