2x3 mild steel perimeter frame and cage questions ? - Yellow Bullet Forums

Go Back   Yellow Bullet Forums > Technical Section > Chassis and Suspension - Tim McAmis Performance Parts

Chassis and Suspension - Tim McAmis Performance Parts

Reply
 
Thread Tools Display Modes
Old 08-26-2008, 04:47 PM   #1
Collinsautomotive
Senior Member
Smoked Another SBC
 
Join Date: Nov 2005
Posts: 37,114
Default 2x3 mild steel perimeter frame and cage questions ?

I am getting ready to get started on building a complete frame for my 1969 dodge charger. The bulk of the factory unibody has heavy rust damage and good replacement parts are very very difficult to find.The cost of restoring outwieghs the cars potential value anyways. Yes it is a big block car. Mopar guys can stay out of this thread with the restore it comments please. I have heard enough of them.

Anyways. I am looking at doing a perimtere frame car with mandrel bent rails made out of mild steel with an intergrated 10 point cage. If I decided to go faster then 7.50 would it be better to build the 2x3 out of chromoly for certification purposes or did they now completely rule out any and all box tube frame faster then that.

I would prefer to build the frame and cage out of Mild steel and tig weld all of it. Mostly due to the fact that I have a tig welder and I like the look over Mig welding. If the box tubbing will not cert faster then 7.50 then I can go mild steel for everything. If box tubbing can cert to faster then 7.50 then I may build everything from chromoly. I am unclear about the legality of 2x3 or 2x4 box tubbing.

The car is mostly going to be a toy. I realize that I will need a funny car cage If I desire to go faster then 8.50. I may or may not due this depending on how sevral of the components in the car come together.

Any input as to the rules of construction are much welcomed. The perimeter frame is a must have for me becuase I plan on building a street legal car and the packaging is much easier to work around in terms of floor construction etc.
Collinsautomotive is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 08-26-2008, 04:50 PM   #2
TheMonster
Junior Member
Launchin
 
Join Date: Mar 2007
Location: Melbourne, FL
Posts: 492
Default

Is there a reason you want to use MS and still tig weld instead of using 4130 for the weight advantage?
__________________
Monster Motorsports And Fabrication
- Precision Fabrication, Tig Welding, Turbo Specialist, Custom Cages
TheMonster is offline   Reply With Quote
Old 08-26-2008, 05:38 PM   #3
CurleysRacecars
Senior Member
Smoked Another SBC
 
Join Date: Aug 2008
Location: Granite Bay, CA
Posts: 4,338
Default

Im with you, with the better looking TIG welds. I TIG everything...only use a MIG to make fixtures and what not. It rearely gets used.
Im 99% sure, that 2x3(or any box tubing) will not cert any faster than 7.50. You'd have to go full round tube to go any faster.
If 7.50 cert is good enough for you, go all MS. If you want it to cert faster, your gonna need to go all round tube moly.
Good luck!
Kyle
__________________
Kyle Curley
Curley's Racecars & Components
(916)-397-3465
www.curleysracecars.com
CurleysRacecars is offline   Reply With Quote
Old 08-26-2008, 06:05 PM   #4
Collinsautomotive
Senior Member
Smoked Another SBC
 
Join Date: Nov 2005
Posts: 37,114
Default

Yeah. I would like the car to absorb crash impacts instead of shatter. I have worked out the wieghts savings. I would save maybe 100 lbs for the whole car tops unless I build a 25.2 or similar or better chassis.

Quote:
Originally Posted by TheMonster View Post
Is there a reason you want to use MS and still tig weld instead of using 4130 for the weight advantage?
Collinsautomotive is offline   Reply With Quote
Old 08-26-2008, 06:06 PM   #5
Collinsautomotive
Senior Member
Smoked Another SBC
 
Join Date: Nov 2005
Posts: 37,114
Default

Thanx for the input. I am hopping somne like GB pops in to clarify it 100% for me. I remember something about the 2x3 and 2x4 only being good till 7.50.

