More Brains, Less Brawn: Straightening a Vehicle - BodyShop Business

More Brains, Less Brawn: Straightening a Vehicle

Brute force isn't necessary to straighten a vehicle. Still, techs like to flex their muscles rather than use their brains to get the job done.

How many times have you seen a technician grab a section of 2×4 and a sledge hammer to punch out a dent in a quarter panel that’s accessible from the inside of the trunk? I’ve seen it many times. Every time that tech strikes the dent, he creates a new dent and lengthens the time required to successfully complete the job. This contradicts the reason he grabbed the 2×4 and the sledge hammer in the first place – he wanted to be fast!

The initial moments of any straightening job are the most important of all the time spent on the job. Why? Because the first steps you physically take on the job determine how much time and how difficult – or easy – the job will be.

My advice: Slow down and be faster. I know that sounds like a contradiction, but it’s true. It’s in those very first moments – let’s say the first 10 minutes – when you should stop and formulate a plan that causes the very least amount of damage possible to repair the collision damage.

Panel Straightening
The craftsman who taught me often said: “Bodymen do more damage to the metal than customers do.” And this is true in many cases. Hammering and pounding in the damaged area causes a lot more damage than the initial dent did.

Let’s go back to our hypothetical quarter panel dent, which is accessible through the trunk. Yes, you could kick out the dent, pound it out or try several other easy-to-think-of methods. But what about setting up a push using your four-ton hydraulic ram with a 1/4-inch slab of rubber on the inner surface of the dent and a 2×4 block for the ram head to push against?

“Why do I need a porta power to push out thin sheetmetal?” you ask.

It’s not the power you need the porta power for; it’s the control.

“Control? What’s control got to do with removing a dent?” you ask.

Everything, if it’s done properly. Everything.

OK, you’ve removed the horizontal spare tire and set up a push from the spare-tire well using blocking and padding to prevent further damage. Now begin jacking the dent out. Watch the action. Proceed slowly – you’re only eight minutes into that six-hour quarter anyway. Be careful and concentrate on what’s happening. After you see the dent move and you’ve got some pressure on it, begin stress relieving it.

“Stress relieving? What’s that and why do I need to do it?” you ask.

“Metal has a memory,” my old teacher used to tell me. “It’s up to you to help it remember.”

As that dent begins to move back to its original shape, you’ll notice high areas evident on the face of the panel. These high areas are actually locking the panel into a distorted position. What’s actually happened is that the position and order of the molecules have been changed by the collision and are holding the dent in. If we can apply pressure in a way that’s approximately the opposite of the pressure that caused the dent, then we can stress relieve these “lock” areas by using a hammer and a dinging spoon or a smooth-faced body hammer. By tapping carefully on these “locked” areas with the pressure applied to the back side, you’re actually re-distributing the molecules and helping the metal to remember.

Do this carefully. Don’t cause a lot of damage. Just lightly tap and ease the damage out.

You wouldn’t be able to accomplish this if you’d pounded that dent out because you can’t pound in two places at the same time. You just don’t have that kind of control.

If you need to move the porta power, go ahead. Stress relieve all of the necessary areas carefully. When it looks pretty good, remove the jack. Looks like there’s still some damage at the point of impact, but it’s much less than what you began with? You’re only 20 minutes into the job now, and you haven’t even broken a sweat! Look at the remaining damage; it’s probably just a crease.


Don’t start hammering on it from the inside. Fight that impulse. Take a smooth-crowned dolly and push against the crease while you tap on either side of it. Don’t hammer on dolly. Hammer off dolly. When you hammer on dolly, you’re stretching the metal.

Work patiently and carefully with skill and pride. You’ll be amazed at the results, and you’ll be better and faster at the same time.

Frame Straightening

It’s the same idea all over again – only this time we’re working with stronger metals, which are more defined by shape.

The first 10 minutes here are crucial planning minutes, rather than action minutes. But, once again, the proper setup and counter blocking while stress relieving will save you hours over using a damaging brute force pull. I understand the overall urge to jump in and act quickly, but fight that desire and opt for a well-planned strategy.

Instead, carefully measure your vehicle with whatever measuring system you have. Too often, the desire to immediately start repairing obvious damage leads to undiscovered damage being found in the suspension alignment phase of the repair – all because the technician never properly measured or diagnosed the damage in the first portion of the job, before the repair phase. And we all know that it isn’t a fast process to re-rack a car and send it back for suspension alignment.

This measuring process is crucial on all vehicles, especially full frames. What looks like an insignificant shot on the end of a frame rail, causing very little visible body misalignment, can translate into serious diamond problems with significant wheel setback – which would go unnoticed to the wheel alignment tech, then turn itself around (in what Australians call the boomerang) right back to you.


Measure and diagnose. Understand, and then proceed with a good plan.

Plan your hookups carefully. Make them in the most secure and advantageous way. Perhaps you should consider two rams and two hookups for a length pull in order to reduce the amount of stress you have on a single location. Two pulls at once, in two separate but close locations, reduce the chance of damaging what you’re pulling on. Remember, we’re repairing the vehicle and seriously attempting to reduce all damage in the process.

Ninety percent of any pull is counter blocking. Just pulling hard on a vehicle without properly counter blocking or counter supporting it will put tremendous force on the anchoring areas, which can then become damaged.

Once again, stop!

Before you begin pulling, anticipate where that pulling force is going to be concentrated and devise a counter support system (porta powers) to the rear of the damage, between the anchor and the damage. This focuses your power where you want it – on the damage. Now apply power and pull. Once again, don’t just use brute force but apply pressure and then stress relieve the area (by carefully using a heavy hammer on the damage and the surrounding areas), allowing the displaced molecules to be redistributed to their original positions and your rail or component to come back to the desired location.

Maintain Control
I’m not trying to oversimplify these straightening operations. I’m appealing to you to slow down at the beginning of the job. Plan your repair strategy with the utmost thought and care, and by doing so, you’ll make your work simpler, better, faster and more profitable.

Writer Mike West, a contributing editor to BodyShop Business, has been a shop owner for almost 30 years and a technician for almost 40 years. His shop in Seattle, Wash., has attained the I-CAR Gold Class distinction and the ASE Blue Seal of Excellence.

Quality Is Job No. 1
I started straightening vehicles in 1963 at Emily Griffith Opportunity School in Denver, Colo., and have been continuously doing so ever since. I was lucky when, at 18, I started out as a helper in a dealership body shop. I worked for a foreman who didn’t allow plastic filler in the shop. We were expected to metal finish all repair work, and any filling was done with 70-30 lead.

While this may seem archaic to some of you, to learn straightening by this method gives you the finest foundation possible for fast, quality work. In the first place, plastic filler was never intended to be used for more than a surfacer. Because of its abuse and misuse by people who don’t know what they’re doing, our image as technicians and as an industry suffers in the eyes of the public.

Why do you think the U.S. Department of Labor states that we’re currently suffering a shortage of autobody workers to the tune of 15.8 percent – and that it’ll get worse for at least eight more years?

Part of the answer, surely, is the image our industry holds in the public eye. Do they want their sons and daughters to grow up to become autobody workers? Because of their perception of us, I fear not. Most of this perception was brought on by shoddy workmanship. (As that comic strip figure Pogo said, “We have met the enemy and … he is us.”)

We need to raise the level of our craft to where it belongs. It’s truly a skill that requires much practice and a craft that demands craftsmanship. I hope I don’t seem “preachy” to you, but the issue of pride in workmanship is so very important to everyone of us, our industry and, most of all, those we serve – our customers. We should all be proud of what we do, and do it in a way we can be proud of.

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