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Changing rear Sierra Diffs question
scoop - 21/8/15 at 09:15 AM

Hi,
I'm changing from the 3.4 with the push in drive shafts to a 3.9 with bolt on 'shafts.
Am I right in thinking that I can just change the cv joints?
If so can anyone recommend a supplier please?

loggyboy - 21/8/15 at 09:31 AM

Outer hubs/carriers will need changing unless you 'hybridise' the shafts.

kingster996 - 21/8/15 at 09:32 AM

Useful info here http://forum.wscc.co.uk/forum/index.php/topic/101143-lsd-diff/

scoop - 21/8/15 at 09:38 AM

Is the 3.9 LSD then?

CosKev3 - 21/8/15 at 09:41 AM

quote:
Originally posted by scoop
Is the 3.9 LSD then?


pretty sure it will be, think there are some odd ball non lsd sierra diffs but 99% are lsd.

doesn't the seller know?

kingster996 - 21/8/15 at 09:42 AM

quote:
Originally posted by scoop
Is the 3.9 LSD then?
Not always - but LSD's will have bolt on Lobros...

kingster996 - 21/8/15 at 09:43 AM

quote:
Originally posted by CosKev3
quote:
Originally posted by scoop
Is the 3.9 LSD then?


pretty sure it will be, think there are some odd ball non lsd sierra diffs but 99% are lsd.

Other way round I'd say Kev - LSD only fitted to XR4x4 and some Cossies I think - but loads of non-lsd Sierras out there

scoop - 21/8/15 at 09:45 AM

I didn't think this was. How can you tell?

kingster996 - 21/8/15 at 10:00 AM

Usual method is to turn the output shaft on one side - if the other one goes the opposite way, it's an open diff.

There's also some numbers on the diff that can ID it - see here for info http://www.super7thheaven.co.uk/components/sierra_rear_differential/

scoop - 21/8/15 at 11:12 AM

Ok will have a look and give it a go.

scoop - 21/8/15 at 11:42 AM

Shame it's not as easy as I thought

CosKev3 - 21/8/15 at 05:16 PM

quote:
Originally posted by kingster996
quote:
Originally posted by CosKev3
quote:
Originally posted by scoop
Is the 3.9 LSD then?


pretty sure it will be, think there are some odd ball non lsd sierra diffs but 99% are lsd.

Other way round I'd say Kev - LSD only fitted to XR4x4 and some Cossies I think - but loads of non-lsd Sierras out there


With bolt on shafts????

CosKev3 - 21/8/15 at 05:17 PM

quote:
Originally posted by scoop
Shame it's not as easy as I thought


You won't get much easier a test then turning the output shafts!!!!

scoop - 21/8/15 at 07:00 PM

Lol. No I meant the swap

[Edited on 21/8/15 by scoop]

CosKev3 - 21/8/15 at 07:54 PM

quote:
Originally posted by scoop
Lol. No I meant the swap

[Edited on 21/8/15 by scoop]


Oh!

That should be pretty easy too,what are you stuck with?

Or is it the shafts your on about?

kingster996 - 21/8/15 at 08:44 PM

quote:
Originally posted by CosKev3
quote:
Originally posted by kingster996
quote:
Originally posted by CosKev3
quote:
Originally posted by scoop
Is the 3.9 LSD then?


pretty sure it will be, think there are some odd ball non lsd sierra diffs but 99% are lsd.

Other way round I'd say Kev - LSD only fitted to XR4x4 and some Cossies I think - but loads of non-lsd Sierras out there


With bolt on shafts????

Ah you didn't say that, but still plenty of open diffs with bolt on shafts, just look on evilbay

scoop - 21/8/15 at 09:07 PM

quote:
Originally posted by CosKev3
quote:
Originally posted by scoop
Lol. No I meant the swap

[Edited on 21/8/15 by scoop]


Oh!

That should be pretty easy too,what are you stuck with?

Or is it the shafts your on about?


Yes it's making my current shafts fit the new 3.92 diff. I was sure I had read in the past that you just changed the cv joints and hey presto.

CosKev3 - 21/8/15 at 09:55 PM

quote:
Originally posted by kingster996
quote:
Originally posted by CosKev3
quote:
Originally posted by kingster996
quote:
Originally posted by CosKev3
quote:
Originally posted by scoop
Is the 3.9 LSD then?


pretty sure it will be, think there are some odd ball non lsd sierra diffs but 99% are lsd.

Other way round I'd say Kev - LSD only fitted to XR4x4 and some Cossies I think - but loads of non-lsd Sierras out there


With bolt on shafts????

Ah you didn't say that, but still plenty of open diffs with bolt on shafts, just look on evilbay


No I didn't,but the OP said in first post the 3.9 is bolt on shafts

quote:
Originally posted by scoop
quote:
Originally posted by CosKev3
quote:
Originally posted by scoop
Lol. No I meant the swap

[Edited on 21/8/15 by scoop]


Oh!

That should be pretty easy too,what are you stuck with?

Or is it the shafts your on about?


Yes it's making my current shafts fit the new 3.92 diff. I was sure I had read in the past that you just changed the cv joints and hey presto.


If you have the correct amount of splines on your push in drive shafts it is that easy,the lobro just goes straight onto your drive shaft.

If you search on here you will find info on doing it,iirc the shafts need to have 23 splines to take a lobro.

scoop - 22/8/15 at 06:39 AM

Can you tell me what iirc and lobro means?

SJ - 22/8/15 at 07:05 AM

Iirc = if I recall correctly

Lobro is a just a different type of joint to the older tripide joint.

Stu

scoop - 22/8/15 at 07:11 AM

Thanks SJ.
So it may be a case of just swapping cv joints if once I have the current ones off I have 23 splines?

kingster996 - 22/8/15 at 07:55 AM

Depends what you mean by cv joints?

You can swap the individual cv joints on each individual driveshaft so one end is tripode (push in) and the other is lobro (bolt on). That is a hybrid shaft as per the link I posted.

If you mean swapping the whole driveshaft from one to the other, then as far as I know, this can't be done without also changing the bearing carrier to suit the shaft.

Happy to be corrected though.

kingster996 - 22/8/15 at 08:01 AM

quote:
Originally posted by CosKev3
No I didn't,but the OP said in first post the 3.9 is bolt on shafts

Now your bringing facts into the equation, that's not fair

scoop - 22/8/15 at 08:01 AM

Mine would be hybrid then

scoop - 24/8/15 at 08:35 PM

It's an open diff