1999-Shackle Reversal- In the spring, I
decided to follow Chris's lead with a shackle reversal/buggy
Chris had tried a "buggy-spring" setup, but had taken it out. I
liked the idea and decided I was going to go whole hog with the buggy.
The first step to all my upcoming suspension
mods was a shackle reversal and buggy spring. The idea is to move the
shackle from the front of the spring to the back to make the suspension
dynamics better. The buggy spring is just a spring with a eye in the
"free" end that forms the top of the shackle. The fixed end is attached
to the frame. The idea is to allow the shackle end to drop away from the
frame, increasing travel.
I measured the "weight on" angle of the
springs where the axle mounts and the eye to eye length of the springs.
All this while the truck was resting in the driveway. Next i removed the
axles, and measured the same stuff with the springs sagging under the
otherwise level truck. Now I removed the springs and ground off all the
brackets and mounts.
The reversal requires the fabrication of
"towers" to drop the front spring eye down far enough to keep the angle
where the axle mounts the same as when the spring was in it's stock
position. This will be 4 or 5 inches. I estimated the position of the
spring ends and cut two towers out of box steel that was 2-1/4" with
1/4" walls. i clamped the setup together to measure all the angles
again. When I was satisfied, I drilled a hole in one of the towers for
the front fixed spring bolt. I tacked it into position on the front of
the frame and mounted the spring in it with new urethane bushings.
Now I could locate the rear shackle
position accurately. I bought a spring with an eye on both ends and cut
it in half. I then assembled the spring to be the top of the shackle. I
clamped the "buggy" spring end to the frame and lowered the truck onto
it to accurately represent ride height. I readjusted the buggy a couple
of times and then marked the position.
To mount the fixed end of the buggy, I
welded two lengths of black pipe into the frame for two grade 8 9/16"
bolts to go through. I found the bolts to closely fit the inside of the
3/4" black pipe. I then drilled the springs for the bolts and bolted
Now I repeated the setup on the other
side and finish welded the towers in.
Considerations: Be sure to carefully
measure the axle position in relation to the body and frame so you don't
change this position. Otherwise you may make clearance problems with the
body. I replicated the spring angles (eye to eye) and axle mount
positions (fore-aft) as closely as possible to avoid any clearance
Spring Over- Since the front axle was going the be the
most difficult and time consuming, I started there. One of the common
things to modify as part of this project is to induce a little caster
into the front end. Stock Scouts have a 0 deg camber angle. Most cars
have no more than 2 deg. This helps the vehicle track straight down the
highway. With big tires, etc, this would help control the beast en route
to the off-road areas.
So, in order to get caster you need to
tilt the angle of the top and bottom ball joints, or lean the axle
backward in the spring mounts. This will point the differential pinion
shaft toward the ground. Tilting the pinion toward the ground makes the
bottom u-joint angle bigger (that's bad).
The way around all the bad stuff (u-joint
angle) but still get the good stuff (more caster) is to grind the welds
loose at the axle tube to knuckle joint and twist the knuckles around
the axle tube. Chris had done this to his truck and made a jig to hold
the knuckles in place while jacking the axle tube to a new alignment
relative to the knuckles. Since this item was being stored in my
driveway, I decided to use it.
I stripped the axle down to the spindle
mounts. I put the axle on a couple of jack stands in the driveway and
started grinding on the welds. I sprayed WD-40 into the joint from the
knuckle side. The idea was that the WD-40 would be wicked up into the
press fit joint toward the weld and would help loosen the joint for the
rotation to come. It also helped to make the joint visible once the weld
was ground away enough.
Joe's hot tip- you wanna get some OLD
grinding wheels for this so they are smaller. the smaller wheels can get
in closer to the welds without taking off a lot of metal from the
knuckles that in just in the way. Keep the plane of the grinding wheel
relatively flat to the axle tube. Don't cut in at an angle too much.
After much grinding I started to see the
crack show up all around the knuckes. I mounted the axle into the jig. I
used a punch and a hammer to mark the "home" position of the axle
tube/knuckle relationship. I attached a couple of 2"x2" box steel tube
to the spring pads on the axle tube with the stock u-bolts and put my
Hi-Lift under them. I gingerly jacked, sledge hammered and ground on the
knuckle joints until I began to see a little movement. The movement
started slow but after it finally started it was easy to move with the
jack. I rotated the tube about 5/8". This gave me 2 deg caster while
pointing the pinion shaft up toward the transfer case. Something like 22
deg total rotation.
Now I tacked the knuckles/tubes together
with my 110v welder. I wasn't going to finish weld anything until I had
everything figured out. Next I ground off the spring pad on the left
side. The right-side spring pad was cast into the bottom of the dana 44
gear case. In order to mount the spring on the right side, I would need
to grind away a good part of the casting on top. I "mounted" the axle in
the truck, loosely bolting it to the left-side spring pad and lowering
the truck onto it to simulate real-world. I jacked the pinion shaft up
to line up with the t-case and marked and measured every angle I could
think of and drew it all out.
I calculated and measured for the angle
of the normally compressed spring related to level. This was about 6
deg. I marked my 6 deg angle onto the cast iron on the axle for the
right-side spring perch. I started with a sawzall to remove a lot of
material fast. Then finish fit it all with a grinder. This took awhile.
I had to get the angle right for the spring to rest on and keep it flat
too. The key angle in all this was the pinion angle. Check all your
angles often. The pinion angle will rotate a bit and throw off all you
measurements. Go slow and careful.
Now that all the spring pads were fitted
and my pinion was pointed in the right direction--- and it had all been
checked 25 times--- i removed the axle and hauled it down to a welding
shop and had the knuckes welded onto the tubes permanent like. Back
home, I finished up all the spring pads and mounted the front axle back
The rear axle was really easy. I measured
the pinion angle with weight on the truck. Then took the axle out and
replaced the spring bushings with urethane, reinstalling the springs.
Next, I just ground off the spring pads and set them on top of the axle,
loosely u-bolting the axle back in. Then I tapped the pinion up and down
until the angle matched. Don't forget to "bounce" the suspension a
couple of times between adjustments to be sure it's right. Now, I just
tacked the pads in place for finish welding later.
Now, of course all my shocks and brake
lines were too short. I tracked down some 18" stainless steel brake
lines. After my brakes worked, I took the truck over to a concrete
retaining wall and twisted it up to measure the max drop and compression
of the suspension. With this data, I ordered the longest travel Rancho
9000 shocks they make. I fabbed some shock mounts (ugly) and installed
the shocks in the front and rear. The long-travel shocks, It turns out,
are too long, but they only bottom out under extreme circumstances.
Now to test the new setup. Again I went
to the retaining wall and twisted. No rubs and the shocks don't bottom
out or fully extend. Total travel is about 13". COOL!
Chris and I learned about this place in Kansas, Tuttle Creek ORV area
and planned a trip.
We had NO idea what we were getting into