How do you install a wheel seal on a mack truck?

Answer 1

Well, we'd need to know first if you have Dana or Mack axles on it. I've never done this with Mack axles, so you'd have to talk to a Mack shop about what the torque specs are for the nuts on the spindle.

For the Dana axles, let's start with a tool list. You will need:

• Wheel chocks
• Jack capable of lifting the axle up
• Jack stands capable of supporting the weight of that axle
• Emery cloth
• Sufficient amount of brake cleaner or a dry solvent tank
• Allen wrench or bit driver for the drain/fill plug on the spindle (offhand, I don't remember what size it is).
• Either a 3/4" drive ratchet, or a long-handled 1/2" drive ratchet with 1/2" to 3/4" adapter.
• 3/4" ratchet extension
• 4" steel socket
• Large hammer
• Large mallet
• Seal driver for the wheel seal
• 3/4" or 1" impact with 33mm socket (to remove the wheels)
• Brake adjustment tool, wrenches, or 1/4", 1/2", or pass-through socket with either a 7/16" or 9/16" socket (depending on if you have Haldex or Meritor type slack adjusters... in the case of the Meritors, you'll also need a set of sidecutters or a large slotted screwdriver).
• Deep welll socket for the axle shaft nuts (memory is a bit foggy, but I want to say it's 18mm)
• Die grinder or angle grinder with surface conditioning pad, or gasket scraper.
• Torque wrench(es) - one 3/4" and one 1/2" which you can put a 1/2" to 3/4" adapter on is preferable, as you'll be measuring from 50 ft/lbs. to 300 ft/lbs.
• Small clean bowl or bucket which you can filll with 75W-90 gear oil and soak the bearings in (if you want one large enough for the cone, as well, you can do that).
• Shop towels.
• Drain pans.

Chock a set of wheels which will NOT be taken off the ground, jack the axle up by the differential, find a sufficient place to put the jack stands under the axle.

Take the wheels off. Once you've done that, you'll need to release the brakes and back the slack adjuster completely off. Then you take off the brake drum (you might need to use a hammer to dislodge it). Set a dran pan under the axle shaft seal and unbolt those nuts. Pull out the axle shaft seal and set it aside (I take one of the plastic seat covers and set it on that). Once you've got the axle shaft removed, you'll see the first 4" nut you'll have to remove. There'll be some metal tabs folded over it - CAREFULLY fold those back with a screwdriver. Then, you take the 4" steel socket and ratchet, and you undo the first nut. Once you remove that nut, then you can pull out the disc with the folding tabs, and there'll be a round metal piece with holds with in, and the yellow plastic ring will sit on top of that. Once you remove those, you'll find the second nut (you might need an extension to get to this one), and you'll remove it in the same manner as you removed the first. Once that's done, you can take the first wheel bearing out, as well as the cone - the two bearings are different sizes, so remember which one goes where, and also the orientation of the cone.

Once that's done, you can pull off the spindle. Set the spindle on the ground, and you can access the wheel seal. Use you prybar to remove the wheel seal, and you can take the second (larger) bearing out at that point.

Before you do anything else, I'd recommend you take the two bearings, clean them off, inspect for divets in the rollers, ensure the rollers are operational, and, if they all check out fine, soak them in some 75W-90 gear oil while you do the rest of this procedure.

Then you clean off the rest of the parts you removed. If your bearings are fine, reuse them - if not, you'll have to replace the bearings and races in the spindle. Clean off the spindle, as well.

Now, if you don't have to replace the bearings and races, you put the larger of the bearings back into the spindle. Then you put the wheel seal in. For this, you'll need a larger rubber mallet and a bearing driver - I know Williams makes one specifically for that model of wheel seal, although I don't recall the part number offhand.

Drive the wheel seal in carefully, and ensure it sits even and flush with the spindle back.

Now, you need to take some emery cloth, and go over the axle shaft with it. Once that's done, I recommend you give the axle shaft a bit of a rubdown with some 75W-90 gear oil. After that, put the spindle back onto the axle shaft. Give the cone a rubdown with some 75W-90 gear oil and insert that. Once the cone is in place, install the first (smaller) bearing. Then you put the second 4" nut on - this one will have a small round post protruding - make sure you install the nut so that this post faces AWAY from the vehicle frame. Hand tighten it, then torque it down to 300 ft/lbs with your torque wrench. This seats the spindle. Then you unbolt the nut (with a ratchet, not with your torque wrench) and torque it down again to 50 - 70 ft. lbs. Now, the round metal ring with the holes goes in. That post protruding from the nut must go into one of these holes - you might have to torque down on the nut a little more in order to get it seated. Then the yellow plastic ring sits on top of that metal ring. After that, the ring with the flaps which folded over the first nut goes into place. And then, the first 4" nut you removed is put on, and torqued to 250 ft./lbs. You should be able to rotate the spindle freely by hand at this point - if not, something is wrong. If that checks out, then you need to take either some emery or a grinder and surface conditioning pad, and clean off the backside of the axle shaft cover, as well as the surface of the spindle which is pressed against. Make sure no pieces of the old gasket remain. Put a new gasket on, and then reinsert the axle shaft - you'l have to manipulate it a little bit to get it in. Put the nuts on those studs, and torque them down (I don't measure those out.. I just hit them with my 1/2" impact until they're snug, but be careful not to overdo it, as those studs are aluminum). Now, you take your allen wrench or bit driver and unscrew the oil fill plug on the spindle. Put in about 4 quarts of 75W-90 gear oil, let it sit for a few minutes, and rotate the spindle until the fill plug is parallel to the ground. If no oil comes out, rotate it to where the plug is at the top, and add more oil. Repeat this procedure until oil comes out when you have the drain plug parallel to the ground. Reinstall the drain/fill plug once this is done.

At this point, you'll probably want to change your brake shoes, as a blown wheel seal gets oil on them, and your drum if need be - in which case, you'll want to change them on both sides of the axle (although if the difference between the existing brake shoes and the new brake shoes are 3/32" or less difference, I'll just change the one set if the drums are in good condition and not in need of replacement).