MHISSTC Posted January 29, 2008 Share Posted January 29, 2008 Believe it. Here's another car that should be ready for the RM Region season opener in March. These are pictures of the car as the cage was being finished up at Hanksville Hotrods. I can't wait to get back to work on the long list of things that need to be done in the next six weeks. Quote Link to comment Share on other sites More sharing options...
RichV Posted January 29, 2008 Share Posted January 29, 2008 Lookin' good guys! Can't wait for 2/11, that's when mine goes in to Hank's!! Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted January 29, 2008 Share Posted January 29, 2008 Nice work! Unfortunately, it's all of the little crap that takes the most time. Mark Quote Link to comment Share on other sites More sharing options...
supermac Posted January 30, 2008 Share Posted January 30, 2008 Hank does nice work, I have a couple of what could be useless observations. 1. I was under the impression that that crossbar in the back was not allowed something about where it attaches, I dunno. 2. Are the nascar bars weak because of that bend back to the B pillar? It looks to me like they would just fold back to the driver if you were hit. If I am wrong and I am sure I am just ignore me. Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted January 30, 2008 Share Posted January 30, 2008 1. Which rear crossbar, the horizontal one just above where the kickers attach to the trunk floor? If anything, I would add a diagonal to the kickers, but I'm not sure what would be "illegal" about it. Other than an oddball item causing a safety hazard in a crash, I'm not sure what should be considered "illegal" about any part of a roll cage. 2. I doubt that those NASCAR side bars would go too far. While they will likely bend in a direct T-bone incident, they will probably just serve as a little bit of a "crush zone." And, the lower bar is braced back to the straight, horizontal rocker bar, so that will provide some bending resistance to the bottom NASCAR bar. If those NASCAR bars bend inward to the point that they severely affect the driver, then the car was probably in a pretty bad situation anyway, and those side bars will be the least of the problems! If worse came to worse, the passenger's side X bars could be duplicated on the driver's side, combined with NASCAR side bars. Mark Quote Link to comment Share on other sites More sharing options...
bsim Posted January 30, 2008 Share Posted January 30, 2008 Other than an oddball item causing a safety hazard in a crash, I'm not sure what should be considered "illegal" about any part of a roll cage. Roll cages stiffen a chassis, but that's not their intent (which is safety). Any tubes that serve to stiffen the chassis without providing safety can be ruled illegal. From the CCR:Parts of the cage deemed by the Chief Scrutineer, to serve no practical purpose other than chassis stiffening may be considered in violation... I think I remember someone here needing to remove that same bar from their cage (was it Keith?). The extra bend in the doorbars isn't optimal, but they meet the requirement. I'd consider gusseting them if I was worried at all... Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted January 30, 2008 Share Posted January 30, 2008 That's the rules passage that I was trying to remember (my printed CMC rulebook is at home, and this jobsite internet connection is too frustratingly slow to download anything but email). But, it seems to me that any additional (but non-frivolous) bars that help to improve the roll cage structure can generally mean that it's a safer design, just as long as those bars aren't filed to a point and aimed at the driver. lol I was checking out a Brazilian touring car at PRI this year that had literally everything triangulated. Now, while one could argue that this makes the car stiffer, it can also be more sensibly argued that it greatly reduces the chances of the cage collapsing on the driver, which sounds like safety to me. Mark Quote Link to comment Share on other sites More sharing options...
bsim Posted January 30, 2008 Share Posted January 30, 2008 That bar doesn't make the driver safer, won't do anything to "prevent the cage from collapsing on the driver" - and it's not triangulated either. The better (and more widely accepted) bar is a diagonal from the main hoop across and down to the opposing side lower mount: Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted January 30, 2008 Share Posted January 30, 2008 That bar doesn't make the driver safer, won't do anything to "prevent the cage from collapsing on the driver" - and it's not triangulated either. While that is true, I certainly wouldn't make him take a sawzall to it, either. At least it might keep the floorpan from compressing inward on itself in a bad side impact (which may or may not be the only impact that the car could see during one particular incident) by holding the rear kickers apart. It could be a good starting point for rear kicker bar triangulation, not unlike the lower rocker sill bars that are used in other photos to connect the hoop base to the A-pillar bar base. Mark Quote Link to comment Share on other sites More sharing options...
