14-Bolt Differential

1. Adjusting Nut Lock (aka Adjusting Nut Retainer)
2. Adjusting Nut
3. Carrier (in this case, a mighty 14-Bolt ARB Air Locker)
4. Ring Gear
5. Carrier Bearing Cap

14-Bolt Pinion Assembly

1. Straddle Bearing Journal
2. Pinion Gear
3. Pinion Bearing Retainer
4. Pinion Oil Seal
5. Yoke

14-Bolt Pinion

1. Straddle Bearing Journal
2. Pinion Head
3. Rear Pinion Bearing
4. Crush Sleeve

Ring Gear Tooth Nomenclature

A – Top. The top of the gear tooth, a.k.a. Face, Top Land
B – Root. The bottom of the gear tooth, a.k.a. Flank
C – Heel. The outside-diameter-end of the gear tooth
D – Toe. The inside-diameter-end of the gear tooth
E – Coast. The concave side of the gear tooth*
F – Drive. The convex side of the gear tooth*

* Don’t be mislead by the terms “coast” and “drive”, as the ring-gear can be driven by the pinion on either side of the teeth. Which side of the teeth will depend on if the gear-set is standard or reverse spiral and whether the vehicle is going forward or in reverse. 

Jack up axle, and secure safely on jack stands.

The job can be done with the axle in or out of the vehicle. I found it actually easier to do it with the axle still in the vehicle as I could then use the brakes to apply load to the gears when checking the pattern - more on that later.

Tap the axle shafts out of the axle with a brass drift. Remove the axles and put them aside

Do not leave them, covered in sticky gear oil, precariously leaning up against the wall in the corner where you do all your cutting and grinding so that they can fall over in the chips, slivers, and grinding dust...it doesn't aid the installation later!

...Don't ask!

Remove the diff cover bolts except for the top-most one. Pry / knock the cover loose (be careful not to damage the sealing surface of the cover or axle housing) and drain the gear oil. Make sure you have a large enough pan - capacity is about 5.4 pints.

When the oil has drained, remove the last bolt and the diff cover. Thoroughly clean the cover ready for installation.

Before tearing down the diff, check the existing backlash with a dial-indicator.

Strictly speaking, this step is only necessary if you will be re-using the gears. The reason you want to check it now, is so that you can re-install the same gears with the original backlash (assuming it was within spec) to avoid changing the gear tooth contact pattern since the gears have broken in together at this lash. In many axles this wouldn't even be an option, but because the 14-Bolt has such a wide range of acceptable backlash (0.003" - 0.012") it can be worth checking if you're going to be re-installing the same gears.

I used new gears, but checked anyway, just for interest's sake. Backlash was 0.030"...pretty loose by anyone's standard!

Remove the bolts securing the adjusting-nut locks.

Remove the adjusting-nut locks.

Keep these small parts in a safe place during the project.

...Don't ask!

Loosen the adjusting nuts so that the carrier can be removed, and carefully remove the carrier. Be careful - it's quite heavy.
Aah - hooray for the mighty 14-Bolt - no prying the carrier out, no case spreader, no cursing!

It's best to use the proper spanner tool, but a #2 Phillips screwdriver will do.

The right adjusting nut is loosened by moving the screwdriver handle DOWN.

The left adjusting nut is loosened by moving the screwdriver handle UP.

In other words, the adjusting nuts are both right-hand thread and screw into the housing.

If you plan on re-using them, tag and keep the carrier bearing cups separate so that they can be re-installed on their original sides.

Remove the carrier bearings from the carrier.

Here I am using a clamshell-style carrier bearing puller.

In the past I have used cheap 2-jaw pullers (that had to have the legs ground to fit in the carrier reliefs below the carrier bearings), hammer and chisel, heel-style pry-bars, and who knows what to remove carrier bearings.

None of these methods works very well, all seem to damage the bearing during removal, and frankly I was tired of them.

On top of that, the design of the stock 14-Bolt carrier leaves virtually no room to get a leg-style puller or a bearing separator in behind the carrier bearings.

For more details check out my review of the Yukon Clamshell Bearing Puller from Randy's Ring & Pinion.

If you're re-using the carrier, scribe an alignment mark on both halves so that it may be reassembled in the original orientation. If you're re-using both the carrier and the ring gear (i.e. if you're just performing maintenance on the differential inside the carrier), make the scribe line on the ring gear as well so everything can be re-assembled in the original position.

