Paccar Kenworth C500 2012, Manual

Page: 214 / 276

7-2
08/12
Section 7
Frame Modifications
MODIFYING FRAME LENGTH
The frame cutoff after the rear axle can be shortened to match a particular body length. Using a torch is acceptable;
however, heat from a torch will affect the material characteristics of the frame rail. The affected material will normally be
confined to within 1 to 2 inches (25 to 50 mm) of the flame cut and may not adversely affect the strength of the chassis or
body installation.
The frame cutoff can be lengthened by adding frame extenders.
When extending 10.5” frame rails, the additional sections can be welded to the existing rails. The joint should be welded
and reinforced as illustrated in Figure 7–1.
See page 7-6 for more information on welding frames.
Frame Insert
A frame insert must be added after welding a frame rail extension to compensate for lost strength. The insert should be
of the same material as the frame member, or of steel, and at least equal to the frame rail in thickness. Attachment of
the insert to the frame should be made with Ream-Fit heat-treated bolts, 5/8 in. (16 mm) dia. or the next larger size. Both
the reinforcement and frame holes should be reamed to provide a fit of from .001 in. to .003 in. (.025 to .076 mm) clear
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ance. Do not weld reinforcing members. The insert should span a distance of at least 24 in. (610 mm) on either side of the
joint to insure an even distribution of stresses. Cut the ends of the insert at 45° as shown in Figure 7–2 unless the insert
extends to the end of the frame.
FIGURE 7-1. Detail of Frame Extension and Joint Welding
Note: