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Tubular Tales--An Investigative Story By Jon Asher Photography, except were noted, by Jon Asher © 2007 Competition Plus Magazine. Used with permission
Understanding The Current Conflict Regarding
No single incident caught the attention of the drag racing public as quickly and pervasively as John Force’s crash in Chassis builder Murf McKinney says, “according to John Medlen (the accidents) were very, very similar.” It’s also possible that John Force Racing was on the verge of what would have then been a second major chassis-related incident at Maple Grove in August when alert crew members spotted chassis damage after Robert Hight’s first round victory during which his car had gone through severe tire shake. Due to that damage Hight was a no-show for the second round, and debuted a brand new car just days later at the NHRA U.S. Nationals.
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There may have also been a fourth incident involving JFR as well, as sources close to the team have told Torco’s CompetitionPlus.com that one of the cars suffered chassis damage during another post-race test, but we’ve been unable to confirm that.
The heart of this issue is whether heat treated 4130 chrome moly (sometimes referred to as “hardened) tubing is fit for use in some portions of Top Fuel and Funny Car chassis, or should these volatile machines be welded together using only Condition N, or “normalized” tubing. Since there now seems to be some disagreement as to what “normalized tubing” consists of, and to avoid confusion, from here on we’ll stick solely with the term “Condition N,” as that seems to be universally accepted. Cracking is definitely not a new problem. The SFI Top Fuel chassis spec “It has come to our attention that very recently a couple of Top Fuel cars have suffered broken or cracked chassis, however this information was not passed on to Ray Alley or NHRA. It is very important that any team having chassis problems bring Ray up to speed so that he and NHRA have all the information they need to help all teams. This information will help teams and NHRA know what to look for and where to look, and help NHRA know if the problems were suffered before or after chassis upgrades.” We do not know what the response of the membership was, or if NHRA took any action as a result of any responses received.
“Ford Racing does not have an official position on the tubing type or material specs. We are currently learning and coming up to speed as
Staunchly in favor of using only Condition N tubing are a significant number of smaller chassis builders, including Brad Hadman, Ty Baumgartner, Steve Plueger (multi-time champion chassis supplier to John Force) and Don Long, among many others. While each side readily references reasons for their decision-making, it’s important to note that no scientifically prepared papers or documents have been offered by those advocating the use of heat treated tubing to back up their position. On the other hand, those in favor of using strictly Condition N tubing have a wealth of published works favoring their position, papers written by respected Ph.Ds in metallurgy and mechanical engineering. Further, the Internet has a significant number of dissertations available that outline the safety reasoning behind the use of Condition N tubing for race car chassis construction, but there don’t appear to be any that outline heat treated tubing as being as “forgiving” as is Condition N tubing. When Murf McKiney was asked to provide documentation in favor of the use of hardened tubing he referred us to Military Specification MIL-T-6736B. This document, which is dated 1965 and has since been superseded, merely outlines the necessary properties of both hardened and Condition N 4130 or 8630 chrome moly tubing of various sizes, shapes and dimensions for military use. Significantly, at no point does this document outline the properties of these materials if they were to be used in race car construction. It goes no further than to outline what these materials must be for military use. Somewhat caught in the middle is the National Hot Rod Association, which depends on the SFI Foundation for its chassis specifications, among other things. SFI, which formerly stood for “SEMA Foundation, Incorporated,” is no longer directly affiliated with SEMA, but retained the alphabetized name for simplicity’s sake. Regardless, the organization has been loosely affiliated with the NHRA for decades, although each tries, in its own way, to maintain some distance so there doesn’t appear to be any direct interaction between the two when it comes to things like determining chassis and other specifications.
Some, including chassis builder McKinney, have suggested that the accident was caused by a Goodyear tire failure. “I am certain that the cause of the chassis failure was the result of the tire coming apart, for whatever reason,” he said. Goodyear is still in the process of completing its examination of the Eagles taken off Force’s car after the crash, and while they’ll acknowledge that one tire was deflated, preliminary examination does not indicate a failure. It’s yet to be determined, but it’s possible that something hit the tire, causing the deflation. It could have also been deflated as a result of the back half of the car being ripped off when the parachutes deployed following the body disintegration. In the Medlen accident the Goodyear tires did play a pivotal role, and Goodyear’s engineers have publicly stated that something struck the inside sidewall of one of the tires, resulting in its failure. The question then becomes, “Where did the object come from that hit the tire, and what was it?”
