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Unread Today, 01:45 PM   #1
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1998 ZJ 
Join Date: Jul 2012
Location: Weare, NH, New Hampshire
Posts: 497
TUTORIAL - How to PROPERLY replace pinion bearings

I've been seeing so much bad information going around the web lately saying "just zip the yoke nut on with an impact gun" or "you don't need to replace the crush sleeve, just mark the nut and tighten it back to where it was."

Well, I just got done rebuilding my front axle (all except the ring and pinion) last week, so this is fresh on my mind. I've done it the "backyard mechanic" way as described above. And it lasted about 10,000 miles before the bearings were junk. The crush sleeve works as a spring when crushed, and as soon as you unload it, it loses its elastic properties and is no longer effective.

The second time around, I did it by spec. And here's how it goes...

Sorry I don't have pictures for a lot of these steps.

If anyone notices anything wrong or missed steps, let me know. This is all by memory so I may have forgotten something.

NOTE - This is for a ZJ, low-pinion Dana 30. They use a crush sleeve to set pinion preload. Many of the high-pinion D30s used preload shims, so some of this info doesn't pertain to them. This is about my ZJ.

A little tip from the wise - Put your new bearing races and seals in the freezer the day before you plan on doing this job. It will go together A LOT easier. Remember, in the cold, metal contracts. In the heat, it expands.

Tear-Down Procedure
1. Jack the vehicle up by the front axle, and put jack stands under so it is STABLE.
2. Remove your wheels.
3. Remove your brake calipers (two bolts attaching it to the knuckle) and zip-tie them up to your coil springs, so they aren't hanging by the lines.
4. Remove your rotors (they just pull straight off).
5. Remove your hub assemblies. There are three bolts on the back side - be sure to use a 12 POINT socket, 13mm, or you will round them off! You'll also need to remove your spindle nut, which could be a 35mm or a 36mm. You can use an impact gun to zip these off. If you don't have one, do this step BEFORE step 1, while the jeep is still on the ground.
6. Remove your ABS sensors (if equipped). One 8mm bolt holding each.
7. Pull your axle shafts out of the axle. They should just pull straight out.
8. Disconnect your front drive shaft from the pinion yoke. You may have four or six bolts depending on your style of drive shaft. During this procedure is a good time to swap to the 4 bolt, u-joint style shaft and yoke, especially if your jeep is lifted and/or you take it off road!
9. Remove your differential cover. Start at the bottom and loosen the bolts a few turns, tap LIGHTLY with a hammer until the gasket unseats and let the fluid drain into a drain pan. Once it's mostly drained, pull the bolts all the way off.
10. Mark your carrier bearing caps, if they aren't marked already. These are the two "clamps" with two bolts each, that hold your carrier (ring & spider gear assembly) into the axle. They should be marked on each cap, and on the housing right next to the cap, with different markings for each side. This is important for when we go to re-assemble everything.
11. Remove your carrier bearing caps. When taking the last bolt out, hold pressure against the carrier. Depending on wear & tear, the carrier may fall out on its own and you want to make sure you don't damage it!
12. Pull the carrier out. If you plan on re-using your old carrier bearings, pay attention to which race came off which side. If you plan on replacing the bearings & races, throw them away.
13. INSPECT all of your gears. Make sure the teeth on your ring gear, and all four spider gears aren't chipped or pitted. Rotate the spiders to check them all the way around.

IF your ring gear is damaged, the pinion probably is too, and they should always be replaced in pairs. At that point, you may want to look into regearing options (especially if you have oversized tires), or just replacing the whole axle assembly. I'm not going to go into detail on setting up ring & pinions, since it's something I've never done before although I have read up on it.

IF your spider gears are damaged, I will explain how to replace them further down...

14. Remove your center pinion nut. To hold the pinion still, you will probably want to use a monkey wrench, wedged against the ground or your control arms (having radius-style long arms on my jeep made this work perfect!). Now you can pull your yoke off - you may need to tap it lightly as it fits onto splines on the pinion shaft.

