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Extreme
Gear Off-Road specializes in performing straight axle conversions on any type of vehicle.
Straight axle suspensions have many benefits over an IFS (Independent Front Suspension).
A straight axle setup is much stronger, allows for more articulation, provides higher ground
clearance, and any height of the vehicle can be attained. This article outlines
a Straight Axle conversion that was performed on a '98 Toyota Tacoma. The owner of the
truck wanted to go extreme, including a reverse cut Dana 44 front and a Dana 60 rear, both
stuffed with ARB Air Lockers and 5:13 gears.
EXTREME GEAR OFF-ROAD DOES NOT SELL A KIT FOR SELF INSTALLATION OF A STRAIGHT AXLE CONVERSION.
EVERY APPLICATION IS DIFFERENT, AND EXTREME GEAR FABRICATES THE COMPONENTS TO BEST SUIT THE
SPECIFIC VEHICLE BEING UPGRADED. THE ARTICLE BELOW IS NOT A STEP BY STEP INSTRUCTION
MANUAL, BUT RATHER A BRIEF OVERVIEW OF THE PROCESS. EXTREME GEAR DOES NOT RECOMMEND
TRYING THIS AT HOME.
The first step of the process was to dismantle the front end
of the vehicle down to the brackets that were welded onto the frame. The upper and lower
control arms, struts, rack and pinion, swaybar, axles, and differential was removed.
Once everything was removed, a temporary jig was installed on the frame to keep the frame
from bowing and keep rails aligned. The next step was to start removing the stock brackets
from the frame. All of the IFS brackets were rough cut from the frame, from the outside
frame rail all the way to the inside frame rail. With all of the IFS brackets removed
from the frame, the grinder was brought in to clean up the frame rails and remove the remaining
welding beads. The entire front frame was grinded where the stock brackets were located,
from the outside frame rail, underneath, and inside rails. A lot of time was spent grinding
the remaining metal to achieve a clean frame rail, but the results were impressive.
A finishing grinder was used to smooth the rails to a texture that would accept paint.
The picture below shows the completed passenger side frame rail before painting.



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Once all of the brackets were removed, attention was focused
on fabricating a custom front cross member for the spring hangers to attach to.
Two separate cross members were created, the first was for added frame strength, and
the second had the spring hangers welded to it.
The front cross member was triangulated to the frame to keep proper wheel alignment.
Once the positioning was calculated, the top cross member was welded into place.
The frame was now supported by the front cross member, and the temporary frame jig was
removed.
Attention was now focused to the second cross member, and fabricating custom spring
hangers and shackle mounts. The rear shackle mounts and front spring hangers were
hand-made by Extreme Gear specifically for this application. Once the mounts
were made, careful measurements and calculations were performed to ensure precise spring
angles and placement. The front spring hangers were welded to second cross member,
then welded below the first cross member. The rear shackle mounts were tack welded
into place. With the mounts installed, the springs were set in place, and the
axle housing was placed under the vehicle. Spring perches were set on the axle
tubes and the centerpins were inserted. The full weight of the vehicle was then
applied to the springs, with the housing supported on jack stands. All of the
measurements of the spring hangers and shackle mounts were rechecked to ensure accuracy.
Pinion angle and caster were carefully calculated before welding the perches to the
housing. Once all the measurements were confirmed, he spring perches were welded
to the axle housing, and u-bolts were installed.
The next area of focus was the steering components. An early model IFS box was
installed on the outside frame rail on the drivers side. A brace was fabricated
for the IFS box and bolted to the frame. A custom built steering shaft was installed
from the steering column down to the IFS box. Next, Extreme Gear steering
arms were installed on the knuckles of the axle housing. A custom tie rod
and drag link was made and installed on the steering arms, and connected to the pitman
arm on the IFS box. This steering setup provided increased turning radius versus
the stock IFS setup, not to mention it is much stronger. With IFS box, tie rod,
and drag link installed, attention was focused to creating custom power steering, pressure,
and return lines to convert from a Tacoma to Toyota IFS steering box. The lines
had to be lengthened to reach to the other side of the vehicle where the new IFS box
was mounted. The brake lines also had to be converted from Toyota to GM fittings. The
oil pan had to be modified to provide additional clearance for the tie rod and drag
link.
Custom shock towers were built and installed on the frame rails. Shock mounts were
welded to the axle, and the RS9000 shocks were installed. The axle shafts, rotors, and
brake calipers were installed and completed. The front was completed after painting
the frame rails and axle housing. With front completed, it was time to move to the rear
of the vehicle and install the Dana 60.
Because the owner wanted to go with a Dana front end instead of Toyota, the rear housing
was converted in order to match the gear ratio in the front (5:13). The stock rear axle
was completely removed from the vehicle. The new Dana 60 housing was installed under
the vehicle with the spring perches in place. The pinion angle was set and the spring
perches were welded into place. The stock Tacoma drum brakes were installed on the housing,
along with the stock axle shafts. The extended steel braided brake lines were installed,
and the stock emergency brake unit was re-installed. The new shocks were installed and
the rear was complete.
The tires were put on the rig and job was complete. A test drive was done to make sure
everything was working properly. The vehicle handled excellent on the road, and the
new front suspension handled the road and bumps better than the IFS setup. The next
step was to test it on the trail. Check out the pictures from the maiden voyage on the
trail. |
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