Mikelly Posted February 18, 2010 Share Posted February 18, 2010 We sent our project Miata out to Mitch Piper for a spec legal cage: http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/4fe36ecb.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/b7c6883f.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/54989ddc.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/50569247.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/20a6cf38.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/0dd172df.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/735ce10d.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/9b4c27da.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/eca854bb.jpg http://i145.photobucket.com/albums/r226/Mikelly_2006/Miata%20Pics/391503f5.jpg Now we need to put it all back together!! Mike Quote Link to comment Share on other sites More sharing options...
jt1 Posted February 18, 2010 Share Posted February 18, 2010 Nicely done! jt Quote Link to comment Share on other sites More sharing options...
Mayolives Posted February 18, 2010 Share Posted February 18, 2010 Mike, I assume that it has a removable hard top. If so, will it fit back on or do you plan to run it with the open top? By the way, nice job! Quote Link to comment Share on other sites More sharing options...
johnc Posted February 18, 2010 Share Posted February 18, 2010 Nice cage. Having done a couple SM cages hopefully the front hoop/halo gives just enough clearance to get the mandatory hardtop clips in place. I missed that when I built the first SM cage and had to make a very special hex key to get the bolts in place. Took me three hours of 10 degree turns and a lot of cussing. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted February 18, 2010 Administrators Share Posted February 18, 2010 Nice looking cage Mike. Quality in the bends, fitment, overall fabrication, welding etc. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 18, 2010 Share Posted February 18, 2010 I see that your design has been compromised for headroom and legroom, so I get why the diag and the roof bars don't meet the A pillar bar, that's basically the same thing I did on my Z so that the seat can back into the plane of the hoop. What I don't get is what is going on behind the hoop. Seems like there is no rhyme or reason to it. The backstays should connect where the A pillar bars meet the hoop. That gusset that hits the A pillar bar junction instead attaches to the middle of the backstay where there is no load path. It looks again like your cage builder has missed the rear suspension pickups and put the cage back to the back of the car on the floor which does not get the maximum benefit from the cage and potentially reduces the rear crumple zone. This is the same guy who did your Z cage that had all those problems (too many bends in the main hoop, backstays went all the way back, etc), right? He welds nice (although he doesn't seem to like cleaning the tubes first) and bends tubing well, but he really doesn't seem to understand load paths. Here is a REALLY good SM cage: http://forums.corner-carvers.com/showpost.php?p=698867&postcount=144 FWIW, if I did my cage again it would come out different because of what I've learned about load paths, so I'm not claiming to be the foremost expert on the subject. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted February 18, 2010 Share Posted February 18, 2010 Wow that looks like it could replace the unibody and serve as the chassis itself, with just a few more feet of tubing and plate! I would feel safe. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted February 19, 2010 Author Share Posted February 19, 2010 Mayolives, The roof was on the car when I picked it up, and has no issues with removal... JohnC, Mitch Piper does about 50 of these per year, and has template bars made for them. I guess he worked the whole roof clip issue out years ago... Mike Kelly Quote Link to comment Share on other sites More sharing options...
junglist Posted February 19, 2010 Share Posted February 19, 2010 Very nice cage. Piper does amazing work. The Franken M3 they built still amazes me: http://www.pipermotorsport.com/moredetail.asp?id=146&ret=cars.asp Quote Link to comment Share on other sites More sharing options...
