The same old Freight-liner axle on the same side. Remember the last thing I talked about? That’s right, the beaten up brakes on the rear axle of the Freightliner. Well, this time it’s a wheel seal. For those who don’t know, a wheel seal is a dynamic seal which keeps oil in the wheel hub, cooling and protecting the wheel bearings from excessive wear. Normally this job is fairly simple and doesn’t take a super long time to complete.
The first step for changing the wheel seal on a drive axle of a tractor is to remove the hub cap and drive shaft. These are normally a one piece deal, with the drive shaft being driven by the differential. The drive shaft is then connected to the hub via 8 studs to the hub cap. The hub cap is held steady by a set of wedges which are forced into over-sized bolt holes on the hub cap. The hub bolts are supposed to be locked in the hub, particularly with lock-tite or a similar substance. One of the 8 studs was not locked in. That’s fine, considering the stud can easily be run back into the hub with no major issues. There were two or three wedges which were seized in the over-sized holes. This is not a nice situation, because the wedges are similar to datum’s, an old style of wheel mounting where wedges become bullets if they aren’t taken off properly.
Of course the wedges fly off, luckily they missed anything important. Finally, the hub cap and drive shaft can be removed. The hub cap seal, which normally covers the whole surface area of the hub and hub cap, is nothing more than a thread around the mouth of the hub. I was amazed that the hub was not leaking through the front as well as the rear.
This job was full of surprises.
The wheel seal itself was not excessively worn; in fact it was a real joy to pull out of its bore. Meaning it was tight and secure. Before the wheel seal can come out, the wheel end bearings and nuts need to come out. This unit has two nuts, and two lock rings, and two bearings. First step is to clean everything up and check for damage or defects. Bearings were good, nuts were good, and retainers were good. Then it’s the job of finding a new seal. The old seal’s part number was so small it took a good 5 minutes to find it. Then it’s a matter of finding a seal install tool. It’s a fancy plate, with a section to fit into the bearing the seal sits on. Pound in your seal and voila! It’s ready to go back on your spindle. Next, you install your front bearing, and your retainer hardware, being sure to do it just right so that you don’t get a nasty phone call about a wheel flying past the driver. It’s a simple procedure, but I will explain at another time.
Once you have done all that, you re-install your hub cap and drive shaft. Because the original seal was not there anymore, I had to put a new one on. All the seal does is prevent oil from weeping out the front of the hub.
The hardest part of re-installing the drive shaft is the differential. I’ve come across units there the diff is just a little out of line, and it’s a real bugger to get the shaft back in. It is similar to trying to hit a target with an arrow in the pitch black. It entails twisting and turning the shaft just right until it clicks in. This went fairly easily followed by re-installing the wedges and nuts on the studs. Since I had to remove the wheels and drum to do brakes, all that was left was putting them back on.
Except for one small issue….I didn’t notice until after everything was done. The wheels were on backwards! Oops…