Gas, tires, oil.

I wanted to know what my ‘68 Tempest had for a rear axle ratio, I’m thinking about using it for commuting and am wondering what I could do to improve mileage. First I jacked up one side of the rear axle (if you have positraction you’ll need both wheels off the ground), then put a chalk mark on the drive shaft and the differential.

Then I put a mark on the tire where it lined up with a crack in pavement.

Next you just rotate the tire, and count how many times the driveshaft rotates and the tire rotates until both marks line up similtaneously. It takes a lot of turns, I kept tally on the sidewalk with a piece of chalk.

It took 32 turns of the driveshaft and 25 turns of the wheel before the marks lined up again. 32/25=1.28, but since only one wheel was turning I have to multiply by 2 to get 2.56 for the actual ratio. I guess I’ll have to look elsewhere for gas mileage improvements.

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.