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F/C chassis integrity

This is a discussion on F/C chassis integrity within the NHRA forum, part of the Pit Area category; What about a Coupler failure. or a reverser failure.. If the reverser broke apart and blew out the side of ...


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  #31  
Old 09-25-2007, 09:21 PM
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Re: F/C chassis integrity

What about a Coupler failure. or a reverser failure.. If the reverser broke apart and blew out the side of the case it could break the frame. If the Coupler broke it would break right under the driver. Who knows what would happen after that. What I can see in the video is some thing under the body flying around and the body coming apart. Which would be either body attachment tubing. Hence Carbon fibre peices cutting a tire. After the fact of the front half making a right turn into Kennys lane. Clearly the streering wheel and frame peices are rolling to a stop.

As far as making a Funny car able to break apart like TF's do. In Front of the Driver... Well I doubt ANY driver would get in one. At least no one who wanted to keep real body parts.

All the Mods Team Force did to Fix the drivers Head problems Stayed in Tack the parts that broke looks to me like the the Engine to Drivers cage rails.

If as you Mistakenly think the Chutes Pulled apart the frame.. Then why would this not happen WAY more often when every one Yanks the chutes. The chutes were not even Out and the front part of the car was all ready in front of KB.

What I find not so Unusual is people saying way to much about tires. Yes they were Chunking and even one driver in his interview said wow your tire is chunked.

Ok so here is a Thought Process for you all to think about....................

Tire Shake + more Tire Shake + More Tire shake = Broke or Cracked FRAME.... If not weakend and oh whats was this Talk about Bumpy tracks..

What I would do if I was in the Position to see whats going on in these cars LONG ago. Is put strain gauges in these cars at various points and a few other Measurement Devices to find out how Much and where in the frames things move. If these cars are flexing way more then they think. I would think it's a good reason to load and unload the rear tires. Due to the Spring back.

I don't know if John was in a Flex Tube Chassis But I would be willing to bet. NHRA and SFI needs to see if things need to be PARKED. If they in fact are flexing to a point of weaking the related tubes under DEcompression then well I guess more brain power needs to be used.

Oh and Were is the Xray machines for older frames. I wonder if one of these would have saved Darrel G. from getting hurt long ago.

Get well soon John I will see you at the Track.

Last edited by Bob Dumont; 09-25-2007 at 09:28 PM.
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  #32  
Old 09-25-2007, 10:03 PM
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Re: F/C chassis integrity

Quote:
Originally Posted by Bob Dumont View Post
If as you Mistakenly think the Chutes Pulled apart the frame.. Then why would this not happen WAY more often when every one Yanks the chutes. The chutes were not even Out and the front part of the car was all ready in front of KB. .


Say what?




As far as the chutes pulling the car apart, It's obvious something is very wrong with the car by the way it looks. The chutes were not the cause of the frame being broken, but in a way did pull the back of the car with John in it away from the rest of the car becasue the chutes were only slowing that small section. They are clearly open in this first pic.


This second shot tells me the chassis is already in 2 pieces, the chutes are out, and the rear spoiler/deck lid is facing us instead of being parallel with the ground. This rear body work stayed with John the rest of the way.
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Last edited by Paul Songas; 09-26-2007 at 08:29 AM.
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  #33  
Old 09-25-2007, 10:15 PM
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Re: F/C chassis integrity

Maybe they should start doing an eddy current test of the chassis after a certain # of runs.
If there are hair line cracks that are not visible to the eye a eddy current test would definitely help.
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  #34  
Old 09-26-2007, 04:22 AM
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Re: F/C chassis integrity

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Originally Posted by Jim Burke View Post

The very fact that we have not seen this till now says that we can thank our lucky stars that there are really good chassis guys out there. Will The Eric Medlin Project and Ford and all the rest of the people figure out what happened??? I believe so. Perhaps they can develope a testing ptogtam to spot trouble before it begins. Give then some time to work their magic.

Just one man's opinion.
jim
You have "not seen this until now" because you have not *heard* of it until now. This is not the second chassis to come apart. Do you think they are going to post all their problems on Nitromater? You will never hear a driver in an interview say "We broke the engine and dropped the crank on that run and by the way every weld on the frame broke, too." You think I'm joking?

Chassis builders were thrown under the bus expressing their opinions about the issues that led up to this. One of them is ready to disconnect his phone because his "worthless opinion" is now more valuable than a spot in the final countdown to the championship. Under his greying hair is all the math, geometry and calculations that have provided safe chassis for many years to the top racers. His cars have crashed hard without a failure, yet they chose to ignore this guy who will give you an engineering lesson so over your head you'll struggle to comprehend any of it no matter who you are. Anyone who knows him knows who I'm talking about.

