Announcement

Collapse
No announcement yet.

Why are Bolt-together/Bolt-in Roll Bars and Cages Against the Rules?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    That is the typical experience from what I've seen over the years. The Mustang was John Garner's car who ran the Anti-tour some years ago and was in Real Street Eliminator. Only one I've ever seen like it.

    Daily driving with a roll bar or especially a roll cage is risky business as their intended function is to protect helmeted passengers.

    James, Drag Week tech was a touch on the light side last year. Two years ago we went to Infinion (Sears Point in NorCal) for a Pinks all Out deal and made one of our buddies move the driver's side bar becuase it didn't properly fall between the elbow and the shoulder. Did to three other guys too. Amazingly there was an on site shop that did the work. The next day they kicked out our same buddy for running 135.2 without a certed cage. You never know.
    Last edited by CDMBill; June 1, 2012, 01:22 PM.
    Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

    Comment


    • #32
      Originally posted by BBR View Post
      I have a Maximum Motorsports bolt-in bar in my car. It even has the bolt in harness bar. My local track has not been concerned with it. They see the bar, the belts, helmet and jacket and give me the green light to run.

      It was teched to 9.99 at Drag Week last year (not that it mattered lol), but I may have a local chassis shop weld in a harness bar before this year's Drag Week.
      I'd bet having a good attitude during inspection and running at a smaller track helps.

      Comment


      • #33
        Originally posted by CDMBill View Post
        That is the typical experience form what I've seen over the years. The Mustang was John garner's car who ran the Anti-tour some years ago and was in Real Street Eliminator. Only one I've ever seen like it.

        Daily driving ith a roll bar or especially a roll cage is risky business as theri intended function is to protect helmeted passengers.

        James, Drag Week was a touch on the light side last year. Two years ago we went to Infinion (Sears Point in NorCal) for a Pinks all Out deal and made one of our bussies move the driver's side bar becuase it didn't properly fall between the elbow and the shoulder. Did to three other guys too. Amazingly there was an on site shop that did the work. The next day they kicked out our same buddy for running 135.2 without a certed cage. You never know.
        Thanks CDMBill. I'd forgotten that its was Garner's RSE Mustang with the "third" down-tube.

        BTW, I've noticed several school busses with factory padded tubing that's roughly the size and shape of roll cage tubing, and I haven't heard of complaints about the no-helmets issue. I wonder if the school bus tubing is designed to deflect.

        And most police cars have a huge "crook cage" in the back nowadays.

        Poorly padded metal is bad in a crash, regardless of whether or not it's a cage tube. On the other hand, sufficient crash padding doesn't seem impossible to accomplish.

        Maybe I've missed it, but I don't recall see dudes with bars or cages riding around with helmets on the street . . . .

        Comment


        • #34
          A bolted joint is inferior to a properly designed welded joint. Each has its place in design. Welded joints offer a more fixed joint with less flex. The bolt holes in the items bolted together produces a stress riser- a point of high stress that is prone to failure prior to the parent material with no hole in it due to stress being concentrated in the area.

          From NHRA and SFI's perspective, they are trying to protect racers. They cannot control the conditions at race tracks, so they have to try to err to the side of caution. A bolted joint holding a cross bar is fine until someone does not put all the bolts in or uses inferior fasteners (they do exist and you can't always tell a bad bolt from a good bolt looking at them- even those marked as grade 8).

          I remember Fat Jacks car- loved it. I thought that the cage was welded everywhere but where it connected to the frame- it was bolted to the frame. I could be wrong on that. My memory says that NHRA never let him run it- but then again, that is my memory.
          Why think when you can be doing something fruitful?

          Comment


          • #35
            Bolts and stress

            The flaw in the "stress riser" logic is the allowance of removable side bars. The cross-bar has four functions:

            1. Increased crush resistance from a "t-bone" impact.

            2. Prevention of "lozenging" of the main hoop (which, BTW, is better accomplished with a triangulating diagonal tube than a cross-tube).

            3. Prevention of driver's seat back collapse.

            4. Harness mount.

            Given that the belts otherwise bolt in, and the human element in the restraint system has inherently low force tolerance limits, harness mounting doesn't justify welding only.

            Reinforcing the driver's seat back also does not impart severe loads into the rollover structure. Besides, the seat itself bolts in.

            While the compression and tension loading of Nos. 1 & 2 do impart sufficient loading to require paying attention to hardware, design and workmanship, they do not exceed the safety margin of double shear mounting and high grade bolts. (if they did, we'd commonly see such failure in road racing incidents where bolt-in cross-bars are frequently used).

            Comment


            • #36
              That was well reasoned.

              I think Orange65 is right in the sense that NHRA stays with the welded requirement as its easier to inpsect and enforce across dozens of inspectors and hundreds of vounteer at the track tech inspectors who need simple guidelines to follow.

              The question I have is why we still have to re-web belts every two years and yet people going a tenth slower can use the belts that came with their 45 year old car.
              Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

              Comment


              • #37
                That's a good point on the seat belts, CDMBill. I guess it comes down to where the insurers are comfortable in making the tracks and sanctioning bodies draw the line.