In the following steps, pay close attention to the order that everything comes out in! I drew a diagram on a piece of paper and kept it in a safe place until re-assembly. There will be a bunch of pieces on the shaft, possibly including some small shims, and you want to make sure you keep them in order!

15. Pull the pinion gear out from the front of the differential.
16. Use a seal puller to remove the pinion seal.
17. Pull the outer pinion bearing out from the rear of the differential (where you just pulled the seal)
18. Remove the crush sleeve.
19. Use Brake Cleaner to thoroughly clean out the inside of the differential.

This is the end of "bare-minimum" tear down, if you're planning on just replacing your pinion yoke. If that's all you're doing, you can skip down to "RE-ASSEMBLY." If you're going to be replacing spider gears and/or bearings, continue reading.

(Starting at Step #13 above - this is once you have the carrier out of the vehicle).
1. Remove your ring gear from the carrier. This is done with the 10 bolts around the ring gear.
2. There is a roll-pin that holds your center shaft pin in place in the carrier. Drive it out using a small punch. If you do not damage the roll-pin, it can be re-used.
3. Slide out the center cross shaft. At this point the gears will probably fall right out.
4. Put your new side gears in first. They have a collar that will fit into the carrier so they stay in place.
5. Put the other two gears in. Make sure each has a thrust washer behind it (these are washers, not shims, so don't worry if you mix them up, but you need to have one on each). There is a trick to doing this - put them both on opposite sides of the side gears, on the same horizontal plane. Now rotate the gears as an assembly, until the spider gears line up with the holes for the cross-shaft.
6. Re-install your cross-shaft. Turn it so that the hole for the roll-pin is lined up.
7. Drive the roll-pin back in all the way.
8. Re-install the bolts attaching the ring gear to the carrier. The proper spec for this according to the factory service manual, is 70-90 ft-lbs. Other gear manufacturers may have different specs, if you have aftermarket gears. DO NOT torque them down to that spec one at a time. Put red Threadlocker on the threads of the bolts. Start by torqueing them to around 40 ft-lbs, going "around the clock." Now step up by 5-10 ft-lbs each time you go around until you get within spec. I set mine to 75 ft-lbs.

(Starting at Step #13 above - this is once you have the carrier out of the vehicle).
1. Use a press/bearing splitter to remove the bearings from the carrier. DO THIS ONE SIDE AT A TIME!!
2. Be ready to catch anything that falls when the bearings pop off - the carrier and its shims.
3. Doing this one side at a time will make sure you don't mix up any of the shims behind the carrier bearings. Some of them can be paper-thin!
4. Put the old shims back on the carrier.
5. Press the new bearing on.
6. Repeat for the other side.

(Starting at step #19 above - Again, be sure to note which pieces came off where on the pinion shaft!)
Again, note from above. If you're going to be replacing the bearings, you should also do the races at the same time, or else you will have new bearings riding on an already-worn race!
1. Your outer bearing should have just pulled out of the back of the axle when you pulled the pinion and seal off. This leaves you with just the inner bearing on the shaft.
2. Use a press/bearing splitter to remove the old bearing from the pinion.
3. Again, note any shims and put them on as they came off. (can't stress this enough)
4. Use a press to put the new bearing on the shaft.
5. You should ALWAYS replace your races when you replace bearings! The old races will have grooves worn into them from where the old bearings wore on them.
6. Use a BRASS punch and small hammer to drive the races out. The outer race will drive out from the front of the differential. The inner race will drive out from the back side. There is a small lip around the race that you can tap on.

NOTE: Make sure to use a BRASS punch. The reason being is that the brass is a softer metal than the race is made out of. You will damage the punch long before you damage the race or axle housing. This is especially important on the new races, since you don't care about the old ones anyway.