bsim Posted January 30, 2008 Share Posted January 30, 2008 While that is true, I certainly wouldn't make him take a sawzall to it, either.I would, if it's deemed to be in violation of the CCRs. At the end of the day, it's the Chief Scrutineer and CMC Director's that approve/disapprove. Like I said, as far as I remember, that bar wasn't deemed to be "OK". Quote Link to comment Share on other sites More sharing options...
King Matt1548534716 Posted January 30, 2008 Share Posted January 30, 2008 While I would not advocate removing it as a CCR violation, that bar is not very useful on a Mustang from a structural perspective because there is already a stamped crossmember under the floor bar bridging the shock towers. A diagonal like in the photo posted above is a much better design. Also, those door bars are not a very elegant engineering solution. Why didn't they at least extend the bars farther back towards the rear of the door jamb? Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted January 30, 2008 Share Posted January 30, 2008 While I would not advocate removing it as a CCR violation, that bar is not very useful on a Mustang from a structural perspective... I'm with you on that one, Matt. So what if somebody took (wasted?) the extra time to install a useless bar that isn't really needed? It's not hurting anything by being there, and I seriously doubt that it's the ONE part that gives him an unfair advantage that helps him win Nationals. So what if a dam in China is getting shorted a 36" piece of pipe? They won't miss it! Mark Quote Link to comment Share on other sites More sharing options...
MHISSTC Posted January 30, 2008 Author Share Posted January 30, 2008 1. I was under the impression that that crossbar in the back was not allowed something about where it attaches, I dunno.2. Are the nascar bars weak because of that bend back to the B pillar? It looks to me like they would just fold back to the driver if you were hit. While I would not advocate removing it as a CCR violation, that bar is not very useful on a Mustang from a structural perspective because there is already a stamped crossmember under the floor bar bridging the shock towers. A diagonal like in the photo posted above is a much better design. Also, those door bars are not a very elegant engineering solution. Why didn't they at least extend the bars farther back towards the rear of the door jamb? While the response I was hoping for was, "Welcome, glad to have you.", I really appriciate the constructive criticism and example photos. It's great for discussion and to show examples that will lead to us all building better roll cages that will keep us safe. You all are making excellent observations about elements of the cage that were thought about and discussed well in advance of it actually being built. I want to point out that Hank is our official regional event tech person and owns the shop in which this cage was fabbed. I'll be glad to fill you in on part of the design discussion and reasons why the cage was built the way it was built. First design element in question: the horizonal cross bar near the bottom of the rear stays. If there was any element of the cage design that I would initially call into questions, it would be this. Do I think it's legal? Yes. Do I think it's optimal? No. It is legal not because of where it attaches, but because of where it does not attach. Rear strut tower (shock tower) braces are not legal because their sole purpose is to provide chassis rigidity. If there were plates welded to the top or the inner sides of the shock mounts and the only bar welded to those plates was the single horizonal cross piece, then absolutely that would not be legal because it would be obvious the sole purpose of that bar would be to support the shock mounts and provide chassis rigidity. However, the mounting plates at the base of the rear stays are not placed in a location where they provide any support to the shock mounts. Therefore, with the horizontal bar only providing additional support to the bottom portion of the rear stays, it is legal. That leads me to my next point. Is this horizontal cross bar an optimal design. No. As was stated above, triangulation is best. Take a basic engineering class, or recall your basic high school physics class. Triangles are stronger than parallelograms. If you try to deform a triangle, it puts the legs of the triangle in either compression or tension. If you try to deform a parallelogram, it folds over because it puts the stress in the corners. However, if you are comparing