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Designing road race truck chassis, could use help.....

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  • #16
    As for a rear end... Crown Vics are weak (at least in a derby)
    Mid 70's GM coil springs are a bolt in! Plus there are more gear ratio choices along with posi units..
    If you put them side by side..the differences is apparent...beefy vs spindly...
    The ford rear is probably ample...
    Last edited by Deaf Bob; April 16, 2012, 01:57 PM.

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    • #17
      I would take a look at Port City cars, they build stock car chassis and they work very well. I dont like the location of a lot of your bars. Plus I would remind you anything big beyond the spring locations and added weight thats not going to be in the right place. In the front I would "bob off" the frame right in front of the control arms, and the same on the frame behind the axle, using round tube to hold up the bed and bumpers, its going to need a lot more bars in the back. If you look at the door bars and front control arm bracing on the Port City cars its very stiff and easy to bendup to build. Should be a very cool project
      2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
      First to run in the .90s .80s and .70's in SBN/A
      2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
      2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

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      • #18
        Made quite a few changes per suggestions and PM's. I finally did some preliminary F/E on the chassis which had predictable results.

        Since daily access to the cab of the truck is a necessity, I am contemplating the use of a removable tube (highlighted in light blue) bolted in place for racing events.

        Our budget for this project, is meager at best, so we have decided to keep the 9" solid axle for now and use a 3 link, unless money falls from the sky into our laps.

        Anything would be an upgrade from the original truck, which was/is downright dangerous IMO. When my friend bought the truck for $900, it had all most no brakes, the steering box had never been adjusted, it had no seat belts, a 300 six with a cracked block and a bad 3 speed gearbox. Boy that guy saw him coming. This is his daily driver and he called me from the side of the road numerous times, until we rebuilt the engine and some of the wiring.

        I decided to teach him how to do engine machine work and he built a nice running 6. We dragged a 4 speed out of the JY from a 79' E-150 and he spliced the drive shaft one night and installed the gear box in a parking lot with a flashlight after the 3 spd gave up. I gave my friend some fairly nice racing seats and he put some seat belts in. I jokingly told him, "at least this way they will find your body after a wreck"


        Last edited by OHC230; April 17, 2012, 10:02 AM.
        sigpic"Take most people, they're crazy about cars† I'd rather have a goddam horse. A horse is at least human, for God's sake."

        Jerome David Salinger

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        • #19
          I don't like the way the rear part of the cage is, you need to run those bars that start at the top of the bed at the cab and run them all the way to back(end) of the frame........What really needs to be done with those is have them connect at the top of the Hoop(cab) and run them to the back(end) of the frame, but if your trying to keep the cage from showing then you're stuck with where your mounting them now........Also mounting them to the top of the hoop makes the hoop stronger and will prevent it from bending backwards in case of a roll over.......... And that light blue bar across the bottom of the window isn't needed.......If anything raise the mounting points of the x brace that is below it........

          Also is the rear of that crown vic a bolt in subframe like the front?? If not how do you plan on mounting the shocks..........
          Last edited by TC; April 17, 2012, 11:06 AM.

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          • #20
            TC there is no reason to have the bar go all the way to the back of a non leaf spring frame. There is no weight to carry and the load would be unsupported for to long a distance. It looks much better, the "Back" bars should land on top of the spring/shock mount to help with the load from them. With limited supports I would use a cross bar comming down from the left top to the door X bar at the right top at the main hoop. I also would add a X in the top of the door bar to the rear rails at the hump for the axle.
            2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
            First to run in the .90s .80s and .70's in SBN/A
            2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
            2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

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            • #21
              Originally posted by JeffMcKC View Post
              TC there is no reason to have the bar go all the way to the back of a non leaf spring frame. There is no weight to carry and the load would be unsupported for to long a distance. It looks much better, the "Back" bars should land on top of the spring/shock mount to help with the load from them. With limited supports I would use a cross bar comming down from the left top to the door X bar at the right top at the main hoop. I also would add a X in the top of the door bar to the rear rails at the hump for the axle.
              You should cage the whole thing not just half of it........Caging to the rear of the car/truck will make the rear a lot more stable, right now there is nothing going to be there but lateral braces, what's going to prevent the frame from twisting under hard cornering..........