In 28 years no one was killed in a FC. Last weekend we almost had two in less than 6 months. Thank GOD it didn't happen. So what has changed? In the last 28 years we have seen the most violent FC wrecks that resulted in relatively minor injuries. Now cars are falling apart without hitting anything. That is a fact. The chutes deploying just disconnected what was already broken. That is a fact.

Pardon me for being totally blunt, but the problem is: Those who thought themselves wise, although having good intentions, have shown themselves to be foolish. Those who thought they know the most have been shown to know the least. Tough decisions have already been made and the scramble is on. The original horse wasn't broken, and for some reason someone screwed up trying to fix it.

If they outlawed funny cars you'd never see me at the track again. Knee jerk reactions to something that wasn't broken in the first place is something we don't need. Like I said, I have a horse in this parade, too. Someone screwed up trying to fix what wasn't broken in the first place. 28 years and no fatalities. Suddenly all this. And decisions made by the rule makers will effect me and everyone else with a FC. I have a good ol' Uyehara chassis/Plueger clone and I'd rather crash in that at 300 miles per hour than take a chance on anything new being considered or mandated by the looks of things. I hope they consider what the establishment has to say about any rules changes (ie, my favorite German).

I'm outta hear because I'm getting myself all fired up and I know too much about all this. No reason to spill any more beans.

Adios,

RG

Last edited by Randy Goodwin; 09-26-2007 at 04:25 AM.
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  #35  
Old 09-26-2007, 07:14 AM
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Re: F/C chassis integrity

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Originally Posted by Bob Dumont View Post



put strain gauges in these cars at various points and a few other Measurement Devices to find out how Much and where in the frames things move.
That is the only way to KNOW what the stresses and deflections are. It will require work to make this type of system work with all of the electrical noise, etc. of the engine, but I'm sure it can be done.

In fact doesn't JFR have a 7post [I thought I read that somewhere previously]? If so, that would make this a routine task for anybody well versed in instrumentation/strain gauge technologies.

I also agree that the chutes may have resulted in final separation of the parts of the car [because the rear was decelerating and the front was not], but no way that the chutes caused the chassis to fail.
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  #36  
Old 09-26-2007, 08:14 AM
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Re: F/C chassis integrity

I just got offf the phone with someone who is very close to this deal and the following is the best info that I can provide on various aspect of this situation.
The funny car frames from McKinney do use heat treated tubing AT THE RECOMMENDATION OF THE TUBING MANUFACTURER. As I have stated many times before the currently supplied tubing varies in tensile strength from batch to batch and lately has tended to be at the low end of the spec. The mill (Plymouth Tubing) can supply tubing with a tighter tolerance re tensile strength but the minumum run is 5000 feet in each size so for practical reasons the tubing goes through a tightly controlled post manufacture modification process to get it to the recommended numbers.
The Force incident was the result of the failure of the left tire and the resulting harmonics are what broke the frame. Basically the frame is held rigidly at the mid plate and at the rear end with the roll cage and seat tubes also supporting the rails and effectively boxing the chassis at their attachment points. When the car began to shake following the tire failure the high amplitude oscillations simply sheared the tubes off at one end of the cockpit area.
Initial analysis has indicated that even if the main rails were as thick as .120 wall at that point they still would have sheared. The frame was not pulled apart by the chutes, they simply slowed down the rear section of the chassis after the rails broke. Force's car did have the "prop" tube under the front of the main hoop as he had requested that the front hoop be moved forward on the upper rail and in doing so it did not meet the minumum 1" set back from the support sleeve inside that rail.
Once again this has nothing to do with heat treated tubing, weld quality or anything else that is easy to fix. The problem lies with the harmonics when a tire fails and causes the car to oscillate violently.
Just my own personal opinion but could the revised tire design that followed the previous incidents have changed the way the tire reacts when it chunks or delaminates?

Roo
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  #37  
Old 09-26-2007, 08:18 AM
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Re: F/C chassis integrity

Amazing, everyone had thought(?) that FC chassis were far safer than TF Chassis after all those TF Chassis Failures we've seen in recent years. That still may be the case, but I've seen far more violent tire Failures on FC's in the past that didn't cause a Chassis failure!
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Last edited by Joe Sherwood; 09-26-2007 at 08:21 AM.
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  #38  
Old 09-26-2007, 08:38 AM
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Re: F/C chassis integrity

There sure is a lot of knowledge out there. Reading it all especially from Randy sure makes you wonder, but also makes you feel like there is a lot of people out there that put a lot of thinking into the fatigue factor that these chassis have to take. Thanks to everyone, and bottom line thank God John is alive.
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  #39  
Old 09-26-2007, 08:44 AM
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Re: F/C chassis integrity

