Ok…THAT was not a good sound at all. A grinding whirring noise was coming from under my truck and since it seemed to be coming from the rear axle…I knew I was in deep mechanical trouble. Taking a socket set with me I slid under the truck and removed the bolts from the differential housing on the rear axle. The ninety weight gear oil came out and by running my fingers through the oil I found numerous bits of metal and this is all I needed to tell me that those gears were history.
The gears in the differential do a couple of different things. They transfer torque from the drive shaft to the axles, and they allow one wheel to turn faster than the other for rounding curves. If the speed allowance wasn’t there, the tires would tend to wear unevenly and you could get a situation of one wheel trying to skid just a bit.
It was time for a visit to the salvage yard to find another axle assembly. Most people don’t know it but the salvage yards of today have become somewhat specialized. In years past, you went to your local yard and hoped they had a vehicle that had on it the parts you were looking for. Those days have come and gone. The yards of today have intercommunication through the web and telephone. One yard can enter the part you are looking for into it’s system, and any other yard, anywhere else in the country can be cross checked to determine if that part is available.
The axle assembly I needed turned out to be in a yard in a neighboring state and for a reasonable shipping fee, would be trucked into my local yard in 3 to 7 business days.
One week later I had my axle and I was ready to replace the whole assembly. With the truck up on jack stands I first removed the drive shaft, taking care to wrap the universal joint in tape to keep the needle bearings all in place. Next I removed the rear shocks from their anchorage on the axle housing. After that I made sure any brake line attachments to the housing or the wheels themselves were removed and I was ready to drop this monster out.
This is a rather big job if only because of the sheer weight on the unit. So I placed another couple of jack stands directly under the axle, to support the weight and prevent it from falling once it was released. The best way to get the unit out was to release it from it’s bolts through the leaf spring mounts and then release the springs at one end so the unit could be dragged out.
Using heavy half inch drive sockets I removed the bolts holding the axle housing to the leaf springs. These are large U shaped bolts that go over the axle housing and then extend through a mounting plate under the housing. Large bolts hold everything together. Next, working from the rear most attachment point of the leaf springs, I removed the bolt holding that spring to the truck frame. Removing the bolt on the other side now had both leaf spring lying on the ground. All I had to do was slide a jack under the axle..lift it..and remove the jack stands supporting it’s weight..and lower the jack. The axle assembly was now loose, free and I could drag it out of there.
Re-assembly was the reverse of taking it apart. Dragging the new assembly under the truck and lifting it into position. Re-attaching the spring bolts to the frame again. And then, aligning the axle housing up with the bolt holes that attach the axle to the springs. Once that was done I could reattach brake lines and shocks.
Still, this was not a complete fix yet. The old axle still had all the brake shoes and parts still on it. And after they were all removed and replaced back onto the new axle, I would have to bleed the brake lines of air for the brakes to work properly. And it would probably be a good idea to check and see if the universal joints might need replacing as well since I already had the drive shaft out of the vehicle.
Everything seemed to work well once I had finished. An differential should last the lifetime of the vehicle, but as time and mileage increase, small imperfections can turn into major problems.