              Also aren't there some rule books that he could be looking at..........No need to build a cage and then go to the track and them tell you you didn't do it right.........Size of tubing, thickness of tubing and tubing placement all are major factors and if the rules require tubes to be place a certain way or in a certain design, it's best to know before hand than have to redo it later.........
              Last edited by TC; April 17, 2012, 11:42 AM.

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              • #22
                I would take some ques from this pic......... This is a Nascar COT design..........

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                • #23
                  TC, we will see how this goes, "I dont See you"
                  2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
                  First to run in the .90s .80s and .70's in SBN/A
                  2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
                  2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

                  Comment


                  • #24
                    Originally posted by JeffMcKC View Post
                    TC, we will see how this goes, "I dont See you"
                    Just my opinion Buddy, just my opinion........Take it as you will.......

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                    • #25
                      Looks good to me... I like the light blue removeable one!
                      Jeff has it on the nail head! Go to the top of the spring mounts if coil sprung
                      On our derby cars we are not allowed to do that so we do it like the drawing shows but not attached to frame (a rule thing), then we run chain from the tops of the humps to the axle tubes... Same principle
                      The COT impractical for street driven cars... And they are made to be bumped and bump.. Apples/oranges...

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                      • #26
                        I may well have missed it, but I didn't see any particular class or rules requirements so for a DD I'd look at ease of entry/exit and the ongoing ability to work in the vehicle over time. More bars equals more pain and suffering, good thing he's young. The removable door bars are a good idea IMHO. The big question is how it ties through the cab structure to the frame itself. I'd be tempted to follow either NHRA or SCCA/NSRA or SCTA/ECTA rules for roll bars/cages as what starts as a fun vehicle often morphs into something that has to pass a tech inpsection or get a certification.
                        Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

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                        • #27
                          CDMBill, 2 nd post, "auto cross, time trials". Doesn't seem to be a governing body... SCCA?


                          Looking at the COT. Frame, I see where the top of the humps are tied in... Prolly for your application, one to the middle MAY be sufficent? Like Bill says...rules/governing body build would be best...
                          We all have ideas... Bill is in drags (right?) I am in demolition derby... Need a road racer's imput...
                          Last edited by Deaf Bob; April 19, 2012, 10:25 AM.

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                          • #28
                            I'm restoring my old IMSA Gremlin and I have been doing some research, My plan is to run both vintage events, and some SCCA solo stuff.
                            The SCCA solo rules are more strict than the vintage rules, so I'm basically building my car to the SCCA solo rule book.
                            I would recomend you do the same, then you covered for just about anything you would want to do with it.

                            Remember the NASCAR stuff is built to run 200 mph next to brick walls, a bit much for most 'street/autoX cars. Still a good basis for reviewing the latest design in cages.

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                            • #29
                              PER Qadrabind: I can't speak of a "normal" panther chassie but the 03 Marauder had parralle bars and a watts link. IMHO except for overall width a pretty good set up for a fun driver/track car. Like the 4 valve MOD motor it carries, way to wide for all but a full size Ford,think 64 up Galaxy.

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                              • #30
                                So, as it stands; I have read through pages and pages of rule books that apply to roll cage construction for NASA, FIA and the SCCA and pored’ over hundreds of pages of banter concerning roll cage construction.

                                I can now say with some certainty, that no pure consensus exists, when it comes to chassis construction. There is a fine line between structures that absorb and those that do not absorb high impact loads and cases made for either side of building a highly rigid structure over one with ample crush zones...CONTINUED ON PAGE 4
                                Last edited by OHC230; April 23, 2012, 09:19 AM.
                                sigpic"Take most people, they're crazy about cars† I'd rather have a goddam horse. A horse is at least human, for God's sake."

                                Jerome David Salinger

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