Nickp
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| posted on 17/5/17 at 06:44 PM |
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Any Sierra diff experts?
So, I've bought a 3.14 open diff to sort the gearing on my Haynes. Had a nightmare stripping it, but that's another story!! 
I've used its case complete with pinion as I didn't want to mess with this and only wanted to set the backlash. I fitted the crown wheel
to my LSD and used the bearing caps that came with the LSD. I set the backlash and preloaded the bearings, all OK.
However, when I've been turning the diff over using the nut on the drive flange it came loose very easy. The guide I've been using says
that this should be tightened to 110nm after the pinion has been set up. But when I tighten it the pinon begins to become very tight to turn.
Something doesn't seem right, am I missing something?
This is the guide I've been using-
http://www.fordscorpio.co.uk/manual/rearaxle/DiffOverhaul.pdf
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obfripper
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| posted on 17/5/17 at 07:45 PM |
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The guide you have is for a shimmed preload pinion bearing type which is torqued to a preset torque, i think you may have a crush tube preload type
pinion which requires a different type of setup.
The crush tube type requires the nut to be tightened to give a specific turning resistance at the drive flange, usually measured with a spring balance
pulling a string around the outside of the drive flange.
Once the required turning force is achieved the pinion nut is staked into position, the force varies depending upon what new parts have been
fitted.
Dave
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Nickp
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| posted on 17/5/17 at 07:57 PM |
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quote:
Originally posted by obfripper
The guide you have is for a shimmed preload pinion bearing type which is torqued to a preset torque, i think you may have a crush tube preload type
pinion which requires a different type of setup.
The crush tube type requires the nut to be tightened to give a specific turning resistance at the drive flange, usually measured with a spring balance
pulling a string around the outside of the drive flange.
Once the required turning force is achieved the pinion nut is staked into position, the force varies depending upon what new parts have been
fitted.
Dave
Ahhh right, that kinda makes sense. Diffs all built up now so I'm a bit limited what I can do regarding measuring it. Can probably just adjust
it until I start to feel a difference. Need to make sure the nut is locking and add loctite as it wont be very tight I guess? Strangely the nut on the
other diff I have is very tight but the pinion spins easily.
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obfripper
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| posted on 17/5/17 at 08:56 PM |
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Looking closer, there is a nut underneath the drive flange which sets the preload. Under normal circumstances tightening the drive flange nut should
not affect the preload as the flange should bear on the back of the (tightened) preload nut, and the drive splines will prevent the flange turning the
preload nut further under friction.
You could remove the drive flange and just check the nut underneath is not obviously loose or has stripped threads, it will not harm anything to do
so, (they're the only reasons i can think of for the flange nut making the pinion tight to turn and would point to prior maladjustment) but
readjusting ideally needs the special tools to set the preload, a new crush sleeve and oil seal, and would need the diff removed from the casing.
I'm sure the older haynes manual had the procedure to set the preload using alternative tools in the way previously described, the force
required can be calculated from the turning torques given for the special tool and the circumference of the flange.
The only thing which isn't adjustable without the special tools is the pinion depth, but that only needs touching if the bearing or pinion is
replaced.
I would look to get the setup as right as possible while things are apart to maximise the diff life.
Dave
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CosKev3
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| posted on 18/5/17 at 04:26 AM |
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The inner nut to set the pinion is left hand thread,the drive flange retaining nut is normal right hand thread.
Must be the inner nut is not locked in position?
[Edited on 18/5/17 by CosKev3]
[Edited on 18/5/17 by CosKev3]
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Nickp
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| posted on 18/5/17 at 05:12 AM |
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quote:
Originally posted by CosKev3
The inner nut to set the pinion is left hand thread,the drive flange retaining nut is normal right hand thread.
Must be the inner nut is not locked in position?
[Edited on 18/5/17 by CosKev3]
[Edited on 18/5/17 by CosKev3]
Ta, I'll get the drive flange off (when I find my puller!!) and have a look.
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mark chandler
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| posted on 18/5/17 at 06:30 AM |
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You can recover the crush washer, just push over a metal rod, big bolt or similar and gentle tap the swollen bit to restore some of its length.
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Nickp
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| posted on 18/5/17 at 09:13 AM |
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Problem solved. Someone had fitted a new front seal but hadn't knocked it in far enough. As I tightened it up it was pushing against the seal
and locking the diff up. Inner nut looked fine and is nicely locked up.
Sorry, just to confirm, they'd fitted the pinion seal back to front!!
[Edited on 18/5/17 by Nickp]
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CosKev3
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| posted on 18/5/17 at 08:22 PM |
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IIRC the pinion seal does look like it's in the wrong way around,but it's meant to be like that!
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Nickp
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| posted on 18/5/17 at 08:27 PM |
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quote:
Originally posted by CosKev3
IIRC the pinion seal does look like it's in the wrong way around,but it's meant to be like that!
Exactly. Never seen one before but the rubber lip didn't make sense the way it was. Thought about it then stripped my current diff flange and
confirmed my thoughts. Luckily had a new one and it's all back together now. The joys of holding a diff in one hand whilst trying to slot the
bolts in!! Good job I've been to the gym!! 
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CosKev3
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| posted on 18/5/17 at 08:33 PM |
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Yeah they are awkward!
I can see how someone would put it in the wrong way though tbh,as I've never seen a seal of that type on anything else in back to front!
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Nickp
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| posted on 18/5/17 at 08:49 PM |
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quote:
Originally posted by CosKev3
Yeah they are awkward!
I can see how someone would put it in the wrong way though tbh,as I've never seen a seal of that type on anything else in back to front!
True, but not if they'd took the old one out
I knew something wasn't right even though it kinda looked right 
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