Gas, tires, oil.

The ac on our suburban was disconnected when we bought it and since I had no plans of ever hooking it up again I decided to remove as much of it as possible. I figured that the compressor had gone bad. But when I removed it, I realized that the compressor turned fine, it was the pulley that was locked up.

You can see above that the pulley is crooked (clutch bearing is shot). Though I still had no plans of getting the ac working, I have wanted to add onboard air to the truck. My brother had a nice rig in his jeep, he put a small 110v air compressor (the kind with a tank, that you might find in any garage) in the back. Then he plumbed the ac compressor up to the tank and wired the ac electric clutch to a pressure switch. When ever the engine was running, it would keep the tank topped off. If he was somewhere with 110v power, he could also run an extension cord to the compressor so he wouldn’t have to keep the engine idling.
I just wanted to be able to re-inflate my tires after airing them down for offroad driving. First I had to fix the clutch bearing. The book says to use special tool j9401 to pull the clutch (and j9480 to reinstall it), but of course I don’t have that tool.

The inside of the hub is threaded, I found that a 1/2″ pipe fitting would kind of thread in (I suspect that it’s actually 13/16″ like an oil filter but haven’t comfirmed it). I sawed off a 1/4″ off the end so it would screw all the way in (it was loose, and since pipe threads are tapered, the farther I could screw it in the better). Then I tack welded a 1/2″ nut to on the end. Then I screwed on to the hub and screwed in a 1/2″ bolt to pull the hub.

Here’s a pic of the tool after I got the hub off.

As you can see below, the bearing was really shot.

The new bearing was pricey, about $40, but worth it in the end. Next time I show how I got an air hose to connect to the compressor and how I controll it.

We wanted to get the baby into his own bed in the kids room, but there wasn’t room for three beds in there. The obvious solution was to put the older kids in a bunkbed, but I was worried about the baby climbing up and falling off. The room is small and there isn’t really a spot to put a bunk bed that’s not close to a dresser. When I was a kid, a friend of my parents had a kid die after falling off a bunkbed and hitting his head on the corner of a dresser, so I want to avoid that if possible. I know there was no way to keep the youngest one from climbing up, so I started thinking of a way to modify a bunkbed so that you climb up to the top bunk a different way. I thought about a ramp or a slanted ladder that would lead out the side instead of the end, but there wasn’t room. But then I thought that if you could climb up from the lower bunk on the inside of the ladder, you would only fall back onto the lower mattress. To prevent climbing (and gymnastics) on the outside of the ladder, the bed could be put in a corner against a wall. Step one was finding a bunkbed at a yardsale for $20. It had a futon for the lower mattress, but I removed that so we could use our current mattress and frame for the bottom ( you can see how I used the futon frame for a railing at the end). Then we got a cheap mattress from Big Lots for the top.

To make an opening to climb through, I used a muffler cutter to remove several slats.

Then I had to shorten the mattress to match the opening. First I pulled the staples and pulled back the covering to see how it was made.

Turns out that this cheap kid’s mattress just has a wooden frame and foam pad.

After laying it out, I cut the frame (there’s two marks because I reused the cross piece at the end and had to shorten the frame by its width also).

Here I using the end piece to layout the cut on the inner frame rail.

A few drywall screws and its stronger than original.

I stapled it back up and made sure they were flush with a mini ball peen hammer.

Within secounds of throwing the shortened mattress up on the frame to check for fit, the baby was already climbing up the outside ladder on the opposite end.

I wanted a railing anyway, since my daughter (who was getting the top bunk) has been known to fall out of bed. I used the futon frame (already the right length in one direction).

I just shortened it in the other direction with a tubing cutter.

I put plastic plugs in the ends of those tubes so no one would take a core sample out of their forehead. So far its worked great. We just fold the fitted sheets under the mattress to take up the slack.

I snapped this pic in Leadfield, a ghost town in Death Valley. It needs a little work but people have started with less.

Here’s an over view of the town from the pass above it.

It’s on Titus canyon road, which is a very nice drive.

A nice example of mosaic.

Some nice narrows.

And some indian pictographs near a spring.

