Replacing pinion bearings in a rear 10B... 9.25.07 - bearings look good???

[user]

yes. when you put the bearings and race into the cup and roll it around, it'll feel gritty-to-rumbly in your hand if it's bad. it'll feel silky-smooth when you rotate it if it's good.

 

[jonrpick]

yes. when you put the bearings and race into the cup and roll it around, it'll feel gritty-to-rumbly in your hand if it's bad. it'll feel silky-smooth when you rotate it if it's good.

that's what I figured...good to know.

 

[user]

You're right about what the service manual says, but that's written for dolts, some of whom work as mechanics at GM dealerships, and assumes that each step needs to be spelled out as if building an entirely new differential from parts. The tech writers had no way of knowing which parts you might want to replace, after all. If you're not replacing the side bearings and shims, all you need to do is put that stuff back together exactly as it was.

Now, I am assuming that the wear pattern on the ring and pinion indicates a normal spatial relationship. See, for example,
http://www.differentials.com/images/pattern-ok.gif -- now, I'd say that if you look at that chart, even though they're all listed as "acceptable patterns", I'd say you need to decrease backlash if your pattern looks like the one in the lower right, and increase it if it looks like the lower left. The closer it looks to the uppermost pair, the better.

 

[daleearnhardt01]

You're right about what the service manual says, but that's written for dolts, some of whom work as mechanics at GM dealerships, and assumes that each step needs to be spelled out as if building an entirely new differential from parts. The tech writers had no way of knowing which parts you might want to replace, after all. If you're not replacing the side bearings and shims, all you need to do is put that stuff back together exactly as it was.

While you are def correct about the morons who work at dealerships etc, I personally just like to be sure everything is to spec after doing something like pinion bearings, etc. Its not like it takes a lot of time to check preload or something. Better safe than sorry IMHO.

 

[jonrpick]

While you are def correct about the morons who work at dealerships etc, I personally just like to be sure everything is to spec after doing something like pinion bearings, etc. Its not like it takes a lot of time to check preload or something. Better safe than sorry IMHO.

Once I get paid again, I'm gonna get one of those magnetic-base dial indicators. I figure it's a good tool to have, and I would like to know how to do it right rather than pay someone else to regear my axles.

It'll make axle-shopping a lot easier if I'm not trying to find something with the exact gear ratio I want already installed.

 

[user]

(for tools http://www.littlemachineshop.com/
good deals on precision measurement stuff
only one transaction with me, but that went well

 

[roadnotca]

For individual bearings or for making a set-up brg., try an industrial brg. supply house. Match the numbers from the current brgs. If they aren't Timken, they can cross reference. <$13.

 

[user]

I always used the old bearings as setup bearings - which you need to do proper adjustment of pinion depth, because the shims are located between the back of the gear and the pressed-on bearing. So my suggestion is, when you take off the old bearings, and assuming they're not totally shot, grind out the inside diameter until they slide on and off the pinion shaft easily. Then you can use those in lieu of new bearings (which would be a pain to get off again without damage) when you go to measure the distance between the center line of the axle shaft to the face of the pinion in thousandths of an inch. Btw, here's another tip - when you do that measurement, be sure to rotate the pinion between measurements and do it about nine or ten times, recording the numbers on a piece of paper. Then take an average. That's 'cause the pinion face itself is usually not flat - it's actually kind of lumpy because of the way they do the final machining and polishing. Hard to see, because the hills are only ten to twenty thousandths of an inch offset from the valleys; so an average of a lot of observations is going to give you the most accurate number.

 

[jonrpick]

Hmm... Noob mistake #1. If you start turning pinion nut with wrench, truck moves.

The only thing I can think of is to put it in 4-Hi and lock the front hubs. I don't have wheel chocks. Of course, I suppose it's good I realized this, as if I were to jack it up, it'd wanna roll. I'll lock the hubs...

 

[jonrpick]

Pinion nut won't budge...

So I locked the front hubs, put it in 4-Hi... even with my breaker bar I can't get it to budge.

FYI, I am trying to loosed the pinion nut first, while the wheels are on the ground since I'm low on tools.