Use a clamp or similar device to keep pressure on the two halves of the carrier as you remove the ring gear bolts because spring pressure from the differential will try and force the two halves apart.

Remove and DISCARD the old ring gear bolts and lock washers.

T tap the ring gear free from the carrier. You should properly use a soft-faced hammer or brass drift.

Hey - I'm just holding that screwdriver for illustrative purposes...I would, of course, never use the wrong tool for the job....oh no...simply unheard of!

Before removing the pinion nut, and with the carrier removed, it can be beneficial to check the pinion bearing preload. This will give you some indication as to the health (or in my case - lack thereof) of your pinion bearings.

To measure pinion bearing preload - use a beam- or dial-type inch-pound torque wrench on the pinion nut and measure the torque required to rotate the pinion. Do not read the initial torque it takes to start the pinion turning, but rather the steady torque it takes to keep the pinion rotating.

Mine was only 2 in/lbs where the spec is 5-15 in/lbs for used bearings!

Note: Yes, the eagle-eyed readers amongst you will notice that this is not a 14-Bolt in the picture. In fact, it looks suspiciously like a D60 front axle. Hey - sometimes a picture doesn't turn out and you have to use what you have available.

Next, remove the 6 bolts and lock washers that secure the pinion bearing retainer to the axle housing.

To remove the pinion bearing retainer, you will probably have to use a brass drift to rap on the straddle bearing journal from the other side of the housing.

Be careful not to drive the retainer out of the housing forcefully so that it flies out of the housing, bounces of the driveshaft, and skids across the floor...

...don't ask!

Carefully remove the original pinion shims from the housing or the back of the bearing retainer. Measure the thickness of each shim with a 0-1" micrometer, total the numbers, and record this value as "original shim stack" for use later when setting up the gears.

I used a small 20-ton shop press to press the pinion out of the yoke and bearing retainer. If you ever want to re-use the pinion, be sure to get the press nice and square and either use a soft end-cap or a brass plug in between the press and pinion threads to avoid damaging the threads.

Also, have a box with rags in it, or something similar, for the pinion to fall into when it pops out - otherwise it will smash into the concrete shop floor and likely damage the straddle bearing journal and/or pinion teeth...

...don't ask!

A view from the rear of the bearing retainer, with the rear pinion bearing race closest to the camera.

The 14-Bolt pinion bearing retainer is a unique and clever beast. It's really just a housing that holds the races for the two pinion bearings - but what it allows you to do is set up the pinion before assembling it into the axle housing.

Also, because it holds the pinion and is removable from the axle housing - it means pinion depth can be controlled simply by shimming this retainer when it's installed into the axle housing. This means shims are not needed on the pinion itself, under the bearings, to set depth; and therefore you don't need set-up bearings and you don't need to remove and install bearings and shims to adjust pinion depth. Simply pull the retainer, add or subtract shims between it and the axle housing, and re-install.

To remove the rear pinion bearing and old crush sleeve I used a large bearing separator and the press.

Once again - be careful not to damage the threads on the pinion and place something underneath to catch the pinion when it falls.

With the pinion removed, it's time to remove the seal and races from the bearing retainer.

Clamp the retainer securely in a vice.

I used a seal-pulling-sharp-pointy-like-thing* tool to remove the seal. It's probably in there fairly tight, and you're likely to ruin it getting it out.

* Note: probably not the real name.

You are left with the retainer with just the two races installed.

Nice corrosion on that race - no wonder preload was so out of spec!

Use a brass drift and a hammer to knock out each race from behind.

Oops - looks like I missed at least once and hit that thumb!

With both races removed, give the retainer a thorough cleaning. Make sure no oiling passages are blocked, and pay particular attention to ensuring that the back face of the mounting flange (where the pinions shims go) is flat and true. Mine had some rough edges where the extreme outside edge had gotten rock-rash so I cleaned them up with a small machinist's hand file.

The final step in disassembly is to remove the straddle bearing from the axle housing. I used the trusty hammer and a large deep socket to carefully drive it out.

That poor thumb's not getting any better!

This pic shows a replacement ring gear bolt for a 4.11 carrier on top, with original part, minus the lock washer, below.