When I went to Death Valley last spring, I got a stone bruise on one of my tires on the nasty washboard road to the Racetrack Playa (I was talking to a couple of guys I met at the Eureka sand dunes, and one of them said that he actually saw a couple bolts fall off the front of his old FJ on that road, he couldn’t find them and had to replace them with bolts from somewhere else on his truck). I got it plugged, but I didn’t trust it anymore. Rather than get a new tire, I decided to go to 16″ tires rather than the 15″ tires that were stock on 1/2 ton trucks in ‘82. The main reason is to get more load capacity: the 15″ tires only have a load range C with a weight rating of 1985 lbs. With the whole family and some camping stuff, the suburban is well over 6000 lbs., so it is very near maximum weight for the tires. And I’m pulling a double axle camper trailer. I also wanted taller tires to make up some of the difference in my axle switch (3.42 to 4.11 gears). However, lots of newer model trucks also use 16″ tires on 1/2 ton trucks. This means that some tire sizes are availible in load ranges C, D and E, which means that just going to 16″ is not sufficient. Unfortunately, I can’t use the stock rims 6 lug rims that come on newer chevy trucks because they have too much backspace and hit the tie rod on the older trucks. After lots of searching for used rims, I gave up and ordered a set of Cragar Soft 8 16″x7″ rims from Summit. Then I started seaching for tires. I wanted a set 255-85/16 tires, I had this size (Kelly Springfield MSR) on a 3/4 ton suburban in the past and really liked them. They are 33+” tall but not too wide. Calling around, everyone wanted $650+ for these tires, so I started to look for used on ebay and craigslist. One morning on my way to work I stopped by a local tire shop that sold used tires. The guy didn’t speak english, so after a bit of non-communication he went over to a tahoe parked inside the building and started beating on the side. Eventually a bleary eyed younger guy (his son) opened the door. He apologized for being so hung over and said he couldn’t get out of the truck because of an injury to his foot (I didn’t ask details). So I started looking through the used tires, coming back to roust him up to ask the prices. Eventually I found a set of 295-75/16 bfg ko’s with ok tread. A little wider and shorter than I wanted, but I got the set for $110 (plus $20 for a 265-75/16 for a spare). They fit fine with no lift.

Unfortunately my tire chains will no longer fit, so I’ll have to watch the weather if I want to go over any passes in winter. But these tires have a weight rating of 3415 lbs. so they should have a lot less sway when towing (stiffer side walls) and I’ll be able to air them down a lot more when going offroad. Of course this means having a way of re-inflating them, so I started working on converting the air conditioning compressor to an air compressor, but that’s for another post.

I’ve been wanting to do a couple led projects, but the lack of cheap leds has been holding me back. Last year, over at the Make blog, someone mentioned using led christmas lights as a source for leds. We hit some day after christmas sales and got three packs of white and one of colored led lights. The whites are going to be for interior lights for my camper trailer, but here I’m going to show how to convert a regular flashlight to led using red leds. I wanted red so that would have flashlight for camping that wouldn’t wreck my night vision (astronomers, the military, wildlife photographer all use red filters on their lights because they preserve your night vision). I was just going to use some sort of red filter, but found this idea on an amature astronomy website. The colored lights used 70 2V leds (what it specified as replacement bulbs anyway) in series (one light goes out, they all go out). 2V seemed like an odd voltage, but they were run on AC, so maybe that’s RMS. I found that they work nicely with 2 dry cells (~3 V).

The leds are in holders that plug in to sockets, you just need to straighten out the legs to remove them. Those sockets may be nice for other led projects. I happened to have a burned out flashlight bulb hanging around. I broke the glass with a pair of pliers.

Now I had to find out which of the filament holders was ground (negative), I used a multimeter. The wikipedia page on leds is a nice reference for determining the polarity of leds, but basically the negative lead is shorter and base has a flat on it. Next I trimmed leads on the leds (has to be short enough not to hit flashlight lens) and soldered them (in parallel) to the filament holders of the flashlight bulb.

They also have to fit through the hole in the flashlight reflector, 2 barely fit, but with some trimming 3 might go.

The AA batteries should run forever with these leds, and while its not terribly bright, its perfect for what I want it for: finding a keyhole or navigating inside the camper without losing my night vision (the camera makes the light look much more yellow than it is).

