When getting prepared to change the differential input pinion oil seal I
seem to have got some apparently conflicting information.
I suspect that Haynes ‘pinion flange nut torque’ is incorrectly
identified and that JHCD ‘backlash’, ‘torque’ and ‘pinion pre-load’ are
being interchanged and do NOT refer to torque on the input pinion nut.
I’ve looked through the online books and archives and could not find
anything about replacing the differential input seal to resolve the
question.
The Haynes manual looks very straightforward and easy to understand
except for the dire warning that if the torque (approximate) and
alignment marks (precise) do not coincide then it’s diff. out and off
to find a specialist(!).
BUT (big but) the torque under ‘differential pinion flange nut’ shows 4
to 6 Nm, i.e. 3 to 4 lbf ft.
(that is about finger tight - well sort of!)
However the JHCD (51.20.01) appears to make it into a far more
involved task.
(The picture shows a UJ not a JURID so I suspect the text is OK but the
picture and '2-legged puller bit are doubtful and not applicable to a
'92 XJ40.)
It says to measure the torque required to turn the pinion through the
backlash.
(My thoughts on this are, because it gives wheel nut torque’s, although
it doesn’t say so, it should be assumed that the wheels are off, and
that this is a torque at the input pinion flange (not backlash) required
to ‘rotate’ the whole differential, i.e. to drive the back wheels
round!)
(The normal interpretation of ‘backlash’ is ‘rotational slack’ and is an
angular amount, not a torque)
I can’t see what it means by ‘Ensure the pinion is reset between each
measurement’** BUT see NOTE below.
On assembly it says to tighten the drive flange nut to the mark. …
check pinion pre-load (35-55 lbs inch).
I.E. there is no mention of a torque on the actual input pinion drive
flange nut.
I note that 35-55 lbs inch ‘pre-load’ equates to near enough 3-4 lbs
feet and this looks remarkably like the Haynes;-
‘Torque wrench settings; Differential; Pinion flange nut 3 to 4 lbf ft’
** NOTE. In JHCD 51.00.00 it says that on the PowerLoc a torque is
required to turn the input if one wheel is prevented from turning. Maybe
the ‘each measurement’ means each wheel being prevented from rotating in
turn.
HOWEVER neither Haynes nor JHCD 51.20.01 suggest any difference in
procedure between ‘Normal’ and ‘PowerLoc’ diffs.
I expect someone has sorted this out and can confirm (or not) that the
3-4 lbf ft in Haynes is the rotational torque ‘drag’ caused by a preload
of the input pinion and that there is no specified pinion flange nut
torque as such, just tighten to the mark and hope the rotational torque
is the same as before (and close to 3-4 lbf ft).
And that there is no difference between Normal and PowerLoc.
(I’m still trying to ‘confirm’ my diff. unit. When topping up with oil I
could see on the casting ‘Salisbury’ GKN and the number 15HU-010-012
stamped in the casting)
Comments appreciated,
TIA
Richard.–
A.R.Mills
'92 XJ40 (Daimler)
Somerset U.K.
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In reply to a message from A.R.Mills sent Sun 11 May 2003:
Richard,
The 35 - 55 lbs/inch is the backlash torque, NOT the torque
required on the pinion nut to achieve that bearing pre-load.
It is measured as the torque to rotate the pinion gear over the few
degrees of backlash between it and the crownwheel. In other words,
all you are measuring in effect is the ‘friction’ of the pinion
bearing and as such it is very difficult to judge accurately - you
are only moving the pinion shaft through perhaps 10� or 20� maximum.
You are not trying to turn the crown wheel, drive shafts or wheels.
The torque required to tighten the pinion nut to achieve the
bearing pre-load by crushing the distance tube is not quoted. All I
can tell you on that is that on my car I could not physically apply
enough force by hand with a long breaker bar to undo the bloody
thing! I had to take it to a garage and have them undo it with an
air impact wrench.
BTW, do you have the 36mm DEEP thinwalled socket to tackle the
pinion nut?–
Bryan N ('91 Sovereign)
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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If you search the archives (use advanced search, the default search only
goes back one year) for my name and “pinion” you’ll find a complete set of
instructions for seal replacement and a link to pictures of the operation on
the Jag-lovers site.
Dave Lokensgard
'90 Vanden Plas Majestic (DAVZCAT)
'55 XK140 OTS
Poway, California
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I expect someone has sorted this out and can confirm (or not) that the
3-4 lbf ft in Haynes is the rotational torque ‘drag’ caused by a preload
of the input pinion and that there is no specified pinion flange nut
torque as such, just tighten to the mark and hope the rotational torque
is the same as before (and close to 3-4 lbf ft).
And that there is no difference between Normal and PowerLoc.
