Paintless dent removal

[s class]

THis is a topic that gets talked about a lot. Some of the more hyped methods are dry ice or similar, suction cups but I'm somewhat skeptical of these.

Perhaps the most widely used in the trade, and what is usually referred to as PDR (Paintless dent removal) is the use of various levers, tips, spoon thingys etc. The technician gently massages the dent out by pressing judiciously on the inside of the panel. The trouble is that even the pros make mistakes, and end up lifting an island. This is usually terminal - the steel is stretched. However, with skill, the pros can achieve a high degree of success with dents. They can usually get perfect results - the dents are impossible to see. To give some idea of how precise their metal work is, they work until the low spots and islands can be sanded out with a block wrapped in P2000 sand paper. Now remember this - the variations are SO slight, that they can achieve perfect flatness with just two or maximum three passes of the block - removing no more than 50% of the paint from the high spot. If your clear coat is a typical 100 microns thick, they are taking off no more that 50 microns to achieve perfection. the mind boggles to see these guys in action.

Today I hired a specialist to help me with some dents on the customer AMG W124. He uses the modern technique of glueing 'tabs' into the dents, and then pulling them out with a light slide hammer connected to the tabs. To me it seems a lot 'safer' than traditional PDR, as I watched him for hours, and there seemed little danger of raising islands. I first let him go on trusty rusty, and he achieved astonishing results on a nasty dent in the C pillar, and a crease in the bonnet. I really am VERY impressed. He works slowly though. In 8 hours he removed those two dents from trusty rusty, and the largish crushed area at the rear of the W124. The W124 will need spray work as the paint was split, but at least it would appear we will get away with no filler at all. This was an explicit goal from the customer, and one which I had been very concerned about achieving.

I am impressed, and that doesn't happen easily.

For interest, this glue technique is a modern variant of the old 'penny' trick. The old time body guys used to braise a rod onto the back of a penny sized steel disk. They would then solder this disk onto the dent (which opviously was stripped to bare metal and fluxed), and then pull on the rods with a slide hammer.

 

[John S]

Years ago I watched an "old timer" take creases out of a body by soldering strips of metal at each end of a buckled section. He then used pullers to stretch the side and very lightly topped what he called the stress points, when BANG, the whole side was straight. Is the metal so different nowadays that this system is not possible to use, or has the technique been forgotten?

 

[s class]

I think its more likely that like all things requiring great artisan skill and experience, its been forgotten.

 

[s class]

What I think is different though nowdays is that panels are thinner, so the steel streches easily, leading to permanent deformation, and making the panel less likely to want to jump back to its original shape.

 

[SEL_69L]

116's don't hail dent as easily as 126's because the steel is thicker. The reason for this is the sheet metal on 126's is thinner, although is is just as crash resistant. When 126's were introduced Mercedes changed the alloy in their sheet metal for bodies to HSLA (High Strength Low Alloy), which has less carbon in the alloy. Note: steel is a solid solution carbon/iron alloy. The result is a reduction of about 300 kg in the mass of the body. Because the steel is thinner in 126's, they dent more easily, but are a bit easier to remove by the paintless dent removal professionals.