Depending on the year, original 14-Bolt ring gear bolts may use split lock washers. Personally, I don't like split lock washers and prefer to avoid them if at all possible (see my Nuts & Bolts article for reasons why); and my opinion wasn't altered any when I found four or five cracked in half upon disassembling my original carrier. As such, I was pleased to discover that the replacements from Randy's don't use them, and are a flanged design instead.

If you are using stock-style ring gear bolts that originally used a spit washer, you must also replace the washers with new ones. If you delete the lock washers - the bolts will be too long, as illustrated in the pic at left.

The final thing to watch for is that the stock lock washers are much thicker than standard SAE pieces. The pic at left shows a standard SAE 9/16" grade 8 hardened lock washer on the left, and a stock 14-Bolt ring gear bolt lock washer beside it. You may find that sourcing the correct replacement lock washers is difficult or ridiculously expensive (from a GM dealer).

In the end, your best bet is probably just to order a set of new, replacement bolts from a reputable vendor like Randy's Ring & Pinion. Be sure to order for the correct gear ratio.

With the ring gear installed, place the carrier on the bench and install the carrier bearings. Install the left (non ring gear side) bearing first.

Carefully place the bearing cone square on the journal.

The right side is just a little more tricky since you already have a bearing installed on the opposite side. This is because the rollers and cage protrude slightly above the end of the carrier. If you were to simply set the carrier on the press bed and press on the right side bearing, you would damage the cage of the other bearing, ruining it.

To avoid this, I placed a small driver underneath the carrier that fit inside the ID of the bearing, against the end of the journal. This way, the load will transmit through the carrier journal to the driver, to the press, without damaging the installed bearing.

With the carrier assembled you can move on to the pinion.

The first step is to install the new pinion races into the bearing retainer.

I used the press and a scrap of steel plate to initially press the rear race into the retainer. However, to seat fully, the edge of the race has to be below the retainer. I finished the last fraction of an inch by placing an old bearing in the race and pressing on the centre of the bearing.

I used the same "old-bearing" technique to seat the front race, as it sits in the retainer quite a distance below the edge of the retainer.

In the pic you can see I've placed a small aluminum seal driver between the end cap of the press and the bearing.

A nice thing about the 14-Bolt design is that, unlike a Dana axle, there are no baffles, slingers, or shims on the pinion to worry about. Also, because pinion depth is controlled by shims between the bearing retainer and the axle housing, there's no need to make or install set-up bearings - you just go straight ahead and install the new bearings.

Install the rear pinion bearing cone onto the pinion. I placed the race on the cone, then used the press and a couple of pieces of square tubing to support the race either side of the pinion, then pressed carefully on the straddle bearing journal.

The next step is the trickiest part of the whole procedure.

You need to press the front pinion bearing cone onto the pinion shaft, seating it in its race, without crushing the crush sleeve too much.

In order to get over the pinion shaft you'll need to use a tube to bear on the inner ring of the bearing cup. Here I'm using an old piece of 3" exhaust tube.

I don't care what anybody else says - never re-use an old pinion nut - always use a new one. They are deformed-thread style locking nuts that play a critical role. Not only does it have to be tight and stay-tight to keep the pinion where it should be, but because of the crush sleeve design - you're going to use this nut to set pinion bearing preload. Imagine the stress in the threads when you're doing this and cranking that nut down to three or four hundred ft/lbs!

If that doesn't convince you - enlarge the picture at left and look at the threads of an old nut compared to a new.

I then reverted to a 3/4"-drive torque wrench to do the final tightening.

Here you can see the bearing retainer clamped securely in a vice (make it tight!) with a pipe wrench on the yoke jammed against the bench to prevent the pinion from turning.

Tighten the pinion nut initially to 300-350 ft/lbs, then remove the torque wrench and yoke holder and take a reading of the torque required to rotate the pinion, using your in/lb torque wrench just as you did on disassembly.

Proper pinion bearing preload is achieved when the torque required to rotate the pinion is 5-15 in/lbs for used bearings or 25-35 in/lbs for new bearings.

The best tool for checking pinion bearing preload, on any axle, is a dial-indicating torque wrench with a fairly small scale. This particular unit is an Armstrong 1/4' drive 0-75 in/lbs model. It also has a red indicator needle for recording the maximum value attained.

Remember though - it's the torque to keep the pinion rotating that you want to measure and record - not the initial torque it takes to get it turning (which, typically, can be anywhere from 10-30 in/lbs higher).