a closed parallelogram to one where one side is removed, the closed parallelogram is still stronger...although still easier to deform than the triangle. So why was the cross piece put in like it was...minimal structural support for a minimal price. Budget. It was cheaper to put in this small cross bar than it was to put in a diagonal. It's also easy to add a diagonal (or other bars) as funds may allow later. Here is my description of what I believe the ideal setup for the rear portion of the cage. The base plates would be welded to the floor btween the two shock mounts...or heck...even directly to the shock mounts...since that is legal according to the CCR. The rear stays would be welded to these plates with the horizontal cross bar near the bottom of the stays close to the plates with an additional diagonal creating two triangles in the rear stays. I would also add additional bars as shown in the above picture and circled in that same picture I modified below. Again, that triangulates in the rear stays to the main hoop. Yes, there is some chassis rigigidy to be gained as a result of a good cage design...not becuse that is it's sole purpose. Here are some pictures describing what I'm talking about. THIS: OR THIS: ADD THIS: Second element in question: NASCAR bars. I'm assmuming Cody in referring to the second bend that brings the bar back into the car before it attaches to the main hoop circled in yellow below. I agree that would be ideal in a NASCAR bar is a type of arch structure (going back to basic engineering) that would provide the strength needed to keep other cars from intruding into your lap and spoiling your day. The entire cage design is based upon the initial design and placement of the main hoop. Everything else is tied to the main hoop. The main hoop is what gives us our initial rollover protection. With the optimal placement of the main hoop taken care of, it was necessary to bend the NASCAR bars back into the car before attaching them to the main hoop. If that had not been done, we would have needed to remove some of the B-pillar to accomodate it. This is also why the rocker bars were added and tied into the NASCAR bars. You guys are good. I'll be dissapointed if you don't find additional elements of the cage to bring into question. Bring it on...I have explanations for everything. Scott Quote Link to comment Share on other sites More sharing options...
BADVENM Posted January 30, 2008 Share Posted January 30, 2008 Hello fellow CMC'ers my name is Dave Thede aka "BADVENM". The '86 Mustang being referred to in this thread is mine. I came from a world of Vipers and Viper powered vehicles ('01 Viper GTS, '04 SRT Ram supercharged in HPDE 3) to the world of wheel to wheel racing and Mustangs. I did own an '03 Mustang Cobra for a short time before jumping to my dream car, an '01 Viper GTS Sapphire/silver stripes. MHISSTC and I both enjoy cars of any and every type. His knowledge of Mustangs and Capris as well as the CMC rules (still reading the CCR myself every once and a while) helped tip me over the edge into the CMC arena (plus, its less expensive than the Viper arena). I dont know a lot about the pro's and con's of cage design so I let those who do know do it. I did want to make sure that everything that was done was legal and was told it was. I'm very excited about this upcoming season and hope to eventually meet more of you as the season goes on. I'm trying to learn as much as I can from you guys and I appreciate the insight and thoughts that you've provided so far. Quote Link to comment Share on other sites More sharing options...
Glenn Posted January 31, 2008 Share Posted January 31, 2008 Keiths car had an X in place of the required rear down bars. they violated the max/min of degrees of angle in relation to the main hoop. he had them cut out and replaced w/ a normal set of rear down bars. the X he had also connected all the way back at the rear of the car, not over the tank like most 3rd/4th gen guys normally do them. as for the cage in question. i dont really have a problem w/ it. i see the same argument for and against Brads bars that go from the lower main hoop up to the lower rear down bars. i feel we should be able to do alot more than what is allowed. NASA and CMC puts too many restrictions on cage design. i think A pillars and those bars along w/ the main hoop should be allowed to be welded to the unibody. just my .02. by the way, i think the fit and finish of that cage is pretty good. very nice work. Quote Link to comment Share on other sites More sharing options...