Quote:
Originally Posted by CurleysRacecars View Post
Im with you, with the better looking TIG welds. I TIG everything...only use a MIG to make fixtures and what not. It rearely gets used.
Im 99% sure, that 2x3(or any box tubing) will not cert any faster than 7.50. You'd have to go full round tube to go any faster.
If 7.50 cert is good enough for you, go all MS. If you want it to cert faster, your gonna need to go all round tube moly.
Good luck!
Kyle
Collinsautomotive is offline   Reply With Quote
Old 08-26-2008, 07:15 PM   #6
TheMonster
Junior Member
Launchin
 
Join Date: Mar 2007
Location: Melbourne, FL
Posts: 492
Default

Quote:
Originally Posted by Collinsautomotive View Post
I am getting ready to get started on building a complete frame for my 1969 dodge charger. The bulk of the factory unibody has heavy rust damage and good replacement parts are very very difficult to find.The cost of restoring outwieghs the cars potential value anyways. Yes it is a big block car. Mopar guys can stay out of this thread with the restore it comments please. I have heard enough of them.

Anyways. I am looking at doing a perimtere frame car with mandrel bent rails made out of mild steel with an intergrated 10 point cage. If I decided to go faster then 7.50 would it be better to build the 2x3 out of chromoly for certification purposes or did they now completely rule out any and all box tube frame faster then that.

I would prefer to build the frame and cage out of Mild steel and tig weld all of it. Mostly due to the fact that I have a tig welder and I like the look over Mig welding. If the box tubbing will not cert faster then 7.50 then I can go mild steel for everything. If box tubbing can cert to faster then 7.50 then I may build everything from chromoly. I am unclear about the legality of 2x3 or 2x4 box tubbing.

The car is mostly going to be a toy. I realize that I will need a funny car cage If I desire to go faster then 8.50. I may or may not due this depending on how sevral of the components in the car come together.

Any input as to the rules of construction are much welcomed. The perimeter frame is a must have for me becuase I plan on building a street legal car and the packaging is much easier to work around in terms of floor construction etc.
You do know that no matter what you do frame wise with a 10pt cage you can't go faster then 8.50s anyways? Not sure why you are mentioning 7.50s when you mentioned first in your post you wanted an integrated 10pt cage. Anything faster then 8.50s requires an SFI cage/chassis.

Looks like you need to decide the purpose of the car and then go from there. You change your mind about 3 or 4 times on what you want to do because of this or that.

Pick one goal and build to that specification. You will save yourself a ton of time, money and headaches.

Quote:
Originally Posted by Collinsautomotive View Post
Yeah. I would like the car to absorb crash impacts instead of shatter. I have worked out the wieghts savings. I would save maybe 100 lbs for the whole car tops unless I build a 25.2 or similar or better chassis.
I was just wondering. 100lbs is a lot for a car running high to mid 7s.
__________________
Monster Motorsports And Fabrication
- Precision Fabrication, Tig Welding, Turbo Specialist, Custom Cages
TheMonster is offline   Reply With Quote
Old 08-26-2008, 07:24 PM   #7
Collinsautomotive
Senior Member
Smoked Another SBC
 
Join Date: Nov 2005
Posts: 37,114
Default

I noted 10 point with the ability to add a funny car hoop. I will not build a round tube chassis for the alternate uses that car will see. I can be fine with a 7.50 cert. Adding a funny car hoop and a few bars is not a problem since I am basically reusing the body shell. In fact I can add most if not all the floor bars needed for the 7.50 cert minus the funny car hoop and stay out of trouble with it.

I can easily settle for 7.50's. I was questioning if the 2x3 would cert faster. If not that was to be my cutoff in terms of putting the chassis together.

For the aleternate uses I really want the shtrength of the 2x3 rials over the round tube.

100lbs is not a big deal with the amount of glass and lexan going in the car.


