NASCAR Driver Offers Tips for Repairing Dents with Bondo - BodyShop Business
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NASCAR Driver Offers Tips for Repairing Dents with Bondo


When the NASCAR racing series visits the tight tracks and short ovals that lead to lots of crashes, the teams are prepared with gallons of Bondo Auto Body Filler, part of the 3M automotive products family.

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3M says an estimated 215 gallons of Bondo Auto Body Filler will be used by the NASCAR Sprint Cup teams on a typical weekend at Bristol. On average, each team consumes 126 gallons a year, totaling more than 5,418 gallons of the body filler used for repairing dents and ensuring sheet metal panels fit the tight NASCAR templates.

For the No. 16 3M team, the body filler saves time and money at the track.

"Close racing can mean a lot of dents, so Bondo body filler from 3M is a great solution," says Greg Biffle, driver of the No. 16 3M Ford Fusion. "If I brush the wall in practice, we can repair the damage quickly without having to replace the body panel. And, if our sheet metal doesn’t quite fit the NASCAR templates, we use body filler to fill out the area."


Biffle also spends a great deal of time working on his own classic cars and uses Bondo Auto Body Filler to repair older car bodies. Whether restoring classics or just fixing dents on a current car, he offers these tips to help car owners do their own dent repair:

1. Clean the vehicle with soap and water, followed by a solvent cleaner, such as Adhesive Remover from 3M. This is important because any contaminants (wax, bug residue, tar, dirt) remaining when sanding begins are ground into the surface and could compromise the adhesion of repair materials.

2. When repairing any dent, it is best to remove as much of the dent as possible prior to filling with body filler. An assortment of slide hammers, hammers, dollies and picks may be needed to perform this step. Always use appropriate eye and respiratory protection.


3. After the dent is roughly removed it is time to start sanding. Use a sanding block or DA orbital sander with 40-80 grit abrasive to remove all paint to approximately 2" around the dent.

4. Using proper techniques, mix Bondo Auto Body Filler from 3M and apply to the dent in thin layers. The first layer should be applied with firm pressure to ensure good adhesion. Avoid over-application of filler as this just requires additional sanding. Let dry for 15 to 20 minutes, dependent on temperature and humidity.

5. Select a sanding block that is appropriate for the size of the repair and attach a 3M 40 grit abrasive sheet. Rough shape/sand the repair area, keeping your block flat to the surface. The 40 grit is used to remove material fast and rough shape the repair. Avoid over-sanding with 40 grit or the finished repair area will be low. If low spots are detected, it may be necessary to apply more Bondo Auto Body Filler from 3M and repeat this sanding step.


6. Once satisfied with the rough shape of the repair, attach an 80 grit abrasive sheet to the sanding block and final shape the repair. After this step, the repair should be level and there should be no 40 grit scratches remaining. The body filler should also have a smooth featheredge all around the repair.

7. Attach a 180 grit abrasive to the sanding block to featheredge the paint away from the body filler and remove all straight line scratches.

8. Mix Bondo Glazing and Spot Putty from 3M and apply to the entire repair area overlapping the body filler and paint featheredge. Allow 15 minutes to dry, depending on the temperature and humidity.


9. Apply a 180 grit abrasive to the sanding block and sand the repair area until level. Remember to keep the block flat to the surface at all times and do not oversand.

10. Apply a 320 abrasive grit to your sanding block and remove all straight line scratches from the paint around the filler area. Once complete the repair is ready for the application of primer surfacer and topcoats. It’s very important to follow the paint manufacturer’s instructions for your specific brand of primer or paint.

More information:

• For video tips of the body repair processes using 3M products, visit  

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