diffs
What is involved in this? Am I able to use the existing drive shafts?
There are far more ratios that I need (4.2+) in the 7.5" form than with the 7" form so it might be more cost effective to change the diff
rather than go for a new crownwheel and pinion which is 500 +vat +fitting
it'll depend how much room you've got around the diff at the moment - the 7.5" is a fair bit wider across the mounts....
Presumably half an inch?
quote:
Originally posted by SeanStone
Presumably half an inch?
Okay, so apart from the difference in top mount width, what other things are effecting the swapping of the different diffs?
swapped my 7 1/2 inch bolt on for a 7 inch bolt on by just dropping out one and putting a spacer on the top mount of the 7 inch to make it 7 1/2 .
shafts just fitted back on.
Paul
Be carefull to get the right size output flanges. There is 108mm (2wd cosworth), and 100mm Flanges.
the differing output shaft wont be a problem if the prop hasnt been made yet will it? Or is the output shaft where the driveshafts join?
I'd be using the 4.27 ratio which i believe is on the 2 litre 16v scorpio
Its the drive shafts that are different
cozzy shaft bolts are 10mm were sierra 's are 8mm
Hmm. Well from the chart on here http://www.fordscorpio.co.uk/mt75.htm
it would seem that the only car the 4.27 is from would be the 2 litre 16v, which isn't the cossie cariant. Whether or not the scorpios have
cossie sizes as standard, I don't know
the 2.0 scorpio's they have the same size CV joints as the 7" bolt-on sierra ones 
I guess you'll have to watch the driveshaft lengths (there are a few different lengths) and the mounting bolts are 6 short ones instead of 2 long
and 2 short.
btw some cars (inc. dax rush's) are designed to fit both types of diff, you just use different bolts and spacers to make them fit 
Well I'm going from a 7 to a 7.5, so Hopefuly it's already needed spacing!
Why are you changing - most people I heard go the other direction - to save weight.
Just curious.
Because to change my 7" diff to a ratio above 4.1 will cost me the best part of £750.
To change to a used 7.5" 4.27 will probably cost around £200 or less.
The S2000 has a final drive of 4.1 and I wanted a ratio either the same or bigger.
^^
do you know that a higher numbered ratio is actuall a lower gear ?
(sorry - just asking the obvious question)
have you had a go with one of the gear calc. programs yet ?
http://locost7.info/gearcalc.php
I know that some of the S2000 dax's use 4.1 / 4.4 ratio diffs and are very happy with them - but tyre size comes into it too and folk tend to use
bigger wheels/ tyres on the dax's
[Edited on 23/4/10 by mcerd1]
quote:
Originally posted by mcerd1
^^
do you know that a higher numbered ratio is actuall a lower gear ?
yea i'm aware of how the ratios work, and that 4.44 ratio will cost me a lot of money to fit into my existing diff.
I'm not so bothered about going past 140, i know there is a westfield with an s2000 engine that topped 150 at spa but i wont achieve that on the
british race tracks that i'll be going on.
And yea, as is correctly pointed out, it revs to 9000 rpm which effectively lengthens the gearing
I didn't think you were wrong - its confused alot of people on here in the past so its normally worth asking
I've actually looked at the same diff's before - my 3.92 should do for now
but if I ever get round to my head upgrades then 9000 rpm is a posability for me too 
assuming I had limitles power the 3.92 would give me a top speed of 196mph 
What engine are you running?
well its not running yet - but it will be a 2.1 pinto :lol: