heavy85 Posted October 21, 2006 Share Posted October 21, 2006 Please critique. Main idea here is to add 1"x.065 square tubing to both top and bottom of rockers to increase the section height and therefore stiffness since I dont want to add a full cage for head knocker reasons. Also extend SFC all the way back to the rear frame rails since all I've seen stop at the rear cross tube which is offset from the rear rails. Really trying to minimze weight since this will be mostly an autox car with only occasional track use. Biggest thing I'm still struggling with is what to use for the SFC as I dont want to cut the floors (I dont really want SFC at all but my rails are so bent up I might as well extend them all the way back). Also still debating in my head if the additional braces to the firewall are really needed since there is the tube in the wheelwell that connects the rockers to the strut horn. Thanks Cameron EDIT - it's so small I dont know how to make any bigger but it's in my album. My pics are either way to0 big or way too small This might be more useful: http://album.hybridz.org/showphoto.php?photo=11271&cat=500&ppuser=9862 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 21, 2006 Share Posted October 21, 2006 Why do the SFCs bend out past the floorpan. Seems like they'd be stronger if they just went straight back to the rear frame. What is the line that looks like a door bar, and how is that going to connect to the bar that goes from the rocker to the upper frame rail? Quote Link to comment Share on other sites More sharing options...
heavy85 Posted October 21, 2006 Author Share Posted October 21, 2006 Why do the SFCs bend out past the floorpan. Seems like they'd be stronger if they just went straight back to the rear frame. What is the line that looks like a door bar, and how is that going to connect to the bar that goes from the rocker to the upper frame rail? The SFC have to bend out because the rear control arm is in the way preventing it from going straight back all the way to the rear rails. The bar that looks like a door bar is the 1"x.065 square tube that welds to the top of the rocker flush up against the lip where the door seal goes. Another similar tube runs along the bottom edge of the rocker. Both then join in the front to a 1 1/4"x.065 round bar that goes to the upper frame rail. If you look at the side view the thinnest and therefore presumably least stiff part of the car is the bottom underneath the door opening. The roof provides a good deal of stiffness and a cage would provide a lot but I dont want a cage. Welding the doors shut duke of hazzard style would also stiffen this are up a lot but that's not going to happen. The idea with the 1" tubes on top and bottom of the rockers is to reinforce the rockers to make the center of the car stiffer. Hope that's clear? Thanks Cameron Quote Link to comment Share on other sites More sharing options...
tube80z Posted October 21, 2006 Share Posted October 21, 2006 I'm not following all this but I don't think you'll get much stiffness from the rocker stiffenning on top and bottom. Maybe stick to the bottom and build an X across the floor. The center would need to come out but then you could connect the four corners. In lieu of a cage that might be the next best thing you could do. The only other option I would see is to make the car more of a back bone design by enlarging the tunnel and integrating the front and rear suspension loads into this. Before you start any of this you may want to build some basic models and see what works best. Even crude balso designs can help you figure a lot out. Class rules, if you're worried about that, will probably get in the way of a lot of this. Cary Quote Link to comment Share on other sites More sharing options...
bjhines Posted October 21, 2006 Share Posted October 21, 2006 Looks nice... I don't know if 1" .065 is going to give much more strength... there is more to the rockers than just an inside and an outside stamping pinch welded together... there are several inner stampings at the front and rear... Tubing would need to be tied in to all of the rocker structure... It would be a neat project for sure... Quote Link to comment Share on other sites More sharing options...
johnc Posted October 21, 2006 Share Posted October 21, 2006 In a sense you are reinforcing an already strong part of the car. Ideally you would want to reinforce weaker sections first. Think triangles instead of beams. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 21, 2006 Share Posted October 21, 2006 What does your rear control arm look like? I have the Bad Dog SFCs installed and I had full range of motion on the control arm. In fact I even notched the frame rail on one side to get full articulation out of the control arm with sectioned struts and camber plates. I just can't imagine for the life of me how the control arm could hit the SFC. I agree you would need a bigger tube across the rocker to stiffen it significantly, and I also have to question its attachment to the bar in front as well. I don't know, it just doesn't seem like the attachment point in the front is going to be very strong compared to having a full cage and having it attach to an A pillar bar, the rocker, and the main hoop. I could be wrong on that, but that's my gut feeling. If you don't want to do a full cage, then I would suggest a larger, heavier walled tube mounted inside the existing rocker panel like the car that Cary has posted pictures of in the past. Quote Link to comment Share on other sites More sharing options...
Metallicar Posted October 22, 2006 Share Posted October 22, 2006 Like this? This I did to a 2+2. I do not have pictures of how I connected the front to a 2 x 3 tube in the wheel well which connected to the front frame rail. I welded on a "skin" to the square tubes. I did all of this because the inner sheet of the rocker was gone. Quote Link to comment Share on other sites More sharing options...
