Cortina Differential

[art]

Hello all ,my name is Art and i`m new to this forum in fact i`ve not subscribed to any forum before, i`m now in possession of a 1980 3L Ford Cortina, I understand there were two options of differential ratios, 5.1 and  3.44,  I suspect  I have the 5.1 because at 60mph revs are around 4k in 4th gear, its a 4 speed box, my question is will the 3.44 be a direct swap, i``m looking for economy rather than being quick off the mark, the 3.44 should lower revs to around 2600 at 60 mph,      thank you for any input   Art

[v8ian]

OK,tell us more,
I'm guessing you are either in OZ or SA, in the UK the largest capacity in the mk5 was 2.3 v6, these were fitted with 2 different types of axle, the Koln or Atlas, if you have an atlas the rations are varied and available, if you have a Koln...... find an atlas. a much stronger animal altogether. smaller engined versions were also fitted with the "English" axle too.

[art]

Ahh right, thanks for the reply v8ian, I must say I`m totally new to this car, so 3L thats my mistake took it for granted when the previous owner said V6 it would be a 3L, well then its a 2.3, how can I tell which type of axel it has, if I`m in luck and its an Atlas where would I look for a differential, I`m in the UK btw,

[v8ian]

Probably the easiest was to id the axle is to look at the rear cover on the diff, if it has no removable rear cover but the Dif bolts in from the front it will be an English,, both the atlas and the koln have a tin cover on the back, which IIRC the Koln has a offset bolt position and the atlas dosent. best have a google, there is plenty about how to find out which is which, another really good site used to be BuySellCortina, have a go other, it is full of cortina knowledgeable cortina people on there.

[art]

looks like I have the Koln axel, you`re right about the bolts on the back cover the Koln`s top and bottom three are offset, not ideal but I`ll run with it if I can get the diff ratio I want, anyway, this is still progress, so now I`m looking for diff options, apart from general googling anyone know of specific sites I could visit, I`ll try BuysellCortina for starters

[igor]

You may also wish to consider a five speed gearbox conversion. My boss has done this to several 2 litre Pinto powered English Fords and is very pleased with the outcome.

[art]

thanks igor yes that`s another option

[Darkspeed]

The 1.3 had a 4.44 which would give you 3900 at 60.
The stock 2.3L and 3.44 axle - would be 3000 @60 - is it a genuine 2.3?

From the Autobooks data there were 7 different ratios covering the 1.3 1.6 2.0 and 2.3 none are 5:1

I would be making sure its a genuine 2.3 and the engine is still a 2.3 - just 2 exhaust outlets per side, although the 2.8 is a siamese as well - and checking that the tacho is not a 4 cyl version.

[Waxoyling Lyrical]

This RR thread from a while back casts further light/tips on the subject:
forum.retro-rides.org/thread/127090/cortina-diff-ratios