How to install gears

Lots of people ask, "How do I re-gear my vehicle? Is it easy? Can I do it myself?"

The answer is: Yes, you can do it, no it is not easy, and you should have some working knowledge of how gears work, and what is needed to set them up.  If you are uncomfortable taking this on, then TAKE IT TO A SHOP!!!!!  If you set your gears up wrong, they will wear out very fast and leave you stranded.  However, if you think you are ready to tackle such a project, then read on.

1. Have a BIG hammer ready. You'll need it to get the pinion out. Put the old pinion nut back on when you whack it or you can tweak the threads and get it stuck on the bearing (ask me how I know).

2. There are some things you'll need. You will want to remove the stock shims from the carrier bearing and remember EXACTLY where they went. You will need to press the pinion bearing off the pinion shaft and retrieve the pinion shims. You will have poor luck hammering this bearing off. Find a local shop with a press and pay them to do it. While you're at it, have them press the new bearing on with the shim retrieved from the old pinion shaft. Did I mention how important it is to keep all the old shims and remember exactly where they went?

3. You will need a new pinion seal. NAPA has it. Buy an extra one or two, just in case you have to remove everything. While you're at it, even if you don't change the carrier bearings, you SHOULD change the pinion bearings (there are two. Change the races while you're at it (I use a Snap-On punch). Odds are good that the large pinion bearing will be destroyed as it's taken off, anyway. Make sure the races are fully seated before you install the pinion shaft.

4. You will need a new CRUSH SLEEVE. Buy a bunch. You cannot back off and re-tighten. Oh, and about tightening the pinion nut, DO NOT use an air gun. I use a 2' breaker bar with a 4' cheater. Get the pinion shaft snug until there is just no play. Then start cranking down on the nut about 1/8 turn at a time. You're trying for 25 - 40 in. lb. of torque to turn the pinion shaft. This is critical. If there is no preload on the bearing, it'll work loose and eat itself. If you put too much, the bearing will burn up in less than 1000 miles. If you get it too tight on the first try, you have to start over. Back it all the way out, remove the pinion shaft, and install a new crush sleeve. BE CAREFUL to not destroy the pinion shaft threads as you're pounding the shaft out of the bearing. Remember the nut on the threads trick.

To tighten the pinion shaft nut: Go to your local metal supply place and buy a 3' long 1" square tube. Then, place the square tube in the yoke with a u-joint strap and tighten. Make sure the tube is set to lodge against the frame rail when turning the nut.

NOTE: this job is WAY easier on a lift.

5. Now you're ready to put the new ring gear on the carrier (note, you cannot change just the ring gear. it must be used with it's matching pinion shaft). Put a dab of locktite on each bolt, and snug 'em down to 90 to 100 ft.lb. I lock 'em down with my air gun and am done with it.

Now you can install the carrier in the housing. Did you remember where the carrier shims went? Put them back in exactly where they came from. Now is a good time to go to your local tool place and buy a dial indicator and a magnetic base. You'll need this to check the backlash. Set the dial indicator up so that the shaft is perpendicular to one of the gear teeth. Then check the backlash. You're shooting for between .008" and .012" Try really hard for .010 and you'll be ok. If you're replacing the carrier bearings as well as the pinion bearings, try for .008". If the bearings are brand new, it's ok if it's a little tight, but if they are old, keep the backlash around .010".

6. Forgot to mention that you need to re-install the axles...heh heh. Now is a very good time to replace the axle bearings and seals. Not entirely necessary, but good insurance. Don't forget those pesky C-clips, if the axle you're working on requires them.

ok. Thats about all you can do. You should now check the pattern. there are lots places on the web that have the contact patterns and what they mean. You did remember to get the old pinion shim, right? Very important.

Click here to see the excellent write-up on Yukon gear installation from Randy's Ring and Pinion.  You'll find gear pattern definitions here, also.

If everything checks out, fill 'er up with 80/90 and go for a drive.

Good luck.