Quote:
Originally Posted by TheMonster View Post
You do know that no matter what you do frame wise with a 10pt cage you can't go faster then 8.50s anyways? Not sure why you are mentioning 7.50s when you mentioned first in your post you wanted an integrated 10pt cage. Anything faster then 8.50s requires an SFI cage/chassis.

Looks like you need to decide the purpose of the car and then go from there. You change your mind about 3 or 4 times on what you want to do because of this or that.

Pick one goal and build to that specification. You will save yourself a ton of time, money and headaches.



I was just wondering. 100lbs is a lot for a car running high to mid 7s.
Collinsautomotive is offline   Reply With Quote
Old 08-26-2008, 07:35 PM   #8
TheMonster
Junior Member
Launchin
 
Join Date: Mar 2007
Location: Melbourne, FL
Posts: 492
Default

Gotcha. I was under the impression you thought with a 10pt cage you would be able to get a 7.50cert when once you go faster then 8.50 you need an SFI setup(all of which include the funny car hoop).

Sounds like a fun project.
__________________
Monster Motorsports And Fabrication
- Precision Fabrication, Tig Welding, Turbo Specialist, Custom Cages
TheMonster is offline   Reply With Quote
Old 08-26-2008, 07:44 PM   #9
Collinsautomotive
Senior Member
Smoked Another SBC
 
Join Date: Nov 2005
Posts: 37,114
Default

No I am planning on building the car with room for 5 to start. Its a big car lots of room. Mostly I wanna go play with top speed on the salt eventually. Mostly a protouring car. I doubt I can afford the motor after I get done with the roller. That why I want to start with a solid foundation to build on. 7.50 is fast enough.


Quote:
Originally Posted by TheMonster View Post
Gotcha. I was under the impression you thought with a 10pt cage you would be able to get a 7.50cert when once you go faster then 8.50 you need an SFI setup(all of which include the funny car hoop).

Sounds like a fun project.
Collinsautomotive is offline   Reply With Quote
Old 08-26-2008, 10:21 PM   #10
race9899
Senior Member
Smoked Another SBC
 
race9899's Avatar
 
Join Date: Feb 2006
Posts: 4,510
Default

4130 does not shatter, it does not crack easier than MS,

4130 is by far the better choice for building a race car out of, particularly if you are intending to Tig weld anyways.

If you are looking to gain the torsional rigidity that comes from the rectangular tubing and think you may want to be able to cert for quicker that 7.50, build a double rail..

I have built several ProStreet shootout type car that had the lower frame rail doubled up, basically picture your all of your floor bars being at the height of the middle of the four link brackets and then building a lower section in the middle of the chassis at the bottom of the 4 link brackets. building the chassis that way makes plenty of room to run the exhaust all the way back to the rear tire also.
__________________

www.makotenfive.com
_________________________________________________
Holloway Race Cars
Broken Arrow Oklahoma
race9899 is offline   Reply With Quote
Old 08-27-2008, 05:50 AM   #11
barszcz
Member
Pullin gears
 
barszcz's Avatar
 
Join Date: Dec 2007
Location: indy
Posts: 604
Default

as far as your weight savings goes ive done the math several times for customers trying to upsell them to go to moly cages in mustangs, camaros etc... (we dont do mild steel anything) in a standard notch back mustang a 10 point cage in 4130 will save you 120# over .134 wall mild steel. i would have to assume that using .120 wall 2x3 would have to add 300# total by the time its all said and done. especially in a big car like youre talking about using when compared to a lil mustang. ps... i cant stand the average mopar whackjob that thinks everything sould be restored. they all need shot. we had a guy come in last year that had us put subframe connectors in and an 8 point bar...