I’ve been using my ‘89 sportster as a daily commuter for about 2 1/2 years, and while it’s had some problems, it’s never left me anywhere. I thought this had changed the other night, the starter had been making some strange noises when the bike was cold, but it had always started. But when I tried to leave work, it wouldn’t crank the motor. It made a noise that indicated that something was turning, but not the motor. Eventually I was able to push start it, and ended up taking the ‘55 to work for the rest of the week. Last weekend I pulled the primary cover.

When I hit the starter button, the ring gear turned, but not the rest of the clutch basket. It wasn’t obvious from the manual how the ring gear was attached, so I pulled the clutch as an assembly. The manual gives instructions that involve disassembling the clutch (using a special tool to compress the clutch spring), but not removing it as a unit. First I removed a snap ring and the clutch adjuster bolt and bearing.

Behind it was another snap ring, this was all that held the clutch on the transmission shaft, but I also needed to pull front primary sprocket. It’s held on by a nut that is torqued to 165 ft/lbs, so I used an air wrench to remove it (for all I know this is a terrible thing to do, maybe it wrecks the bearings or crank or something, but it’s what I did).

When I got the clutch off, it looked like the ring gear was just pressed on. I used an aluminum drift and hammer and gently tapped it off. It was fairly tight, but it was obvious that it had spun ruining both surfaces. Now I could have bought a new primary sprocket and ring gear, but left to my own devices I just rig stuff up. So I decided to just tack weld the gear on.

I spotted it in 4 places with the mig welder, then cleaned up the welds and any weld beads. The blue tape is covering up the alternator magnets, weld beads and grinding dust would stick to them like crazy. So far this fix has worked fine, but who knows, maybe the welds will cause the ring gear to crack and come apart, wrecking then entire motor and trans.