Mikelly Posted February 19, 2010 Author Share Posted February 19, 2010 Thanks for the positive comments... Apparently it's getting ripped appart elsewhere by those who over-engineer and over-think and are superior in their designs and cage fabrication. I've forwarded those threads to Mitch Piper and I'll let him defend his work. This guy builds professional cages for professional teams, and one of his best traits is that his cages are used so much by those in the Mid Atlantic region that they get tested in severe crash testing in competition. So much has been made about the "mistakes" made on my other cage, and the "inferior" design of this cage. The Zcar's cage will suit my needs well, and that's all that matters to me. The car was built to be a DE car. If we have issues with getting it past tech inspection, then I'll sell the albatros and move on... It's really not a concern to me at this stage of my life. However, I've been given assurances I'll get a waiver if I do enter the car in competition. Reality is we looked at a bunch of cages from a number of spec builders and talked to some who actually raced and more importantly crashed these cages. The biggest complaint we heard from several who totaled their $10K plus builds was the "crush zone" theory. I won't argue that you want a safe cage in the car. I will how ever argue that it's a balance. You have to weigh the investment vs. what is a reasonable risk. Backing the car into a tire wall at 45MPH and having the tub totalled seems pointless to me. I saw no less than FOUR examples of "superior" miatas with crush zones that were used at those speeds. We decided to go the route that made the most sense for us, given the way these cars get beat up. I'll offset the "inferior design" with more safety gear. It's done, I'm happy and that's all that matters. Mike Quote Link to comment Share on other sites More sharing options...
johnc Posted February 19, 2010 Share Posted February 19, 2010 The amount of "crush zone" implemented in a cage design depends a lot on the expected impact speeds for the class the cars run in. A "typical" SCCA IT/SM wreck occurs at speeds less then 80 mph (80 mph into 0 or combined 40 mph). That's why SCCA allows a 6 point cage as legal in IT. For higher speed levels more cage is required and, in the latest thinking, more crush zone is needed. That's a decision that's best made between the cage builder and the car owner. Additional options to add "crush" where not much is available (doors for instance) is Impaxx foam or aluminum honeycomb. FIA rated seats also add a good level of impact attenuation because they are designed to flex and move somewhat. That's why its important not to install a seatback brace on FIA certified seats. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 19, 2010 Share Posted February 19, 2010 I don't think anyone has said that either cage is unsafe. Just that they're inefficient and the Z cage is technically illegal. If you can get a waiver on the Z cage, more power to you. What is lacking in the Miata cage is some forethought about how loads get transferred through the tubes of the cage and into the chassis. My opinion is that if you install a cage and fail to make the chassis more rigid, you've missed a golden opportunity to make the car handle more consistently. I saw on the SM forum where a guy said the "rear shocks are not structural". I can only assume that he means that unlike a Z, changing the angle of the strut tower doesn't change the angle of the suspension, but they are definitely structural. Most of the load in the suspension comes from the shocks, even more than you get from the springs. If the chassis can be made stiffer there then it can use the springs and shocks more efficiently, with less of the vertical motion of the wheel being wasted in chassis deflection. In the Z car world you occasionally hear people say "I changed the sway bar and there was no difference" and that is because the chassis flexes and the sway bar change is nullified. The Miata's strut tower flexing could absorb some of a shock or spring change making it less effective than it would be if the chassis were more rigid. Mustang racers typically run their backstays to the shock tower, even though it's just a shock tower and any movement there also doesn't affect suspension angles, for precisely the same reason. It makes the shocks more effective so changes to the shocks are also more effective. If the desire was then to run bars from the strut towers back to the back of the car to eliminate the crumple zone, there's nothing preventing that either. In this case the car would have enhanced chassis rigidity AND less crumple zone if that was what was desired (although I think I'd prefer to have the car crumple and take less of that force with my body). Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted February 21, 2010 Share Posted February 21, 2010 The cage is beautifully done. It appears to be 1 3/4 in. tubing, why not 1 1/2 inch? With the amount of tubing in that configuration it would seem to be heavier than necessary, and would allow just a little bit more room in there. Just my 2 cents, no offence is intended! Quote Link to comment Share on other sites More sharing options...
Mikelly Posted July 10, 2011 Author Share Posted July 10, 2011 The cage is actually 1.5 inch tubing. Mike The cage is beautifully done. It appears to be 1 3/4 in. tubing, why not 1 1/2 inch? With the amount of tubing in that configuration it would seem to be heavier than necessary, and would allow just a little bit more room in there. Just my 2 cents, no offence is intended! Quote Link to comment Share on other sites More sharing options...
z-ya Posted August 30, 2011 Share Posted August 30, 2011 Nice cage Mike. Quote Link to comment Share on other sites More sharing options...
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