Final Drive Ratio (FDR)

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chil6ep

Active Member
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--EDIT - Title should read "Final Drive Ratio" (dont know where the n came from) --

Earlier I was reading a few posts on here about using R380 boxes out of a Disco on a Defender. It reminded me that it is the Transfer box that has different ratios in the vehicles. However Landrover themselves claim that both my old outgoing Disco (300Tdi, R reg) and my "new" incoming Def110 (300Tdi, P reg) have the same Final Drive Ratio of 3.54.

How do different Transfer boxes end up with the same FDR and whay have different transfer boxes if they are going to be the same FDR anyway?

I'm sure its really obvious, it has just missed me.

I don't believe they can be the same or the defender wouldn't begin to rattle at 60 when the Disco holds out to 70, would it?
 
Last edited:
The FDR (crown wheel in diffs) doesn't know what transfer box is in the vehicle it just converts the prop speed fed into it.
low geared Transfer box sends slower prop speed to diffs than higher geared transfer box does
 
OK, that makes sense, I obviously missread something else earlier as I'd got it into my head that the FDR value was the total ratio Engine output: wheels.

Whilst on gthe subject is it right that 90s and 110s have diferent transfer box ratios?
 
--EDIT - Title should read "Final Drive Ratio" (dont know where the n came from) --

Earlier I was reading a few posts on here about using R380 boxes out of a Disco on a Defender. It reminded me that it is the Transfer box that has different ratios in the vehicles. However Landrover themselves claim that both my old outgoing Disco (300Tdi, R reg) and my "new" incoming Def110 (300Tdi, P reg) have the same Final Drive Ratio of 3.54.

How do different Transfer boxes end up with the same FDR and whay have different transfer boxes if they are going to be the same FDR anyway?

I'm sure its really obvious, it has just missed me.

I don't believe they can be the same or the defender wouldn't begin to rattle at 60 when the Disco holds out to 70, would it?

defender and disco r380 gear boxes are the same gear wise ,so are diffs (the final drive)only the ratio of t/box changes
 
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