Impact resistant adhesives are an entirely new category of super strong epoxies that provide GM vehicles with significant upgrades in safety and driveability.
How They Work
These adhesives are a central part of the engineering of most 2015 and newer GM vehicles. As their name implies, they’re designed to resist collision impacts. They provide added structural durability for increased protection of both passengers and the vehicle itself. A stiffer vehicle chassis also cuts noise and provides a noticeably improved ride. These adhesives do not become brittle, nor do they lose strength over time.
Where They Work
Impact resistant adhesives allow engineers to create stronger, more complete bonds between parts. They replace many traditional adhesives and sealers and work with mechanical bonds and welds in areas where adhesives previously weren’t applied. These include: front and rear, upper and lower rail attachments, inner and outer rocker panel joints and all occupant compartment framing.
Collision Repair Considerations
When an impact resistant adhesive is removed or damaged, it always must be replaced with the same adhesive type. If another adhesive is substituted, the vehicle will not be returned to pre-accident condition. Safety could be compromised and a drop-off in driveability will be apparent.
Impact resistant adhesives are relatively easy to apply. The following steps provide the basis for most repairs:
Step 1. Using 60-grit paper, sand away only the e-coat to reveal the bare surface.
Step 2. Spread a thin coat of adhesive on the bonding flanges and anywhere else the e-coat was removed and will not be refinished.
Step 3. Apply another layer of adhesive on top of the first. Note that the adhesive contains glass beads for bond-line control.
Step 4. Clamp components together and be sure to use structural rivets, such as 11519023 (where specified) or Flow Form Rivets (where specified) to mechanically fasten all mating surfaces to the vehicle.
Step 5. Skive joints to remove excess adhesive (as required) and use a recommended solvent such as a wax and grease remover to wipe the area clean. Doing so allows sealing and refinishing before the adhesive attains full cure.
Impact resistant adhesives will bond to bare, coated and e-coated metals. They bond best, however, to freshly abraded aluminum. Resistance spot welding should be conducted only through uncured adhesive. Rivet bonding can be used where resistant spot welding cannot be accessed.
Ambient temperature cure times tend to be longer than other adhesives but can be shortened with infrared lamps. Temperatures, however, must be kept below 350° F.
During product development, GM testing staff test drove two new Cadillac ATS models. One featured the new adhesives; the other did not. The testing crew reported that the difference in ride quality was comparable to the variation between a luxury automobile and an entry-level compact. The study indicated that it will be essential for technicians repairing collision-damaged vehicles to use suitable adhesives, says Bob Hiser, Advanced Serviceability of Design Engineer at General Motors.
General Motors has created General Specification GMW16252, which is a structural adhesive performance guideline for the bonding of metallic substrate for aftermarket use. It is the intention and purpose of this guideline to provide a test protocol for evaluation of adhesive systems that could be utilized in service repair of vehicles.
The adhesives listed below may be used in service to bond replacement body panels (door, deck lid, hood or roof skins) as an option to, or in conjunction with welding, rivets or other mechanical attachment means. These adhesive systems may also be used in service to bond other automotive parts such as structural components, reinforcements and body rails. Be sure to follow the adhesive manufacturer’s prep, application and curing instructions for each use.
- Fusor 2098
- 3M IRSA (07333)
- Ashland Pliogrip 5770