Chrome moly vs dom

[wayfast1]

Im gonna build a car should i use moly or dom so need some ideas wich way to go. Thanks

[zeroracing]

Are you familiar with welding chromoly?

If no, then don't touch it, improperly welded chromoly can fail easily and injur or kill. Personally I would only TIG chromoly, which many don't but that is the safer way to do it.

Also if your not using the strength of chromoly to go lighter then your only saving wallet weight.

[MasterSbilt_Racer]

If you can properly weld chrome moly, use if for the driver protection areas and DOM for the rest of the car. The stiffness of the two materials is the same. The yield point is what is different.

[F22 RAPTOR]

I personally still prefer DOM, chromoly just seems to finicky. I've seen Chrome cars built by GRT and Masters crack and fail and they know what they're doing. Below is a Chrome Goat that broke in several places in a flip and it scares the crap out of me to even consider chromoly. If you look close both breaks were "Next" to the welds, first at the drivers left shoulder where the main hoop and top door bars meet. Then the main "X" split in two inside the main hoop. Sure the car stayed intact and the driver survived, but the cage isn't suppose to break, but bend. DOM for me every time. JMO

[merc123]

I personally still prefer DOM, chromoly just seems to finicky. I've seen Chrome cars built by GRT and Masters crack and fail and they know what they're doing. Below is a Chrome Goat that broke in several places in a flip and it scares the crap out of me to even consider chromoly. If you look close both breaks were "Next" to the welds, first at the drivers left shoulder where the main hoop and top door bars meet. Then the main "X" split in two inside the main hoop. Sure the car stayed intact and the driver survived, but the cage isn't suppose to break, but bend. DOM for me every time. JMO

Straight out of the GRT book:

"4130 material needs to be heat treated after welding....the weak point will be the area right where the heat concentration stopped while welding..."

This explains why it broke where it did. According to the book GRT builds 95% of their cars out of DOM and it is more forgiving in crash situations than chromemoly.

Also, my opinion, if you are asking what type of tubing to use maybe building a chassis isn't the thing you need to start with.

[F22 RAPTOR]

Straight out of the GRT book:

"4130 material needs to be heat treated after welding....the weak point will be the area right where the heat concentration stopped while welding..."

This explains why it broke where it did. According to the book GRT builds 95% of their cars out of DOM and it is more forgiving in crash situations than chromemoly.

Also, my opinion, if you are asking what type of tubing to use maybe building a chassis isn't the thing you need to start with.
Is that the old GRT book? I think that number has flip/flop'd now with most cars being chromoly these days and they offer Tig welding at an added cost. Seeing how this was a GRT car and I assume they heat treated the frame the way "they" recommend, it appears chromoly fails at the weld point anyway, regardless of prep. Me, I still like a 2x2 frame with DOM cage or at the very least 2"RND frame, but thats just me. These 1-3/4" cars aren't referred to as, "crash and trash" for nothing.

[zeroracing]

Great pictures of failures. A lot of learning can be done from them, thank you for posting.

[F22 RAPTOR]

Great pictures of failures. A lot of learning can be done from them, thank you for posting.

No problemo. I keep them just for that reason, to learn. I actually got them off Facebook, but nobody was even talking about the failure, just Ooo-ing and Ahh-ing the wrecked car... Go figure.

[jason29a]

All sprint cars and midgets are built out of moly, they don't break like that.... I have been in the fab business for almost 20 years and thats just a case of annealing the material. If it's welded right it won't break like that. It will bend to a point and break though. DOM is the way to go though IMO.

[dirty white boy]

chrome moly tube been used for years in NHRA an IHRA but there needed strengths are different than what strengths dirt racing needs,...think somebody needs to do some crash study analissies on dirt chassis like NASCAR an NHRA an such do....for safety sake...

[twisterf5]

I personally still prefer DOM, chromoly just seems to finicky. I've seen Chrome cars built by GRT and Masters crack and fail and they know what they're doing. Below is a Chrome Goat that broke in several places in a flip and it scares the crap out of me to even consider chromoly. If you look close both breaks were "Next" to the welds, first at the drivers left shoulder where the main hoop and top door bars meet. Then the main "X" split in two inside the main hoop. Sure the car stayed intact and the driver survived, but the cage isn't suppose to break, but bend. DOM for me every time. JMO

you asked to see pics of our new chassis. could not get them to load yesterday but you can go on my FB page they are there ( richard clew )
our new car is 100% moly as has been our owm cars in the past our last owm was 4 years old when it started cracking so we got rid of it. most people weld it wrong and think they can use the same wire they use on mild steel. we use a special moly wire that you do not have to heat bars before welding.it is around 15 dollars a pound /instead of the 3 bucks the other wire cost there was no expense spared on this chassis could of built 3 chassis for what this one cost.well we will see in march how it works out.

