Axle differentials can be pretty robust, but problems can crop up with them. Reliable gear setup takes experience and the proper tools to ensure a quiet-running unit and one setup to provide good strength. However, sometimes when funds are an issue and repair is needed to get back on the road, some shade tree work can be in order.
Recently, a concerning clicking noise was coming from a 10-Bolt rear axle in a Blazer on the highway coming back from a trail run. Once we limped it home and pulled the cover, we found the cause of the noise. The differential carrier was cracked, and it was allowing the side gears to flex out of position and slowly destroy themselves. Fortunately, the ring-and-pinion were not damaged, but we needed a new differential. We scored a cheap, used unit that would serve our purposes of getting us back on the road quickly.
In a case where the ring or pinion gears were damaged, you must replace them with a new set and accurately set up the pinion depth using the proper tools. However, you can generally swap a differential out on a typical domestic axle without special tools to get you up and running again.
Step By Step
The axle C-clips must be pulled and the axle shafts removed, Once the carrier bearing caps are unbolted and removed, the differential carrier should slide out of the housing. If you still have good bearing preload, the carrier bearing will fit snugly in the housing, and you may have to gently pry to get the unit to drop free. Make sure you keep any loose shims from the carrier bearings and note the side they came from.
We removed our ring gear from the old differential. We placed the new differential in the freezer for a while to shrink it slightly and allow the ring gear to slip on easily. We bolted the ring on using red thread locker on the bolts and torqued them to spec. Always clean the mating surfaces first and never pull the ring onto the carrier with the bolts.
We found the side gears were pretty chewed up, but luckily the missing chunks didn’t end up in the ring-and-pinion gears. Our limited slip differential, however, was pretty much a lost cause. The used unit we found had good bearings with it, which saved us from having to press new ones on.
We reinstalled the replacement differential and tightened the carrier bearing caps. In our case, we had a dial indicator to check the ring gear backlash. However, if you don’t, just ensure you reinstall the carrier bearing shims exactly as they were before you removed them, and you should be close enough for a decent repair job. This basic method can help with a simple differential replacement when you’re not dealing with a gear change or pinion stack.