Bumper

This category covers chassis components mounted behind the front bumper, such as front underrun protection and metal brackets that support front bumpers. When assessing damage, the inspection must go beyond the visible outer skin: the bumper supports, mounting brackets and connections to the chassis rails behind it may also be deformed. A bumper cover is not necessarily an impact-absorbing structure or an approved underrun protection device.

Distinguish between front underrun protection and metal bumper supports or mounting brackets: these components do not necessarily serve the same purpose. Steel versions must be checked for corrosion and permanent deformation. The material marking determines which repair and painting procedures may be applicable.

Always identify parts using the vehicle's chassis number. Visual comparison or selection based solely on the model name is never sufficient. Year of manufacture, vehicle width, off-road specification, sensor equipment, fog lights and openings for towing equipment all affect fitment. For MAN TGX with XL, XLX or XXL cabs and Mercedes Actros with Lang StreamSpace, Lang BigSpace or Lang GigaSpace, the fit against the cab front must be checked, without assuming interchangeability based on cab height. Different bodywork and mounting variants apply to MAN TGE and Mercedes Sprinter, as well as buses such as Citaro.

Relevant design parameters include wall thickness, material strength, bolt grade, mounting hole centre distances and specified panel gaps. The geometry and material thickness in front of radar sensors also affect functionality: a part that appears to fit is therefore not necessarily suitable for the same sensor configuration.

Common symptoms include rattling, uneven panel gaps, vibrating lights and faults following a minor collision. These are often caused by torn-out clips, deformed brackets, loose bolted connections or corrosion between overlapping steel panels. Replacing only the outer cover will not resolve these underlying problems.

1. Park the vehicle safely, chock the wheels and support heavy bumper components before removal. Follow the manufacturer's shutdown procedure when working on electrical connections.
2. Clean the structure and inspect the rear as well. Check mounting tabs, weld seams, wiring harnesses, connectors and any energy-absorbing elements for fractures, kinks and moisture ingress.
3. Measure reference points and diagonals using a measuring rule or body measuring system. Check panel gaps with a feeler gauge and compare the left and right sides against the manufacturer's dimensions. Do not apply a universal millimetre tolerance.
4. Check mounting holes for ovality and bolts for damaged threads. If brackets have shifted, also inspect the adjoining chassis rails; do not use the mounting bolts to pull the bumper into position.
5. If ADAS (Advanced Driver Assistance Systems) are fitted, read the fault codes and check sensor mounts for angular misalignment. A sensor with no fault codes may still be incorrectly aligned after a collision.

Replace supports with structural cracks or permanent deformation in accordance with the vehicle manufacturer's instructions. Do not straighten or weld them unless an explicitly approved repair procedure permits it. For front underrun protection, use only the components and fasteners specified for the vehicle variant concerned.

Install without placing components under stress, using the specified fasteners and tightening torques. Restore corrosion protection on permitted contact surfaces and check clearance to cooling packs, bodywork and tilting cabs. Keep air intakes and towing equipment accessible. Then test the lights and parking sensors; carry out radar calibration when required by the repair procedure. When painting, observe the permitted paint layer build-up in radar zones. A thorough final inspection helps prevent recurring faults and unnecessary repeat disassembly.