Hem Flange Corrosion

Hem Flange Corrosion

Overview:

Hem flange corrosion generally starts at the bottom of a down standing hem flange where water can collect. The condition can occur on hoods, liftgates, and door skins. The condition usually begins where the outer panel makes the turn upward to form the hem flange on the inside of the panel. The condition can vary from minor surface corrosion to perforation. The repair process will vaiy based on the severity of the condition.

Hem Flange Repair:

Overview:

When the condition is surface rust at the edge of the hem you would remove the corrosion, and apply a corrosion resistant primer. Seal the hem edge using seam sealer and topcoat following paint suppliers recommendations.

A slightly more aggressive corrosion condition may require opening of the hem to remove all the corrosion. Once the hem is opened you must remove all the corrosion and apply a corrosion resistant material to protect the sheet metal.

A couple of the most common corrosion resistant primers are acid etch primers and epoxy primers.

The adhesive The Chrysler Group recommends for hem repairs contains corosion resistant properties (built in) so no primer is required.

Once the corrosion is removed from the hem area apply the Mopar / Fusor #112B adhesive, follow the directions that are supplied with the adhesive.

Move the hem back into place remove any excessive adhesive squeeze-out. After the adhesive has cured finish sand, prime, seam seal and paint.

Hem Flange Removal Repair:

Overview:

In cases where there are parts of the hem missing or the hem is very thin it may be easier to remove the hem completely to achieve an acceptable repair.

The outer door skin is bonded to the inner door structure around the perimeter of the door assembly. The hem is applied during the assembly process to hold the inner and outer door panels together until the adhesive is cured using heat from the paint process. Once the adhesive is cured there is no need for a full hem flange.

1. Use a grinder equipped with a 36 grit-grinding disc to remove the hem flange by grinding through the lower edge of the door skin. To do this you must use the grinder so the rotation of the grinding disc moves inward toward the inside of the vehicle at the cutting surface. If the grinding disc moves outward away from the door skin on the cutting edge you will peel the outer door skin away from the inner door causing damage to the skin.

2. Once you have cut through the skin, peel the remaining hem from the inner door.

3. Check the bond between the inner and outer door panels, at the bottom of the door if there are locations that require adhesive bonding use Mopar (part 05083S55AA) / Fusor #112B structural adhesive. Follow the information on the instruction sheet for curing and work time.

Illustration H:

Note: There must be drain holes in the bottom of the door. If you apply adhesive to the bottom of the door make sure to you have a drain hole at the front and rear of the door.

4. finish sand, prime, and topcoat per paint supplier's recommendation.