[twisterf5]

chrome moly tube been used for years in NHRA an IHRA but there needed strengths are different than what strengths dirt racing needs,...think somebody needs to do some crash study analissies on dirt chassis like NASCAR an NHRA an such do....for safety sake...think that would cost to much/ i have welded several bars together with different wire and then put them i a press until they broke. that is as best as i can do with our budget LOL but feel 100% we will be OK with this chassis.

[dirty white boy]

think that would cost to much/ i have welded several bars together with different wire and then put them i a press until they broke. that is as best as i can do with our budget LOL but feel 100% we will be OK with this chassis.

seen the pics on FB,..its a nice chassis,..very professional looking!

[merc123]

Is that the old GRT book? I think that number has flip/flop'd now with most cars being chromoly these days and they offer Tig welding at an added cost. Seeing how this was a GRT car and I assume they heat treated the frame the way "they" recommend, it appears chromoly fails at the weld point anyway, regardless of prep. Me, I still like a 2x2 frame with DOM cage or at the very least 2"RND frame, but thats just me. These 1-3/4" cars aren't referred to as, "crash and trash" for nothing.

Maybe so, probably because that's what everyone wants now.

[MasterSbilt_Racer]

Is that the old GRT book? I think that number has flip/flop'd now with most cars being chromoly these days and they offer Tig welding at an added cost. Seeing how this was a GRT car and I assume they heat treated the frame the way "they" recommend, it appears chromoly fails at the weld point anyway, regardless of prep. Me, I still like a 2x2 frame with DOM cage or at the very least 2"RND frame, but thats just me. These 1-3/4" cars aren't referred to as, "crash and trash" for nothing.

It fails next to the weld because of the martensite that forms when the area cools from a molten metal to room temperature too quickly. The only way to avoid this process would be to heat in an oven and cool it slowly.

No matter what rod you use, this process still happens. It just may not be as big of a problem when an experienced welder uses a time-tested technique.

As I have said on here many times, why? Moly is NOT lighter. It is NOT stiffer. Only the yield and ultimate strengths are higher. (about a factor of 2). If your chassis has members that see stresses near the yield of mild steel, you need to go back to the drawing board.

[4bangerhotrod]

they make machines that stress relieve the welds which will keep it from breaking next to the heat line on the weld. but im sure none of your average shops have this equipment

[F22 RAPTOR]

It fails next to the weld because of the martensite that forms when the area cools from a molten metal to room temperature too quickly. The only way to avoid this process would be to heat in an oven and cool it slowly.

No matter what rod you use, this process still happens. It just may not be as big of a problem when an experienced welder uses a time-tested technique.

As I have said on here many times, why? Moly is NOT lighter. It is NOT stiffer. Only the yield and ultimate strengths are higher. (about a factor of 2). If your chassis has members that see stresses near the yield of mild steel, you need to go back to the drawing board.

Exacta-Mundo! Why?

[dynoman14]

The main reason people think Cro-mo is lighter is because it is usually available in lighter gauges than steel tubing. You don't have to have annealing equipment in your shop you just take it down to the heat treater just like you would the powder coater.

Annealing a chassis consists of heating it up and then cooling it in a controlled environment. All it is , is a high tech metal relaxation technique. You have to do it every 2 years in NHRA Professional classses. Most racers sell them as multiple annealling will embrittle the frame. That is why some of the older ProCars crack and break and hurt people.

I know a couple guys won't powder a car just for that reason.

I personally use ERW thin wall stuff for bumpers and body supports so it provides a crush or crumple zone to absorb some of the G's of a wreck. I like .095 DOM in the drivers compartment as well as steel sheet in the floor and around the driver as I have seen drive shafts and flywheels cut folks hands and arms off. You have to add lead anyway so may as well keep driverman safe.

The further away from the cG of the car the bigger the pendulum effect so then you can make fuel cell cage outer from lighter 1" material, I have even used aluminum. With a carbon fiber bladder, Ti-Sheet cover and alum you can save almost 40# over standard config. on a Pave car. I will be building the same stuff for my dirt car as I feel the fuel cell area is very neglected by most racers and I have seen numerous fuel cell punctures and thank God they never caught fire til the driver got out.

If you have any friends in the computer modeling business have them run your chassis design thru plastic deformation program. You will find that triangulation in chassis segments is a bigger influence on strength than the materials you use ( within reason that is ). I designed my chassis in 2-3ft sections and analyzed each one by itself and then as a whole and I was able to eliminate 20% of tubing used in a pavement car while increasing chassis rigidity over 200%. You should also consider using gussets at most of your load carrying joints. You will increase chassis rigidity greatly and only add about 20# of material.