he wanted a roll bar because he didnt want to turn it into a racecar and he needed subframe connectors put in. the way we do our cages/bars in subframe cars is we use the 6x6 plates and break them so that they make boxes that mount off of the rockers etc... so, that shit aint going anywhere easily if you wanna take the cage out. so, he wanted us to fit the 2x3 to match the under side of his floor so it could be cut back out at a later date and time. i laughed and told him okay. when he came to get his car it was done like everyone else's and he was a lil upset but when i told him what i would have charged him to do it his way, he understood. oh, then after it was all done he brought the car back to have it changed into a 10 point cage. mopar guys are a different breed.
barszcz is offline   Reply With Quote
Old 08-27-2008, 10:07 AM   #12
Collinsautomotive
Senior Member
Smoked Another SBC
 
Join Date: Nov 2005
Posts: 37,114
Default

Well. I am building the car along more proven crash worthy nascar cage and frame design. I hate to say it but Nascar has the most proven 200+ mph structure. The only leauge with anything that is proven and faster is F1 and Indy and those are carbon tub cars. That comment excludes rail cars.

My car is in the world of restorable but it would cost so much money to do it that is makes no sense. Most of the sheetmetal I would need would have to be hand made.

I am replacing the doors,Hood,Fenders,Bumper,Trunk Lid, and Glass with lexan and plexi and the interior will be really sparse as well. The car only wieghed 3400lbs with a big block Iron heads etc in it with all those parts in it being steel. I think If i can get to 3200-3400 lbs I should be just fine.

I have a ton of ideas that I got out the tape for last night. Most of them will reduce the wieght of the car even more. Most likely gonna run a c5 corvette front IRS.

As to the other comment about chromoly. It does not have the enlongation properties of MS and it will tear/crack before MS will. MS will also absorb far mroe impact and deform more then MS. There is a reason nascar uses it.


Quote:
Originally Posted by barszcz View Post
as far as your weight savings goes ive done the math several times for customers trying to upsell them to go to moly cages in mustangs, camaros etc... (we dont do mild steel anything) in a standard notch back mustang a 10 point cage in 4130 will save you 120# over .134 wall mild steel. i would have to assume that using .120 wall 2x3 would have to add 300# total by the time its all said and done. especially in a big car like youre talking about using when compared to a lil mustang. ps... i cant stand the average mopar whackjob that thinks everything sould be restored. they all need shot. we had a guy come in last year that had us put subframe connectors in and an 8 point bar...

he wanted a roll bar because he didnt want to turn it into a racecar and he needed subframe connectors put in. the way we do our cages/bars in subframe cars is we use the 6x6 plates and break them so that they make boxes that mount off of the rockers etc... so, that shit aint going anywhere easily if you wanna take the cage out. so, he wanted us to fit the 2x3 to match the under side of his floor so it could be cut back out at a later date and time. i laughed and told him okay. when he came to get his car it was done like everyone else's and he was a lil upset but when i told him what i would have charged him to do it his way, he understood. oh, then after it was all done he brought the car back to have it changed into a 10 point cage. mopar guys are a different breed.
Collinsautomotive is offline   Reply With Quote
Old 08-27-2008, 11:43 AM   #13
barszcz
Member
Pullin gears
 
barszcz's Avatar
 
Join Date: Dec 2007
Location: indy
Posts: 604
Default

okay, i assumed that since you asked questions about building a racecar i assumed that meant you didnt have much knowledge or experience with doing so. so, i put my $.02 in. since you threw out the whole MS versus 4130 elongation theory as to why NASCAR uses it over 4130 i thought i would enlighten you on a few things since i may have built a "few" cars over the years. NASCAR typically uses 1020 DOM or 1026 DOM which is mild steel in a sense, but the refining process is closer to 4130. if you are planning on using this car for more of PRO TOURING deal than a drag race car then you should be using DOM not ERW mild steel. you are probably safe to TIG DOM as it is a lil cleaner than ERW and that is where the undercut comes from that i have talked about in other posts that has been shot down by numerous folks on here as "they have TIGged mild steel for years and not had any problems." the average person isnt going to see it, but i am getting off topic here. keep in mind though your weight issue, as you increase your mass it now becomes more of a projectile that will be harder to stop if needed and when it does stop, the G forces will become greater because of the added force exerted to stop a heavier race vehicle. but, do i really need to go into detail of intricate vehicle dynamics? and, 3% elongation difference is minute when to compared to the tensile strength differences between the three.

