How to Repair a Cracked Rear Bumper?

[DelLucy]

If the rear bumper is cracked due to a collision and cannot be repaired, the solution is to replace it with a brand-new rear bumper. The rear bumper is a body panel that serves an aesthetic purpose. Here is more information about the rear bumper: 1. The rear bumper is made of relatively soft plastic, which provides certain flexibility to prevent shattering upon minor impacts. Both the front and rear bumpers of a car use softer plastic to protect pedestrians from severe injuries in case of a collision. 2. Using softer plastic also helps reduce the repair costs for the owner after minor collisions. If the bumper is damaged beyond repair after a collision, it needs to be replaced with a new one.

[ClaireAnn]

Last time my rear bumper got cracked, I took it straight to the repair shop. First, they check the size of the crack - small cracks can be fixed with a plastic welding gun. The technician will clean the crack, heat up the welding rod to fill the gap. After repair, it needs to be sanded smooth, filled with putty, and repainted to match the original factory color. The whole process takes about three to four hours, with the paint baking being critical - improper temperature or timing can cause bubbles. For large cracks, replacement is usually necessary since many modern bumpers are single-piece molded plastic - repair often isn't worth it. Don't forget to check the radar and reversing camera wiring, as there are many sensors hidden inside the bumper. I recommend going to a professional shop - using tape yourself is just a temporary fix that might worsen at highway speeds.

[McRose]

As someone who frequently works on construction sites, I've seen plenty of bumper cracks. There are three repair methods: for simple cracks, apply epoxy resin to the back, then sand and repaint after curing; moderate cracks require reinforcing the back with plastic sheets, similar to putting a cast on a fracture; severe cracks mean replacing the entire bumper, with aftermarket parts costing around 800 yuan and OEM parts over a thousand. For DIY repairs, prepare sandpaper, AB glue, and spray paint—sand the crack edges, glue both sides, wait two days for complete drying, then repaint. If you're handy, you can try, but the results won't match machine welding. After repair, test the crash performance—cracked bumpers lose some energy absorption.

[EdenFitz]

From a design perspective, repairing bumper cracks is essentially a reshaping process. First, clean the rough edges of the crack, soften the plastic with a heat gun, and align and clamp the edges. Then reinforce the backside with fiberglass mesh and epoxy resin, similar to repairing a fiberglass boat hull. The surface should be filled with putty in layers, sanded with sandpaper after each layer dries, and finally painted three times: primer for leveling, basecoat for color, and clear coat for shine. Nowadays, there are also carbon fiber repair films that can be directly applied to the crack, both concealing the damage and adding texture. Note that the color change area should not exceed 30%, otherwise it needs to be registered. After repair, it's recommended to apply anti-collision strips to avoid secondary damage to the same spot.