I would also talk to someone with some chassis building experience to get you some help in wire and gas selection for the tubing you select. It is also a critical part of our chassis that is way overlooked by most everybody doing it in their back yard shop. Wire and gas are critical to heat and penetration as well as weld purity.

[50j]

The main reason people think Cro-mo is lighter is because it is usually available in lighter gauges than steel tubing. You don't have to have annealing equipment in your shop you just take it down to the heat treater just like you would the powder coater.

Annealing a chassis consists of heating it up and then cooling it in a controlled environment. All it is , is a high tech metal relaxation technique. You have to do it every 2 years in NHRA Professional classses. Most racers sell them as multiple annealling will embrittle the frame. That is why some of the older ProCars crack and break and hurt people.

I know a couple guys won't powder a car just for that reason.

I personally use ERW thin wall stuff for bumpers and body supports so it provides a crush or crumple zone to absorb some of the G's of a wreck. I like .095 DOM in the drivers compartment as well as steel sheet in the floor and around the driver as I have seen drive shafts and flywheels cut folks hands and arms off. You have to add lead anyway so may as well keep driverman safe.

The further away from the cG of the car the bigger the pendulum effect so then you can make fuel cell cage outer from lighter 1" material, I have even used aluminum. With a carbon fiber bladder, Ti-Sheet cover and alum you can save almost 40# over standard config. on a Pave car. I will be building the same stuff for my dirt car as I feel the fuel cell area is very neglected by most racers and I have seen numerous fuel cell punctures and thank God they never caught fire til the driver got out.

If you have any friends in the computer modeling business have them run your chassis design thru plastic deformation program. You will find that triangulation in chassis segments is a bigger influence on strength than the materials you use ( within reason that is ). I designed my chassis in 2-3ft sections and analyzed each one by itself and then as a whole and I was able to eliminate 20% of tubing used in a pavement car while increasing chassis rigidity over 200%. You should also consider using gussets at most of your load carrying joints. You will increase chassis rigidity greatly and only add about 20# of material.

I would also talk to someone with some chassis building experience to get you some help in wire and gas selection for the tubing you select. It is also a critical part of our chassis that is way overlooked by most everybody doing it in their back yard shop. Wire and gas are critical to heat and penetration as well as weld purity.

Argon and 70-s2 rod or in some cases 80-s2. Where does one find this every 2 year heat treat rule for the "ProCars".? Here's a hint, the Pro Stocks and Pro Modifieds are 25.1E. 4130 is used because the required wall thickness is less than mild steel so it's a lighter chassis. Going back over welds or welding with too much heat will make it brittle and it'll break by the weld. Too hard a rod will crack at the weld. Drag race chassis are welded with the right heat and allowed to cool at room temperature. Tig welded.

[twisterf5]

just for the he-- of it i took a piece of 083 1-3/4 and a piece of 065 1-1/2 and welded them this morning. let it air cool for 20 minutes then put them in the vice and beat them to death with a 5 pound sludge hammer bent the end of the pipe flat wore my self out trying to brake it. not a chance no cracks / nothing. so i guess i will stay with my way of welding moral of my story is don't go cheap on the wire and the gas.

[merc123]

just for the he-- of it i took a piece of 083 1-3/4 and a piece of 065 1-1/2 and welded them this morning. let it air cool for 20 minutes then put them in the vice and beat them to death with a 5 pound sludge hammer bent the end of the pipe flat wore my self out trying to brake it. not a chance no cracks / nothing. so i guess i will stay with my way of welding moral of my story is don't go cheap on the wire and the gas.

Drop a 2300# piece of lead from 5 feet onto concrete. Then drop a 5 pound piece of lead from 5 feet and see which ones has more damage on the concrete... I don't think you're using an accurate example. A 5 pound sledge, or a 100 pound sledge, wouldn't be anything comparable to hitting a wall in a race car at 50 MPH no matter how hard you sling it.

[twisterf5]

Drop a 2300# piece of lead from 5 feet onto concrete. Then drop a 5 pound piece of lead from 5 feet and see which ones has more damage on the concrete... I don't think you're using an accurate example. A 5 pound sledge, or a 100 pound sledge, wouldn't be anything comparable to hitting a wall in a race car at 50 MPH no matter how hard you sling it.
ya your right but we did put some pieces in a press a few years back all welded different and this set up is the best we found. i have knocked some clips off in my time but never had a failure like the pic that was posted. that is why i beat a piece to crap yesterday.it was hit well over 100 time and not even a crack. all our molly is out of germany that is what is printed on the pipe that is what our supplier has. maybe our is stronger than us stuff or what ever they are using. all i can say is it take a 10 time the strength to bend it in our bender and i have not broke any yet.

