F/C chassis integrity (2 Viewers)

[Randy]

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Maybe Bob Meyer, our resident chassis fabricator can weigh in on this one.

Close up on TV revealed the chassis broke at locations where multiple welding of the tubes took place. The top frame rails broke where the cage meets the shoulder hoops and upright (and the upper frame rail is doubled in that area). The bottom frame rails broke where the "K" or X" member meets near the uprights that connect the bottom frame rails to the top. The upright is also used to support the lower seat bar. One side appeared to have the upright detached from the lower frame rail as well as the lower frame rail being broken.

I have seen many violent crashes including Force's many years ago where a tire let go, the car hits the wall, etc., etc. but the tubing never failed at all 4 points like this one did. And Force's failed without any impact at all. His car was pulled apart by the decelleration of the chutes.

My question is: If the tubing is heat treated prior to assembly then the points where the tubes come together are welded with multiple tubes hitting close to each other what does that due to the integrity of the heat treated tubing? I have heard complaints that welded heat treated tubing becomes brittle. Is this a true statement? Looks like it to me.

I understand that non-heat treated tubing is not as adversely effected by welds. Also, I know one chassis builder who intentionally staggers the lower "X" member to keep the number of welds in one area to a minimum.

Having worked with chrome moly I find it hard to believe it could just fail for no reason.

Force's deal could have been a lot worse. Our prayers go out to him for a speedy recovery.

RG

 

[Just Paul]

Whoever deleted the rest of this thread PM me please.

 

[Randy]

Whoever deleted the rest of this thread PM me please.

Paul:

To answer your previous question, the chutes pulled the chassis apart because it was already broken. The chutes didn't break the chassis.

RG

 

[DrRocket]

Did John's car have the same information gathering system that Ashley's car has? If so, I hope the computer survived the crash so they can download and study the data. They'll probably know a lot more about what happened if they can. I'll reserve any judgment on how this happened until then.

 

["Dr. Dirt"]

Whoever deleted the rest of this thread PM me please.

Me too! I thought I was losing my memory prematurely?

 

[mike]

I have a question,

Now when Force and the other teams changed their roll cage design, did they have new cars built in the process? Because is it not a fact that when you weld a new piece on to something that has been welded previously, wouldn't this make the chassis weak? I'm no expert on welding, but I figure it would make the frames weaker? I'm sure someone will get what I'm trying to say.

Mike

 

[NHRAMike]

I think that John brought out a new chassis at the Norwalk event because the team thought the old chassis was the reason he was performing so inconsistently.

 

[handsome]

i wish someone could explain just how these cars are "designed to break apart"..... i have owned a few f/c's and to me a weld is a weld. there is no shear pins or aluminum bolts holding the chassis tubes together. i find it sort of rediculous for t.v. announcers to tell the general public "this is what is suposed to happen".

 

[Keith Burgan]

Randy,
as far as I know the only place where the heat treated tubing is used is in the engine bay of the top fuel cars although with the current lax standards of manufacture Murf may be having some of his other size tubing done as well.
AND for the umpteenth time the tubing is not heat treated to the point of excessive hardness. The current 4130 tubing is usually towards the bottom of the spec re tensile strength and the process used by McKinney simply elevates that tensile number to just above the top of the original range. This was originally done to make the difference between matching cars less so that they would be able to use the same tune-up.
That said, the area of the fractures is definitely a major concern. If the tire did in fact fail to initiate the incident it would appear that the harmonics induced the failure just as they trashed Hight's chassis at Reading.

Roo

 

[TAFC 5 81]

I have owned both a TAD and TAFC (not at the same time), but over 25 years ago. I thought after Shirley's 1984 accident, that the "tub construction" (RE Indy Car) was incorperated into chassis where the driver compartments stayed in one piece. However I have noticed that even the Indy Car driver's compartment can be compromised in a wreck.

 

[Todd]

It appeared to me that the top-fuel cars had lots of tire chunking in the
shutdown area. You could actually see the chunks flying off of a number of cars.
(fuller and Dixon).

