DIY DENT REMOVAL
HERE’S 11 TIPS FOR USING A STUD WELDER AND SLIDE HAMMER TO FIX OLD COLLISION DAMAGE AND PREP FOR PAINT.
Here’s 11 tips for using a stud welder and slide hammer to fix old collision damage and prep for paint.
It’s a well-known fact that a highquality paintjob is expensive. Body shops invest a lot in their facilities, their tools, and their staff, and we’re just talking about normal collision repair. Add the special needs for restoring vintage cars, and the cost of a paintjob multiplies. How expensive can it be? Getting out of paint jail for under five figures is a real accomplishment if you can pull it off.
What’s not well known is that most of the cost for a show-quality paintjob isn’t in the actual paint and materials, it’s in the prep labor — specifically stuff like rust repair and fixing old collision damage. It turns out that much of this requires more patience than skill or money, and with a few inexpensive tools can be done at home. We previously covered the basics of hammer and dolly work in a previous story, but that alone may leave you short in areas that are hard to reach, or that have tight compound curves.
You could bypass these repairs by using new sheetmetal if it’s available, but from a fit and authenticity standpoint, reusing the damaged original panels and repairing crunched corners and dents yourself with a stud welder and slide hammer makes more sense and saves dollars. Doing it the right way, however, is the key to actually saving money. For that, we turned to expert Geoff Gates, who operates one of the top muscle car restoration shops on the West Coast. His shop — Alloy Motors in Oakland, California — specializes in Mopars, so we asked Geoff to show us the step-by-step procedure for removing dents with a stud welder and slide hammer using our ’68 Plymouth Valiant project as the subject.
Geoff explains: “Sometimes you can’t get to the back of a dent to hammer and dolly it out. Back in the day at my dad’s shop, they’d drill holes, screw a slide hammer in, and pull it out. They’d leave the holes to help the body filler grab.” Using this outdated technique on an important vintage restoration today though is the road to ruin. “I spend a ton of time fixing this type of work on my customers’ cars, welding holes shut, and working the metal,” Gates says. Thanks to modern technology, there’s a better way.
A stud welder replaces the drilling of holes by welding a mild steel pin to the bodywork. The pin provides the slide hammer with a precise impact point for moving metal. A stud welder is a very inexpensive tool that you’ll want to have
if you’re doing your own bodywork; you can get one from your local Harbor Freight dealer for as little as $99 (Chicago Electric model 61433). A good companion to that is Harbor Freight’s 14-piece slide-hammer set (model 62959) for about $25. Even if you load up with a hammer and dolly set and a few boxes of studs, you’re all in for under well $200.
Use these 11 tips to take nasty dents out of your Mopar and save big bucks on your paintjob bill. You’ll also have the satisfaction of doing it yourself!
Here are the tools we’ll be using: a pin welder (you can get a hobbyist one from Harbor freight and they work fine), slide hammer, 2-inch grinder, cutoff wheel, and for deeper pulls, you might use a MIG welder on the pins.
You need to get all the paint out of the dents so you can weld the pin to the bare metal. Use a 2-inch roll grinder with 80-grit abrasive.
When you pull the trigger, you’ll get some sparks. Hold the trigger for a few beats; most of these tools have timers built in so you can just hold the trigger until the tool cuts off.
See that glow! The controlled electrical arc just welds the pin to the metal.
You want to weld the pin where the most tension is: deep into the dent. With a fresh pin loaded in the stud welder, push the tool all the way to the metal.
The metal moved out, much closer to where it should be. Now we have to get rid of this pin that’s welded to the fender.
Here’s a close-up of the pin welded in. A little bit of heat gets into the metal, which will shrink it a bit, but that’s better than drilling a hole.
Put the slide hammer on the pin and work the wheel on the end to lock it onto the pin.
A couple of pulls back on the slide hammer while keeping an eye on the metal movement is all you need. You don’t need to wail on it, just tap, tap, tap like you would with a hammer and dolly.
Occasionally, the pins pull out and leave a hole in the metal. No big deal. Just Mig-weld that little hole shut.
Geoff just cuts them off close with a “cookie wheel” abrasive disc on a die grinder. The,n he uses a 2-inch grinder to take off the rest.
Then just grind the tack welds smooth. The less body filler, the better. You can’t do this in the middle of a big panel, but on an edge like this it works really well.
Sometimes if Geoff can’t pull any further on a heavy tension area like this he’ll MIG some tack welds to fill the low spot with metal.
If you have a bigger dent in a high-tension area and the stud welder just can’t stick the pins well, don’t be afraid to Mig-weld the pin to the metal.
Two tack welds on opposite sides of the pin is all it takes to get it to stick really well.
This dent required an extreme angle to pull. It was likely done by the corner of the bumper pinging the fender in a little accident.
Pay attention to the angle of your pull. Look at the way the dent was made and pull it in reverse.