(I’m still trying to ‘confirm’ my diff. unit. When topping up with oil I
could see on the casting ‘Salisbury’ GKN and the number 15HU-010-012
stamped in the casting)
That’s correct. Additionally, the torque (if measured) should be measured
through the backlash (or more correctly the rotation required to move the
pinion through the backlash distance between the pinion gear teeth and the
ring gear teeth) at several points throughout the pinion bearing rotation to
get an average value. Tough to do. If you are just replacing the seal and
you don’t have noise, mark the relation of the nut relative to the shaft and
the flange, and restore to this configuration after replacing the seal. If
you have noise and want to try to reduce it, you can go past the marks when
you tighten the nut, but you risk ruining the bearing. Don’t forget to
polish the flange sealing surface.
The powerlock can be distinguished from the open diff by jacking up both
rear wheels, releasing the brake, placing the tranny in neutral and rotating
one wheel in the forward direction. If the diff is open, the other wheel
will tend to rotate in the opposite direction (if it rotates at all… if
not, put the tranny in park and try again), but if you have a PowerLoc diff
the other wheel will rotate in the same direction. There’s no difference
between the two types as regards the pinion setup.
Dave Lokensgard
'90 Vanden Plas Majestic (DAVZCAT)
'55 XK140 OTS
Poway, California
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Thank you Dave & Bryan for the information.
I’ll head over to the archives advanced search right now.
And I’ll make sure I’ve got a 36mm deep thin wall socket for my 1" drive
bar (and 4ft tube extension! I’ll have to sort out how to seriously lock
the flange to avoid loading the gears) and be prepared for a bit of
effort to get it undone.
I don’t think I would have worked out that bit about the backlash - I
had (wrongly) envisaged a constant turning torque as I rotated the input
pinion.
goes back one year) for my name and “pinion” you’ll find a complete set of
instructions for seal replacement and a link to pictures of the operation on
the Jag-lovers site.
–
A.R.Mills
'92 XJ40 (Daimler)
Somerset U.K.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Some pinion nuts are almost impossible to shift.
I had one that took a 3 foot pipe on the breaker bar,
me pushing it with both feet, back braced against the garage wall,
and I could shove the car over but not shift the nut.
Others came off with reasonable force.
I put a socket between the flange and the sub frame brace that runs
below it…bent the sub frame edge up a bit trying to get the
tight one loose (never did), but it did not hurt things…
Brett
Thank you Dave & Bryan for the information.
I’ll head over to the archives advanced search right now.
And I’ll make sure I’ve got a 36mm deep thin wall socket for
my 1" drive
bar (and 4ft tube extension! I’ll have to sort out how to
seriously lock
the flange to avoid loading the gears) and be prepared for a bit of
effort to get it undone.
I don’t think I would have worked out that bit about the backlash - I
had (wrongly) envisaged a constant turning torque as I
rotated the input
pinion.
If you search the archives (use advanced search, the default
search only
goes back one year) for my name and “pinion” you’ll find a
complete set of
instructions for seal replacement and a link to pictures of
the operation on
the Jag-lovers site.
–
A.R.Mills
'92 XJ40 (Daimler)
Somerset U.K.
Visit the Jag Lovers homepage at http://www.jag-lovers.org
for exciting services and resources including Photo Albums,
Event Diary / Calendar, On Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Perhaps in view of the potential difficulties and hazards (I’d hate to
spoil a silent diff.) it would be prudent not to jump in too quickly.
A preliminary rough estimate is that I cold be getting through about 0.4
Ltrs between 7500 mile services.
At my annual mileage that is less than 2 top ups per year.
So for now (the next year or so!!) I’ll monitor it at say 3k intervals
and then decide.
A bonus is that there is no sign of rust in the region of the
differential input
I had one that took a 3 foot pipe on the breaker bar,
me pushing it with both feet, back braced against the garage wall,
and I could shove the car over but not shift the nut.
–
A.R.Mills
'92 XJ40 (Daimler)
Somerset U.K.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Wise move.
As long as you keep lube in it, you are ok.
You can also use the thick Lucas oil stabilizer, it leaks slower.
If you decide to fix the leak, the dealers might be worthwhile,
as they will have experience, and should stand behind the results…
Brett
Perhaps in view of the potential difficulties and hazards (I’d hate to
spoil a silent diff.) it would be prudent not to jump in too quickly.
A preliminary rough estimate is that I cold be getting
through about 0.4
Ltrs between 7500 mile services.
At my annual mileage that is less than 2 top ups per year.
So for now (the next year or so!!) I’ll monitor it at say 3k intervals
and then decide.
A bonus is that there is no sign of rust in the region of the
differential input
Some pinion nuts are almost impossible to shift.
I had one that took a 3 foot pipe on the breaker bar,
me pushing it with both feet, back braced against the garage wall,
and I could shove the car over but not shift the nut.
–
A.R.Mills
'92 XJ40 (Daimler)
Somerset U.K.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
then it’s diff. out and off