Swapping Gears Yourself

16 With the pinion in place,... read full caption 16 With the pinion in place, install the carrier assembly, races, adjusters, and bearing caps in the housing. Make sure that the bearing caps are installed correctly (follow the marks made during disassembly) and that the adjusters aren't cross-threaded (it's not as easy as you'd think). The side bearing adjusters can be, well, adjusted with a punch, but it's easier to spring for a spanner tool (arrow). Run the adjuster closest to the pinion all the way in to seat the bearings, then back it off and slowly thread in the adjuster on the ring gear side to bring the ring gear close to the pinion.	17 Now you need to set backlash.... read full caption 17 Now you need to set backlash. This is the amount of slack or play between the ring and the pinion gears measured in thousandths of an inch. This is where a dial indicator comes in. Mount the magnetic base on the housing, then set the dial so that it engages a tooth on the ring. Lock the pinion in place (we wrapped a rag around the companion flange several times and held it tightly) and rock the ring gear back and forth to take a measurement. There is usually a small acceptable range (0.005-0.007 inch in this case) for backlash, but it's important to get it right for an accurate pattern.	18 All this work culminates... read full caption 18 All this work culminates in one crucial moment: reading the pattern. It involves painting five or six teeth on the ring and then running them back and forth across the pinion under tension. The pinion contact wipes away some of the paint so that you can "see" the tooth contact. Fortunately Randy's booklet offers several dozen illustrations of acceptable and unacceptable patterns for the unenlightened with recommendations on what to adjust if the patterns don't look good. In our case, the pattern indicated that the pinion was too far away, so everything had to come back apart.
19 Remember when we mentioned... read full caption 19 Remember when we mentioned the pinion is shimmed behind a pressed-on bearing and we cut the bearing off the old pinion because we didn't have a puller? We gambled that the gears would set up right the first time and lost. A trip to the tool store and $40 netted this slick two-jaw bearing puller so we could change shims.	20 Finally, three tries and... read full caption 20 Finally, three tries and quite a bit of frustration later, we obtained an acceptable pattern. A good pattern should have contact in the middle of the coast and drive sides of the ring gear teeth. Although difficult to see here, ours was a little high on the teeth but perfectly centered from heel to toe. We decided to let it fly and fortunately everything worked out. This is where patience really comes into play--you must be willing to take everything apart as many times as necessary to get the pattern right.	21 After disassembling the... read full caption 21 After disassembling the centersection and installing the crush collar on the pinion, we attached our homemade companion flange holder and carefully tightened the pinion nut. This is tricky because if you go too far, you have to start over with a new crush collar. Once the slack is taken out of the pinion bearings, the drag on the pinion increases very quickly. The goal on this setup is only 8-12 in-lb of drag, so tighten just a little at a time. Fortunately Toyota crush collars crush fairly easily; be ready to break out the 3/4-inch drive sockets and cheater bars to crush the collars in GM axles.
22 The very last step is to... read full caption 22 The very last step is to stake the pinion nut, which involves deforming it into a recess on the end of the pinion. An expert we consulted prior to the installation cautioned that Toyota pinion nuts are notorious for backing off and highly recommended using Loctite as well, so we followed his advice.	23 Since the technical setup... read full caption 23 Since the technical setup is identical, we'll hit the highlights of what is different on a Toyota IFS frontend. After wrestling the differential out of the vehicle, we discovered the axleshafts don't just slide out like the rearend. Plus, the service manual was calling for a special tool. With visions of making yet another trip to the parts store to rent a slide hammer, we popped off the diff cover to see if there was any way around needing another tool. Sure enough, we were able to pop the axleshafts out by carefully using a prybar against the cross shaft and the axle ends.	24 Unlike the rear, the frontend... read full caption 24 Unlike the rear, the frontend does not use threaded adjusters. Instead, it uses shims placed on the outside of the carrier bearings similar to a GM 10- or 12-bolt axle. Therefore, the carrier has a press-fit in the housing. A case spreader is handy to relieve the tight fit, but two prybars above and below the axle centerline in this manner can be used to pull the carrier out. Be sure to mark the shims to match the original setup with the new gears.
25 Assembly of all the new... read full caption 25 Assembly of all the new components for the front is identical to the rearend. Once the pinion is installed, the carrier goes back in the housing with the shims on the outside of the side bearings. It's a tight fit, and we had a heck of a time getting the carrier back in on the bench. Then it dawned on us to let gravity help and we set the housing vertically on the floor. Once in position as shown, it took some light persuading from a plastic dead-blow hammer to seat the carrier in the housing without damaging it.	26 Other than what was noted,... read full caption 26 Other than what was noted, the setup for the front differential was the same as the rear. Believe it or not, the gears for the front set up properly the first time! This is where keeping track of the original shims and using quality components really pay off. The multitude of helpful hints from Randy's booklet didn't hurt either.

Are You Worthy?
We're all for diving into a project in order to learn something (we sure did in this case). However, we should issue a word of caution before you dive neck-deep into a fairly technical project such as this one. First, you need to take a close look at your toolbox and experience. You need a better-than-average complement of handtools, and having air tools makes things faster and easier. More importantly, we'd strongly recommend having some previous experience with big projects, such as rebuilding an engine or a transfer case, as well as some experience with axle work. It's also a big help to observe or assist in a gear installation with someone who has some experience prior to tackling your own project. Above all, you need to be confident in your capabilities. Although doing the labor on a gear installation saves a bunch of money, remember that you'll be out a wad of cash in parts if you get it wrong. Lastly, we can't stress enough the helpfulness of the booklet Randy's provides with all Yukon gearsets. We wouldn't have succeeded without it.