heavy85 Posted July 11, 2006 Author Share Posted July 11, 2006 I also think that SFC are not the most elegant solution it's just that mine are trashed and need replaced anyway so why not go all the way back with them. Also, only looking at the 2.5" ones since they are the same weight but 44% stiffer than the standard 2x3 most people use. I've been looking at modern higher performance cars and from what I see they all tend to use the rockers and the trans tunnel as the main structural members. I'm just not sure how to tie the front frame rails into either the rockers or the trans tunnel (and then how to adequately re-inforce the tunnel) and I'm not looking to completely redesign the uni-body .... quite yet. Have to get the yet-to-be-purchased-but-have-green-light-from-wife-LS1-swap completed first. What about like someone said below run like a 1x3 (3 tall, 1 wide) along the inside of the rocker then tie it at the front into the T/C bucket. Not sunk in like Cary's pic just to the inside along the floor. Thinking out loud here. Cameron Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2006 Share Posted July 11, 2006 JMortensen,I like that idea,I noticed 240Hoke 'grooved' the front rear wheelwell to possibly add strength to the mainbar.I like how the mainbar is 1/2 'sunk' into the rocker.I wanted my mainbar pad to tie in the SFC,rear frame,and rocker and box in from underneath.Does your pad tie into the perpendicular rear frame?BTW,What dia. is your mainbar?Thickness? My bar is 1.75 x .120. I did that because the SCCA rulebook says 1.75 x .095 in one place, then in an addendum it says 1.75 x .120. I think that most guys who run 1.75 are running .095, but I just wanted to be on the safe side, and if the regulations change again I'll still be OK. If you look at this picture, from underneath, you can see that the frame rail ends before the rocker, so no, my bar doesn't attach directly to that frame rail. I had been trying to figure out a way to strengthen this area, and I think if I ran a small tube diagonally from the end of the frame rail to the rocker area that might just do it. Maybe just a simple gusset in the corner there. As it is the cage attaches to the rocker, and the wheel well, which is connected to that rail, but they are not connected directly. Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted July 11, 2006 Share Posted July 11, 2006 i was over at dave's (azcar) house and we were talking about cages and what i wanted to do. he was the one that suggested using the 1x3 along the rockers and using that as the platform that the rest of the cage sat on. you could stitch weld the 1x3 to the rockers and then use the 100 sq. in. plate to tie those in at the toe box and at the back at the seat belt mount location. then you would not have to worry at all about the main hoop bar punching a hole in the floor if something were to happen. i would have to take out 4' feet of bar and rockers. way overkill, yeah probably. dave thought that if he had to do it over again, he would do this. he thought it would have kept his legs from getting as injured as bad when he turned his car into a little ball of scrap. with that being said, i have looked through the nasa rule book and it said nothing about building a cage like that (that i could find). katman did not think they would permit that when i last asked him about cages. maybe john c can chime in on this as well. i am in the position now wher it would be an easy install as the floors are out and the sfc are about to go in. i need to go out to firebird this friday and check out the races and speak with the tech guys to find out for sure. jim Quote Link to comment Share on other sites More sharing options...
tube80z Posted July 11, 2006 Share Posted July 11, 2006 Tube,Did you fab box steel to the inner rocker?Along the lines of what I was thinking.I'm digging that idea,so post a couple more photos if you have them of front and rear mounting,steel thickness,etc.... Attached are a couple more photos to help with the idea. The reinforcement is 2x2x0.120 wall tubing. The rocker was openned at the front and rear the a continuous piece of tube was fitted. In addition they sectioned the inside of the rocker to allow the cage to be hooked directly to it and for better attachement to the car. The idea for this originally came after seeing a competitor get seriously injured at a hillclimb. His car left the road and hit a tree at speed. The cage worked perfectly but the car rolled up onto the rocker, which failed and the this lead to his getting partially crushed. Looking at the wreckage it was pretty clear that is this area were stronger his injuries may have been a lot less. The car belongs to Dave Kipperman and if you happen to be at Shasta you can ask to get a closer look. Dave would be more than willing to show some of the hidden details of this car. Cary Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2006 Share Posted July 11, 2006 Just ran a tape measure down the side of the car, and it looks as though you'd need about 9' of tubing to run it all the way down the rocker. Got me thinking about weight and strength. Correct me if I'm wrong in any of this, but I show: rectangle 3x1x.065 = 1.7146 lbs/ft so *9 = 15.4314 lbs 3x1x.120 = 3.0754 lbs/ft *9 = 27.6786 lbs square 2.5x2.5x.120 = 3.05 lbs/ft *9 = 27.45lbs round 1.75x.120 = 2.089 lbs/ft * 9 = 18.801 lbs 1.625x.065 = 1.0818 lbs/ft *9 = 9.7362 lbs 1.5x.095 = 1.426 lbs/ft *9 = 12.834 lbs So these are some materials that people might use to do this rocker reinforcement. I have some vague notions of strength which I'd like to put forth, hopefully if they're wrong someone will let me know. Rectangular tubing is stiffer in bending than round. Round tube is stiffer torsionally than square. DOM is stronger than ERW. Rectangular is usually (always?) ERW, but round DOM is easily found. What I don't know is which tube is the better choice for this project. Looks like you can get out of it for a pretty minimal weight penalty by going with round thin walled tubing, but the question is what strength is actually required here? Is it better to carry the extra 30 lbs, or the 9 lbs? How would the strength of the rocker compare if one uses a flanged hole section of of sheet to connect the round tube to the rocker like Mikelly did on his A pillar: http://pg.photos.yahoo.com/ph/dat74z/detail?.dir=fb30&.dnm=2465.jpg&.src=ph The one other thing I want to check is clearance to the seat. I think in my particular case that the 1x3 might just interfere with the seat sliders. Just something else to consider. Quote Link to comment Share on other sites More sharing options...