 

[user]

Here's links to some pictures of a tool I made for
holding the flange while removing the pinion nut.
It consists of a piece of 1" angle iron with two
holes drilled in one end using the U-joint flange
strap as a template. It's important to drill the
holes in such a way as to avoid covering up the
nut with part of the tool. After installation
of the tool, I used a 18" long 3/4" drive breaker
bar to loosen the pinion nut, and whizzed it off
with an air-impact wrench.

http://virginialegaldefense.com/INFO/DSC00922.JPG
http://virginialegaldefense.com/INFO/DSC00924.JPG
http://virginialegaldefense.com/INFO/DSC00925.JPG
http://virginialegaldefense.com/INFO/DSC00926.JPG

 

[jonrpick]

Here's links to some pictures of a tool I made for
holding the flange while removing the pinion nut.
It consists of a piece of 1" angle iron with two
holes drilled in one end using the U-joint flange
strap as a template. It's important to drill the
holes in such a way as to avoid covering up the
nut with part of the tool. After installation
of the tool, I used a 18" long 3/4" drive breaker
bar to loosen the pinion nut, and whizzed it off
with an air-impact wrench.

http://virginialegaldefense.com/INFO/DSC00922.JPG
http://virginialegaldefense.com/INFO/DSC00924.JPG
http://virginialegaldefense.com/INFO/DSC00925.JPG
http://virginialegaldefense.com/INFO/DSC00926.JPG

Excellent... My breaker bar is probably right at 18", 1/2" drive, and yesterday I ran to Sears to get a Craftsman 1.25" socket to fit it. Sounds like I'm using a similar setup. Hopefully the angle-iron brace will do it.

I don't have any air tools at the moment, nor a compressor, but if I need to I can borrow some from a friend next week.

On a side note, I pretty much destroyed the rear u-joint trying to get the driveshaft separated from the yoke. It was stuck on there pretty good. It took some prying from different angles, and finally one end of the joint let go and shot it's cap and roller needles across the floor

Thanks for the tip!

 

[jonrpick]

Excellent... My breaker bar is probably right at 18", 1/2" drive, and yesterday I ran to Sears to get a Craftsman 1.25" socket to fit it. Sounds like I'm using a similar setup. Hopefully the angle-iron brace will do it.

I don't have any air tools at the moment, nor a compressor, but if I need to I can borrow some from a friend next week.

On a side note, I pretty much destroyed the rear u-joint trying to get the driveshaft separated from the yoke. It was stuck on there pretty good. It took some prying from different angles, and finally one end of the joint let go and shot it's cap and roller needles across the floor

Thanks for the tip!

Well... I made the tool as described, and installed it the same way on the pinion. The only difference is I still haven't jacked up the rear, and the tires are still on the ground (somehow I feel safer that way).

So now the problem is that I'm unable to even slightly budge that friggin' pinion nut. I know that in order to crush the sleeve, it must've been torqued down pretty tight to begin with. I was practically hanging on the breaker bar and bouncing myself up and down to try to loosen it... But no go.

Anyone want to chime in and possibly provide an alternate way of getting it off?

 

[user]

Put the breaker bar on the right hand side of the nut (left or driver's side of the truck) angled slightly downward, say at four to five o'clock. then roll your floor jack up underneath of the end of it and start jacking. Use the weight of the truck to get the thing loose. That's why I use blue loctite on these things rather than red! Make sure when you do this that the breaker bar is at 90 degrees, or else the jack will just make the bar swing inwards rather than up. If you want to add leverage, use a piece of galvanized steel pipe (not iron gas pipe, 'cause it'll bend too easily) the inside diameter of which is just larger than the largest outer dimension of your bar handle, maybe four to six feet long; slip it over the bar and jack up the end of THAT. More length equals more leverage equals more torque at the nut, which will acting as the fulcrum point of the leverage system. If that doesn't work, use an electric heat gun (not an arc, you'll fry the alternator; and not acetylene or mapp, too hot; and not even a propane torch, too much risk of catching stuff on fire) on the nut and try again, but be careful not to ignite the oil, grease, and gasoline that's in that area, and recognize that you'll be trashing the oil seal and possibly the bearings. Of course if you catch some of those flammables alight while you're under the truck with limited crawl space, you'll be re-creating the napalm experience of Viet Nam, right? It'll be a horrible death. You want to get the nut hot enough to do the thermal expansion thing, and possibly to melt the loctite a bit, but it doesn't need to start glowing, right?

 

[jonrpick]

Put the breaker bar on the right hand side of the nut (left or driver's side of the truck) angled slightly downward, say at four to five o'clock. then roll your floor jack up underneath of the end of it and start jacking. Use the weight of the truck to get the thing loose. That's why I use blue loctite on these things rather than red! Make sure when you do this that the breaker bar is at 90 degrees, or else the jack will just make the bar swing inwards rather than up. If you want to add leverage, use a piece of galvanized steel pipe (not iron gas pipe, 'cause it'll bend too easily) the inside diameter of which is just larger than the largest outer dimension of your bar handle, maybe four to six feet long; slip it over the bar and jack up the end of THAT. More length equals more leverage equals more torque at the nut, which will acting as the fulcrum point of the leverage system. If that doesn't work, use an electric heat gun (not an arc, you'll fry the alternator; and not acetylene or mapp, too hot; and not even a propane torch, too much risk of catching stuff on fire) on the nut and try again, but be careful not to ignite the oil, grease, and gasoline that's in that area, and recognize that you'll be trashing the oil seal and possibly the bearings. Of course if you catch some of those flammables alight while you're under the truck with limited crawl space, you'll be re-creating the napalm experience of Viet Nam, right? It'll be a horrible death. You want to get the nut hot enough to do the thermal expansion thing, and possibly to melt the loctite a bit, but it doesn't need to start glowing, right?

