Notes from Windward: #66


Repairing the Work Truck

keeping the equipment working

  November 1:

     Lots of folks talk about wanting to create a community from scratch, but not many are able to actually make it happen. One reason for that is the incredible amount of capital needed in order to take raw land and create sustainable housing, gardens and a right livelihood where none of those things existed before. Not only does it take time and money, but it takes tools, and not just the tools needed to do the work, but also the tools needed to repair those tools.

     I mentioned last week that the rear end had failed on our main work truck. Since we live 1,200' above the Klickitat river, we regularly have to haul heavy loads up that grade, a task which requires a serious truck with a standard transmission. For years we've relied on a 3/4 ton 4x4 Chevy truck to do our heavy hauling, and it's been a real work horse for us.

     They stopped making these heavy duty work trucks in '99, so folks are going out of their way to keep the ones still on the road in good working order. Indeed, we have a whole second truck stored away to bring on line when we're finished working using this one as a test bed for our wood to fuel research. That truck is a twin to the one we use except that it's body isn't all beaten up from years of use in the woods, and it has a blown diesel engine in it--putting diesel engines in them turned out to be one of Chevy's no-so-good ideas.

     The Plan is that when we're finished experimenting, we'll pull the engine and alternative fuel equipment off the old, beat-up truck, and reassemble it in the "new," nice body truck. The upshot is that although we have another 3/4 ton axle on site, we don't want to start breaking that truck down into parts--we'd rather fix the one we're using.

     One of the reasons why I'm so attached to the work truck is that it has this habit of breaking down at home. For example, two years back I had just returned from a run down into California, and the next morning when I go in the truck it wouldn't start. Turned out the solid-state ignition was fried and some components needed to be replaced. Now, it could have broken down a long way from home--and break downs on the road are always expensive--but how can you feel bad about a rig that waits until you're home to fail?

     In a similar vein, the failure of the work truck's rear end didn't leave me stranded down in Klickitat since I was able to engage the front axle and make it home using "front wheel drive." I knew that something serious had failed, but it's hard to complain when you can still get home under your own power.

what used to be the pinion gear


     After we screwed up our courage enough to start the process of figuring how how badly the truck was damaged, the first step was to remove the drive line. With that disconnected we could see that the transmission and transfer case were still functioning normally, and that the problem was in the rear end.

     The next step was to remove the bearing assembly that holds the pinion gear in place, and that revealed the problem. Best guess is that the bearings failed and started to generate friction heat. That got the pinion gear hot enough that it took the temper out of the steel, at which point the ring gear just ate it up.

     3/4 ton, four-wheel drive trucks come with three different gear ratios in the rear end, ratios which have to be matched by the gears in the front axle. And so the next step was to determine what gear ratio we had in the rear axle so that we could see if a replacement axle with the same ratio could be found. The way that was done was by removing the back cover and checking the ring gear for numbers; in this case the numbers were 11 41 12 79 which translates to a pinion gear with eleven teeth and a ring gear with fourty-one teeth that was made in December of '79.

checking the ring gear for numbers


     Ring and pinion gears are always replaced as a matched set, so the worst case scenario will involve purchasing a new set of gears along with the necessary bearings and gaskets, which will come to around $350. That's not a trivial sum, but then again it's certainly a lot less than a month's payment on a new truck capable of doing what the work truck does. However, before we take that route, we'll spend some time seeing if a replacement axle with the right ratio will turn up.

  December 14:

     We quickly learned that the gear ratio in our truck was not the most common ratio installed in that year's trucks, and that where there were used axles available in the more common ratios, after considerable looking we weren't able to find one in ours, short of going to a commercial wrecking yard in Portland and paying full price.

     Since we didn't really need to replace the entie axle, we turned our focus on replacing the damaged part, the pinion gear, and the ring gear that has to match it exactly. As a result, they're sold in matched sets.

     After a good deal of phone work, we tracked down a new set of gears at the shop of a fellow who does this sort of work out of a shop built behind his house. He'd had the odd-gear ratio set for some years and was willing to selling it at a good price, about a hundred dollars less that it would have cost us to order the set from after-market manufactures.

the new ring and pinion gears


     On a recent trip to Portland, I went by his shop and picked up the gear set, and so now we're ready to start the process of removing the old ring gear and installing the new one.

  December 26:

     Not quite, actually, in that we still needed to track down a set of new bearing for the pinion gear assembly. Turned out that there were three different sizes of bearing for that truck, depending on the gear ratio, and the correct set for our truck needed to be ordered in from the regional warehouse. Not a big deal, just the sort of delay that you get used to when working with old equipment out in the country.

the new bearings for the pinion gear


     Even then it turned out that our parts list wasn't complete because we needed a new crush sleeve, a part that we had to buy from the Chevy dealer. The two sets of pinion bearings face each other, and as you tighten the nut on the end of the pinion gear, the two sets are brought closer together, and if you went too far, the bearing would be stress to the point where they'd be damaged as they tried to turn with the pinion shaft. And if you didn't tighten them enough, they'd slop around and cause trouble that way.

     The crush sleeve goes in between the two bearing to insure that there'll be enough pressure but not too much. The crush sleeve is that odd looking bit in the upper right hand corner of the pic. It's a soft metal sleeve with a bulge in the middle. The design is such that as you screw down the pinion nut and start to exceed the right amount of loading, the sleeve will start to crush, thereby making sure that the bearings are loaded just enough to work properly, but no more.

     Now that we've got all the parts collected, we'll be waiting for a nice spell of cold weather to start on the work. For now, we're having a steady mix of snow and rain such that the ground is covered with slush, and there's no point in making ourselves miserable trying to work on the truck in that. Once winter settles in a bit more, the snow will freeze solid and it won't be a problem to throw down an old sheet of plywood to work on, but for now it's much more pleasant to go work on improvements in the kitchen.

Notes From Windward - Index - Vol. 66