I've spent the last week putting in a new master cylinder and brake lines. The master is a corvette style, dual-reservoir under floor unit connected to the stock pedal. Yesterday I finished bending up all the new hard brake lines and got the system bled.
After a long time of no work on the truck I finally decided to put the leaf springs back on. A while back I had taken each spring pack apart and removed every other leaf to soften the ride and lower the ride height a little. I also used the angle grinder to round the edges of each leaf to keep them from digging into the leaf above it.
Today I put the polyurathane bushings into the rear spring eyes. The bushings were originally for a early model Jeep, and while they're not an exact fit they do squeeze pretty well into the oblong, worn-out holes in the leaf spring eyes.
Yesterday I was able to disconnect the torque tube u-joint at the transmission and remove most of the u-bolts holding the back axle in place. Today I finished, removing the rear leaf spring shackles and dropping the springs down so I could slide out the old rear end.
Once that was done I moved on to trying to get out the threaded pins that run through the leaf spring eyes and the shackle hangers on the frame. These are greasable, threaded, tapered pins that screw in to bushings in both the spring and the shackle mount - the shackle plates sit over the ends of these pins and are held together by a center bolt.
After I got the frame pins out I noticed that both frame shackle hangers were badly worn. Although the bushing is removable the wear goes well beyond the bushing into the surrounding metal. You can see in the picture what should be a round hole. It isn't.
This sounds expensive - these frame mounts are welded on and not available new. Not good. I'm thinking I may be able to replace them with jeep spring hangers (which run about $12 each new) and rubber bushings. Although the jeep hangers are made for 2" wide springs I think I could cut or grind them down to work with the trucks 1 3/4" wide leaf springs. Another idea is using leaf spring sliders from Speedway. Sliders mounted against the bottom of the frame would move the spring a little closer to the frame, helping to reduce ride height.
All this assumes that the old springs will be reusable. I haven't gotten the spring pins out yet on the rear eye of the leaf spring but if they are worn like the frame pins I don't think there's any way to repair them - it would be new spring time. Cha-ching.
If anyone has any suggestions on how to fix these please feel free to leave me a comment.
Yesterday I pressure washed the frame to knock off 50 years worth of crud and dirt. Today I had a few spare minutes so I used a wire cup on the angle grinder to clean up part of the frame and then put on a little POR-15. While the truck was still sitting on the wheels I used a plumb bob to mark the centerline of the rear end on the frame as a reference point.
Then I put the truck on jack stands and took off the rear wheels and shocks - and noticed that the current shocks seem to be too short. When I took them off the rear dropped another inch. (Note to self: buy longer shocks.) Then I marked the centerline of the axle again on the frame since the axle moved forward slightly in reference to the frame (1/2" with the suspension at full droop.)
I also took a few more measurements in preparation for changing the rear end. From wheel mounting surface to wheel mounting surface the the current rear end is 62" wide. (Bummer. I have two rear ends in the yard; one is 60" and one is 65".)
The center of the axle tube is about 2.5" above the leaf spring. Those universal spring perch kits I see in catalogs look like they would sit the axle tubes a lot closer to the leaf and that would increase ride height. I'll have to remember to look for a way to put at least 2.5" of space between the tube and the leaf or maybe remove leaves to get the truck to sit lower.
There's also a picture here of the stock axle perch. You can see that it has a hinge built into it to allow the torque tube rear to pivot when the suspension works. The actual axle tube also trails a few inches behind the stock perch location.
These pictures are pretty boring but they are to help me establish the position of the rear end in reference to the frame.
Since the truck won't be going very far with a cracked head I thought I'd work on some non-engine related projects: Cleaning and POR-15 coating the back half of the frame, getting the open rear end in place, and maybe even putting the SM420 in. To simplify the first two my Dad and I decided to remove the bed.
Since the bed wood had rotted away a long time ago it was pretty easy to remove most of the rusted bolts holding the bed to the frame. I cut off most of them with a angle grinder and a cutoff wheel but there were a lot more other little bolts keeping the bed attached that I didn't expect - two or three on each side holding the fender to the running board and one or two on each side through the fender to the splash shield above the running board. Most of these were nice enough to snap in half while I was taking them out, but some were determined to make us unscrew them completely.
In addition, I forgot to unbolt the rear fender braces until we tried to lift the bed and found the tail end still firmly attached. Oops. After disconnecting those (and a frame to body ground wire I overlooked) we were able to lift off the bed and store it on some 2x4s stacked on upside-down 5 gallon buckets. My wife is very happy to see that her parking space in the garage is now taken up by a rusty, 50 year old truck bed.
The frame rails in these Advance Design trucks taper in from rear to front and the leaf springs are parallel with the frame rails - but not with each other. This means the leaf springs are not perpendicular to the rear end and I think this needs to be taken into account when setting up the new rear end. I took a few measurements while I had the chance (measured from inner most frame point to inner most frame point):
L front leaf spring perch to R front leaf spring perch: 35-36"
L rear leaf spring perch to R rear leaf spring perch: 48"
In the pictures you can see that the tops of the frame rails have already been POR-15'd but that there's still a lot of cleaning and coating to do.