Minimizer B4578BTPA User manual

Revised 10/23/2017 Page 1
B4578BTPA
Fender Mounting Instructions for MIN4000, MIN900, MIN1500 & MIN1554 Fenders
STEP 1
A. Unpack all cartons and lay out parts.
B. Compare the parts with hardware kit B4578BTPA as shown in Figure 1.
STEP 2
A. Lay the fenders out and clamp them together (Figure 2).
This will make bolting them together much easier.
B. Bolt the fenders together. A pack of 5/16 x 1” bolts, 5/16”
nuts and 5/16” x 1- ½” fender washers is included in the
kit. Use four bolts per joint. Recommended torque is
10-15 ft-lbs.
PART NUMBER DESCRIPTION QTY
PB5015 4.25" SWIVEL BRACKET 4
I62C450BFL8/RBZFT 5/8-11 X 4 1/2 HEX FLANGE BOLT 4
I62CNCG/RBZ 5/8-11 CLASS G FLANGE LOCK N 4
PB1/2"SPACER 1/2" POLY SPACER 12
PB501026 26.5 COMPOSITE TAPERED BKT 4
PBLOCK COMP BRACKET BACKING BLOCK 4
I31C300BSF/RBZ 5/16- X 18 X 3 HEX WASH HEAD B 16
I31C100BSF/RBZ 5/16-18 X 1 HEX WASHER HEAD BL 24
I31N150WFEZ 5/16 X 1 1/2 FENDER WASHER 24
I31CNCF/RBZ 5/16-18 CLASS F FLANGE LOCK 40
PB5067 STEEL ANGLE FOR PB5069 2
I62C250BFL8/RBZ 5/8-11 X 2 1/2 HEX FLG BOLT BZ 2
I62CNCG/RBZ 5/8-11 CLASS G FLANGE LOCK N 2
PB1/2"SPACER 1/2" POLY SPACER 2
PB5069 COMPOSITE CENTER BRACKET 2
I31C125BSF/RBZ 5/16-18 X 11/4 HEX WASH HEAD B 8
I31CNCF/RBZ 5/16-18 CLASS F FLANGE LOCK 8
PB5071 COMPOSITE ANGLE FOR PB5069 2
I31C125BSF/RBZ 5/16-18 X 11/4 HEX WASH HEAD B 14
I31CNCF/RBZ 5/16-18 CLASS F FLANGE LOCK 14
I31C100BSF/RBZ 5/16-18 X 1 HEX WASHER HEAD BL 8
I31CNCF/RBZ 5/16-18 CLASS F FLANGE LOCK 8
I31N150WFEZ 5/16 X 1 1/2 FENDER WASHER 16
B4578BTPA Mounting Kit
Figure 1
Figure 2

Revised 10/23/2017 Page 2
Figure 3
STEP 3
A. Measure the suspension travel. This measurement is used to determine the distance
between the fender and the wheel.
a. For air suspension systems, let the air out of the air bags.
b. For spring systems, measure from the stops on the springs to the bottom of the
frame.
NOTE: For air suspensions with travel exceeding 6”:
In some cases a travel stop may need to be installed to prevent such large gaps
between the fenders & tires. This will help with alignment and 5th wheel plate clearance.
(Please call Minimizer @ 800-248-3855 for questions regarding this issue).
B. Gap the fenders ¾” over the maximum travel point of the suspension system. The goal is
to make sure the fender does not rub on the tire. A gap larger than ¾” may be necessary
if using worn tires.
TIP: Establish the ¾” minimum gap required in Step 3B.
a. For an air suspension system, place a ¾”
board on top of the tires after the air has
been let out of the airbags (Figure 3).
Place the fender on top of the board.
b. For a spring suspension system, add ¾”
to the measurement from Step 3A.
STEP 4
A. Position the fenders exactly where they will be mounted.
a. Visually pick and mark the locations that the brackets will bolt
to the frame.
B. Try to use existing holes in the frame to bolt through. It is possible
to remove any existing frame bolt and replace it with the supplied
bolt in the bracket kit.
Tip: It is common for the front bracket to align with the
existing quarter fender holes and the rear bracket to align
with the holes left from the mud flap hanger.
NOTE: Depending on the length of the truck frame and the placement of the mud flap hangers,
the fender may tuck inside the mud flap hanger. Figure 4 shows a truck with flaps and fenders.
Figure 4