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Originally Posted by Keith Burgan View Post
I
Once again this has nothing to do with heat treated tubing, weld quality or anything else that is easy to fix. The problem lies with the harmonics when a tire fails and causes the car to oscillate violently.
Roo
I may be off base here, but wouldn't the heat treat process make the metal more brittle as well as stronger? Would a non heat treated tube have more of a tendancy to flex and bend instead of fail completely?
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  #40  
Old 09-26-2007, 09:01 AM
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Re: F/C chassis integrity

Randy,
I know you are up on the tire about this but what I said was about the chassis coming apart. You can't be racing these for very long and not know that they crack welds and break bars. I have seen that for years. What I DID say was I had never seen one come completely apart........

The most reasonable explaination I have heard and read was that it was harmonics the broke the chassis. Just like any metal if you bend it continously it will break.

I would think that the combination of rule changes may have changed the playing field as far as harmonics and how it affects the chassis. This would include tires and chassis.

jim
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  #41  
Old 09-26-2007, 09:09 AM
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Re: F/C chassis integrity

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Originally Posted by Brian Smiley View Post
I may be off base here, but wouldn't the heat treat process make the metal more brittle as well as stronger? Would a non heat treated tube have more of a tendancy to flex and bend instead of fail completely?
Brian,
the increase in tensile strength over the "regular" 4130 is minor. The main reason for the post manufacture heat treat is to make the numbers more consistent so that the chassis all react the same. If the tubing is on the low side of the spec the car works like a wet noodle. It is the amplitude and frequency of the vibrations that is causing the cars to break and for now there appears to be no simple solution.

Roo
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  #42  
Old 09-26-2007, 10:15 AM
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Re: F/C chassis integrity

Quote:
Originally Posted by Keith Burgan View Post
Brian,
the increase in tensile strength over the "regular" 4130 is minor. The main reason for the post manufacture heat treat is to make the numbers more consistent so that the chassis all react the same. If the tubing is on the low side of the spec the car works like a wet noodle. It is the amplitude and frequency of the vibrations that is causing the cars to break and for now there appears to be no simple solution.

Roo
Keith,
Thanks for the explanation.
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  #43  
Old 09-26-2007, 10:24 AM
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Re: F/C chassis integrity

I read where Bill Miller said that by NHRA heat treating the dragsters It was the dumbset thing they could have done, Due to making it brittle, Many have said Corys car would not have broke like it did if it had not been heat treated. I understand what some of you are saying about heating them just enough, I take it the longer the treat the more brittle it gets. I'm like Randy I think that car was in a cracking procces when they took it up there to run it. Harmonics I'm sure was hudge part of this as well has the chutes. I was in Joliet when Gary Selz. backhalf came off when the chutes hit.
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  #44  
Old 09-26-2007, 10:45 AM
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Re: F/C chassis integrity

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Originally Posted by Jason Ison View Post
I read where Bill Miller said that by NHRA heat treating the dragsters It was the dumbset thing they could have done, Due to making it brittle, Many have said Corys car would not have broke like it did if it had not been heat treated. I understand what some of you are saying about heating them just enough, I take it the longer the treat the more brittle it gets. I'm like Randy I think that car was in a cracking procces when they took it up there to run it. Harmonics I'm sure was hudge part of this as well has the chutes. I was in Joliet when Gary Selz. backhalf came off when the chutes hit.
Jason,
Cory's car suffered what was basically an elongation fracture which would not have happened if the tubing was too brittle.

Heat treating is not a time based process as such and the post manufacture heat treat is very tightly controlled. That is why they use the process--to get the tensile strength to a narrow window. This is not a wave a big rosebud tipped torch over the tubing deal. The tubing is placed in an oven and heated and cooled at specific rates to specific levels.
From my understanding (and I am talking to people a lot closer to this than you) the frame was broken before the chutes blossomed. I was told specifically that the tire was the first thing to fail and that it chunked initially to set up the harmonics that caused the rails to fracture.

Roo
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  #45  
Old 09-26-2007, 11:21 AM
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Re: F/C chassis integrity

The "harmonics" is what caused all the issues with Eric's car also....you have to really understand how much rubber is swinging around and shaking when they fail or even during tire shake. John was very lucky that the chutes caught the wall at the end and kept the cage from bouncing and continuing to roll down track with his legs exposed...would have been MUCH worse. It shows that all the work they did on the cage area and the belts kept John from worse head and neck injuries. With all that was blowing up around him, he was well protected. With my new car that is just about done, I have used some of the ideas that they used for seat belt mounting...when I had my crash I would have loved to have the head protection they have now....the belt mounting is an idea that was way over due.
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