tube80z Posted July 11, 2006 Share Posted July 11, 2006 DOM is stronger than ERW. I know this is commonly stated and may be true. What I do know is that almost all DOM tube that I've seen these days is made from ERW and then has a die ran down it to set the ID. This will cause some work hardenning but I don't know how much stronger that really makes it. Some good hard data would be great. I only have a few simple experiments I did to see if DOM was really any better than ERW and in my case I didn't see any advantage. What I don't know is which tube is the better choice for this project. Looks like you can get out of it for a pretty minimal weight penalty by going with round thin walled tubing' date=' but the question is what strength is actually required here? Is it better to carry the extra 30 lbs, or the 9 lbs? How would the strength of the rocker compare if one uses a flanged hole section of of sheet to connect the round tube to the rocker[/quote'] I think you have to ask your self why are you bracing this area to answer that question. If it's beam strength then a deeper structure would be the answer (tube on top with plates down). If it's for side impact then either tube inside the rocker or inside the cabin and more likely thicker. On my old race car I was going to go the route of adding a tube that same thickness as the cage that sat on top of the rocker and used flanged panels. I wanted more side impact protection but couldn't give up room inside the car. I also already had a cage that didn't lend itself to tube in the rockers and I wanted to keep this as light as possible. Cary Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted July 11, 2006 Share Posted July 11, 2006 the seat issue is a good one. i will have to check that out. my ultra sheilds came in and i will see what happens. the tubes are good for out of plane forces, like at a funky angle to the bar where as the rectangular steel i better when the froces are applied to the right angles. stronger when the force is applied parallel to the longer side. i think that if the tech guys say no to that idea, beefing up the rockers or replacing them with fresh metal is still better. jim Quote Link to comment Share on other sites More sharing options...
heavy85 Posted July 11, 2006 Author Share Posted July 11, 2006 Attached are a couple more photos to help with the idea. After crawling around under the car for the last week I definitely thing the second pic is a good idea - connecting the rocker to the T/C bucket. Otherwise there really isn't anything connecting the rockers to anything but the sheetmetal firewall. (EDIT: is that a tube I see connecting the floor to the rocker from underneath?) Now for another idea. What if you were to take a flat or flanged plate and weld it at about a 45 degree angle from about mid way up the rocker to the floor? That way you could cut around the seat mount and even the dead pedal in front but still box in the rocker. Could add some stiffness and side impact (but maybe too low to be effective for side impact with anything but a go-kart or curb?) with little weight. Also I realize that the tranny tunnel is pretty flimsy but what about adding a tube from the rocker to the tunnel just in front of the seat for side impact protection. There is a little bit there factory with the seat mount but I want to lower the seat similar to what Jon and others have done for more head room so this would add some of that back in ... just directly in front of the seat instead of under it. Cameron Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2006 Share Posted July 11, 2006 I think you have that backwards. The idea there is to brace up the flimsy TC rod bucket. I don't think you'd hurt the side impact protection with the brace, but that isn't it's intention and I definitely wouldn't rely on it. Quote Link to comment Share on other sites More sharing options...
