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SlingShot
05-29-2010, 10:46 AM
I was cruising FB looking at different peoples pics of race cars and came across a crashed Super. My horror was that the car broke in what I believe are two key areas. The first break was where the main hoop meets the top door bar right beside the drivers head and left shoulder. The second break was in the main "X" behind the driver, within the main hoop, it once again broke cleanly at the center of the "X". Now it appears the car took a wild flip and I didn't witness it myself, but I didn't think we wanted the cars to break anywhere, ever... What was even more shocking is that it as a GRT, a well known builder with tons of experience. My question is this, "are these breaks the result of Chromoly construction"? Also I've seen where GRT advertises "Tig welded" chassis now, could this be a contributing factor? The driver was Kyle Beard and he was unhurt, but the breaking of the chassis is troubling to me. Any input would be appreciated... I've included links to the pics below.

[/URL]http://www.facebook.com/photo.php?pid=30346989&id=1029450012 (http://www.facebook.com/photo.php?pid=30346985&id=1029450012)
[URL]http://www.facebook.com/photo.php?pid=30346991&id=1029450012
http://www.facebook.com/photo.php?pid=30346984&id=1029450012

charcoal01
05-29-2010, 12:00 PM
i'm no expert but that looks like the general problem with chromoly, it is so rigid, that it doesnt bend like your normal mild steel, it shears. you can see that the welds didnt give way, it sheared just where the weld ended. at least that's what it looks like.

pretty scary stuff.

MasterSbilt_Racer
05-29-2010, 08:33 PM
Tig welding is better than mig for welding moly. It is still no substitute for annealing the welds.

414banger
05-29-2010, 09:46 PM
like previosly stated it looks like it broke where the weld ended probobly in the heat effected zone the heat from the weld changed the properties of the metal making it brittle in that zone but the weld itself held

4bangerhotrod
05-30-2010, 12:35 AM
at the edge of the weld it makes the metal hard and brittle at the heat line, you could stress relieve every weld and not have that problem but that would take alot of money and alot of time. atleast the welds did there job, a good weld is always stronger than the metal its on.

MasterSbilt_Racer
05-30-2010, 11:20 AM
Moly doesn't really have much business in a race chassis, IMO.

It offers no additional stiffness over DOM. That makes it have no benefit in structural parts of the chassis. It does have a higher yield, so that can make it beneficial in driver protection areas like the halo. That benefit is negated without proper procedures, however.

SlingShot
05-31-2010, 09:44 AM
Moly doesn't really have much business in a race chassis, IMO.

It offers no additional stiffness over DOM. That makes it have no benefit in structural parts of the chassis. It does have a higher yield, so that can make it beneficial in driver protection areas like the halo. That benefit is negated without proper procedures, however.
Thats kinda what I thought... I think I'll stay with DOM. The way it broke/sheared just gave me pause and thought I'd share what I was seeing. I had heard that moly tended to crack, even when not crashed. There is a guy on here, Ron Miller I think is his name, that builds moly cars but sends the frame out to be treated before having it coated. I wonder if this treatment makes the difference, I would have thought GRT would do this...

MasterSbilt_Racer
05-31-2010, 10:16 AM
If the whole car was heated in a furnace and cooled at the correct rate, all the Martensite could be tempered or removed in the process. This would rid the HAZ areas of the brittleness caused by the high heat and rapid cooling.

SlingShot
05-31-2010, 11:30 AM
If the whole car was heated in a furnace and cooled at the correct rate, all the Martensite could be tempered or removed in the process. This would rid the HAZ areas of the brittleness caused by the high heat and rapid cooling.
What?:eek: You lost me there...

MasterSbilt_Racer
05-31-2010, 11:45 AM
Rapid heating and cooling causes the grain structure of the steel to change. Rapid cooling causes a crystaline grain structure called martensite. This is where an abundance of the carbon becomes trapped in the grains of a localized area instead of being mixed within the steel more uniformly. Martensite is very hard and very brittle.

This occurs in the HAZ or heat-affected-zone adjacent to the weld. The weld is very hot when performed, but the rest of the tube is room temp. This long section of tube acts a heat sink to cool the HAZ relatively quickly. The result is similar to heating carbon steel and cooling quickly in a bucket of water.

SlingShot
05-31-2010, 05:48 PM
Rapid heating and cooling causes the grain structure of the steel to change. Rapid cooling causes a crystaline grain structure called martensite. This is where an abundance of the carbon becomes trapped in the grains of a localized area instead of being mixed within the steel more uniformly. Martensite is very hard and very brittle.

This occurs in the HAZ or heat-affected-zone adjacent to the weld. The weld is very hot when performed, but the rest of the tube is room temp. This long section of tube acts a heat sink to cool the HAZ relatively quickly. The result is similar to heating carbon steel and cooling quickly in a bucket of water.
Ohhh, thanks for explaining. Some of the tech terms were over my head even though I understand the priciples involved. The weld is strong but the area around it becomes brittle, I gotcha. :D

DIRTSLINGER38
05-31-2010, 06:38 PM
ok i currently am pit crew for kyle beard, the car was about 20 feet in the air before it hit the halo on the drivers side to this day we still have the chassis sitting outside the shop as a reminder of what the results of hard racing with two nondriving people that were trying to drive thru the infield when kyle was trying to pass to the outside and they clipped his left front tire which put him in the wall and sent him airborne

SlingShot
06-01-2010, 09:04 AM
ok i currently am pit crew for kyle beard, the car was about 20 feet in the air before it hit the halo on the drivers side to this day we still have the chassis sitting outside the shop as a reminder of what the results of hard racing with two nondriving people that were trying to drive thru the infield when kyle was trying to pass to the outside and they clipped his left front tire which put him in the wall and sent him airborne
Is Kyle still running the moly type chassis? I'd think Joe Garrison would want this frame for crash data... I'm neither Pro or Con GRT, but this gives me concern for moly type chassis construction. JMO

DIRTSLINGER38
06-01-2010, 01:07 PM
nothing has been said about the chassis goin to grt but the other 2 older cars i think are moly