Working on the little gray truck, Tuffy II
Rear Axle Clock
The main purpose for clocking the rear axle is to gain a little ground
clearance, and get the u-joint away from the rocks.
I also hope to reduce a driveline vibration.
the Marlin 4" Spring swap, I noticed a severe vibration at highway speed. I presumed it was because of the increased angle at the u-joint, created by
the extra lift gained with the springs. This shot of the u-joint, at the
transfer-case output flange, shows the angle of the driveshaft.
shot shows the angle of the driveshaft, at the u-joint connected to the pinion
flange. I hope clocking the rear, will eliminate the vibration by decreasing the
angle that the driveshaft has to operate at.
wanted to just pull the axle, cut the old perches off, and weld on the new ones,
but I didn't want to take the chance of melting the axle seals. So...first step
in the process...drain the lube.
that was draining, I pulled the bolts holding the driveshaft on. I'm pulling the
axle completely out of the truck and stripping it bare, so everything has to
brake lines are disconnected. I hung a coffee can to catch the steady drip of
shocks will have to come off.
job is made a lot easier, because I don't have rear drum brakes on Tuffy II. One
of the earlier modifications was building the '86-'95 rear axle. Part of that
build included a rear disc brake conversion from
Just unbolt and pull the calipers. Then the rotors slip right off.
adapter bracket unbolts from the axle flange.
the drivers' side, the caliper has been removed and the rotor is being
you can see the adapter still bolted on to the axle. The bolts holding it on
also hold the rear axle bearing housing to the end of the axle tube.
removing the bolts, the adapter comes off...
from the passenger side now, the axle assembly slide out.
is a good shot of the rear axle seal. I want to preserve these, I don't have
replacements, so I'm not going to pull it. I hope my welding doesn't hurt it. I
don't think it will.
I've got the u-bolts holding the axle to the springs removed .
the pile of parts. Imagine if I had drum brakes?
will be easier handling the axle with the differential removed, but the
blue silicone RV sealant is holding the assembly together.
the axle out, I can work on separating the diff housing from the axle housing.
hammered a putty knife in between the two pieces and carefully separated them.
Now I can start to remove the old spring perches. The shock mounting brackets
will also have to be relocated .
are the new spring perches. I bought them a while ago, form
Marlin Crawler. I
will use one of the offset holes to move the axle forward. Notice the new perch
is longer for more support of the spring pack.
don't have a torch, so I tackled the job with my trusty Harbor Freight nose saw
is a long and noisy process.
little while later, a nice clean job.
to put these to good use.
best way to tell where they should weld on; mock it up. I want to make sure I
center the axle and clock it as close to 'just right' as I can. The jack stands
are keeping the springs from drooping. I have taller ones supporting the truck
at the frame. The floorjack is holding the axle in place.
With a CV joint at the output flange of the transfer-case, I
want to point the pinion directly at it under load. I'm applying the science of
estimated guesswork to determine the correct positioning.
I'm happy with it, it's time to weld it. Looks like my seal is going to hold up
to the heat o.k.
I'm moving the axle forward, I need to do a little modification to the u-bolt
the axle moved forward, the spring pin falls in the rear offset hole of the
newly welded on spring perch. Modifying the hole in the plate, allows the
u-bolts and plate to sit square over the axle tube.
I wanted to shorten my wheelbase to be within W.E. Rock specs. They allow up
to 3" from stock. Mine was at 115.5 inches, while the stock wheelbase for this
truck was 112.2".
I was outside the specs by less than 1/4 inch. Now I should be within specs.
I haven't measured yet, but I think the offset holes in the new perches are
about 1 inch apart, so I should be at 114.5 now.
not pretty, but this stuff will seal the diff housing to the mounting surface
and keep the lube in the axle. No leaks.
V6 rear diff housing is bolted back in.
driveshaft is back on. You can tell the angle is better already.
rear axle is in and caliper bracket is bolted on. The brake rotor is in place
and the u-bolts are set in place.
I get to far, I want to weld the shock tabs back on in their new position. Using
the handle of the wire brush as a spacer, the gas pressure shocks hold the
brackets right where I want them.
tacking, I pulled the shocks back out, ( I didn't want to melt the bushings), and
finished the welding. Here you can see the brake line going back in too.
The brake line needs to be re-fit, because the tabs holding the ends had to be
re-mounted. The old perches had them welded to them, so after I cut them off,
the little tabs needed a new mounting place.
they are, welded to the back of the new spring perches.
are bolted back in place. These are gas pressure shocks, folks. They are a bear
to position. They want to be fully extended.
brake lines are run, the wheels are back on and the u-bolts are tightened.
may have over-clocked it a bit, but after the test run, the springs settled and
it looks great. Oh yeah, and the vibration is gone!
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