Peterbilt 520 - Frame

values. PACCAR proprietary suspension u-
bolts must be tightened in a specific
sequence. T
ake your vehicle to an
authorized dealer to tighten the U-bolts on
your vehicle.
Torque for Grade 8 U-Bolts
Peterbilt Front Suspension U-bolts
U-Bolt Size
Diameter (-
in.)
Torque (lb-
ft)
Torque
(N•m)
3/4 260-290 353-393
7/8 370-415 502-563
For all non-PACCAR suspension
systems, see the manufacturer
’s
operator’s manual for torque
specifications.
Peterbilt Rear Suspension U-bolts
Rear
Suspensio
n T
ype
U-Bolt
Diamet
er
Torque lb-ft
(N•m)
28
Low Air
Leaf (U-bolt,
spring)
M22 x
1.5
375–475 (508–
644)
Flex Air M22 x
1.5
325–375 (440–
508)
Tandem
Low Air
Leaf
M22 x
1.5
375–475 (508–
644)
Air Leaf (U-
bolt, spring)
1.0 -in.
NF
450–550 (610–
746)
Air-Trac 1.0 -in.
NF
450–550 (610–
746)
13.5K Taper
Leaf (Axle
U-bolt)
¾ -in.
16 UNF
275–320 (373–
434)
18K Taper
Leaf (Axle
U-bolt)
¾ -in.
16 UNF
275–320 (373–
434)
Peterbilt Rear Suspension U-bolts
Rear
Suspensio
n T
ype
U-Bolt
Diamet
er
Torque lb-ft
(N•m)
18K Air Leaf
(Axle U-
bolt)
¾ -in.
16 UNF
275–320 (373–
434)
For all non-PACCAR suspension
systems, see the manufacturer’s
operator’s manual for torque
specifications.
NOTE
The values shown here are for sus-
pension
U-bolts and should not be ap-
plied to bolts and fasteners for the
frame.
28
T
orques listed are for primed (or non-oiled) U-bolts.
MAINTENANCE - Specification Reference Charts
252 Y53-6096-1C1 (09/20)
5
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