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Freelander diff / IRD ratios


FridgeFreezer
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I'm sure someone posted a link about this a while back but I can't find it :(

Does anyone have info to hand about the various rear diff and IRD ratios that are fitted to various freelanders (models/years)?

Mine is pretty early (1998) and I threw the rear prop away 40k ago. With winter approaching I'm tempted to get a new/recon VCU and prop for it but if my diff is going to wind it up I may not bother, or might try to track down a different ratio unit to bring the gearing to something less stressful.

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Some actual data courtesy of TSD and RAVE:

early FL:

rear diff is 4.200 (petrol) 3.647 (diesel)

late FL: 3.182 td4 manual, 2.91 td4 auto, 4.20 K series, 3.66 kv6

IRD is a bit complex

IRD to IRD countershaft 0.828:1

IRD countershaft to front driveshaft 1.762:1

IRD countershaft to propshaft 0.553:1

IRD ratios (late) td4 + K 1.458:1

KV6 1.351:1

early IRD same as late k for all engines

* All according to manual * which I'm not certain I beleive. Cant find a TSB about the rear diff change, though I can find diff part numbers for early and late versions

So drive comes in, and multiplies up to IRD countershaft. Then ratios output to front shafts, and propshaft with the ratios listed. Which makes it all a bit daft, if thats true

So 1.458 = 0.828 x 1.762

The weird thing is, according to the internet:

"They're all 3.21, except some early ones which were 3.19"

And Ashcroft only list two part numbers - early & late, late having beefier bearings.

I'm quite confused now! :(

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Having trawled back through the posts on this forum and searching elsewhere but I am still none the wiser, been trying to clarify when things changed and what ratio was fitted where

Have been saving bits of info from various sources as I come across them and so far have this lot, not sure if its gonna help or confuse things even more

"The earlier diff fitted to the Freelander was TVK100380, due to premature failing by the problems created by the viscous coupling siezing this was superceeded to TVK000180 which has larger journal bearings and is thus stronger."

"Early IRDs (lets say the one with wrong diff. ratios) was LR part no: TAG000020 and replaced by the TAG000230.

Bad news is no one can tell us for sure which is the one that LR fitted to our vehicles and also the detailed differences between the two IRDs, but we suspect different (right) diff. ratios in the TAG000230 and maybe stronger bearings."

"It is the drive to the front wheels that is changed. The later IRDs have higher gearing to the front wheels than the older ones, bringing the overall front gearing closer to the overall gearing of the rear, hence the VC is "less locked" and works less and hopefully doesn't fail."

"In my L series diesel - 100kph was about 3200 rpm with the old IRD. With my new IRD 100kph is about 2700 rpm. The downside is that overall gearing is higher so offroad in first I don't quite have the pulling power I once did but this is not an issue for me."

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