[50j]

It's hard to see in those pictures but from what I can see it looks like it was mig welded and it broke at the joints. It could have been too much heat, wrong wire, big gaps, too thin a tube, who knows. There's nothing that can't be done wrong. I would probably use DOM on something that'll be on a rough track myself but to break on impact like that isn't normal for 4130. If I used 4130 I would tig weld it only so that I could control the heat. No gaps larger than the rod. Tig welding takes time and skill so there will be people that will try to mig it.

[dirty white boy]

ya your right but we did put some pieces in a press a few years back all welded different and this set up is the best we found. i have knocked some clips off in my time but never had a failure like the pic that was posted. that is why i beat a piece to crap yesterday.it was hit well over 100 time and not even a crack. all our molly is out of germany that is what is printed on the pipe that is what our supplier has. maybe our is stronger than us stuff or what ever they are using. all i can say is it take a 10 time the strength to bend it in our bender and i have not broke any yet.
dont let these experts get ya down man,...your chassis seen to take abuse as good or better than the rockets an mastersbuilts you run with,..an hold up just fine!

[twisterf5]

dont let these experts get ya down man,...your chassis seen to take abuse as good or better than the rockets an mastersbuilts you run with,..an hold up just fine!no man im good been doing this for 30 years now. like any chat site you can't tell if you talkin to a racer or a seat warmer. but with all the talk i just had to try to brake it(think i pulled something trying LOL .this chassis was built with supers in mind but you right there is not a chassis out there that can take what mine can one tried last year and ended up in a scrap heap LOL you just can't fix stupid maybe he learned.

[rayburn62]

There is no way the heat involved in the powder coating process affects the chassis metalurgical structure. The process simply does not get hot enough. More racer science going on there. Proper filler material, shielding gas, heat, fit and technique all play a roll in the welding of moly.

[twisterf5]

There is no way the heat involved in the powder coating process affects the chassis metalurgical structure. The process simply does not get hot enough. More racer science going on there. Proper filler material, shielding gas, heat, fit and technique all play a roll in the welding of moly.
thought that was funny myself

[Matt49]

To anneal 4130 you have to hold it over 1500 degrees. I doubt you'll find many powder coating operations that go over 400.
Just another example of dynoman trying to pretend like he knows something.

[fastford]

i tried to stay out of this but i cant stand it any longer without putting my 2 cents in the mix, ive been welding all my 4130 with mild steel and a mig ever since it was discovered that its blend creates a flexible enough weld to keep from stress cracking for a long time, as for powder coating, i do it because the bond it has is so great that after a crash or long periods of stress it makes it easier to spot cracks, ive saw cracks that was under conventional types of paint, but the paint didnt crack so you would not have known, JMO

[50j]

I have heard that aircraft manufacturers mig weld it too but it isn't done by Boo Boo with his 110 buzz box. Tig welding lets you back the heat off on outside areas and put more to inside joints. You've got a lot more control over it. All pro level 4130 drag cars are tig welded without exception. Whatever works though.

[fastford]

I have heard that aircraft manufacturers mig weld it too but it isn't done by Boo Boo with his 110 buzz box. Tig welding lets you back the heat off on outside areas and put more to inside joints. You've got a lot more control over it. All pro level 4130 drag cars are tig welded without exception. Whatever works though.

wow, how did you know my name was boo boo? how ever i use a millermatic 200 with a flow meter to control my 75/25 argon. i have used tig and mig and if your joint, and not the one your smoking, is properly fitted , i prefer the mig, but if all you know how to do is braze, then tig would be better

[50j]

wow, how did you know my name was boo boo? how ever i use a millermatic 200 with a flow meter to control my 75/25 argon. i have used tig and mig and if your joint, and not the one your smoking, is properly fitted , i prefer the mig, but if all you know how to do is braze, then tig would be better

Nobody said that you were the Boo Boo, but... As long as the person welding the car up is also driving it have at it. If you're building chassis for other people to drive and they're putting their lives in your hands you have an obligation to do it right. Mig is a whole lot easier and faster and works fine on mild steel. Tig is much more difficult on a chassis because you're welding overhead and out of position a lot of the time but if you're actually qualified to be building chassis it's the way to go with 4130. Yes, I can do both. Educate yourself. Good luck.

