timex
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 posted on 22/11/07 at 08:07 PM |
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Whats my Diff ratio?
I think it is a 3.92 but not sure.
Its from a 4X4 Sierra 2.0 DOHC
H reg So it is Aug 1990 - Jul 1991
7"
Can anybody please help?
Cheers, Phill
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mookaloid
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| posted on 22/11/07 at 08:10 PM |
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has it got an identity tag on it? the ratio will be on it if it has.
Failing that count the number of turns of the prop flange compared with the number of turns of the wheels,
Failing that take the back off and see what is written on the crown wheel
Cheers
Mark
edit - it should be a 3.92 though 
[Edited on 22/11/07 by mookaloid]
"That thing you're thinking - it wont be that."
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timex
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| posted on 22/11/07 at 08:13 PM |
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Thanks 
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trikerneil
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| posted on 23/11/07 at 02:56 AM |
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If you still have access to the VIN plate this may help.
vin plate codes are as follows
Ratio Code
3.14 M
3.36 A
3.38 U
3.62 V
3.64 3
3.92 D
Neil
ACE Cafe - Just say No.
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snapper
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| posted on 23/11/07 at 07:01 AM |
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quote:
4X4 Sierra 2.0 DOHC
should be a 3.9 LSD 7"
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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viatron
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| posted on 23/11/07 at 08:45 AM |
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as above if its off the 2.0 litre it should be a 3.92 lsd, the 2.8 ran a 3.6 lsd.
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mcerd1
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| posted on 23/11/07 at 10:55 AM |
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as everyone else says: 4x4 2.0l = 3.92 LSD
its worth at least counting the number of turns though - just to make sure (incase someones swaped the ratios on the sierra)
all the V6 and cossie 4x4's have 7" 3.62 LSD's
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timex
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| posted on 23/11/07 at 01:56 PM |
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I thaught that all LSD diffs were 7.5" tho?
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bigrich
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| posted on 23/11/07 at 04:42 PM |
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i would agree with 3.92 LSD 7 inch.
heres a list of ratios and sizes etc
Push in type shafts
KC 3.14 7"
LC 3.38 7"
MC 3.62 7"
JD 3.92 7"
DA 3.91 7.5"
Bolt on shafts
BA 3.14 7"
GB 3.14 7.5"
DAA 3.14 7.5" LSD
FA 3.36 7.5"
AAA 3.36 7.5" LSD
AC 3.38 7"
CAA 3.38 7" LSD
BC 3.62 7"
BAA 3.62 7" LSD
AAA 3.64 7.5" COSWORTH (this has the same number as the 3.36 7.5" LSD BUT is ID'ed by 108mm drive flanges)
ADA 3.64 7.5" GRANADA COSWORTH
DC 3.92 7"
AA 3.92 7" LSD
GA 3.91 7.5"
ABA 3.91 7.5" LSD
Rich
.JPG)
A pint for the gent and a white wine/fruit based drink for the lady. Those are the rules
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timex
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| posted on 23/11/07 at 06:36 PM |
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Thanks for that list!
Cant look at the vin plate as that went ages ago. Also the diff ID tag is missing and the diff is already mounted in the car.
http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=rsz_000_0143.jpg
We did not realy think about diff ratios until now 
Is they any way of checking to see if its a LSD with it in the car?
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L5W
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| posted on 23/11/07 at 08:49 PM |
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Hi there,
just having a look at the vin plate from my donor sierra, a J reg saloon 1.8cvh LX.
On the left hand side of the VIN plate, just under half way down theres a box labelled "AXLE PT. AR." with a "D" in it.
Am I looking in the right place and does this mean its a 3.92?
cheers,
Lee
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bigrich
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| posted on 24/11/07 at 10:44 PM |
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my first doner was a 1.8lx and i had a 3.92 aswell
A pint for the gent and a white wine/fruit based drink for the lady. Those are the rules
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bigrich
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| posted on 24/11/07 at 10:48 PM |
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quote:
Is they any way of checking to see if its a LSD with it in the car?
