Rear pinion seal

Hey Guys
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.
Doug
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snipped-for-privacy@gmail.com wrote:

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.
Ian
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wrote:

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. ----------------- TheSnoMan.com
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SnoMan wrote:

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?
Ian
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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?
Doug
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On 9 Oct 2006 12:35:44 -0700, snipped-for-privacy@gmail.com 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. ----------------- TheSnoMan.com
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wrote:

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. ----------------- TheSnoMan.com
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Yeah, like that will ever happen.

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 three?

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?
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On Mon, 09 Oct 2006 20:43:43 GMT, aarcuda69062

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. - Regards Gordie
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SnoMan wrote:

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 confirms that you haven't really done very many diff overhauls, if any!

You're unbelievable! Heh heh!
Ian
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wrote:

I was taught to never re-use the old pinion nut. Has this changed? Heck, we were taught not to even reverse the rotation without replacing the nut.
Al
Al
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Big Al wrote:

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 haunt me.
Ian
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