heavy85 Posted October 22, 2006 Author Share Posted October 22, 2006 What does your rear control arm look like? I have the Bad Dog SFCs installed and I had full range of motion on the control arm. Jon - look at your SFC and see they end at the factory cross tube (well it's really a channel welded to the floor) that runs side to side in the car. This is where all the SFC I've ever seen end. Now follow that factory cross tube outboard about 5" or so and you will see the rear frame rails start to go back. I'm just suggesting to connect that cross tube to the rear rails. Back in that area the factory LCA are in the way which is why I show that piece angling out. Now in general I dont seem to be getting my thoughts across. I do understand efficient load paths, triangulation, etc. Background: Both my daily drive Focus and the LS1 donor Camaro are so stiff that if I jack from one corner three wheels come off the ground (assuming it's balanced). On the other hand if I jack one corner of the Z only that one corner moves and you can visibly see twisting of the chassis through the door and hood gaps changing. Also notice that if I place jack stands under the frames rails at the base of the firewall that the front end sags quite a bit. My thoughts: It seems to me that it's relatively easy to stiffen the front and rear ends which I plan to do but then how do you stiffen the middle to connect the two ends and stop this sag / twist. This is not a dedicated track car so I am not going to put a cage in it. It also seems to me that the second best way would be to put a big X across the door opening to effectively connect the front and rear ends together. But then I would need a quick release steering wheel and it would be a real PITA to get in and out of and again it's not a dedicated track car. So again IMHO the third best choice would be to strengthen the rockers as the 'backbone' that connects the front to the rear. Adding material to the top and bottom of the rockers effectively increases the section height and therefore moment of inertia and therefore stiffness ... at least that's my thoughts. Cameron Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 22, 2006 Share Posted October 22, 2006 Jon - look at your SFC and see they end at the factory cross tube (well it's really a channel welded to the floor) that runs side to side in the car. This is where all the SFC I've ever seen end. Now follow that factory cross tube outboard about 5" or so and you will see the rear frame rails start to go back. I'm just suggesting to connect that cross tube to the rear rails. Back in that area the factory LCA are in the way which is why I show that piece angling out. I see, so you're more interested in trying to connect to the fore/aft frame rail that the suspension connects to. Just seems like an indirect load path. I haven't looked, but it makes me wonder if it wouldn't be possible to put a corner gusset in between the cross bar and the frame rail. EDIT. Wait a minute... The front of the rear control arm bolts into that same cross bar, and the rear hangs off of another crossbar... So why the emphasis on getting the SFC to connect to the fore/aft frame rail? Should be that getting it to the crossbar is the important part? Crap. I can't remember how that all attaches. Might have to go out and look at the car... Quote Link to comment Share on other sites More sharing options...
dj paul Posted October 24, 2006 Share Posted October 24, 2006 check out my cage. i havent updated in a little while because im out of money and in school right now. it sucks. but the cage i think is good. keep in mind im also adding on that S13 subframe. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted October 24, 2006 Share Posted October 24, 2006 ... my daily drive Focus and the LS1 donor Camaro are so stiff that if I jack from one corner three wheels come off the ground (assuming it's balanced). On the other hand if I jack one corner of the Z only that one corner moves and you can visibly see twisting of the chassis through the door and hood gaps changing. Also notice that if I place jack stands under the frames rails at the base of the firewall that the front end sags quite a bit... Cameron: I remember you talking about this in another thread and reading this thread makes me think. I think we'll all agree that first gen. Zcars are flexy flyers. The comparison to the focus is valid. That is a modern unibody, and from casual observation I'd be willing to bet that it's pretty stiff. Unibody construction has come a long way. But every camaro I've ever worked on (paint and body guy - 25 + years) was flimsy as all get out. Maybe a little stiffer then a z, but not much. My car is a 77, and it's flimsy, but it doesn't sag in the manner you describe. The hood gaps moving around... no way. Rust wise, my car is pretty clean, it's got some rust (they all do) but structurally it's all there. I can't help but wonder if you shell is compromised. I assume you've looked it over real well. Were the floor pans replaced? My point is the first step is getting the stock unibody to a point of structural integrity. If this is the case then I appologize. A lot can hide under all that undercoating. Things like the wheel wells being rusted, or quarter bottoms, cracks in the sail pillars, they can all add up to a lot of body flex. Just a thought. Quote Link to comment Share on other sites More sharing options...
Jeff Posted October 24, 2006 Share Posted October 24, 2006 With my 1"x3" subframes, roll bar and 2 1/2" x 2 1/2" front frame rails when you jack up one corner the other corner will lift off the ground at the same time. The car wasn't fully assembled at the time but it sure seems pretty stiff to me. Here is a picture of my sub frames. Quote Link to comment Share on other sites More sharing options...
heavy85 Posted October 25, 2006 Author Share Posted October 25, 2006 But every camaro I've ever worked on (paint and body guy - 25 + years) was flimsy as all get out. Maybe a little stiffer then a z, but not much.... I assume you've looked it over real well? Donor is an '02 Z28 and it'll pull three wheels by jacking in one corner without noticable deflection - it's actually a PITA because that makes it hard to put on jackstands but anyway .... on to my car. It's a Cali car and is totally solid. NO rust in the frame rail nor anywhere that I can find and I've looked (OK just light rust under the battery but very light). Scraped all the tar paper off the floors, just took off the front fenders, etc. Only place is the rear doglegs were replaced in the early 90's but seem solid now. There are no signs of any kind off previous accident but the frame rails are pathetic as they are so bent up it seems someone must have jacked it up with a little bottle jack or something about a thousand times on every square inch of the rails. This is why I am replacing the rails because otherwise there is zero rust on them. Otherwise I'm just trying to stiffen up things why it's appart for the LS1 swap without adding a cage. Jon - see Jeff's pic for what I'm talking about out back. Thanks Cameron Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted October 25, 2006 Share Posted October 25, 2006 Donor is an '02 Z28 I had moved on to my second career by then. I imagine the newer ones are much stiffer. is totally solid. NO rust in the frame rail nor anywhere that I can find and I've looked nice... I thought you had mentioned in another thread that the floor pans had been replaced, must be mixed up... sorry Quote Link to comment Share on other sites More sharing options...
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