On our last trip last fall, something went very, very wrong in our right rear axle of our bus conversion. There was grease leaking into the brake drum, rendering it useless… which is a really big deal when it comes time to stopping a 25,000 pound vehicle. The rear brakes on a two-axle coach like ours provides something like 70% of the stopping power of the brake system. So losing one side of the 70% percent makes for a very dangerous condition. I was able to limp the bus home from Texas last November, and by the grace of the Good Lord, we didn’t kill anyone or ourselves, nor even have any close calls with stops.

Record-setting snowfalls then descended from the Colorado skies, burying the bus in varying levels of the white stuff for the next three months. By the time March rolled around, I was anxious to dig into the axle to see what kind of damage awaited.

Whilst still in Dallas last fall, and still in dismay with my newfound grease issues, I had asked the good folks on my favorite bus conversion forum (MAK’s) what they thought could be causing this leakage, which touched off a lively discussion. If you’re so inclined, take a look at that post. At one point, I even began to doubt that it could be a wheel seal failure. But boy was I ever wrong!

Three months later, once I broke through the years of rust that had attached the brake drum onto the hub, here’s what greeted me… oodles and oodles of grease. The big blob on top is the upper brake shoe. The gap in the middle of the pic is the wheel seal. And it doesn’t take a CSI to intuit where the grease came from! What astounded me was the shear amounts of the stuff. It was dripping off the shoes, soaked into the drum, flung onto the inside dual tire, and all over the rear wheelwell and slack adjuster.

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The grease-soaked brake shoes came off in pieces, the brake drums, once cleaned of offending gook, were scored and glazed, and once I finally got to the wheel seal, it was bent and distorted… likely from the initial hub installation. Based upon the amounts of grease coating the parts, the driveway, and me, I don’t think the last people into this axle followed GMC’s guidelines of “do not pack the hub with grease”.

Here’s a few more pics (click on the thumbnails) of the grease damage, the scored seal wiper and it’s replacement I installed, which is a very thin stainless ring that went over the damaged one, once I filled the scoring, heated up the ring, and forced it into place with an old wheel bearing.

Amazingly, I was able to find all of the parts I needed to rebuild the brakes and axle, including two new massive brake drums, from Drive Train Industries down in Denver. I even had to replace the brake shoes and not just the linings, since they were rusted and distorted, no doubt from too much heat. For the parts to eventually rebuild both sides, I was out almost $1,500! Big rigs have big priced parts eh?

Once I got the parts and pieces put back together, and the big dual tires torqued back on, the first road test was eye-opening. My bus has never stopped this well. Ever. Based upon the heat damage I found, this axle was ineffectual at best. And once the grease got in there, it was obviously useless. But the grease forced me to fix an issue that I didn’t know was there, because I never would have pulled the drum in the first place since I could see that the linings were within acceptable limits before.

Here’s the cleaned-up axle, with new brake shoes, linings, spings, s-cam rollers, seals, axle nut, shocks, re-packed, and ready for the big drum. What you can’t see is the smile on my face, knowing that I was able to do this work myself… but more importantly, knowing that my family and others that we share the road with, are now safer.

Back to my blog…

This entry was posted on Thursday, June 7th, 2007 at 12:04 pm and is filed under photos, bus. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.