It’s conceivable, but unlikely, that Medlen ran over something on the track with his front tires, which picked up that object, throwing it to the back of the car, where it struck the inside sidewall. More likely is that something came off the car and hit the tire, causing its failure.
What can’t be denied is how severely and dramatically Medlen’s chassis failed in his accident. Observers on the scene in Gainesville report his mechanics being visibly shaken and outspoken in their displeasure upon discovering how many places the car seemed to come apart in the accident.
In a post-accident-study press conference during which a number of those involved, including NHRA officials, spoke publicly for the first time, John Force said, “We gave John Melvin (from Wayne State University) nothing to go to the labs with except a chassis that was broken into a million pieces.”
On Friday, September 21st Top Fuel team owner Bill Miller presented a three-page document to the PRO Top Fuel and Funny Car Committee and NHRA officials, including Graham Light and Dan Olson, a document dated August 27th and addressed to the PRO membership.
Accompanying the letter was a supporting document from Dr. Rory R. Davis, PE, of Convergence Engineering Corporation of Gardnerville, Nevada. Miller’s letter, broken down into four sections, outlined the current chassis situation regarding SFI and NHRA. It went on to a similar outline of Funny Car chassis specs, then offered some general points. The letter ended with a conclusions and recommendations section. The gist of Miller’s missive was that the use of heat treated tubing in Top Fuel and Funny Car chassis had not been made with any scientific supporting documentation, and that there had been a significant number of chassis failures as a result of its use. He cited incidents involving both Tony Schumacher and Cory McClenathan, but for different reasons. According to Miller, in his opinion, the Schumacher problem was the result of the use of too small tubing, mandated by the SFI chassis spec at that time, while the McClenathan problem was the result of the Heat Affected Zone (HAZ) failing from welding hardened or heat treated tubing in that area of the car. Again according to Miller’s letter, “There is no provision for the use of hardened tubing in the present SFI Funny Car Spec. Without explanation the Funny Car Spec mandates normalized (not hardened) tubing…” Miller continues, “McKinney has admitted using hardened tubing in Funny Car chassis. Funny Car chassis failures, like Top Fuel, have increased since the use of hardened tubing.” On April 9, 2006 Miller sent a letter to Arnie Kuhns of SFI. In it he writes, “Keeping in mind that McKinney has told JFR that the bottom frame rails of their chassis are not normalized SAE 4130 tubing as mandated by SFI 10.1E, please answer the following question: How did these JFR racecars get technical approval?” Kuhns did not respond, and in Miller’s words, “hasn’t responded to anything I’ve said or written in the last two years.” The underlining for emphasis appears in Miller’s original letter. Dr. Davis has offered two documents, an original outline of his research work dated August 28th, and a follow-up dated a month later. The document is lengthy and detailed, but some sections cry out for inclusion here. Following his introduction Dr. Davis writes, “At the time, I found the analysis to date for the design of the (Top Fuel) frame, and the resulting specifications as a result, to be seriously flawed, and the knowledge of loads experienced by the cars not well understood. There was a need for a complete over-haul of the engineering involved. Linear analysis of the frame was being used, despite the fact that the important response of the frame was nonlinear, namely tube span buckling.” (We italicized the previous statement for emphasis.)