heavy85 Posted July 11, 2006 Author Share Posted July 11, 2006 I think you have that backwards. The idea there is to brace up the flimsy TC rod bucket. I don't think you'd hurt the side impact protection with the brace, but that isn't it's intention and I definitely wouldn't rely on it. I'm thinking the whole system here. Trying to tie the front engine subframe (that's what I meant to say when I said T/C bucket) to the rockers, re-inforcing the rockers, then tying the rocker to the back ... if needed ... haven't started thinking about the back end yet ... Cameron Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2006 Share Posted July 11, 2006 How about a straight shot from the rocker to the SFC in addition to the TC bucket? I just did that on mine, it would take a side impact a heck of a lot better... Quote Link to comment Share on other sites More sharing options...
bjhines Posted July 12, 2006 Share Posted July 12, 2006 JM.... I saw those rocker additions you did.... That is something I am toying with at this moment... Quote Link to comment Share on other sites More sharing options...
Zerrari GTO Posted July 12, 2006 Share Posted July 12, 2006 JM.... I saw those rocker additions you did.... That is something I am toying with at this moment... I wanna see! Please post some pictures if you've have some. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 12, 2006 Share Posted July 12, 2006 http://forums.hybridz.org/showthread.php?t=106974&page=5 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 14, 2006 Share Posted July 14, 2006 Just went out and put my seat in the car, and with my seat and bracket, etc there IS room for the 3x1 tubing on the rocker if one were so inclined. Still not sure on doing that though. I think I might go the other way and do the round tube. Quote Link to comment Share on other sites More sharing options...
rags Posted July 15, 2006 Share Posted July 15, 2006 I guess I should have continued to watch this thread. Tube, who did your car and how long ago? That looks almost exactly like how I did my car! The only difference I can see is I used 2x3 .120 and I took the rocker boxes off and welded the box tube directly to the inner rocker. Plated the back just like yours. Dropped the front down to 1x3 and fit it through the front just like you did and tied it to the TC cup with a 1.75 .120 tube. I also welded 1x3 from the rocker to the trans tunnel over the floor behind the seat and covered it with sheet metal. Sorta raised the floor by 3 inches. This gave me something to tie the roll bar to with another piece of 1.75 tube. Mine was done in 82 in NJ. Since no one answered the first time I'll ask again. Has anyone seen braces that tie the TC cup to the front crossmember? It was built to bolt on with 2 holes drilled into the insode of the TC cup. Joe Quote Link to comment Share on other sites More sharing options...
tube80z Posted July 15, 2006 Share Posted July 15, 2006 Tube, who did your car and how long ago? The car belongs to Dave Kipperman and he built it about three years ago. So you were well ahead of him. I first saw it in the mid 80s at a shop that built convertables. Has anyone seen braces that tie the TC cup to the front crossmember? It was built to bolt on with 2 holes drilled into the insode of the TC cup. No, can't say I did. Many people have built similar but I haven't seen any as a bolt on kit from a company. Cary Quote Link to comment Share on other sites More sharing options...
heavy85 Posted August 13, 2006 Author Share Posted August 13, 2006 The idea for this originally came after seeing a competitor get seriously injured at a hillclimb. His car left the road and hit a tree at speed. The cage worked perfectly but the car rolled up onto the rocker' date=' which failed and the this lead to his getting partially crushed. Looking at the wreckage it was pretty clear that is this area were stronger his injuries may have been a lot less. [/quote'] Cary - how exactly did it fail? Did it buckle in the middle or did the while rocker get shoved in? Trying to understand the failure mode to better judge exactly how to re-inforce it. Thanks Cameron PS - just got the welder, scraped off all the tar paper, steel is in the mail, just have to get the bottle. Oh yeah and learn to weld! Quote Link to comment Share on other sites More sharing options...
Jeff Posted August 13, 2006 Share Posted August 13, 2006 I didn't want to penetrate the floor pans so I went with 1x3 tubing in lieu of Pete's 2x3 method. I know it isn't as strong but I think it turned out well. Quote Link to comment Share on other sites More sharing options...
tube80z Posted August 13, 2006 Share Posted August 13, 2006 Cary - how exactly did it fail? Did it buckle in the middle or did the while rocker get shoved in? Trying to understand the failure mode to better judge exactly how to re-inforce it. I guess technically it didn't fail. As the car left the road it hit a tree left in the side. I've attached pics below. What you can't see from the pics is the car rolled onto the tree and the weak spot was the rocker, which had no tube running along it. It folded in along with the floor breaking the drivers leg/hip in multiple spots. The door bars where nascar style and you can see how folded they are as well. This car was a beast and left the road a very low speed comapred to what it could have been going. If the bottom of the rocker had been reinforced I think the driver would have been able to walk away. Cary Quote Link to comment Share on other sites More sharing options...
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