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C. Spacers are supplied to bring the steel swivel away
from the frame in the event of any obstructions
(Figure 5).
c. The ideal setup is to mount the
steel swivel directly to the frame.
NOTE: Use spacers only when necessary.
D. Install center bracket assembly (Figure 6).
a. Try to use existing holes in the frame to bolt through. It is possible to remove any
existing frame bolt and replace it with the supplied bolt in the bracket kit.
Recommended torque for the 5/8 x 2-1/2” bolt with washer is 110-115 ft-lbs.
E. Install center bracket as close to where the two fenders join
together as possible (Figure 7).
a. Drill three 5/16” holes through the fenders using the holes in
bracket PB5069 as a guide.
b. Use three 5/16” x 1 ¼” bolts to bolt the center bracket and
fenders together. Recommended torque for all 5/16”
hardware is 10-15 ft-lbs.
c. Use 5/16” fender washers and 5/16” nuts provided with the
kit on the inside of the fenders.
Figure 5
Figure 6
Figure 7
NOTE: Do not drill into the weld or any other
part of the light box. If a mud flap is mounted to
the light box style fender and the mud flap is
backed over, it may cause the interior welded
plate to become loose. Slot the mud flaps to
prevent this issue. This is NOT covered under
warranty.
See IMPORTANT assembly
instructions for center bracket
PB5069 & PB5067, last page
of this form.

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F. Some installations may not allow the center bracket to bolt through the ends of the
fenders.
a. In these cases use the plastic angle
(PB5071) to connect the fenders to the
center bracket assembly (Figure 8).
b. Use three 5/16” x 1” bolts, washers, and
nuts to bolt PB5071 to the center bracket
assembly. Do not tighten these until the
fender assembly is level. Recommended
torque is 10-15 ft-lbs.
Tip: PB5071 is also used as a height adjustment for the fender assembly.
G. Drill four 5/16” holes through the fender using the holes in bracket PB5071
as a pattern (Figure 9).
a. Install the 5/16” x 1 ¼” bolts through the bracket and into the
fender.
b. Use 5/16” fender washers and 5/16” nuts provided with the kit on
the underside of the fender.
c. Recommended torque for all 5/16” bolts is 10-15 ft-lbs.
H. If possible, position the mounting brackets so they
are located within 15” of the bottom of the fender.
This protects against wind blowing the leading edge
of the fender back into the tire (Figure 10).
Tip: If the front fender bracket is mounted
higher than 15”, refer to
http://www.minimizer.com/instructions%20.ht
ml for further suggestions on adding
additional support.
Figure 10
Figure 8
Figure 9

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STEP 5
A. Use four 5/16” x 3” bolts to attach the
bracket (part number PB501026) and the
backing block (part number PBLOCK) to
the steel swivel (part number PB5015).
See Figure 11. Make sure the steel
swivel is fully inserted into the
bracket.
TIP: USE CARE WITH POWER TOOLS
AS OVER-TORQUING WILL CAUSE
CRACKS IN THE BRACKET. RECOMMENDED TORQUE IS 10-15 ft-lbs.
NOTE: DO NOT EXCEED RECOMMENDED TORQUE. THIS WILL VOID THE
WARRANTY.
TIP: Do not completely tighten one side
of the backing block before moving to
the other side. Alternate tightening
bolts as pictured in Figure 12. Make
sure to only tighten halfway and then
repeat the pattern in Figure 12 until
backing block is tight.
STEP 6
A. Once the brackets are placed in position
with the fender, securely tighten the 5/8” x 4-
1/2” bolts that go through the PB5015 steel
swivel to attach the swivel securely to the
frame (Figure 13). Recommended torque
is 160-170 ft-lbs.
Figure 12
Figure 9
Figure 13
Figure 11

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STEP 7
A. Attach the bracket (PB501026A) to the fender.
a. Drill six 5/16” holes through the
fender using the holes in bracket
PB501026A as a guide.
b. Install the 5/16” x 1” bolts through
the bracket and into the fender.
c. Use six 5/16” fender washers and
5/16” nuts provided with the kit on
the underside of the fender.
d. Tighten the bolts to
recommended torque of 10-15
FT-LBS. Hand tightening with
Torque wrench is recommended.
DO NOT EXCEED
RECOMMENDED TORQUE.
e. Make sure the fenders are square
and aligned (Figure 14). Twists or
bows in the fender will fatigue the
material over time.
STEP 8
A. For trucks with air suspension, raise and lower the suspension one final time to confirm
that there is adequate clearance between the fenders and wheels.
B. Recheck all brackets and bolts to ensure they are tightened to the recommended torque.
NOTE: ONCE FENDERS ARE IN SERVICE OCCASIONALLY CHECK TORQUE ON 5/8”
X 4-1/2” HEX BOLTS IN THE FRAME TO MAKE SURE THEY DO NOT LOOSEN OVER
TIME.
Figure 14

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