WILL STRESS RELIEVING SAVE CHASSIS FATIGUE?

We at DRO are certainly for anything that will make racing safer. We received the following letter to the editor and since one of our tech experts, Dave Koehler is familiar with Metalax stress relieving (having offered that service in his shop a few years ago before he specialized in nitrous and injection systems) we asked him his thoughts on the subject, which follow. -Editor

After the two NHRA crashes, with the car coming apart, then Wayne Bailey dying at Red River in the IHRA, there has to be something done about the cars fatiguing. I think the Metalax stress relieving system should be done on a monthly basis to all those flexi-flyer chassis.

I am an old SEMA certified chassis builder, (#246) so I do know what I am talking about. This is possibly a service some one could have in a large trailer, and follow the circuit.

It is a shame to lose any one, and I am sure the IHRA has as good a safety crew as does NHRA, but things happen in racing, look at Blaine Johnson. His brother still uses Hadman chassis even after his brother was killed in one. I don't know if I would have continued building cars if one of mine had killed someone. But then there are circumstances where no chassis could save someone.

Let's pray a method is devised to save even the few racers we lose now.

Richard Burbick

Response:
I will have to agree with Mr. Burbick. Stress relieving the chassis would definitely extend their useful life. It will not solve in-progress stress, but that stress could be removed after each event. I used to offer the Metalax stress relieving service and I used it on my own chassis during the building phase.

Stress relieving removes damaging thermal stress that occurs during manufacture or modification. If a component has been cast, forged, welded, or machined it will have thermal stress. Aluminum parts have the most built-in stress. Metalax is a sub-harmonic, vibratory process that removes all thermal stress. There is no heat treat loss or dimensional change to the parts.

To illustrate the possibilities, I will relate an experience of my own. I (along with the editor of Drag Racing Online) was one of the three or four nut cases who tried the twin engine nitrous set-up a few years ago. One version was a front engine 200-inch car. One test day, just as the car launched, it put my face in the dash. What had happened was the control bar between the two injectors came apart due to a motor mount break. The lead engine went stone dead while the second engine tried to accelerate during a wheelstand.

Yes, the wheelie bars worked. The resulting damage was unreal. The chassis twisted up so badly that the main upright at the rear plate twisted and collapsed in on itself, along with some diagonal bars. The force involved had to be incredible.

After the usual grumbling back at the shop, I was curious so we magafluxed everything and found no cracks. Zero, zip, nada. No cracks in the welds or next to the welds. Checked it three times.

Those of you who work with chromoly know that it has its place, but can crack fairly easily. I firmly believe that the Metalax stress relieving during the chassis welding and after completion kept the damage to a minimum, at least concerning cracking.

I believe from my experiences working with this process daily, that if a chassis builder built two identical chassis and stress relieved them, they would be more apt to react identically and consistently, which they don't currently do.

While this process is not the end-all cure for everything that ails race cars, it is one more step in the right direction to improving the life and safety of tube chassis cars. The equipment is way overpriced for the sportsman race, but well within the budget of the sponsored teams.

The health, stability, and life of cranks, blower cases, etc. also step up with stress relieving. Hmmm, perhaps I should offer this service again.

David Koehler
www.koehlerinjection.com