My Sierra XR6 running gear
25-08-2018 | 09:28 PM
#1
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From: Boston Lincolnshire
My Sierra XR6 running gear
I have a 1987 Sierra XR6 from South Africa which has the Essex V6 engine as standard, the engine has been stage three modified so plenty of power. I have just fitted a T5 Cosworth Gearbox and prop shaft but my Diff has come from a Sierra Ghia. I have little power at the bottom end (ie I need lots of reeves to get started), so I’m convinced I have the wrong Diff. I want to fit a Cosworth diff but I’m not sure what ratios I need? Any help or guidance would be appreciated David
Last edited by daiboy370; 25-08-2018 at 09:31 PM.
25-08-2018 | 09:46 PM
#3
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From: Boston Lincolnshire
Thanks very much for coming back to me, am I right in thinking the Sierra Cosworth was 3.62:1 ratio, if so that should definitely work as the rest of my runnning gear is Cosworth?
David
David
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25-08-2018 | 10:52 PM
#8
25-08-2018 | 10:55 PM
#10
Copied from another post
The difference between the 7" and 7.5" can obviously be seen on the size, but that can be difficult when you don't have them next to each other. An other thing to look for is that the 7" diff has 2 long bolts (one at the bottom, other at the top) going through the diff to mount it in the beam. The 7.5" diff has only one 1 long bolt at the bottom and uses 2 short bolts from both sides for the top mounting point.
The difference between the 7" and 7.5" can obviously be seen on the size, but that can be difficult when you don't have them next to each other. An other thing to look for is that the 7" diff has 2 long bolts (one at the bottom, other at the top) going through the diff to mount it in the beam. The 7.5" diff has only one 1 long bolt at the bottom and uses 2 short bolts from both sides for the top mounting point.
26-08-2018 | 07:22 AM
#14
I would first check what ratio you have now. There should be a tag on the back of the diff that has something like 362 in it. That number is the ratio of the diff, 362 means 3.62:1.
26-08-2018 | 11:23 AM
#16
Might be worth looking for a 2 litre XR4x4 diff as it's a 3.9:1 and has a lsd.
http://www.super7thheaven.co.uk/comp..._differential/
http://www.super7thheaven.co.uk/comp..._differential/
26-08-2018 | 12:07 PM
#17
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From: Boston Lincolnshire
Hi, am I wrong or would it make sense that because the rest of my drive train is Cosworth ( 2wd) I should be fitting a 2wd Cosworth Diff?
appologise if this nonsense but I only have limited knowledge and I’m getting on a bit.
the diff currently fitted cam from a Sierra Ghia
appologise if this nonsense but I only have limited knowledge and I’m getting on a bit.
the diff currently fitted cam from a Sierra Ghia
26-08-2018 | 12:35 PM
#18
Cosworth 2WD diff is wider than the one you have fitted and will not fit your beam without modifications.
Have a look at the tag on the diff you have now and use the link I posted to find out what the ratio is, if you're struggling with low end torque you'll need a lower ratio diff to help pull away.
There's not much point changing it if you end up with a similar ratio, I'm surprised even a tuned Essex V6 has a lack of low down torque though!
Have a look at the tag on the diff you have now and use the link I posted to find out what the ratio is, if you're struggling with low end torque you'll need a lower ratio diff to help pull away.
There's not much point changing it if you end up with a similar ratio, I'm surprised even a tuned Essex V6 has a lack of low down torque though!
26-08-2018 | 03:36 PM
#22
It seems like the tag on the diff is gone. It should have been on the upper left rear corner of the diff. Another option is to remove the rear diff cover. The ratio is written on the crown wheel in white.
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26-08-2018 | 05:24 PM
#24
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From: Holbury,Southampton
Cosworth 2WD diff is wider than the one you have fitted and will not fit your beam without modifications.
Have a look at the tag on the diff you have now and use the link I posted to find out what the ratio is, if you're struggling with low end torque you'll need a lower ratio diff to help pull away.
There's not much point changing it if you end up with a similar ratio, I'm surprised even a tuned Essex V6 has a lack of low down torque though!
Have a look at the tag on the diff you have now and use the link I posted to find out what the ratio is, if you're struggling with low end torque you'll need a lower ratio diff to help pull away.
There's not much point changing it if you end up with a similar ratio, I'm surprised even a tuned Essex V6 has a lack of low down torque though!
26-08-2018 | 06:57 PM
#25
Probably worth getting the car set up on a rolling road before changing the diff, the 3.0 Capri had a 3:1 ratio and they never struggled to pull it...
27-08-2018 | 09:39 AM
#30
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From: Boston Lincolnshire
Hi, I have a T5 that was re-built by CTS back to standard, the gearing was not right when I had the type 9 fitted. The diff I have fitted was from a Sierra Ghia ether 2 or 2.3 ltr I think. My Essex V6 is pushing our well over 300 bhp at the wheels so I wanted something fitted that can handle that!
Im no going back to the old running gear therefore I need to solve this Diff issue, to a layman like me with little knowledge it made sense to fit a diff from a 2wd Cosworth. Can somebody confirm if the Sierra Diff was the same fitted to the Scorpio Cosworth?
what was the 2wd Diff, 7 or 7.5?
David
Im no going back to the old running gear therefore I need to solve this Diff issue, to a layman like me with little knowledge it made sense to fit a diff from a 2wd Cosworth. Can somebody confirm if the Sierra Diff was the same fitted to the Scorpio Cosworth?
what was the 2wd Diff, 7 or 7.5?
David
27-08-2018 | 10:23 AM
#31
David first I'd like to see some pics of the engine.
and then some pics of the diff and shafts.
Are you still running drums on the rear?
Most diffs should have the tag on the back to tell ya.
and then some pics of the diff and shafts.
Are you still running drums on the rear?
Most diffs should have the tag on the back to tell ya.
27-08-2018 | 12:21 PM
#32
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From: Boston Lincolnshire
[img]blob:https://passionford.com/9e30c6ca-821d-427b-bd0f-7c3e26ca90a8[/img][img]blob:https://passionford.com/5788198a-1c7d-4de6-af26-c4de4fc153ae[/img][img]blob:https://passionford.com/282ce2dc-bc9a-4fa6-8ad5-8d2d3cff9dae[/img][img]blob:https://passionford.com/691cfab3-0ec6-4e64-bdf2-d69a53d134bc[/img]
27-08-2018 | 06:16 PM
#39
Imo if you still running drums on the rear you will have a std type diff.
So you will need a complete rear end from a 2wd cosworth which includes lsd with correct shafts disc brakes and the arms with special spherical bushes in them.
So you will need a complete rear end from a 2wd cosworth which includes lsd with correct shafts disc brakes and the arms with special spherical bushes in them.