mitchntx1548534714 Posted January 31, 2008 Share Posted January 31, 2008 We employed a "double bend" in the door bars on this car While not as dramatic an ogee as the Mustang, it serves a purpose ... a 360 weld. Not sure where Hank got the inspiration, but Glenn and I saw the C5Rs being done this way ... mostly for seat clearance. I can see both the cross bar at the base of the rear down tubes and at the base of the main hoop transferring loading to the other side of the car and cage in the event of a side impact. Alan explained to me the cripples installed in Brad's illustration were there for load transfer ... the same argument can be made for those cross tubes. I like the cage and I like the sill bar. But ... one thing you guys need to address is the upper cross bar and where are you gonna attach the shoulder harness. That cross bar is way too high, if you are using that seat in that configuration. Quote Link to comment Share on other sites More sharing options...
MHISSTC Posted January 31, 2008 Author Share Posted January 31, 2008 But ... one thing you guys need to address is the upper cross bar and where are you gonna attach the shoulder harness. That cross bar is way too high, if you are using that seat in that configuration. We are going to play with the seat postion. The harness cross bar should be OK where it is once we get things properly adjusted. Dave and I both have long torso's and I have stumpy legs. Since we wanted to make sure we both fit in the car, we had to incorporate a wide range of adjustment. In that picture the seat is installed in a tempory location as low as it could go in order to facilitate driver entry and exit while transporting it from shop to shop. In order to fit two different sized drivers, the RaceTech seat, and the RaceTech seat brackets all in the car without the top of our helmets coming too close to the top of the cage and roof, we had to have the factory cross floor support/front seat mounting bracket on the driver's side cut out and have custom seat mounting bracket perches made along with some massaging done to the transmission tunnel. ...i think the fit and finish of that cage is pretty good. very nice work. We are very pleased with the quality of the work. That's why we hired guys who do this type of fabbing for a living to do it for us. It's a shame you can't see them, but the custom seat mouning bracket perches are just as nice, if not nicer. Quote Link to comment Share on other sites More sharing options...
tacovini Posted January 31, 2008 Share Posted January 31, 2008 Welcome Dave & Scott! Nice car and great to see the RM Region growing still evermore! (May there come a day when new racers can post pics of their stuff and bask in joy instead of reel back in defense! ) -=- Todd Quote Link to comment Share on other sites More sharing options...
mitchntx1548534714 Posted January 31, 2008 Share Posted January 31, 2008 We are going to play with the seat postion. The harness cross bar should be OK where it is once we get things properly adjusted I figured as much. Hanks does top notch work from what I've seen. Quote Link to comment Share on other sites More sharing options...
BADVENM Posted January 31, 2008 Share Posted January 31, 2008 One thing I wanted to add about the cross bar. From what Hank told me (from a few experiences) the cross bar was put another inch or so higher then usual because of the Hans device being required in mid June. He did another car (not sure what type) recently and found that the cross bar needed to be adjusted up a bit more than usual. I sat in the seat last Friday so Hank could get his measurements for the cross bar. Quote Link to comment Share on other sites More sharing options...
K Shaw Posted January 31, 2008 Share Posted January 31, 2008 Yep. We have added a few new cars this year. I just got back from Richs place. We have been working our rears off on that car the last two weeks. CMC #71 will be at Hanks next month for the cage work. kyle Quote Link to comment Share on other sites More sharing options...
K Shaw Posted January 31, 2008 Share Posted January 31, 2008 Hank also did my cage and I love it. kyle Quote Link to comment Share on other sites More sharing options...
nasa-rm Posted February 11, 2008 Share Posted February 11, 2008 THIS: Scott That is how ours was done. Hank stole that design from us. Quote Link to comment Share on other sites More sharing options...
MHISSTC Posted February 11, 2008 Author Share Posted February 11, 2008 Yes...very similar...but not the same. Quote Link to comment Share on other sites More sharing options...
MHISSTC Posted February 11, 2008 Author Share Posted February 11, 2008 Double post. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.