[fastford]

Nobody said that you were the Boo Boo, but... As long as the person welding the car up is also driving it have at it. If you're building chassis for other people to drive and they're putting their lives in your hands you have an obligation to do it right. Mig is a whole lot easier and faster and works fine on mild steel. Tig is much more difficult on a chassis because you're welding overhead and out of position a lot of the time but if you're actually qualified to be building chassis it's the way to go with 4130. Yes, I can do both. Educate yourself. Good luck.

where do you get this so called qualification your talking about, is it some sort of certificate or some thing? ive been in some of the biggest and well known shops around and ive yet to see any

[50j]

I guarantee you that you've never been in a shop building pro drag cars and mig welding 4130. A simple call to NHRA would let you know that you can't do it and certify the chassis. My info is firsthand. As far as working in pro level shops, you truly have no idea. Again, educate yourself and then post on the subject. No hard feelings, if you don't know you don't know.

[fastford]

I guarantee you that you've never been in a shop building pro drag cars and mig welding 4130. A simple call to NHRA would let you know that you can't do it and certify the chassis. My info is firsthand. As far as working in pro level shops, you truly have no idea. Again, educate yourself and then post on the subject. No hard feelings, if you don't know you don't know.

90% of people on here ,including you, have probably never held a mig or a tig, and as for your dragracing statement , thats why i quit fooling with that BS a long time ago, ive welded nearly every thing known to man over the last 30 yrs, but you dont have to believe me thats your right, no hard feelings here either, have a good day

[50j]

Like I said, make the call. I could make you look real ignorant right now but I'm not into whizzing contests. Pride and stupidity are found together, and you're hurling personal insults at someone you know nothing about. I have the credentials but I'm not interested in putting a resume on the internet.

[fastford]

Like I said, make the call. I could make you look real ignorant right now but I'm not into whizzing contests. Pride and stupidity are found together, and you're hurling personal insults at someone you know nothing about. I have the credentials but I'm not interested in putting a resume on the internet.

i could make the same reference to you, and like the famous forest gumps mama said " stupid is as stupid does" take it any way you want, the end.......

[50j]

i could make the same reference to you, and like the famous forest gumps mama said " stupid is as stupid does" take it any way you want, the end.......

Everything I said was 100% accurate and can be confirmed with even minimal effort. The type of rod, shielding gas, and procedure is what is used in pro chassis shops. NHRA, SFI, and now circle track chassis builders agree that it should be tig welded. You however are more brilliant than than the people who have been building hundreds of cars, structural engineers, and the people doing the testing because you have a Millermatic and a Flow Meter. Big deal who doesn't have one. If you look at your super duper spool it's probably ER70-S2 wire, maybe ER70-S6. You just can't control the heat as easily. Go back to beating tubes with a hammer for testing. I don't know where some of you people come from, but I've never seen a forum like this where people don't want correct information.

[JustAddDirt]

How does Rocket weld their moly cars? i know it is mig welded, but do they stress relieve it?

[fastford]

Everything I said was 100% accurate and can be confirmed with even minimal effort. The type of rod, shielding gas, and procedure is what is used in pro chassis shops. NHRA, SFI, and now circle track chassis builders agree that it should be tig welded. You however are more brilliant than than the people who have been building hundreds of cars, structural engineers, and the people doing the testing because you have a Millermatic and a Flow Meter. Big deal who doesn't have one. If you look at your super duper spool it's probably ER70-S2 wire, maybe ER70-S6. You just can't control the heat as easily. Go back to beating tubes with a hammer for testing. I don't know where some of you people come from, but I've never seen a forum like this where people don't want correct information.

the stay the he!! off here FOOL

[50j]

the stay the he!! off here FOOL

Oh. I'm a fool. This comes from a guy that quotes Forrest Gump, can't spell or use correct grammar, and has contributed nothing constructive to the thread. I provided information about filler rod, shielding gas, and how it's done in a pro level chassis shop. The smarter people on here have already checked it out and confirmed it so it'll just be natural selection from here. You haven't even mentioned what magic wire you use so you're just making noise.

[Werflus]

LETS GET READY TO RUMBLE.... and the gloves come off...

[twisterf5]

this is why i stopped posting / i could post my magic wire LOL but you can get it at any welding supply store ( but most do not stock it but will order it for about 15 bucks a pound. but here's a fun fact have 287 wins 9 champion ships all in our own chassis so i guess i will stay with that works. now guys that my stats that you can google my name to confirm LOL richard clew . now you guys play nice

[twisterf5]

lets get ready to rumble.... And the gloves come off...

now thats funny

[50j]

this is why i stopped posting / i could post my magic wire LOL but you can get it at any welding supply store ( but most do not stock it but will order it for about 15 bucks a pound. but here's a fun fact have 287 wins 9 champion ships all in our own chassis so i guess i will stay with that works. now guys that my stats that you can google my name to confirm LOL richard clew . now you guys play nice

Why not post it? If it's a good way to do it maybe it'll keep people from getting hurt.