                Anyone who's racing (or just driving, for that matter) with a 45-year old seat belt at any speed is probably not too concerned with self-preservation.

                I'm just puzzled why the sports car dudes (who rely on volunteers and local inspectors) seem to draw the line in a different spot on the roll bars. Different traditions, I guess.

                Comment


                • #38
                  Good luck trying to make complete sense of rules like that. There are some arbitrary decisions the rule makers had to make, and that's how it is.

                  I drove my 55 around with my helmet on once, it was fun.

                  And I've had adults ride in the back seat many times...it requires some contortion on their part, but it's possible to get in there. I made the 5 point roll bar that way on purpose.
                  My fabulous web page

                  "If it don't go, chrome it!" --Stroker McGurk

                  Comment


                  • #39
                    I remember Fat Jacks car- loved it. I thought that the cage was welded everywhere but where it connected to the frame- it was bolted to the frame.
                    You are quite right on that, I am still trying to find the article on the car (lack of organization) but it did make passes
                    World's fastest street rod class, Nostalgia Nationals, Bakersfield CA c. 1985ONE BAD BOY!!!!


                    the crash

                    The car survived quite well with a good cage (welded) but bolted to the frame. Still I think maybe with some of the connectors today it would be way better. These are common to off road guys and I am considering using them as a bolt in side bar as opposed to the normal style swing-out. I feel these are much more structural than what NHRA allows and they are held together with cap screws which are better than grade 8.
                    Attached Files

                    Comment


                    • #40
                      Originally posted by Manifestospeed View Post
                      T
                      While the compression and tension loading of Nos. 1 & 2 do impart sufficient loading to require paying attention to hardware, design and workmanship, they do not exceed the safety margin of double shear mounting and high grade bolts. (if they did, we'd commonly see such failure in road racing incidents where bolt-in cross-bars are frequently used).
                      How would you design a bolted joint that is in double shear that would resist bending? Compression and tension, yes. But bending would require some distance between the bolts and make for one ugly joint.
                      Why think when you can be doing something fruitful?

                      Comment


                      • #41
                        Originally posted by starterguy View Post
                        You are quite right on that, I am still trying to find the article on the car (lack of organization) but it did make passes
                        World's fastest street rod class, Nostalgia Nationals, Bakersfield CA c. 1985ONE BAD BOY!!!!


                        the crash

                        The car survived quite well with a good cage (welded) but bolted to the frame. Still I think maybe with some of the connectors today it would be way better. These are common to off road guys and I am considering using them as a bolt in side bar as opposed to the normal style swing-out. I feel these are much more structural than what NHRA allows and they are held together with cap screws which are better than grade 8.
                        Thanks for the videos- that was a cool car.

                        The connectors you show- are they NHRA approved? If you plan on racing at their tracks, I would talk to the tech department and get a ruling before using these.
                        Why think when you can be doing something fruitful?

                        Comment


                        • #42
                          By fluke I found a thread in one of the Mercedes Benz forums about a company building a bolt in bar for MB's using the interlocking tube clamps for the crossbar as well as other points. They are going to NHRA with their designs and are looking for an ok.
                          This is worth following and I am going to watch it. On another note the NHRA Div.6 Tech Director is a local and I have known him for a few years. I will ask for his input on this and the current "official" stance on these. I never asked him yet because I am not far enough into my project to have seriously pursued this, I guess now is the time.

                          Comment


                          • #43
                            Click image for larger version

Name:	photo.jpg
Views:	1
Size:	28.8 KB
ID:	862227
                            I know this isn't necessarily a function of cage strength however it did pass tech at a recent Super Chevy Show and I want to say this car was a mid 10 sec car.

                            Comment


                            • #44
                              Just got a reply from the Div 6 tech guy and it was a "no" for the tube clamps on the drivers side bar although he would have no problem for a pass side bar. They currently are not approved but there is a process to have them approved.
                              The Mercedes guys are currently going through that process so it is going to be a wait and see approach for these bolt together clamps

                              Comment


                              • #45
                                Originally posted by starterguy View Post
                                People forget about "Fat Jack" Robinsons 46 Ford coupe from the mid 80's, one of the fast street rods from that era and a cover car to boot. I remember reading that NHRA was not amused by the BOLT IN roll cage but let him run it anyway. Ironically the car was crashed at the top end of Fremont Raceway and was totalled. The bolt in cage held up fine and the driver was ok.
                                That car ran 9's (quick for then) at nearly 150. I don't think NHRA wants anybody to remember how well it held up Does anyone know more about that car or story (Groucho?)
                                I still have the pull out poster! That car was "flat out, no matter how you look at it, one bad MO FO ".
                                Reading , Pa
                                Good Guys rodders rep.
                                "putting the seat down is women's work" Archie Bunker.
                                Ban low performance drivers not high performance cars .

                                Comment

                                Working...
                                X