If you rotate the prop flange and the driveshaft flanges both turn the same way you have a LSD if they turn in opposite directions then its an
open/non LSD
Rich
A pint for the gent and a white wine/fruit based drink for the lady. Those are the rules
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timex
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| posted on 25/11/07 at 02:48 PM |
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Right, I removed the rear cover of the diff case today to have a look at the pinion gear.
It had 47 teeth. In white writing it had 3.92 on it and it also had 83BG4210-JF stamped into the pinion.
The pinion also had a "S and a star shape" symbol stamped on it if that means any thing? Other codes on it were X17 and O}9837
Like said I was told that it came from a 2.0 DOHC Sierra 4X4
It is a 7" Diff
Has 100mm Bolt on drive shafts
Can anybody please comfirm what diff we have got?
Thanks, Phill
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mcerd1
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| posted on 26/11/07 at 08:39 AM |
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quote:
Originally posted by bigrich
If you rotate the prop flange and the driveshaft flanges both turn the same way you have a LSD if they turn in opposite directions then its an
open/non LSD
^^^^
what rich said - thats the easiest way to ckeck its an LSD
but if you've got the cover off - post some pic's of the insides and we'll have a look (its quite easy to tell the difference when
you see the insides of both kinds)
also have a look here for more info:
http://forum.fordsierraclub.co.uk/viewtopic.php?t=5843&highlight=diffs
[Edited on 26/11/07 by mcerd1]
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timex
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| posted on 26/11/07 at 05:30 PM |
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Dam covers back on now and seeld. Just took the codes, writing and counted the teeth on the pinions. 
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mookaloid
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| posted on 26/11/07 at 09:15 PM |
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If you jack the rear of the car off the ground, then try and turn the wheels, the lsd will be stiff to turn but the open diff will be easy to turn.
Cheers
Mark
"That thing you're thinking - it wont be that."
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mcerd1
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| posted on 27/11/07 at 09:29 AM |
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^^^^^^^
what Mark said
unless you have a good memory:
these pics are from that FSOC thread (someone here might have better ones)
thats an LSD in the pics, you can almost see in those pics that there is a big 'lump' on the back of the crown wheel, were all those
stiffener ribs/ webs are
as oposed to an open diff where the back is almost flat and the stiffeners go all the way to the centre
its hard to explain, but when you see the two types together its obvious
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timex
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| posted on 28/11/07 at 06:09 PM |
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Yep, Im pretty dam sure that we have a 3.92 LSD now. Looked just the same as that but in much beter condition. Also when we jacked the back of the
car up and put it into 1st to stop the prop from moving it was very hard to turn the wheels.
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mcerd1
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| posted on 29/11/07 at 08:54 AM |
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the test procedure in the haynes book (sierra V6 & 4x4) is basically the same as you've just done
but you use a socket & torque indicator/ wrench (on the hub nut) and try to turn it 1/2 a turn in a few seconds - if it gets to the torque range
they say then you have a working LSD
[Edited on 29/11/07 by mcerd1]
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DarrenW
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| posted on 29/11/07 at 11:06 AM |
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quote:
Originally posted by timex
Yep, Im pretty dam sure that we have a 3.92 LSD now. Looked just the same as that but in much beter condition. Also when we jacked the back of the
car up and put it into 1st to stop the prop from moving it was very hard to turn the wheels.
Wouldnt it be harder to turn the wheels with any diff if you put it in gear? I thought the turning test was with the car in neutral.
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mcerd1
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| posted on 29/11/07 at 12:27 PM |
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now you mention it, I'd better read it again to check exactly whats in the test....(unless someone else beats me to it)
in the mean time:
with it in gear and both wheels off the ground --- if you turn one wheel, the other wheel has to turn the opposite way regardless of any LSD
with an open diff it will be a little harder to turn than normal - with an LSD it will be alot harder
(that is right, isn't it ??)
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timex
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| posted on 29/11/07 at 05:26 PM |
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Well I imagine with a non LSD and input stoped from rotating I,E put into gear, it would be easyer to turn than an LSD diff. Ours was very stiff to
turn using the wheel.
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mcerd1
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| posted on 10/12/07 at 03:43 PM |
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eventually
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