[twisterf5]

the best thing to do is call your local supplier/ all the best wire or gas means nothing if you can not use it. not going to post it and have a pissing match of what some one thinks is right or wrong. to hot to cold or your gaps are to big and you still will have a failure no matter what wire you are using.

[50j]

I'll agree with that.

[fwdbite]

Lincoln50 MIG wire

[twisterf5]

9 championships? googled your name and found a 4 cyl car in 2008? Limited sportsman results other than that?

http://www.luvracin.com/03_z_SC/Buffalo/driver/17-clew.html
well big boy you must not be that good 2008 was the last year we run mods. ran IMCA AT BOON THAT YEAR AND SOLD THE CAR THERE. but here is a small history lesson. 2006 IMCA STATE CHAMP.2007 EAST LINCON TRACK CHAMP. 2OO7 FASTRACK OWM CHAMP 2007 MODOC OWM CHAMP traveled in 08 have wins in MS/AL/GA/NC/ and which 4 cyl black sunfire #o5 purple and pink eclips #05 black escort #05 white caviler # 05 FUNNY HOW YOU CAN'T READ that my kid oh wait i forgot her #05 IMCA mod she ran when she was 12 and i know there is a pic out there of both our cars at IMCA nationals in 07 . going to take a little more than you. what you mad because you looked like a fool on that alt thread every one know msd pulls more power that a hei. you really need to get a life.

[Werflus]

"man down" 123456....

[dirty white boy]

9 championships? googled your name and found a 4 cyl car in 2008? Limited sportsman results other than that?

http://www.luvracin.com/03_z_SC/Buffalo/driver/17-clew.html

your google must be slipping...i know for fact mr clew has did what he says he's dun....an has a nice personality too...how bout you??

[dirty white boy]

well big boy you must not be that good 2008 was the last year we run mods. ran IMCA AT BOON THAT YEAR AND SOLD THE CAR THERE. but here is a small history lesson. 2006 IMCA STATE CHAMP.2007 EAST LINCON TRACK CHAMP. 2OO7 FASTRACK OWM CHAMP 2007 MODOC OWM CHAMP traveled in 08 have wins in MS/AL/GA/NC/ and which 4 cyl black sunfire #o5 purple and pink eclips #05 black escort #05 white caviler # 05 FUNNY HOW YOU CAN'T READ that my kid oh wait i forgot her #05 IMCA mod she ran when she was 12 and i know there is a pic out there of both our cars at IMCA nationals in 07 . going to take a little more than you. what you mad because you looked like a fool on that alt thread every one know msd pulls more power that a hei. you really need to get a life.

wheres stephanie an auston running this season,..or thay gonna bring that grand baby an follow poppa5?? seen pics of auston's mod4,..you helping him with that too??

[twisterf5]

wheres stephanie an auston running this season,..or thay gonna bring that grand baby an follow poppa5?? seen pics of auston's mod4,..you helping him with that too??
friend ship they on there own we going to hit big races this year

[LM14]

Also, my opinion, if you are asking what type of tubing to use maybe building a chassis isn't the thing you need to start with.

Been reading this thread with interest. I think this statement is the best one on the subject.

I know people that use a vibrating plate to stress relieve a moly chassis after mig welding. I've seen a 3 year old car that they ran every available night, ran up front, won, and it didn't have a single crack on it. I've also seen moly cars that had cracks all over them after a few nights.

It boils down to this....can you weld? Properly?

You are putting your life in the hands of the welder. I've seen DOM cages break beside the weld because they were too hot when welding. No different.

To the original poster. I would suggest DOM in the cage/driver's area. I would then build the rest of the car from electric weld tubing of a lighter gauge so it will take the bumps and bruises that come in this sport. That is how we have built cars for years and it seems to work for us. This is not a place to learn to weld, no matter what tubing you use.

JMO,
SPark

[dirty white boy]

friend ship they on there own we going to hit big races this year

there seems to be questions on weather friendship is gonna run,..jason going back to rtr an has nothing to do with elkin now....guess ill be at 311 when i can afford to run...if mike dont get to crazy...

