Tuff Country 16720 - GM 73-87 6 3/4 ton box kit - Manual (Page 7)

grips on each side of the stock centering bolt. Carefully
remove the stock centering bolt and nut and discard.
Carefully remove the “C” clamp vise grips that are holding
the stock springs together. Special note: Be very careful
when removing the “C” clamps, the stock springs are
under tension and can be dangerous. Repeat procedure
on passenger side.
38. Locate (2) new rear add-a-leaf, (2) 3/8” x 6” centering
bolt and (2) 3/8” fine nut from box kit 81250. Install the new
rear add-a-leaf into the stock spring assembly. Secure the
new rear add-a-leaf to the stock spring assembly using the
new 3/8” center bolt and nut. Torque to 28 ft. lbs. Special
note: If the new add-a-leaf that you are installing into the
stock spring assembly has an offset center hole loca-
tion, place the longest side of the add-a-leaf towards the
rear of the vehicle. Also the new add-a-leaf should be
installed into the stock spring assembly in progression
in order, from longest to shortest. The new add-a-leaf
should be installed between the stock overload and the
stock spring pack. The stock overload is usually the un-
arched spring at the bottom of the stock leaf pack. Also,
Tuff Country EZ-Ride Suspension recommends not
using any air tools when installing the new add-a-leafs
into the stock spring assembly. If air tools are used the
centering bolt may strip, causing the stock spring
assembly to come apart. With a suitable cutting tool, cut
off the extra thread from the new centering bolt. Repeat
procedure on passenger side.
39. Locate the new 4” rear lifted blocks from box kit 79004.
Working on the driver side, install the new 4” block between
the modified stock spring assembly and the rear differential.
Special note: The new 4” block has a slight taper to it,
make sure that the smaller end of the block is installed
towards the front end of the vehicle. Repeat procedure on
the passenger side.
40. Carefully raise up on both hydraulic floor jacks at the
same time until the modified stock spring comes into contact
with the newly installed 4” block. Special note: Make sure
that the head of the centering bolts seats properly into
the newly installed blocks.
41. Locate (4) new 5/8” x 3 1/2” x 13 1/2” round u-bolts.
Locate (8) 5/8” high nuts and (8) 5/8” u-bolt harden washers.
Also, locate the stock u-bolt plates. Working on the driver
side, install the new u-bolts into the stock location and
secure using the new hardware and the stock u-bolt plates.
Repeat procedure on the passenger side. Working in a criss-
cross direction, torque
the new u-bolts on the
driver and passenger
side to 110 ft lbs.
42. Locate the new rear shocks. Special note: New longer
rear shocks are needed after this suspension system
has been installed and the rear shocks need to be
ordered as a separate part #. If you have not already
ordered your rear shocks, please feel free to contact Tuff
Country or your local Tuff Country dealer and order your
new rear shocks. Tuff Country recommends installing a
30” fully extended nitrogen gas shock in the rear.
Working on the new shocks, install the new bushings and
proper sleeves that are packaged with the new shocks into
each eyelet of the new shocks. Special note: Make sure to
use a lithium or moly base grease prior to installing the
new bushings and sleeves into the eyelets of the new
shocks. This will help with the life of the bushings as
well as prevent squeaking.
43. Locate the stock upper and lower shock mounting hard-
ware. Working on the driver side, install the new shocks into
the stock location using the stock upper and lower hardware.
Make sure to use thread locker or loctite and torque both the
upper and lower hardware to 65 ft lbs. Repeat procedure on
the passenger side. Special note: Tuff Country highly rec-
ommends installing shock boots onto the new shocks. If
shocks boots are not installed, damage may occur to the
piston of the new shock. If you have not already ordered
your new shocks boots, please contact Tuff Country or
your local Tuff Country dealer and order some new
shock boots. Tuff Country offers, dark blue, light blue,
gray, black, red or yellow shock boots.
44. Remove both hydraulic floor jacks from under the rear
differential.
45. Install the tires and wheels and carefully lower the vehi-
cle to the ground.
46. Check and double check to make sure that all steps were
performed properly for the rear end and check again.
47. Move back to the front of the vehicle and add some
thread locker or loctite to the newly installed hardware that
connects the new front spring to the stock shackle. Torque
the stock upper and new lower hardware to 35 ft lbs.
Special note: if these bolts are over torqued, they will
have an effect on the ride quality of the front springs.
48. Add the proper type of brake fluid in the brake fluid reser-
voir and with the help from a buddy, bleed the front and rear
brake lines.
49. If you were not able to install the new front sway bar relo-