FEA, or Finite Element Analysis procedures, have been used in the testing conducted by Dr. Davis and others, and rather than go into such detail as to lose the reader’s interest and attention, we’ll keep things as simple as possible. The questions surrounding the use of heat treated tubing include - What changes to the tubing does heat treating produce? and At what point does heat treating eliminate the durability of that tubing? Another appropriate question is - How much quality control has gone into the heat treating process? This latter question is particularly important, because the vast majority of heat treating operations are conducted by hand, i.e., someone manually inserts tubing or whatever’s to be treated into a furnace, checks the temperature to make sure it’s correct, and then removes and quenches the material at what’s hopefully the right time. But, what if the guy removing the tubing from the furnace stops for a puff on his cigarette or swallow of his coffee, and inserts the tubing in the quenching liquid two minutes after it should have been inserted? Such a human error – certainly a possibility – would completely negate and/or alter the value of the heat treating process. Even if the heat treating process is more “controlled” than our outline, someone must still manually set the temperature and “cooking time,” and an error in setting either of those parameters could result in tubing that doesn’t have the properties its end user was seeking. Batch testing of heat treated tubing is a time-consuming but absolutely necessary process to insure uniformity across the entire tubing order. That means testing each end and the middle of the first tube to obtain baseline numbers, then performing enough similar tests to insure across-the-board quality control. By “enough similar tests” we mean that after the each-end-and-the-middle test of Tube #1, and then Tube #2 you could probably go to Tube #9 for your next evaluation. The bottom line is that with, say, an order of 100 tubes 1 1/2X.065 wall 10 feet long you’d have to check 20 to 30 individual tubes. More would be even better. According to our sources who studied the data provided by SFI after Similar samples from a different source allegedly provided to SFI for evaluation by Brad Hadman had a coefficient of variation of 5% or less. Samples provided by and tested for builder Ty Baumgartner demonstrated a coefficient of variation of 6.2% when samples from the SFI and CEC tests were combined. Elongation is of critical importance, because race cars are constantly flexing, twisting and bending in ways that we can only imagine – or try to replicate on a computer. “Seeing” those twists is impossible without serious instrumentation, but one thing does appear to be certain: Minimum elongation properties for chrome moly tubing should be a minimum of 10 percent of the length of the tube in question. Simplistically, a piece of tubing 10-inches in length should be flexible enough to stretch an additional inch without breaking. Correctly heat treated tubes can produce somewhat greater
Chrome-moly tubing has been used in aircraft construction since before World War II, and with all of the government’s resources directed towards winning that war the best minds the nation had to offer were brought on board in various capacities, including airframe evaluations. The result of the scientific work on air frame construction was that only Condition N tubing was used. Consideration of the use of heat treated or hardened tubing was quickly abandoned because every test conducted resulted in early failures due to a lack of elongation of the tubing. The testers understood that failures on grounded test stands would be inconsequential compared to the vibrations a combat aircraft would encounter once airborne, thus the determination to use only Condition N tubing. Simply put, heat treated tubing was too brittle and fracture-prone for use in the “vibration factory” that is an airplane. What, if not “vibration factories,” are Top Fuel dragsters and Funny Cars? The current SFI specs for Funny Car (10.1E) and Top Fuel (2.3M) both begin with the same sentence: “All structural material for the roll cage, rear-end mounting, and suspension mounting must be normalized SAE 4130 chrome-molybdenum steel (SAE 4130N) purchased to the requirements of military specification MIL-T-6736B and its subsidiary documents or equivalent.” The question then becomes one of definition. Does the word “equivalent” mean that the documentation must be equal to that of the military specification, or does it mean the tubing needs to be equal in properties to the 4130N? If, as is likely, “equivalent” means tubing of an equivalent nature, that tubing would have to have the same chemical makeup, yield, tensile strength and elongation characteristics attributed to Condition N tubing. Heat treated tubing, by its very nature, does not have the same characteristics outlined above as does Condition N tubing of a similar size. We’ve been unable to come up with anyone with any legitimate expertise, either in terms of practical experience or educational background, who will go on record saying that heated treated tubing is the equivalent of Condition N tubing. Our search for corroboration included chassis builders, Ph.Ds in metallurgy and even a contractor supplying defense materials to the government. None would agree that heat treated tubing is the same as – or “equivalent” to Condition N tubing. There’s an ancillary safety issue in play here as well. Numerous observers have reported that the titanium tubular “trees” used to
Why are we mentioning this? Eric Medlen’s car hit the wall during eliminations on Sunday at the Gatornationals, and observers on the scene report that Monday morning the team had considerable difficulty getting the body to properly mate with the chassis. Could it be that one of the titanium tubes underneath the body broke completely off during the run, and that’s what pierced his Goodyear tire? We will probably never know for sure – but it’s a possibility. Some years ago Louisiana chassis builder Chuck Haase became increasingly concerned about driver safety after watching a series of televised crashes, including one involving Gary Scelzi in which his car J-bent in half after a tire failure. Haase concluded that the skid blocks mandated for the chassis were mounted in the wrong place, and would increase the likelihood of chassis failure when the tire failed. The skid blocks would simply move the axis or “pivot point” forward, making the moment or “lever” longer. In order to prove his theory as well as to test chassis themselves for flexibility he built a massive fixture and did some initial testing with it. He and a friend then traveled to the U.S. Nationals where he had a meeting with Ray Alley, then in charge of Top Fuel and Funny Car racing for NHRA. He outlined his “test bench,” showed Alley the photos he had, and told him that NHRA was free to use the device in any way they saw fit. According to Haase and the friend who witnessed the exchange, Alley was interested in seeing the device utilized by NHRA to test the safety of chassis but Haase never heard a word from him or anyone else at NHRA following his visit to Indy. A few years later Haase contacted Bill Miller and explained his device. Miller had it shipped to
The tubing that failed had been hardened, i.e. heat treated.
