Interesting article

jaybee · January 03, 2008, 11:25:51 PM

So where we're really going with this is that the heat treated tube makes the frame a little stiffer in beam but puts it close to the edge of failure. Of course the same thing could be accomplished by increasing the triangulation of in side view but that would take more tubing and increase the weight. So yes, the safety of the drivers and anyone near the racing surface has been compromised for hundredths of a second.

wayne petty · January 04, 2008, 05:08:50 AM

the problem for many years was the tubes cracking a few inches from the welds..

not in the weld.. not in the middle of the tube... but where the heat of the weld had changed the hardness of the tube near the weld..... so you get hard spots and soft spots.. this problem needed the entire chassie to be stress relieved before racing it... 1100F for several hours.. this makes the entire assembly the same temper/ hardness.. 4130 reaches its final designed strength after stress relieving...

the latest problem is the tubing is telescoping upon it self... the solid mounted rear end is trying to lift the front of the car.. via the lower tubes.. the forward part of the body and the wing or box area is trying to streach the upper tube to keep both ends down and compress the lower tube.. the motor is trying to twist out of the frame..... then the parachutes come out and yank everything back.....

garlits wrote an editorial about how he used to insert a tube inside the lower frame tube to add strength... and prevent these type of problems.. it was in drive magazine a while back.. somebody got my copy./...

jaybee · January 04, 2008, 05:42:51 PM

No doubt the amount of flex in those chassis is just amazing, when you look at how much arch is in the chassis during a run a little thought tells you the forces are enormous.

Dave · January 04, 2008, 06:41:48 PM

Quote from: "jaybee"No doubt the amount of flex in those chassis is just amazing, when you look at how much arch is in the chassis during a run a little thought tells you the forces are enormous.

Maybe a little off topic but maybe not .. Ever look a a flat bed semi trailer unloaded going down the road.. Check it out next time you see one.. The amount of arch built into them unloaded is incredible.. But.... It works.. From what ive studied over the years looking while driving and enclosed semi has a lot less arch but they do have some.. But they have more support from the side walls of the trailer.. Oh ya on the flatbed stuff if i remember right the aluminum ones are real crazy with arch..
Dave

kb426 · January 04, 2008, 06:54:05 PM

The funny car chassis is really different from the dragster because of the wheelbase. They are most rigid from the rear motor plate back to the rear end mounts because of alignment but also because the drivers cage is mounted to it. Bear in mind that I'm a dinosaur because when I quit in 1996, I have paid no attention at all to what's going on. With what little I have read, it sounds like the motor plate area was stiffened up so much that something broke around it. I'm a believer in controlled flex by design, As I stated before, the tubing has a specific life span so if the heat treat alters that, someone needs to be aware and act accordingly.

chimp koose · January 04, 2008, 07:56:42 PM

dragster chassis deal with the flex differently than a funny car can due to wheelbase limitations. The latest thing I have seen with front engine dragsters is the 'floater' chassis . The upper frame rail and uprights forward of the engine are welded solid , the lower frame rail is not welded to the uprights but rather 'floats' inside sections of tubing that are welded to the uprights . this allows the forward part of the chassis to arch upward a lot. Downward flex is limited by stainless steel cables that are attached to the upper frame rail at the front motor plate, thread down to the bottom frame rail and run along that rail till just before the axle where they are rejoined to the upper frame rail.threaded ends allow for tuning the amount of flex in the chassis.

kb426 · January 04, 2008, 08:05:31 PM

A similar design has been used by some rear engine dragster builders for around 10 years.

Bugpac · January 04, 2008, 08:27:34 PM

Quote from: "kb426"A similar design has been used by some rear engine dragster builders for around 10 years.

so your an old drag racer from Kansas, You ever see a 7 second vega endo and barrel roll a few hundred feet? His name was Wes!

enjenjo · January 04, 2008, 09:42:29 PM

Quote from: "jusjunk"
Quote from: "jaybee"No doubt the amount of flex in those chassis is just amazing, when you look at how much arch is in the chassis during a run a little thought tells you the forces are enormous.

Maybe a little off topic but maybe not .. Ever look a a flat bed semi trailer unloaded going down the road.. Check it out next time you see one.. The amount of arch built into them unloaded is incredible.. But.... It works.. From what ive studied over the years looking while driving and enclosed semi has a lot less arch but they do have some.. But they have more support from the side walls of the trailer.. Oh ya on the flatbed stuff if i remember right the aluminum ones are real crazy with arch..
Dave

On closed trailers, they use monocoque construction. The load is carried by the sides. we had a series of trailers that did not have enough rivets where the sides connected to the roof. They would pop the rivets out, and collapse in a pile going down the road. Now think about this, 40,000 lbs supported by.023 aluminum sheet, and a rib every 12 to 24". The new trailers have no ribs, just twin sheets of 24 ga. steel, and 3/16" of plastic between them.

jaybee · January 07, 2008, 04:19:21 PM

I spent 8 1/2yrs with a flatbed company running aluminum trailers. The steel trailers have arch, the aluminum units have a LOT of arch because the aluminum is "springier". These things always amazed me because a 9,000# trailer can take the stress of a 50,000# steel coil concentrated by the coil racks in a space about 2' long!

unklian · February 14, 2008, 01:42:21 AM

John Force racing has new chassis,
designed by Niranjan Singh,a Ford Engineer
with Formula 1 experience.

The new chassis is 100 lbs heavier than last years,
using more tubing,larger diameters and thicker walls.

3 of their 4 team cars made it to the semi finals this past weekend.
Robert Hight won the final over Pedregon.

Hopefully SFI and NHRA will get their acts together
before someone else gets hurt.