Could his tire of been chunking causing the chain reaction that occurred?

 

[Rexfiles]

i wish someone could explain just how these cars are "designed to break apart"..... i have owned a few f/c's and to me a weld is a weld. there is no shear pins or aluminum bolts holding the chassis tubes together. i find it sort of rediculous for t.v. announcers to tell the general public "this is what is suposed to happen".

I hear ya' there, I have had more than casual contact with f/c's and I was never under that impression or told that.

If I had I might not have ever got in the damned thing

REX

 

[Silly Savage]

Did John's car have the same information gathering system that Ashley's car has? If so, I hope the computer survived the crash so they can download and study the data. They'll probably know a lot more about what happened if they can. I'll reserve any judgment on how this happened until then.

All of Force's car have the computers on board from Ford.....

 

[Randy]

I've owned several funny car frames and none of them had their first step down in tubing size until the tube was in front of the engine. All the chassis builders I talk to do not intentionally make weak points in the drivers area or anywhere else.

I remember seeing Del go off the end of the track and into the sand at Pomona a few years ago and go head over heals 2-3 times. The frame never broke in half. If they are supposed to break that certainly would have been enough energy to do it. But harmonic vibrations for less than a second from a blown tire shattering welded tubing in the drivers area? Heck, Bernstein's car hit the wall very hard after the front half of Force's car collected him. Although I'm sure it was bent Kenny was plenty able to safely drive it off the track. After the crash they were still able to tow Bernstein's car with a tow strap back to the pits and put it up in the air on the Pro Jacks to work on it.

 

[TR]

Didn't The Drivers Compartment Impact The Wall, And Fold Those Rails In Towards The Seat And John? I Am Not An Expert But That Part Slamming Into The Wall Could Have Broken Those Tubes Plus The Damage Done To John. If Indeed The Chassis Did Break Away At The Motor Plate The Damage Would Be Consistant With The Cockpit Hitting The Wall In A Forward Type Of Motion. Only Speculation And My 2 Cents.

 

[Randy]

Didn't The Drivers Compartment Impact The Wall, And Fold Those Rails In Towards The Seat And John? I Am Not An Expert But That Part Slamming Into The Wall Could Have Broken Those Tubes Plus The Damage Done To John. If Indeed The Chassis Did Break Away At The Motor Plate The Damage Would Be Consistant With The Cockpit Hitting The Wall In A Forward Type Of Motion. Only Speculation And My 2 Cents.

If you saw the replays on TV you would see that the tubing broke at the seat not the motor plate. The remaining chassis section that slid in to the sand trap still had the rear motor plate and a majority of the lengths of frame tubing attached to it that broke off at the drivers seat area.

The tubes were broken before the chutes came out before the car hit anything. When the chutes deployed the car ripped itself in half sending the front half in to KB's car and the rear half with JF seated inside in to the left wall.

 

[mick]

yesterday was not a good day to be a drag racing fan.
we are soooooooo fortunate this incident left two racing legends
relatively unscathed, all things considered.
regarding the chassis; is it possible there may have been debris
that comprimised the chassis in one area (i.e. only one side), then
as the chutes opened, the force may have 'levered' the chassis,
causing failure on the other side, leading to it's separation??

 

[Marty Staggs]

Whoever deleted the rest of this thread PM me please.

Me too please.

 

["Dr. Dirt"]

Despite the cause of the accident, I'm positive the driver's compartment was designed to remain in tact throughout such an incident. I belt my sons into such chassis and wouldn't do so if there were intentional weak spots within their driver's compartments. What happened yesterday was an anomaly to say the very least. More surprising is that John still has legs today.

 

[unclebob]

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Maybe Bob Meyer, our resident chassis fabricator can weigh in on this one.

Interesting you should ask Randy. SFI and NHRA have stated my thoughts and experience, along with Don Long and Dave Uyehara (total of 120+ years) have been invalidated. I guess I have nothing to contribute.
I no longer wish to be involved in "the heat treat issue".

Bob