Plueger also reports that in his desire to locate as new a Plueger-built car as quickly as possible, Force or his employees tracked down a Funny Car built for Canadian Todd Paton. The plan was to have someone pick up the car in California (don’t ask, we don’t know why it was out there either), truck it to Force’s shop in Indianapolis, where its GM body would be exchanged for a Mustang, and then blast off for the Torco Race Fuels Nationals in Richmond. But, when Plueger spoke to driver Robert Hight early in the week of the race he was told the plan had changed, and that the team would accept the chassis changes as recommended by We made numerous attempts to contact members of John Force Racing for their input on this situation, and were unsuccessful. As a team insider put it, “No one wants to talk for fear of offending some of the people who are trying to help us with this project.” The heat treated vs. Condition N tubing controversy has also apparently taken a political turn in the makeup of the SFI chassis committee. After a vote was taken regarding the issue, six members of the committee were replaced by four others by Arnie Kuhns of SFI. Among those removed were Dave Uyehara, Marc Rowe, and Richard Earle, all of whom had attached notes to their ballots asking for additional time and study before a decision was made regarding the use of heat treated tubing. Bob Meyer, Don Long and Geoff Houser were also replaced. Added in their places were Ty Baumgartner, who supports normalized tubing use, Chuck Lett of Attac Race Cars, who votes consistently with Arnie Kuhns of SFI disputes the characterization of the change in personnel in the chassis committees as “arbitrary,” the term used by some of those replaced. “They weren’t totally replaced,” he said. “What happened over time is that committee increased in responsibility from only two specifications to close to 10. The workload became quite extensive for that committee, and it further became obvious that we had people not dealing with cars with which they had the most knowledge. In addition to that we had people who were not involved in the process who, quite frankly, were very much involved in building the cars. A case in point would be Brad Hadman. Hadman was, and I guess he still is, building about half of the cars that were racing, and he wasn’t on the committee. That clearly was not right. Basically, we said if you hadn’t built a Top Fuel car in a year, you weren’t really an active builder, and if you had built a Top Fuel car in a year you were an active builder, and that then defined the Top Fuel committee. Each group now represents the cars they’re most familiar with.”
“For Funny Cars, that’s correct,” he said, adding, “You understand, I (meaning SFI) do not enforce the spec. It’s the same with all of the (approximately) 100 specs we have.” Simply put, SFI is not an enforcement arm. In fact, the organization goes to some lengths to emphasize that they create no specifications per se, but rather depend on the committees they’ve formed that are supposed to have expertise in their respective areas to come up with those specs. SFI then endorses them. It’s their version of the old “Good Houskeeping Seal of Approval” without which some housewives wouldn’t purchase a domestic product in years gone by. SFI’s endorsement lends a certain degree of credibility to an item, be it safety or performance oriented. Enforcement of the SFI spec, then, is the responsibility of the NHRA, which, in turn, can have only one meaning: NHRA has allowed cars that have not been built to the SFI Funny Car chassis specification to compete in the POWERade Series with impunity.
Fact: The SFI Funny Car chassis spec does not call for the use of heat treated tubing.
