The deformation of the bridge beam is checked in both horizontal and vertical planes.
Having attached flange A.70172 to each end of the beam, install the beam with flanges on identical prisms located on a test plate at least 1600 mm long so that the surface of the crankcase mating to the beam is in a vertical plane.
Check the deformation of the beam by placing a square against the outside (figure 3-50) and side (figure 3-51) flange surfaces A.70172; if the beam is not deformed, the square will fit tightly.
Figure 3-50. Checking the vertical deformations of the rear axle beam with a square on the outer surface of flange A.70172.
Figure 3-51. Checking the twist of the rear axle beam with a square on the side surface of flange A.70172.
The amount of deformation is checked with a feeler gauge. If the 0.2 mm feeler gauge passes through any flange, the beam must be straightened.
With a square (figure 3-52) check the perpendicularity of the gearbox mounting surface relative to the support surface of the A.70172 flange. A 0.2 mm feeler gauge should not pass through.
Figure 3-52. Checking the perpendicularity of the gearbox mounting surface.
Rotate the bridge beam 90° and install it on the prisms. Attached to the outer surface of the flange (figure 3-53) the square must fit tightly, otherwise check the deformation value with a feeler gauge. A 0.2 mm feeler gauge should not pass.
Figure 3-53. Checking the horizontal deformations of the rear axle beam with a square on the outer surface of flange A.70172.
If the deformation exceeds the specified value, straighten the beam following the instructions below.
After making adjustments, thoroughly wash the beam, clean the magnetic plug, install it in place and check:
- quality of welds and tightness of the beam;
- cleanliness inside the beam (absence of burrs, chips and oil residues) and the cleanliness of the beam breather.
After this, paint the beam on the outside to protect it from corrosion.