MILD STEEL:
35,000 tensile strength
15% yield per 2" elongation

1020 DOM
80,000 tensile strength
12% yield per 2" elongation

1026 DOM
87,000 tensile strength
12-15% yield per 2" elongation

4130N
95,000 tensile strength
12-15% elongation per 2"
barszcz is offline   Reply With Quote
Old 08-27-2008, 11:59 AM   #14
CurleysRacecars
Senior Member
Smoked Another SBC
 
Join Date: Aug 2008
Location: Granite Bay, CA
Posts: 4,338
Default

Quote:
Originally Posted by Collinsautomotive View Post
Well. I am building the car along more proven crash worthy nascar cage and frame design. I hate to say it but Nascar has the most proven 200+ mph structure. The only leauge with anything that is proven and faster is F1 and Indy and those are carbon tub cars. That comment excludes rail cars.

My car is in the world of restorable but it would cost so much money to do it that is makes no sense. Most of the sheetmetal I would need would have to be hand made.

I am replacing the doors,Hood,Fenders,Bumper,Trunk Lid, and Glass with lexan and plexi and the interior will be really sparse as well. The car only wieghed 3400lbs with a big block Iron heads etc in it with all those parts in it being steel. I think If i can get to 3200-3400 lbs I should be just fine.

I have a ton of ideas that I got out the tape for last night. Most of them will reduce the wieght of the car even more. Most likely gonna run a c5 corvette front IRS.

As to the other comment about chromoly. It does not have the enlongation properties of MS and it will tear/crack before MS will. MS will also absorb far mroe impact and deform more then MS. There is a reason nascar uses it.
LOL. Nascar tube structures have been the same for years. They are more worried aboput aerodynamics, engine research and suspension. Its a very simple rule of engineering/physics. Whats the strongest isometric shape? The circle...beings you cant put a circle in for a door bar, whats the next strongest? The triangle. Now look at a drag car vs. a NASCAR...?? Should be pretty simple. Im not bashing NASCAR, as they are VERY safe, however, the teams spend more time in other areas to go faster.
4130 WILL NOT crack or tear. This entire topic has been beaten to death all over the internet. If it is TIG welded, and done right(there should be some coloration to the weld, not dark grey and ashy looking), it will be fine. You use er70s-2 filler so that it does give before tearing. If you use 4130 as a filler, it would crack or break.
NASCAR boys use the DOM because it is slightly cheaper, and can be MIG welded just fine(so can 4130 but it will produce hair line cracks, although it has been MIG welded forever in the oil industry), as well as the simple fact that they dont keep cars very long. Whens the last time you saw a NASCAR from 2006 or later going around the track(exclusing the "car of tomorrow bullshit", but you get the point)? They dont keep the cars very long, so why put tons of hours into welding and such? Its a smart move realistically...drag cars and NASCAR's are just 2 totally different animals.
For you to say a NASCAr is safer is funny as hell. Go read up on physics and engineering a little bit more!
Kyle
__________________
Kyle Curley
Curley's Racecars & Components
(916)-397-3465
www.curleysracecars.com
CurleysRacecars is offline   Reply With Quote
Old 08-27-2008, 12:05 PM   #15
barszcz
Member
Pullin gears
 
barszcz's Avatar
 
Join Date: Dec 2007
Location: indy
Posts: 604
Default

kyle, you might look into ER80Sd2. we started using it about 6 years ago and have been very happy with it. it actually provides a lil more elongation which to me is funny given the argument above. lol.
__________________
www.theindycartel.com
barszcz is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -4. The time now is 06:28 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.
Resources saved on this page: MySQL 3.33%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Yellow Bullet LLC