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DOHC Diff Info?
coozer - 9/9/09 at 02:49 PM

I have just bagged a LSD diff from what was described as 2.0L DOHC, but they argued as to whether it was a Granada or a Sierra... it had a MT75 box attached (saw it)

Its 7" across the top mount which is open. Flanges are 100mm.

What I'm after is the diff ratio. Theres no tag to look at and I've tried turning the flange to see how many turns on the input. I figure it to be 3.92 but not sure.

Anyone know how to calculate the ratio without taking the cover off and counting the teeth

Either way its going in but I need a pair of drive shafts. WHY?

Any info would be much appreciated.
Steve

Johneturbo - 9/9/09 at 02:52 PM

It should be a 3.92, if it was from a 2.8/2.9 then it would be a 3.62


ETA
data from sierra owners club

3.64:1 7.5" for the RWD Cosworth (with 108mm drive-flanges)
The Granada Cosworth 24v diff is the same as the 2WD Cosworth BUT with Sierra compatible 100mm drive flanges.

and the 4x4 Cosworth is the same as the 2.8/9 Sierra's 4x4's

and 2.0 DOHC 4x4 is 3.92:1 in a 7" diff

and some 2.0 RWD DOHC's are 3.91:1 in a 7.5" diff

and finally some 2.3 diesels have a 3.14:1 7" (hens teeth)


[Edited on 9/9/09 by Johneturbo]

tomgregory2000 - 9/9/09 at 02:52 PM

3.6something poss
thats what was fitted to my xr4x4 with the 2L DOHC 8v engine fitted but could be wrong edit: yep i was wrong sorry it is 3.92

i thought the only LSD diff fitted in 7" was the 3.6something

[Edited on 9/9/09 by tomgregory2000]

[Edited on 9/9/09 by tomgregory2000]

Johneturbo - 9/9/09 at 03:00 PM

you can get 7" lsd diffs in 3.6 and 3.9

if it was a 3.6 lsd coozer i'd take it

mcerd1 - 9/9/09 at 04:50 PM

quote:
Originally posted by coozer
I have just bagged a LSD diff from what was described as 2.0L DOHC, but they argued as to whether it was a Granada or a Sierra... it had a MT75 box attached (saw it)

doesn't matter, they are both the same running gear anyway

assuming its definatly a 7" LSD...
(1 long bolt on top mount, not 2 short ones)

if its from a 2.0l 4x4 (DOHC + MT75) it'll be a 3.92

if its from 2.9l 4x4 (V6) it'll be a 3.62

if it was a 7.5" from a granada cossie (24v V6) then it would still be a LSD with 100mm flanges, but with a 3.64 ratio

you can always take the back cover off - the ratio is often writen on the ring gear or just count the teeth
(there is no gasket, just use that sealant stuff) - besides it would hurt to drain the oil and have a look anyway




do you need whole drive shafts, or just the inner CV's (and the right push-in shafts to fit them)



[Edited on 9/9/09 by mcerd1]

coozer - 9/9/09 at 06:32 PM

Don't want to take the cover off, no point.

Current diff is an open 3.62 with push in shafts.
I'll clean it up and whack it in then I'll find out through the speedo and the Sat nav...

I have some XR4i drums to fit as well so would rather have the whole shaft to fit.

Or, is its possible to slip the inner push in cv off the shaft and fit bolt on ones?

mcerd1 - 9/9/09 at 08:11 PM

if your new one is a 3.92, your speedo will be 8% out (if it says 60 you'll really be doing 55.4)

quote:
Originally posted by coozer
Or, is its possible to slip the inner push in cv off the shaft and fit bolt on ones?


if your shafts are the right size then yes, I might have the bits you need going spare
but ask someone else who knows more about the conversion first (I don't know much about the push-in shafts - I've got bolt-on's with discs for the dax and on all donors)