7. If you didn't already, clean out the differential with Brake Cleaner. Be sure to get the "nooks and crannies" like at the very front of the differential, and the spot between where your two pinion bearings/races would go. You'll probably find the fluid in that pocket to be nasty since it doesn't circulate out of there too well.
8. Take your new races out of the freezer (assuming you used my tip at the top of this tutorial - it makes things a lot easier!)
9. HEAT the axle housing. No need to use an oxy/acetylene torch. The small Bernzomatic handheld torches will work just fine. It doesn't have to be glowing red, just warm to the touch - especially if it's cold outside or wherever you're doing this.
10. Using a BRASS punch (again, refer to note on Step #6), drive the race in. The cone surface should be facing whichever way is easiest to access (inner race should have the cone surface toward the front, and the outer race should have the cone surface facing toward the rear). Small, slow taps going around the outer lip of the race and you should be able to drive it in evenly. Listen carefully as you're doing this - when the race bottoms out, the sound will change.
11. Repeat this for the other race.

(Starting at Step # 13 above, with the carrier removed)
It is strongly recommended to have a second set of hands for this, so they can hold the driver on straight, especially when doing the driver's side seal.
1. Use a socket slightly larger than the axle shaft hole to drive each seal out toward the inside of the differential.
2. Take your seals out of the freezer (assuming you took my advice at the top of this tutorial).
3. Heat your axle housing by where the seal goes in (again as explained in the pinion bearing/race install, it doesn't need to be glowing red, just use a hand held Bernzomatic torch to get the housing warm).
4. Install the seals. I tried using a Race & seal driver and found it to be useless. But there were two things I did find that would work. One was the cup from my ball joint press. The other, the spindle nut socket for a Dana 44 axle - the kind with the 4 notch pattern. Both of these fit perfectly around the edge of the seal without touching the axle housing, and also cleared the inner lip of the seal. I opted to go with the ball joint press cup, since I wasn't sure how I felt about the spindle nut socket putting even pressure around the seal due to the notches. Use one of those pieces, with a long piece of rod, and tap the rod lightly with a hammer until the seal drives in. (I used a piece of rod, though you could use 1/2" drive extensions, but they will bow in the middle making it hard to get a straight and even tap on the seal) As with the pinion races, listen as you do this. The sound it makes will change when the seal is bottomed out.
5. Repeat for the other side.

No matter how much of the above you did, the re-assembly procedure is the same, and following this is very important!
1. Load your pinion through the front of the differential.
2. Put your crush sleeve on the pinion shaft, from the back side.
3. Put your rear pinion bearing in. Note this is "free floating" and not pressed. For now anyways - it'll stay in place once you get everything assembled!
4. Install your pinion seal. As with the other seals, LIGHT, even taps around it with a brass punch.
5. Slide your pinion yoke on.
6. Install your pinion washer and put the pinion nut on FINGER TIGHT.

Now for the most important, most commonly overlooked, and most tedious part! Setting pinion pre-load!