[fastford]

Oh. I'm a fool. This comes from a guy that quotes Forrest Gump, can't spell or use correct grammar, and has contributed nothing constructive to the thread. I provided information about filler rod, shielding gas, and how it's done in a pro level chassis shop. The smarter people on here have already checked it out and confirmed it so it'll just be natural selection from here. You haven't even mentioned what magic wire you use so you're just making noise.

first off your the one that replied to MY post with your boo boo welding for nasa bull sh!t, second maybe you should have done like ole forest gump and listened to your mama a little more, so i will stand by my statement, " you sir are a fool"

[CHRISTINE]

Is that lincoln 70s3 l50 wire if so you are getting ripped off i work at a welding supply shop and can get that for 3.45 per lb

[hpmaster]

After all the stuff whackin into the fan on here what do all you steel gurus think of a car with chrome moly main frame rails and all other parts dom? Just trying to get the next round started. DING

[twisterf5]

After all the stuff whackin into the fan on here what do all you steel gurus think of a car with chrome moly main frame rails and all other parts dom? Just trying to get the next round started. DINGthats how some are/but i do not like to mix metals just go lighter in the crush areas. DING DING

[F22 RAPTOR]

After all the stuff whackin into the fan on here what do all you steel gurus think of a car with chrome moly main frame rails and all other parts dom? Just trying to get the next round started. DING

I have a friend who builds his cars that way. No issues I know of to date and the cars work very well. I myself just prefer DOM.

[Bubstr]

I wonder if you guys know, that braising was the preferred method of joining chrome molly for years. From the time they started manufacturing different chrome molly in the 40s threw the 50s all your F1 cars and WW2 aircraft where braised and held up very well. There was no real problem till mass manufacturing needed a faster way to join them. The fact is you can weld them with a torch, FAA still approves this method on experimental aircraft. You can Mig and you can Tig even though NHRA won't let you Mig. Excessive heat is the culprit that weakens joints. Your heat settings rod or wire, how the joint fits and how fast you travel with your rod all enter in to a good weld. If you have any doubts about your weld, first look at the heat ring by the weld. If it extends more than the width of the weld, you may be too hot, too slow or using wrong rod or wire. Then cut a couple apart and see if your bead goes to the bottom of the joint. If the bead on the bottom of the joint is more than about 1/3 the width of the top, you may be too hot. If you see a line of the joint your too cold. If it was easy everyone would be willie the welder. I don't care for joining dissimilar metals especially if the wall thickness is different, but it can be done well. It just taxes your ability to direct the heat more. The Tig is a little easier to control the heat and run, but a good welder with an oxy acct torch can do it also and not impossible with a Mig. Beating a joint to test strength is probably not as effective as pulling them apart with your frame machine. Tensile strength is where they most likely fail. One other tip. Make sure your CM is of the normalized variety. usually has a N at the end of the number. This should not have to be annealed after a proper weld.

I'm not a chassis builder but I stayed in a Holiday Inn once.

[50j]

That's interesting information on the aircraft manufacturing. Be careful though, you provided too many facts and some mongoloid will probably want to argue. Since you mentioned aircraft they might think you're talking about "NASA space sh#$".

[rmrc]

I haven't been here for quite a while so I missed the goofy stuff.
First off, 1 foot of 1 1/2" x .083 Chromemoly and 1 foot of 1 1/2" x .083 DOM weigh the same. There is no weight savings with moly EXCEPT that moly is stronger and builders feel that can use a lighter gage tubing. I won't get into that debate right now.
I have built LM racecars since 1987. After seeing a chromemoly car severely break apart after a grinding crash, I vowed to NEVER build one. That changed in 1999 when a structural engineer at a local steel treating plant approached me about normalizing our racecars. Over almost 6 months we tested and destroyed and microscopically examined hundreds of welds. We found that welding moly with a normal mig welder, using normal, everyday .030 wire provided the best weld. There is a mixing of properties between the parent material and the filler. You wind up with a very elastic weld that picks up some of the strength of the moly. We also found that if the entire chassis is normalized at 1100 deg. F and allowed to slowly air cool, the welded material and adjacent tubing return to virtually virgin integrity. ( they used the number 98%) Our moly chassis racecars have been proven over the years to be extremely durable and very repeatable. We have never seen any tubing fractures adjacent to the welds. As far as I'm concerned this is the only economical way to normalize an entire racecar. Crash repairs can be done by post heating the welds and adjacent tubing with an oxy acetalene torch and a temp stick to verify the correct temperature. (should be available at your local welding store)
I've recently heard of normalizing by using vibration but have no first hand knowledge of it's use for our application.
One final thought, anyone who tells you that powder coating "sorta" normalizes the racecar is FOS.

