Project Mini - Front Straight Axle Swap - Part 2
|Author: Jay Kopycinski September 2000
Last month we started our front straight axle swap. We torched off
the original IFS suspension and added our leaf springs and a straight
axle. This month we do a brake swap, install a new steering system,
and add shock mounts and a driveshaft.
With the basic front axle mounted, we added the wheel hubs, brake
components, and locking hubs. We retained the stock IFS calipers, which were
in good condition, and simply replaced the pads in them. However, the
stock IFS vented rotors will not work on the straight axle and the
original straight axle rotors are single plate design. As such, we
swapped in rotors from a '81-'89 model Land Cruiser. These bolt right up to
the straight axle wheel hubs and mate to the stock IFS calipers mounted
to the straight axle knuckles. (Note: If using a '79-'80 front truck axle
you will need to swap to later model wheel hubs or you can use '76-'79
Land Cruiser rotors with the early wheel hubs.)
| Relocated brake line brackets and stainless line
To top off the brake swap, we added 20" long Earl's stainless steel
brake lines. Note that when using stainless lines, be sure that they are
not positioned so that they rub on any surface, such as the shock.
Constant rubbing will abrade the stainless mesh. Once the mesh has
started to break, it will unravel relatively quickly and the rubber line
may bubble outward and burst. We also reused two of the brake mount
clips from the IFS bracketry and rewelded them to the side of the frame to
secure our new brake lines.
We used a set of stock Aisin straight axle locking hubs. Experience
shows that these hubs seem to be stronger than any of the aftermarket
hubs available. With a quick cleanup and regrease, they'll last many,
many miles. Note also....while externally the IFS hubs look the same as
the straight axle hubs, the assemblies are different. The straight axle
shafts are 30 spline while IFS axle shafts are 27 spline. Hence, the
sliding collar in the two hubs differs. However, as far as I've been
able to tell, all the other parts within the two hubs are the same.
| High Steer Kit passenger side arm
|| High Steer Kit driver side arm
For our steering system, we chose to use the proven High Steer Crossover
conversion kit from All Pro Off Road. This kit retains the stock IFS
steering box and provides two replacement steering arms that bolt onto
the straight axle knuckles. A beefy 1" draglink and tie rod are used
along with large FJ80 tie rod ends. When converting an IFS truck to a
straight axle, this kit provides simple, bolt-on convenience.
We had already chosen to use Rancho RS9012 shocks (~19" compressed, ~33
inches extended), so custom shock mounts were in order. We decided to
use my Ford shock mount swap. We purchased a pair of F-250 bolt-on
mounts (part # E5TZ*18183*A) for about $30 a pair. Our plan was to weld
these to the tops of the frame rails, butted up against the metal box
areas next to the motor mounts. We also planned to support the tops of
the mounts by adding a bolt-on crossover support running over the top of
| Ford F-250 shock mount we used
|| Another view of the Ford shock mount
|| Surplus rear shock mount welded to Ford mount
To attach this bar to each shock mount, we used the leftover shocks
mounts provided with our All Pro rear u-bolt flip kit. We welded these
shock mounts to the backs of our Ford shock mounts, just opposite of the
top ears. We made our crossover from a piece of " black iron pipe and
terminated each end with salvaged metal shock eyes and hour glass poly
bushings. " hex bolts and nyloc nuts secure the crossover ends to the
shock mounts we welded on the Ford mounts. With the upper mounts
complete, we attached the RS9012s using poly bushings, " hex bolts, and
nyloc nuts. The lower bushings were trimmed a bit to get them to fit in
the stock shock mount ears on the front axle.
| Ford shock mount welded to the frame
|| Another view showing the fender cutout
|| The crossover support for the shock mounts
|| Crossover end mating to the shock mount
As of now we have no bumpstops up front. Time will tell if we will
need to add a set to limit the front travel in any way. Should we
need to add a set, it should be an easy task.
| Long Travel Front Driveshaft
With the amount of travel we expected from the new front suspension, we
needed a driveshaft with plenty of angular movement and spline travel.
The IFS front driveshaft is quite limited in both of these areas. We
chose to have a custom Gloeco driveshaft made. We got a long spline
travel (~10" long) standard u-joint shaft. We chose to save money and
complication by using a u-joint shaft rather than a CV shaft as we
really have no need for the high speed smoothness of a CV joint.
| A front view of the dropped front mounts
|| Side view showing dropped mount
|| Side view of dropped mount and pitman arm
|| Resulting shackle angle using stock rear shackle
Overall, we gained about 4.5" of lift in the front. Our shackle angle
looks good and our steering and ride are smooth and predictable. Our
caster angle is fine with the dropped front mount and shackle configuration
we used. No spring shims were needed to adjust the pinion angle.
This concludes the front straight axle swap for Project Mini. With the
front and rear lifted, we now have good clearance, articulation, and a
reasonably smooth ride. Coming soon.....installation of 4.88 gears and
Thanks for reading!