Over the years people have used various schemes to measure the aerodynamics and parasitic drag of a vehicle using what is called a “coast down” technique. What you do is take a car up to speed, put it in neutral and let it drift. You can then use a stop watch to measure the time it takes to decelerate a certain amount (say, from 65 mph to 60 mph). Given the weight of the vehicle, you can calculate force opposing the vehicle at this speed and the horsepower needed to maintain that speed. If the measurement is done at several speeds, you can separate the rolling resistance (tires, wheel bearings, brakes dragging, etc), which is proportional to speed, from the air resistance, which is proportional to the square of velocity. Obviously, you need to find a section of road that is flat and level, and you should ideally avoid windy days, though repeating the test in opposite directions would help.
What I would like to develope is a method to record continuous deceleration data. This would allow you to fit the data and obtain much more accurate results. These sorts of results could be very interesting, for instance, you could determine the effect of various modifications on performance. Is it better to leave the tailgate up or down on a pickup, is the drag from a rooftop luggage carrier enough to make it worth removing when you are not using it, what is the change in rolling resistance with tire pressure? Now, I can think of several ways to obtain this data, first, you could use an inertia detector to directly record the deceleration. I believe there are commercial devices designed to measure acceleration performance in just this manner and I wonder if the hard drive protection inertia detector in mac laptops could be used. Another method would be to take data from the computer of a modern car through a laptop interface. One of the data channels is speed, though you would be limited by the accuracy of the speedometer. Having neither a mac nor a modern car I decided to use my GPS (a garmin 12map) and pc laptop. While gps reciever have a well known error in position, the speed seems to be very accurate. In addition, they also indicate elevation, which may be useful in finding a flat piece of road for the test.
Most GPS recievers can ouput real time data through a serial cable. Mine can do so with either a proprietary Garmin protocol (which is documented) or a standard called NMEA, which is plain text. I searched around for couple days for an interface program, but was unable to find exactly what I wanted. Plenty of programs record position, but not speed. So, I decided to just log the entire output, then pull out the data that I wanted. I used Hypertermial (comes with Windows) to connect to the gps. You need to specify Com port (com 1 for me), 8 bits and no parity and 4800 baud. If successful you will see a bunch of text scroll by on your screen. You can either cut and paste from the screen (set the buffer way up) or log the session to a file. Here is some example output:
$GPBOD,,T,,M,,*47
$GPRTE,0,1,c,*36
$GPRMC,024433,A,3958.908,N,13148.360,W,025.8,358.9,261106,015.1,E*6B
$GPRMB,A,,,,,,,,,,,,V*71
$GPGGA,024434,3658.910,N,12148.360,W,1,09,1.4,79.9,M,-28.9,M,,*4B
$GPGSA,A,3,,06,07,10,16,18,21,,26,29,30,,2.4,1.4,1.9*38
$GPGSV,3,1,11,03,00,315,00,06,63,140,49,07,67,305,47,10,07,043,38*7D
$GPGSV,3,2,11,16,26,298,43,18,58,214,38,21,63,323,46,22,20,219,00*79
$GPGSV,3,3,11,26,33,089,42,29,30,072,42,30,08,185,34,,,,*41
$PGRME,3.7,M,4.6,M,5.9,M*24
$GPGLL,3658.914,N,12148.360,W,024434,A*32
$PGRMZ,262,f,3*1D
$PGRMM,WGS 84*06
$GPBOD,,T,,M,,*47
$GPRTE,0,1,c,*36
$GPRMC,024435,A,3958.922,N,13148.360,W,024.6,358.5,261106,015.1,E*66
$GPRMB,A,,,,,,,,,,,,V*71
$GPGGA,024436,3958.923,N,13148.361,W,1,09,1.4,80.1,M,-28.9,M,,*46
$GPGSA,A,3,,06,07,10,16,18,21,,26,29,30,,2.4,1.5,1.9*39
$GPGSV,3,1,11,03,00,315,00,06,63,140,49,07,67,305,47,10,07,043,37*72
$GPGSV,3,2,11,16,26,298,43,18,58,214,38,21,63,323,46,22,20,219,00*79
$GPGSV,3,3,11,26,33,089,42,29,30,072,42,30,08,185,34,,,,*41
$PGRME,3.9,M,5.0,M,6.3,M*24
$GPGLL,3958.927,N,13148.361,W,024436,A*31
$PGRMZ,262,f,3*1D
$PGRMM,WGS 84*06
The data we want is in $GPRMC (GPRMC = global positioning recommended minium navigation information). Next time, I’ll show a Perl script that I wrote to pluck out the time and speed, and an example calculation. But here is a little preview just to show that this might work (i.e. data is recorded at a rate sufficient to fit):

I recorded this with my suburban on the road outside my house (you can see effect of couple small hills near the end coast down section and a car was coming up behind me so I didn’t come to a complete stop), but even at 40 mph you can see the effect of air resistance (the speed falls much faster per second at 40 than at 10 mph), but of course the suburban has the aerodynamics of a brick.

The 14 bolt semi-float axle that I bought for my suburban had recently been in a ‘70 chevy pickup (it was originally out of an ‘88) and the distance between spring perches was not right for the ‘82 suburban. So, first I pulled out the stock 10 bolt rear and put it next to the 14 bolt for comparison.

Next I ground off the welds with a 4 1/2″ angle grinder and knocked off the perches with a hammer. Then I cleaned them up and champhered the edge in preparation for re-welding them.

I needed to be able to measure the center to center distance of the perches, but the differential prevents you from being able to just measure them with a tape measure. So what I did is use a set of outside calipers to measure the width of the center section.

Then I could use a set of inside calipers to set the distance from the perches to the center section.

I also needed to set the angle. I the angle between the perches the the yoke with a magnetic protractor, setting it to be the same as the stock 10 bolt.

Then it was just welding them on.

So, let’s finish up this paint job (part 1, part 2). I thinned the paint for spraying, I think a lot of people have problems using spray guns because the paint is too thick. Most automotive paint has specific thinning instructions and there are tools for measuring viscosity, but here is a good rule of thumb: thin until when you pull the paint stick out of the paint, the paint running off the stick breaks into two streams (instead of one).

I thin in a separate container (necessary if it’s catalyzed paint), you can buy disposable plastic containers just for this. This way you strain thinned paint into the gun.

Double up the strainers to make sure you keep dirt out.

Here’s the paint on the trailer.