Fact: McKinney Corporation’s owner, Murf McKinney, has publicly stated he’s used, and continues to use, heat treated tubing in Funny Car chassis construction. Conclusion: NHRA, despite knowing about the use of heat treated tubing, and despite their own rules that demand strict adherence to the SFI chassis spec, has allowed this to continue, with their logic apparently being that the word “equivalent” in the spec allows a builder to substitute the called-for Condition N tubing with heat treated tubing of greater dimensions. Dan Olson, NHRA Director of Top Fuel and Funny Car Racing, was contacted for the organization’s stance on whether or not the use of heat treated tubing is permissible or appropriate in Funny Car chassis design. “I can’t answer that,” he said. “This is something I’ll have to look into, to be honest with you. I thought that spec got changed when we were able to use heat treated tubing on Top Fuel cars years ago. I can’t answer that, how’s that?
“I walked into a lot of what’s coming down the pipeline right now, and that’s the reason why I’m investigating. This has been since John (Force’s) incident and Eric (Medlen’s) problem, and I’ve been investigating numerous metallurgists trying to come to some kind of conclusion myself, but there is such a mixed result of opinions, especially with metallurgists, and aircraft hands-on people with mixed opinions that that’s why I can’t answer right now. “We’re doing some tests, some physical tests, actually on both materials to find out what is the best. I read Dr. Davis’s paper, and if you read it carefully he left a lot of things open. “I was in the meeting in “We’re working as hard as we can on this, but we’ve got to make sure that what we come up with is the right answer. I just got off the phone with an airframe engineer that’s been doing this for 25 years, and he would recommend heat treat. I’ve got about three other hands-on engineer metallurgists who recommend heat treat. I can find as many or more who would favor heat treat versus Condition N.” When we asked Olson about the SFI Funny Car chassis spec and its relationship to the NHRA rules, he said, “I’ll have to look into that. Remember, our stance and my stance is that our Number One thing is safety. I don’t care if these cars are made out of whatever, electric weld tubing, it doesn’t matter. Safety is our Number One concern. We aren’t dragging our feet, we just don’t want to make a wrong decision. We want to make sure that what we come up with is the right answer. I’ve been working on this from sunup to sundown, seven days a week for a long time, and I don’t have all the answers yet.”
Among other statements in Dr. Metz’s letter, he writes, “Even a rudimentary calculation of tire forces applied to the chassis during a tire failure shows that the loads generated under such conditions are far, far greater than the design loads to which the chassis was designed and built. The recent Medlin (sic.) and Force F/C accidents were both catastrophic and both were initiated by a rear tire failure.” Later he states, “In the case of many race accidents, certainly in the case of the Force and Medlin (sic.) accidents, the tire failures involved suggest that the chassis tubes that failed did so because of the accident, and did not initiate the accident sequence.” Dr. Metz told Torco’s CompetitionPlus.com in a taped conversation, “I have looked at the Medlen car and photographed it in great detail, and I’m going to look at the Force car this week, but other people have looked at it before me. But, certainly for the Medlen accident and, I have been told, for the Force accident, there is no evidence that the structure failed first, thus initiating the accident.” As previously reported, Goodyear has said that in the Medlen accident one tire was punctured by something hitting it on the inside sidewall. They have made no ruling to date in the Force incident. Dr. Metz offers no explanation in his letter as to how he concludes both accidents were the result of tire failures, so we asked him about that. “That’s what I’ve been told by Dan (Olson) and by the chassis constructor as well. I looked at videos of both of them, and I don’t think there’s any question about Medlen’s. The video I saw of John Force’s accident was a head-on video, so I didn’t get a good look at that, but both Dan Olson and Murf McKinney, who built the chassis, (and) I talked to both of them, and they both said that they thought that accident was initiated by rear tire failure.” Dr. Metz further suggests that, “A successful chassis could be made from either condition N or heat treated 4130 chrome-moly tubing – or from 6061-T6 aluminum for that matter – provided that the chassis is correctly designed and constructed with care.” On October 2, 2007 we received an e-mail from Murf McKinney in which he states that Dr. Metz is on retainer to McKinney Corporation: “We also retain Daniel Metz, Ph.D., P.E. who is retired from the The web site ALMEXPERTS.com, “your source for experts, consultants & litigation