weight difference between chromoly/mild steel
03-27-2010, 11:43 PM
#5
^wrong..mild steal is strong **** in cages..i can tell you ive seen alot more broken chromoly bars vs steal...there was a big stink about this years ago on yb and alot of people went into detial and did load testing on welds and such...the stuff was sent over to sfi to show that a chromoly cage aint really stronger pretty much..ill look for the thread tomarrow and link it..but im off to bed now
03-28-2010, 09:40 AM
#6
One thing that is misleading is that moly tubing is basically the same weight as mild steel. The inherent weight savings is due to the moly tubing being a thinner wall thickness.
As for strength, moly is stronger & therefore allowed by racing sanctioning bodies to be thinner, for a comparable overall strength, but less weight.
The difference is that mild steel is softer & has more of a tendency to bend upon severe impact, whereas moly has a somewhat torsional property that lets it bend & spring back within certain limits. Above this limit it has more tendency to fracture.
The biggest item with moly is the proper welding so the joints are not brittle. This is likely where most breaks are found... at the weld or within an inch or so of the weld. Moly suspension or cages are not something the average DIY person should attempt to built at home without proper welding training.
As for strength, moly is stronger & therefore allowed by racing sanctioning bodies to be thinner, for a comparable overall strength, but less weight.
The difference is that mild steel is softer & has more of a tendency to bend upon severe impact, whereas moly has a somewhat torsional property that lets it bend & spring back within certain limits. Above this limit it has more tendency to fracture.
The biggest item with moly is the proper welding so the joints are not brittle. This is likely where most breaks are found... at the weld or within an inch or so of the weld. Moly suspension or cages are not something the average DIY person should attempt to built at home without proper welding training.
03-28-2010, 02:45 PM
#7
i agree moly should only be welded by a pro and tiged..shoot all cages should be tiged..but you are right moly will fracture and break vs steal bending on high impact..
case in point..all nascar cars are built useing only mild steel an if you dont know nascar cars weight 3500#s now these cars take more impact then a drag car..they not only have to take a impact from a wall but other cars coming at them doing 190mph or so also..they dont get ripped a part an some times even come back out to run laps..
drag cars chromoly at these levels prostocks,pro mods,and 10.5 cars weight 2300#-3k and if you ever seen one hit the wall and then impacted by a car in the other lane your gut will drop..these cars become nothing at all..parts and tubes break and go flying..
i would rather have a cage bend around me then to break apart and become nothing to even support the car anymore..
remember mass x speed x object hit = total impact force..
heres some wrecks
cage comes apart like butter
http://www.youtube.com/watch?v=IiEv0j-SzlQ
cant see but his cage had mutiple breaks in it and one right at the a peller on drivers side
http://www.youtube.com/watch?v=HQ2ovdTp794
nascar
http://www.youtube.com/watch?v=ZkUg9MV3DhQ
case in point..all nascar cars are built useing only mild steel an if you dont know nascar cars weight 3500#s now these cars take more impact then a drag car..they not only have to take a impact from a wall but other cars coming at them doing 190mph or so also..they dont get ripped a part an some times even come back out to run laps..
drag cars chromoly at these levels prostocks,pro mods,and 10.5 cars weight 2300#-3k and if you ever seen one hit the wall and then impacted by a car in the other lane your gut will drop..these cars become nothing at all..parts and tubes break and go flying..
i would rather have a cage bend around me then to break apart and become nothing to even support the car anymore..
remember mass x speed x object hit = total impact force..
heres some wrecks
cage comes apart like butter
http://www.youtube.com/watch?v=IiEv0j-SzlQ
cant see but his cage had mutiple breaks in it and one right at the a peller on drivers side
http://www.youtube.com/watch?v=HQ2ovdTp794
nascar
http://www.youtube.com/watch?v=ZkUg9MV3DhQ
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03-28-2010, 03:13 PM
#9
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I knew about the stronger so they make it thinner but never knew about the breaking. That's a little scary. If it was that bad I would be surprised the sanctioning bodies would allow it?
03-28-2010, 05:34 PM
#13
what i find strange is that they use old aircraft info to get the facts on moly..instead of useing info they gatherd them selfs.
03-28-2010, 06:53 PM
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A shotty built chassis is just that regardless of the construction materials, thats why you never put your cars construction (your life) in the hands of anyone except a skilled professional.
03-29-2010, 03:00 AM
#17
I somewhat agree with you but not this. One of the many differences in cage construction between a pro stock car and a stock car, is that stock cars are built to withstand a 200-mph side impact collision, where as a drag cars are built mainly to enclose and protect the driver in the event of rollover. You can't compare two completely different chassis' built for two different things to argue the strength of their materials. Apples to oranges man, and if mild steel was superior in drag racing I'm sure John Force would be building his chassis with it, because running 300+mph and especially after losing Medlen to a fatal track accident he doesn't build anything but the absolute best for himself or his raceteams (which include 1 daughter in TF/FC and 2 in A/fuel dragsters.)
A shotty built chassis is just that regardless of the construction materials, thats why you never put your cars construction (your life) in the hands of anyone except a skilled professional.
A shotty built chassis is just that regardless of the construction materials, thats why you never put your cars construction (your life) in the hands of anyone except a skilled professional.
nascar
pro mod