[50j]

I haven't been here for quite a while so I missed the goofy stuff.
First off, 1 foot of 1 1/2" x .083 Chromemoly and 1 foot of 1 1/2" x .083 DOM weigh the same. There is no weight savings with moly EXCEPT that moly is stronger and builders feel that can use a lighter gage tubing. I won't get into that debate right now.
I have built LM racecars since 1987. After seeing a chromemoly car severely break apart after a grinding crash, I vowed to NEVER build one. That changed in 1999 when a structural engineer at a local steel treating plant approached me about normalizing our racecars. Over almost 6 months we tested and destroyed and microscopically examined hundreds of welds. We found that welding moly with a normal mig welder, using normal, everyday .030 wire provided the best weld. There is a mixing of properties between the parent material and the filler. You wind up with a very elastic weld that picks up some of the strength of the moly. We also found that if the entire chassis is normalized at 1100 deg. F and allowed to slowly air cool, the welded material and adjacent tubing return to virtually virgin integrity. ( they used the number 98%) Our moly chassis racecars have been proven over the years to be extremely durable and very repeatable. We have never seen any tubing fractures adjacent to the welds. As far as I'm concerned this is the only economical way to normalize an entire racecar. Crash repairs can be done by post heating the welds and adjacent tubing with an oxy acetalene torch and a temp stick to verify the correct temperature. (should be available at your local welding store)
I've recently heard of normalizing by using vibration but have no first hand knowledge of it's use for our application.
One final thought, anyone who tells you that powder coating "sorta" normalizes the racecar is FOS.
That's interesting too. I do have a couple of questions though. Other than the obvious advantage of being able to speed up production by mig welding them, why would you rather do it that way than tig weld it where you have more control over the heat as you weld a joint? I'm assuming that when you say "everyday wire" you're referring to ER70-S2 or ER70-S6, and if you are using the same filler material but have less control what would the advantage be? Also, how was the tig welding done? What shielding gas? Was the welder experienced at welding 4130? You didn't see better penetration with the tig? Having done a lot of both I'm curious but not arguing with your procedure.

[fastford]

I haven't been here for quite a while so I missed the goofy stuff.
First off, 1 foot of 1 1/2" x .083 Chromemoly and 1 foot of 1 1/2" x .083 DOM weigh the same. There is no weight savings with moly EXCEPT that moly is stronger and builders feel that can use a lighter gage tubing. I won't get into that debate right now.
I have built LM racecars since 1987. After seeing a chromemoly car severely break apart after a grinding crash, I vowed to NEVER build one. That changed in 1999 when a structural engineer at a local steel treating plant approached me about normalizing our racecars. Over almost 6 months we tested and destroyed and microscopically examined hundreds of welds. We found that welding moly with a normal mig welder, using normal, everyday .030 wire provided the best weld. There is a mixing of properties between the parent material and the filler. You wind up with a very elastic weld that picks up some of the strength of the moly. We also found that if the entire chassis is normalized at 1100 deg. F and allowed to slowly air cool, the welded material and adjacent tubing return to virtually virgin integrity. ( they used the number 98%) Our moly chassis racecars have been proven over the years to be extremely durable and very repeatable. We have never seen any tubing fractures adjacent to the welds. As far as I'm concerned this is the only economical way to normalize an entire racecar. Crash repairs can be done by post heating the welds and adjacent tubing with an oxy acetalene torch and a temp stick to verify the correct temperature. (should be available at your local welding store)
I've recently heard of normalizing by using vibration but have no first hand knowledge of it's use for our application.
One final thought, anyone who tells you that powder coating "sorta" normalizes the racecar is FOS.

you are absolutely correct and i made a statement like this somewhere earlier in this post, i have been looking into a sonic vibration table my self, i think it may be helpful, but there is no need to say to much about it on here because some dumb a$$ nasa engineer may try to argue with you LOL

[rmrc]

That's interesting too. I do have a couple of questions though. Other than the obvious advantage of being able to speed up production by mig welding them, why would you rather do it that way than tig weld it where you have more control over the heat as you weld a joint? I'm assuming that when you say "everyday wire" you're referring to ER70-S2 or ER70-S6, and if you are using the same filler material but have less control what would the advantage be? Also, how was the tig welding done? What shielding gas? Was the welder experienced at welding 4130? You didn't see better penetration with the tig? Having done a lot of both I'm curious but not arguing with your procedure.

Well, let's quote Mr. Obvious "Other than the obvious advantage of being able to speed up production by mig welding them"....... Realizing that most chassis builders build more than a couple cars a year, why would you want to spend 2-3 days tig welding a complete LM when you can mig one in 3-4 hours. Time is money! At the end of the day you MIGHT wind up with a product that didn't break on impact by using either method. BUT, and I believe that it's a big BUT, when you normalize a chassis using the method that I described, the car comes out of the furnace with absolutely no memory. It is completely free of any welding induced stress. It's a process that we suggested to a couple of Cup teams. They decided to keep making cars that varied from one to another. Even NASCAR teams will tell you that they weld in a specific pattern, attempting to make the cars consistent. I hope that answers your questions!

[rmrc]

BTW
All of our testing was done with standard S7 welding wire from Lincoln Electric. We still use that wire today for mild steel or moly welding.

[50j]

Check your pm rmrc.