Homebuilt Adjustable Perches - Suicidal!

The spring perches started out life as a 3/8-inch-thick, 6-inch I-beam that I cut into a T shape.

I then laid out the bolt pattern for the crossmember side. Six half-inch Grade 8 bolts on 4-inch vertical centers will fasten the rear perch to the crossmember.

Once the crossmember mounting holes were drilled, the perch boltholes were marked and drilled, and then the perch was checked for fitment on the POSIES Super Slide rear spring. It should also be noted that this application uses a spring in front of the axle instead of behind, as is standard Ford practice. Doing so prevents any clearance issues that may arise between the crossmember and quick-change rearend that will be installed at a later date.

Instead of laying the vertical bolthole configuration out again for the crossmember, the perch was centered on the 6-inch square tubing and drilled with the perch in place.

The same procedure was repeated for the other two perch locations, each row 2 inches apart for a total adjustment of 4 inches.

The perch portion of the crossmember will be welded to a piece of 2-inch tubing that will transverse the rear framerails via a vertical kickup. A 2-inch hole was drilled in the center of the sides and then trimmed diagonally to the corners with a cutoff wheel.

At this point, it's critical that the rearend is positioned exactly in relation to the frame. Using predetermined lines laid out on the shop floor, plumb bobs are used to locate the rearend fore and aft and to center it with the chassis.

With the rearend in place, the remainder of the crossmember, consisting of a transverse tube and two uprights, can be slipped into place. Note how the uprights have been fish-mouthed to fit snugly with each adjacent piece of tubing. The height of the uprights is determined by the location of the perch crossmember once bolted to the spring. Once everything is nice and level, the uprights, transverse tube, and crossmember perch can be tacked together.

The rear crossmember is now mocked into place and it's time to add the upper framerail and the corresponding uprights that mate it to the lower framerail. Note that the upper framerail has been trimmed off to meet the rear crossmember uprights.

With the help of my friends at the Roadster Shop, a custom X-member was crafted from 1 1/2-inch tubing and slid into place along with the Pete & Jake's ladder bar crossmember. We incorporated a trans mount into the X-member that will need to be modified at a later date. There were also a couple of clearance issues that needed to be taken care of in regards to the X-member and the ladder bars.

The last part of the equation was to install a pair of diagonal brackets to support the rear kickup and crossmember. You can also see the transverse tubes that had to be trimmed to clear the ladder bars and the transmission out of the X-member.

Here's a shot of the rear crossmember section once the chassis has been welded and pulled out of the jig.

The rear crossmember perch was boxed and drilled on both the top and bottom to prevent any deflection, as well as the sides of the perch itself. This provides a more finished look and also makes a nice, stiff structure from which the rearend can hang.

We're moving forward now, on to the frontend. Like the rear, the first thing to do is to locate the axle. In this photo, you can see some of the markings I made onto the shop floor as reference. Note that I'm using a POSIES Super Slide Spring and adjustable spring perches. These will let me dial in my caster angle regardless of the orientation of the crossmember.

Once again, the axle is set up at ride height, this time for a 5.50x16 tire.

I also "rough up" the caster in the axle by adjusting the temporary radius rods up and down. The magnetic finder tells me I have about 9 degrees in the front axle, which is a little much, so the radius rods are adjusted until the dial reads around 6 degrees.

The same process was used to make the front spring perch and crossmember as the rear, although the front has 3 inches of total adjustment instead of 4. The shape of the crossmember will also be drastically different since there will be no kickup.

To make sure the height of the crossmember will suffice, it's bolted to the spring and mocked into position before being trimmed to shape. You can see how the upright will look by the layout on its side.

The upright basically rests on the bottom tube and is intersected by the top tube. These tubes are on the same plane as the upper and lower framerails.

I used this cheap tubing notcher and a 2-inch hole-saw on the end of a hand drill for the round tube intersections throughout the chassis. The key here is to buy a good hole-saw, keep the speed slow, don't apply too much pressure, and use plenty of cutting fluid. I used LPG Tap Matic fluid for cutting steel.

Here's the upright and the tubes all cut, fish-mouthed, and mocked in place. At this point, every plane possible has to be measured, checked, and level before being tacked into place.

Since the spring perches can adjust the caster, the upright is set to zero degrees.

The spring perch is then bolted to the upright and checked for level as well.

The front crossmember also needs to be square with the rear crossmember, as well as the rest of the chassis. Measure diagonally, from one corner of the chassis to the other, as well as down the length of the chassis. It also doesn't hurt to take measurements from the X-member diagonally to the front to make sure everything is nice and square.

Once everything checks out, the entire unit can be tacked together.

Careful planning allowed me to mount the radius rods from the second upright between the upper and lower framerail. The radius rods are custom Curtis-style hairpins mounted off SO-CAL Speed Shop batwings. This angle gives you a good idea of how much adjustment is built into the front crossmember.

To reduce possible deflection and strengthen the rather tall front crossmember upright, I boxed about three-quarters of it with a drilled 1/4-inch plate, as well as boxing the sides of the perch for strength and style.