I'll try the jack in just a little while. If that doesn't work I'll wait till next week and borrow some air tools.

 

[user]

steel pipe leverage multiplier & other special tools

I've been thinking some more about the original mission, which was to replace pinion bearings, in connection with the too-hard-to-get-off pinion shaft retainer nut. The fact that the nut is on there so tight explains why the bearings went bad. It takes a lot of torque (300 to 400 foot pounds) to get the nut into the proper position, because the crush sleeve has to be compressed. But you have to do that very carefully, because it should take between one and two foot pounds of torque to overcome the friction necessary to make the pinion shaft move with bearings and nut installed, because of the preload the crush sleeve is imparting to the bearings. So your "real" problem is that some idiot overtightened the pinion nut.

I use a four-foot length of one-inch galvanized steel pipe as a torque multiplier; I slip the breaker bar (a Craftsman 3/4 inch drive, 18 inch long model) into the end of the pipe, which fits perfectly. The frame of the truck has to be about 20 inches off the ground in order to do this properly, but I turn that pinion nut about one-sixth of a turn from each side of the truck (I'm using a six-point socket - if it were twelve, I wouldn't have to move from one side of the truck to the other, but I'd probably break the socket) until I get the requisite torque in turning the shaft. Here's the hard part, which lazy people who overtighten pinion nuts seem to want to skip: you have to remove your flange-holding tool after every couple of tightening moves with the breaker bar after you've got it down tight, until you (1) can feel that there's no play in the bearings, and (2) get the bearings tight enough to give the necessary preload. That means, tighten the nut a little, remove the flange retainer, check the shaft, replace the flange retainer, tighten a little, ... - repeating as necessary. It's a time-consuming process, but self-discipline and patience will pay off.

AS to the use of the special flange retainer tool I made out of a piece of angle iron: When you're removing the pinion nut, you want that piece of iron to stick out from under the truck ABOVE the leaf spring on the passenger side, so that turning the pinion compresses the iron against the spring - that's what keeps the flange from turning. But when you're installing the pinion nut, you want the angle iron to stick out from BELOW the leaf spring so that twisting the shaft clockwise compresses the angle iron upwards against the spring. I use a bungee cord to hold the iron tightly to the spring while I'm turning the pinion nut. So it's really the leaf spring that's holding the flange in place while you're turning the pinion nut.

Another btw: the crush sleeve acts as a compression spring, so, at least in theory (I don't go to this much trouble if all I'm doing is replacing an oil seal), you're supposed to use a new crush sleeve and pinion retainer nut every time you loosen or remove the pinion nut, because that decompresses the crush sleeve and it can never be compressed exactly that way again.

Also, when you put the flange back on, be sure to stick some Permatex Ultra-Black oil resistant non-hardening sealer on the splines of the pinion shaft down onto the smooth part and into the recess of the oil seal, but not so much as to get it into the bearing. My 1990 shop manual refers to a Permatex non-hardening sealer product that is no longer made, but the black silicone stuff works better, in my opinion. And don't shove the oil seal too far in - it's got to be flush with the surface of the top of the hole in the third member that the shaft sticks out of. The seal doesn't seal the shaft, it seals the flange.

Ok, now I think I've said everything I know about differentials, so like Forrest Gump, "that's all I've got to say about that."

 

[bear76]

Or just spend the $50.00 and get another rear off craiglist or JY.

 

[jonrpick]

I've been thinking some more about the original mission, which was to replace pinion bearings, in connection with the too-hard-to-get-off pinion shaft retainer nut. The fact that the nut is on there so tight explains why the bearings went bad. It takes a lot of torque (300 to 400 foot pounds) to get the nut into the proper position, because the crush sleeve has to be compressed. But you have to do that very carefully, because it should take between one and two foot pounds of torque to overcome the friction necessary to make the pinion shaft move with bearings and nut installed, because of the preload the crush sleeve is imparting to the bearings. So your "real" problem is that some idiot overtightened the pinion nut.