7. Use a foot-pound torque wrench to torque the pinion nut to 160 ft-lbs. Use a monkey wrench to hold the yoke still as we did during disassembly.
8. Pull the monkey wrench back off there so the pinion can turn freely. (Note, at 160 ft-lbs you will probably still have play up and down in the pinion, since the crush sleeve hasn't started crushing yet).
9. Use a dial type or beam-type INCH-POUND torque wrench to measure the force that it takes to turn the pinion. (Again, at 160 ft-lbs the sleeve probably hasn't started crushing, so it will have no preload. I used a GearWrench #2955D for this. Significantly cheaper than a dial type, and gets the job done.
10. Hold the pinion yoke again, and increase your torque by 5 ft-lbs.
11. Measure the pre-load with your inch-lb torque wrench.
12. Repeat Steps #10 and 11, until you first notice that you have no more play in the pinion yoke. At that point you need to start paying very close attention, because the crush sleeve has started to crush and pre-load spec will come up very quickly! Now continue to repeat this, in 5 ft-lb increments, until you measure that it takes between 12-15 INCH-POUNDS to turn your pinion (again, this is without the carrier installed - just a free spinning pinion with bearings and seal installed).
Note: I set my pre-load to 15 in-lb so it would stay within spec after everything is broken in. This happened around 245 ft-lbs on the pinion nut, but remember every crush sleeve is different so don't go by that number.
13. Install your carrier. If you replaced your carrier bearings and races, it may go in hard. Make sure everything is lined up, and you may need to use a rubber mallet to help tap it in to place. If it still won't go in, you may need to use the bearing caps to suck it in.
14. Re-install your carrier bearing caps, paying attention to the marks on them to put them on the same side and the same orientation as they came off. Use red Threadlocker on these, and tighten them first to 40, and increase by 5 until you reach the spec of 60 ft-lbs.
15. Using a suction gun, like you would use to fill your differential, put some gear oil of your choice, through the hole in the top of the inside of the housing, so it will go into that pocket between your two pinion bearings. There is an "oil slinger" which is one of those round metal things on your pinion that is supposed to do this, but I did this just to be sure everything would be lubricated as soon as I started driving. When it's full, fluid will start coming out through the inside of your axle housing.
16. Install your axle shafts. Make sure they go through the seals and are engaged into the splines. If you do this before installing your diff cover, you'll be able to see this inside the diff.
17. Re-install your front drive shaft.
18. Re-install your differential cover.
19. Fill your differential through the fill plug in the cover with the gear oil of your choice. You'll know it's full when fluid starts coming back out the fill plug.
20. Re-install your hub assemblies. Be sure to put the thrust washer on before the center nut, and torque the center nut to 175 ft-lbs.
21. Re-install your brake rotors.
22. Re-install your brake calipers.
23. Put your wheels & tires back on.
24. Let the jeep down off jack stands. Do a final inspection of everything.
25. Go drive it!

The "Mall Crawler" - 1998 ZJ Grand Cherokee 5.2 V8, 5.5" LongArms, 32s, 12000lb winch & more.
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Unread Today, 04:42 PM   #2
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1996 ZJ 
Join Date: Nov 2012
Location: Cupertino, CA
Posts: 3,256

1996 ZJ Green Laredo V8, 2.5" OME and Bilsteins, 31's, Holes drilled in the roof.
1998 ZJ Platinum Limited 5.9, New engine and trans, no front driveshaft, but it's pretty

"Whats wrong with a PT Cruiser?"
"Coulda had a V8!"

96 build thread

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Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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Unread Today, 05:13 PM   #3
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1994 ZJ 
Join Date: Jul 2009
Location: Calgary, Alberta
Posts: 1,262
Very nice step-by-step!

In the tool department, the Park Tool TW-1 is another inexpensive 0-60 in-lb beam wrench that works very well for pinion preloads.
1994 5.9L ZJ, retrofitted UC package, NP242 swap, 17" JK Moabs with 32" BFG MT KM's.
The Jeep of Theseus
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Unread Today, 05:55 PM   #4
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1998 ZJ 
Join Date: Jul 2012
Location: Weare, NH, New Hampshire
Posts: 497
Originally Posted by CatSplat View Post
Very nice step-by-step!

In the tool department, the Park Tool TW-1 is another inexpensive 0-60 in-lb beam wrench that works very well for pinion preloads.
Thanks. I tried local bike shops and none of them carried torque wrenches. I work at O'Reilly Auto Parts and we were able to order me the GearWrench 2955D and got it next day from the warehouse.

On the subject of where to find stuff - the computer catalog at O'Reillys and AutoZone only list the carrier bearings as "Special Order." So I opened up the paper catalog and found the part number from National. It's the same bearing as in the early D30s (I think the catalog said up to 1995?). Right there on the shelf. We matched them up and they were identical to my old ones.

So if the person behind the counter at your parts store doesn't know what you're talking about, or is too lazy to pull out the paper books, give them the hint.

I'd post up the part numbers but all my paperwork is out in my jeep and I don't feel like going back outside... maybe I'll do that tomorrow.
The "Mall Crawler" - 1998 ZJ Grand Cherokee 5.2 V8, 5.5" LongArms, 32s, 12000lb winch & more.
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