support services,” lists L. Daniel Metz, Metz Engineering & Racing as available for hire as an expert witness. His profile reads, “Specialize in vehicle dynamics, vehicle aerodynamics, and accident reconstruction. Have worked for every major auto manufacturer, insurance company and racing organization in the world.” During our conversation with Dr. Metz we asked him if he had ever worked for either the NHRA or NASCAR, either under contract or as an employee, and he responded in the negative to both questions. Both are considered major racing organizations, yet Dr. Metz has worked for neither. Further, when we spoke again with Dan Olson he expressed surprise at being told of Dr. Metz being on retainer with McKinney Corporation. Discovering heat treated tubing during the inspection process may be somewhat problematical. Although some experts contend that heat treated tubing is slightly darker than Condition N, that color difference can be negated by lightly sanding the tube or wiping down the entire chassis with an oil-dampened rag. A portable Rockwell Hardness tester would probably get the job done, but regardless of what’s needed, at this point it would appear that no effort is being made to either discover the use of heat treated tubing in Funny Cars, or discourage its use. In regards to the chassis fix rushed into use for the Torco Nationals, one chassis builder probably put it best when he said “It’s nothing but more mass to cover your ass.” In other words, it weighs more, it looks effective, but it’s still utilizing heat treated tubing in places where it’s been proven ineffective up to now. And any fix may be better than none when it comes to potential legal actions somewhere down the road. McKinney told us that the chassis fix added to a number of cars prior to Richmond was designed to offset the massive vibrations that might be caused by an out of balance tire situation, but others have suggested this problem may be more basic. It could be the result of the materials used in the original chassis build – heat treated tubing. This is far from over. On the day following the Torco Race Fuels Nationals, Robert Hight’s car, fresh from the addition of the chassis “fix” at McKinney’s shop, suffered a chassis failure during testing. “It cracked a couple of frame rails by the rear end,” acknowledged crew chief Jimmy Prock. “I don’t honestly know why it happened,” he continued. “I have my opinions, but I don’t know for sure. I think I know what happened, but I believe it broke because of what we did (to fix the previous problem). When it shook the tires it bent something else. Yeah, I believe that. I have some ideas on all of this, but I’m not going to say.” In the aftermath of the Hight incident in Interestingly, despite the reluctance of anyone from John Force Racing to discuss any aspect of this scenario, we’ve received a copy of an e-mail that crew chief Austin Coil forwarded to 16 people, including drivers, tuners, Niranjan Singh of Ford Racing Technology, and both Graham Light and Dan Olson of NHRA. It’s titled “Real World Elongation” by Coil. Rob Wendlend, the JFR employee who conducted this test, confirmed having done it, but refused to add any further comment. Here is the entire text of the e-mail: Sent: Friday, October 12, 2007 6:02 AM Subject: Tubing Tests As most of you know I have been trying to develop a "Real World Elongation" test. Our first efforts were to weld stub of 1.5" X.065 tubing to a leg of 1.5"X.065 tubing. We anchored the leg in a big lathe and put a pipe over the stub 6" from the weld and applied pressure until failure. We measured how far the various materials moved before failure. This is what happened. Test 1: Normalized Stub and Heat treated tubing leg. Deflection 23" before failure Test 2 Normalized Stub and Normalized tubing leg. Deflection 19" before failure Test 3 The distance from the pointer on the scale to the weld is 57.5" Any questions about how the test was performed please call the man who did the testing.
That’s the entire text of the message with the exception of a short paragraph regarding shipping a video of the test and a private phone number.
It should be noted that of the 39 builders polled a substantial number must be considered largely inactive in terms of building cars currently competing. But, with that said it should also be noted that the list includes drag racing’s A-list constructors of the last two decades. A similar poll was taken of the 11-member PRO Board of Directors, with nine in favor of Condition N tubing and only one in favor of the use of heat treated tubing, with one other declining to offer an opinion. The issues of chassis construction methods and driver safety go hand in hand. Despite the comment of a prominent NHRA official in a meeting with team owners on Friday at the Bill Miller Engineering would like to thank author, Jon Asher, and Competition Plus Publisher, Bobby Bennett, for making this article available for posting on this web site. |
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