First, install the new pinion straddle bearing into the housing by driving it in from the front until is seats firmly.

Oh look - I haven't managed to smash that thumb with the hammer yet!

Insert the pinion bearing retainer, with pinion installed, into the axle housing. At this point I just re-used the original pinion depth shim between the retainer and axle housing as I like to set backlash before worrying about pinion depth.

When installing the bearing retainer, make sure that the oiling port on the retainer (yellow arrow) matches up with...

...the oiling galley in the axle housing (red arrow). Strangely, no manual I have ever read mentions this - which is strange because the bolt pattern is symmetrical, meaning you could overlook this step and still install the retainer in the housing...with predictably disastrous results!

Don't ask!

When installing the pinion bearing retainer assembly into the axle housing, the journal on the head of the pinion will have to be driven into the bore of the straddle bearing.

It's a tight fit but shouldn't require you to pound it in. Use a brass drift on the end of the pinion to tap the retainer and pinion into place.

Install the six bearing retainer bolts and lock washers and torque in a crosswise pattern to 65 ft/lbs.

Of note, the stock 3/8-NC16 bolts used to secure the pinion bearing retainer to the axle housing (middle) are neither 3/4" nor 1" in length.

I wanted to replace mine, so I checked the depth of the tapped blind holes in the axle housing and discovered that the longer 1" bolts work fine without bottoming.

With the carrier bearing races installed, place the carrier in the axle housing.

Using the punch marks made earlier, install the carrier bearing caps in their original positions and tighten them until just snug. Over tightening them at this point will freeze the carrier bearings in their bores and interfere with setting carrier preload.

Loosen the right-side adjusting nut and tighten the left-side adjusting nut until the ring gear contacts the pinion without binding. This is zero backlash.

With the starting shim stack calculated, proceed as follows:

1. Ensure that mating surfaces of bearing retainer and axle housing are clean.

2. Place the pinion depth shims on the bearing retainer.

3. Carefully line up the bolt holes in the retainer, shims, and housing.

4. Install the bearing retainer assembly in the housing, making sure the journal on the pinion head seats in the straddle bearing.

5. Install the six bearing retainer bolts and lock washers and torque in a crosswise pattern to 65 ft/lbs.

6. Check the gear contact pattern.

To check the contact pattern, proceed as follows:

1. Clean ring-gear teeth and wipe any oil out of the housing.

2. Using a small, stiff brush, apply gear-marking compound to three or four teeth of the ring gear, in at least two different places. Use the marking compound sparingly, but be sure to completely cover both the coast and drive side of the teeth. Some folks like to mix a little gear oil with the marking compound to aid in application but I found using it straight worked best for me. If you have new gears or gears with a dark finish the yellow coloured compound works well, but if you have used gears or gears with a silver or metallic finish, you may have more success with the blue coloured marking compound – a popular brand is “Prussian Blue” made by Permatex.

6. Observe and record whether the pattern is towards the top or towards the root of the ring gear teeth. Also note whether contact is at the heel or toe of the teeth.

For the top - root contact check you can use either the drive or the coast side pattern, as the indication of pinion depth is the same on either side. In the case of used gears it is sometimes easier to read the coast side pattern due to wear on the gear teeth.

In this picture we can see that my initial pattern displayed top/heel contact - indicating that the pinion depth needs to be increased (shims removed) and the backlash decreased slightly.

Refer to the diagram at left and adjust pinion depth by adding or subtracting shims as follows:

a. If the pattern is towards the root, the pinion is too deep and must be moved away from the ring gear centreline by increasing the shim stack.
b. If the pattern is towards the top, the pinion is not deep enough and must be moved closer to the ring gear centreline by subtracting from the shim stack.
c. Add or subtract shims in large increments at first until the correct setting is bracketed; then make progressively smaller adjustments until the final setting is achieved. As you home in on the ideal setting, adding or subtracting a single shim of one thou can, and does, make a difference.

Note that changing pinion depth also changes backlash. Increasing pinion depth (removing shims) decreases backlash; decreasing pinion depth (adding shims) increases backlash.

As a result you should re-check and adjust backlash after each shim stack adjustment before re-reading the pattern.

If you are having trouble juggling pinion depth and backlash, try setting backlash to the middle of the range, and then concentrating on pinion depth by concerning yourself only with the position of the pattern between the root and the toe. Once you get close to a good pinion depth pattern, re-check and re-set backlash.