I use a four-foot length of one-inch galvanized steel pipe as a torque multiplier; I slip the breaker bar (a Craftsman 3/4 inch drive, 18 inch long model) into the end of the pipe, which fits perfectly. The frame of the truck has to be about 20 inches off the ground in order to do this properly, but I turn that pinion nut about one-sixth of a turn from each side of the truck (I'm using a six-point socket - if it were twelve, I wouldn't have to move from one side of the truck to the other, but I'd probably break the socket) until I get the requisite torque in turning the shaft. Here's the hard part, which lazy people who overtighten pinion nuts seem to want to skip: you have to remove your flange-holding tool after every couple of tightening moves with the breaker bar after you've got it down tight, until you (1) can feel that there's no play in the bearings, and (2) get the bearings tight enough to give the necessary preload. That means, tighten the nut a little, remove the flange retainer, check the shaft, replace the flange retainer, tighten a little, ... - repeating as necessary. It's a time-consuming process, but self-discipline and patience will pay off.

AS to the use of the special flange retainer tool I made out of a piece of angle iron: When you're removing the pinion nut, you want that piece of iron to stick out from under the truck ABOVE the leaf spring on the passenger side, so that turning the pinion compresses the iron against the spring - that's what keeps the flange from turning. But when you're installing the pinion nut, you want the angle iron to stick out from BELOW the leaf spring so that twisting the shaft clockwise compresses the angle iron upwards against the spring. I use a bungee cord to hold the iron tightly to the spring while I'm turning the pinion nut. So it's really the leaf spring that's holding the flange in place while you're turning the pinion nut.

Another btw: the crush sleeve acts as a compression spring, so, at least in theory (I don't go to this much trouble if all I'm doing is replacing an oil seal), you're supposed to use a new crush sleeve and pinion retainer nut every time you loosen or remove the pinion nut, because that decompresses the crush sleeve and it can never be compressed exactly that way again.

Also, when you put the flange back on, be sure to stick some Permatex Ultra-Black oil resistant non-hardening sealer on the splines of the pinion shaft down onto the smooth part and into the recess of the oil seal, but not so much as to get it into the bearing. My 1990 shop manual refers to a Permatex non-hardening sealer product that is no longer made, but the black silicone stuff works better, in my opinion. And don't shove the oil seal too far in - it's got to be flush with the surface of the top of the hole in the third member that the shaft sticks out of. The seal doesn't seal the shaft, it seals the flange.

Ok, now I think I've said everything I know about differentials, so like Forrest Gump, "that's all I've got to say about that."

Well, I appreciate all your help and good advice. I ran out of time before going on vacation. I'm going to try the thing with the jack and if that doesn't work, borrow the air tools.

I also considered that the pinion nut was too tight, and that it could've caused damage. However I'm still leaning toward it being a bad seal at the pinion. Not necessarily a bad "pinion seal" but possibly the sealing surface as well. When they opened it up, it was clearly low on oil. And the trouble started when I went up a steep and long grade (3/4 mile or so) that allowed the remaining oil to run to the back of the axle, away from the pinion.

Regardless, I got in from vacation yesterday and checked the mail to find that my "Rebuilding Differentials" DVD had arrived. I watched the 10-bolt section, which took about 30 minutes, and lost about 50% of my fear of working on the axle immediately...maybe more. I actually feel pretty confident now about rebuilding the thing and even setting up the ring & pinion on my own. I just need a few more tools to pull it off.

 

[jonrpick]

Or just spend the $50.00 and get another rear off craiglist or JY.

I can never find one when I need one. I've found 'em now, but I have no vehicle to transport them in, seeing as how the K5 is the only one that can.

Also, you don't learn very much doing an axle swap when compared to a full rebuild.

 

[jonrpick]

Holy crap... I finally got the pinion nut loose! Thanks to User for the tip to use the jack.

I don't have a floor jack, instead I have 2 of the stock Sub/Blazer jacks that you have to crank on with that long, flimsy, collapsible crankrod, and I have 2 borrowed jackstands. I jacked up the rear axle right next to the housing on one side, and put a jackstand next to the wheel. I kept lifting till I could get 4 'clicks' of lift on the jackstand, then I repeated on the other side.

Obviously, I'm limited in how high I can lift the truck with that style of jack, so my clearance underneath was equally limited. I wouldn't have had enough room to use an extension on the breaker bar. The breaker bar isn't the greatest. It's a "Great Necks" brand, 18" 1/2" drive bar. I went to Sears and got a 1.25" socket just for this task.

I used the factory jack under the end of the breaker bar after making sure that the swivel-head on the bar was at a perfect 90-degree angle so it wouldn't slip off the nut. Also, I moved the socket 90-degrees so that in a resting position, the bar was pointed down. This gave me some additional working room, allowing me to start with the jack lower than I would have been able to otherwise.

I jacked it up until the bar had a slight, yet noticeable bend in it (yikes). I let it back down, and put my regular ratchet on it...nothing. I was getting pissed at this point.

I made one final attempt using the breaker bar and my own strength. Luckily, using the jack had broke it free just enough to let me get a good turn by hand. So the nut is off, and I'm taking a little break (haven't eaten all day, getting kinda shaky :-( )

I'll continue with more as it comes...