I am looking to replace the rear pinion seal on my 98 Silverado but
have never done so. The Haynes manual I have is a little vague on the
seal replacement. I was told by a friend that I need to put a torque
wrench on the pinion nut with the wheels off of the ground and check
the rotational torque. I need to scribe the shaft, nut, and flange and
count the exposed thread. I then remove the whole works, install the
new seal, and tighten the nut down until the rotational force on the
axle is 3 inch-lbs higher than the original measurement. Does this all
sound right? Is there anything else I am forgetting. Thanks.
I will be very surprised if you can find an inch/lb torque wrench (has
to be a deflection style, click type won't work) that you can read
accurately down to 3 inch/lbs. You really want to see between
30-50 inch/lbs of rotating torque (and that's combined....pinion
bearings and side bearings, without the axles engaged, which means
that a proper repair involves some dis-assemby of the axle).
Having said that, his methodology is sound. I do not bother with
measuring rotational torque when doing a rear pinion seal. My method
is to first determine if there is any freeplay in the pinion shaft that
you can feel. If so, forget about just replacing the pinion seal, unless
you don't really care whether it fails quickly after the repair. In this
case, the only proper way to repair is to replace the pinion bearings,
crush sleeve, and adjust the pinion bearing preload properly.
If there is no discernable play, then I just mark the pinion shaft and
the pinion nut. Remove the nut, the yoke, remove the seal, install
the new one, and then just spin the nut back to it's original position.
The last thing that you want to do with used bearings is to "increase"
the preload. In fact, the specs in the manual will call for a much
lower preload with used bearings.
Adives is not bad but if they was any play you would know it because
rear end with be noisy. If it is fine otherwise just mark and remove
nut as stated above and them replace nut to exact same position. A
good air powered impact wrench is great for removing pinion nut as
they can kinda get stuck on there. Lacking air tools, get a socket
wrench and a breaker bar and postion wrench on nut so that when you
push the vehicle the bar will grab and hold bolt and break it loose.
This works really good. It will break in a counter clockwise rotation
so leave a several inches of play in bar before contact with frame or
ground and give vechical a push forward and momentum will do the rest
to break it loose.
These are the type of statements that lets everyone who "is in the know"
that you often speak of that which "you do not know". If you think that
every rear end that
has a loose pinion is noisy, think again. I've been rebuilding diffs since
the late 70's, I've seen just about every and any scenario regarding
diffs in general.
Thanks for the "adives is not bad" statement. Just can't resist adding
your own two cents to mine, eh?
Thanks for the help guys. I guess I will try and replace the seal and
see what happens. I would like to replace the pinion on the truck but I
was told that doing so was pretty tough on these Chevrolets. I am not a
beginner as a mechanic but this is the first truck I have ever owned.
Kind of new to this stuff. Everything else was front wheel drive. How
tough are the pinions to replace. I know the axles have to come out but
other than time consuming, are they tough to do?
On 9 Oct 2006 12:35:44 -0700, firstname.lastname@example.org wrote:
You cannot replace pinion without replacing ring gear as they are
matched sets (you could do it but it will likely be noisy and not last
long). As far as how hard it is to replace it well you must remove
axles and carrier anyway to replace ring gear too and depending on
axle type, you will either have to jack it up and remove diff cover to
remove spider gear cross shaft and push axles in a bit and remove C
clips holding them in on a 10 bolt or 14 bolt 9.5 semi floater and
then pull them out or just pull axles without jacking vehical up by
unbolting axle flanges at hubs and pulling axles if you have a 10.5
inch 14 bolt full floater. The problem is though that this is not
simple a bolt in replacement and the new gears have to be set to
proper perload in bearings and backlash as well and pinion depth. This
is not for the faint hearted but if you can get the tools needs and
follow instruction from a service manual it is doable. Patience is a
virtue when doing this work to take the time to do it correctly.
You know the difference between you and me is that you act like a
spoiled child that looks for trouble and likes to attack (a sign of
insecurity) while I will give someone their due whether I like them
or not. Also your expoeriance is in question because if the pinion
bearing were loose it would be noisy because it would change the gear
mesh/wear pattern as pinion moved from its desired rotational axis as
it responded to trust forces at gear tooth contact and transfer of
power which you would know if you really knew what you claimed too.
Maybe you have done it for 30 years but I am glad it was not on my
axle because your logic is not sound for such a simple piece of
mechanics and theory of operation. Years do not make experiance,
application of learned knowledge and being able to use it properly and
adapting it as needed does.
The thing is, Ian is correct. They don't always make noise.
Thrust forces eh? Is the thrust force on the pinion towards the
front or the rear? Which is the bigger bearing? What shape is
the pinion tooth? Are there two bearings supporting the pinion or
I await the day that automotive components can read the rule book.
You're right, "years don't make experience." Successfully
completed jobs do.
You've been handed how many repair orders that involve diagnosis
and repair of drive axles?
I've replaced a pinion seal and the nut worked loose again on me
enough to cause a vibration but NO noise did it make. Didn't clean
the threads thoroughly enough for the loctite to grip. Also, I didn't
use enough sealant on the spline and oil got out that way.
I tried again and everything was OK.
All the intellectualizing aside - it didn't make any noise.
Hey, Snoman, I've given you "your due". Unfortunately, you
act like a brain dead person who doesn't seem to get the fact
that they provide poor/erroneous information on a consistent
basis. Some of the stuff you throw out isn't bad. But really,
if you want to post consistently with the view to "helping" people,
I think you should be right on the money a lot more of the time.
I know exactly what you are talking about, but the very fact that you think
"all" loose pinions will produce a noisy gear set is false. This just
that you haven't really done very many diff overhauls, if any!
It depends. I re-use pinion nuts when just replacing the
pinion seal. But you could use a new one. I always use
a new one when overhauling a diff. Believe me, there
are many things that you are "supposed" to do, and many
things that you "can do". The fact is that if you were to
replace a pinion seal "properly", you should really dis-assemble
the diff, replace the crush sleeve and set the bearings up properly.
Nobody is going to do this because of the excessive cost to
the customer. But in reality, the theory is that once a crush
sleeve has been "crushed", it's no longer useful.
Much of what you are taught in tech school is the
"preferred" way of doing things. But it doesn't always
work out that way once you are out in the trade,
actually "doing" it. Just like you will be taught in
tech school to use a case spreader when doing Chevy
rear ends. I haven't even "seen" a case spreader in
15 years, let alone used one. And I can say that I
haven't had any of my diff overhauls come back to
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