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Roll cage ?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by James90, Apr 10, 2001.

  1. James90

    James90 1/2 ton status

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    in a roll cage for a blazer do i need a bar at the bottom of the windshild or will a cage like on money pit be fine

    I plan on muding and some rock crawling

    http://www.trailblazer90.coloradok5.com
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well first let me explain why you put cross bars from leg to leg. In the event that the cage comes in to play it helps keep the cage from pushing over or from the legs flaring out.
    Now the fact of the matter is there is just not a good way to do it in a K5. Above the dash it will make it impossible to remove the dash pad. You need to do that to change bulbs and repair items like heater controls. Below the dash less is in the way but it becomes a Knee knocker. The only way I can se doing it would be to remove the dash and go to a custom dash that the Bar can either become part of or pass through. Idealy in a custom dash the best point would be just above the steering colum and use it to suport the colum. The problem it that's a lot of work and I really don't mind the factory dash.
    I looked at it from every angle and while I want to be as safe as possible there are some things that I had to pass on. Again the bar behind the seats does the same thing but Again I left it out on mine for 2 reasons. I have 2 kids and it makes it difficult to get into the back seat. What I am doing since I don't have a anchor for 4 point belts is I am welding a tab on the bar so that I can run 3 point belts to add some safety. I am also going to do some corner gusseting to add some strength. Regardless even without those bars your probably as safer with a full cage with out the cross bars than you are with just a hard top.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  3. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Have a look at Steve Frisbee's setup or a newer post by Michael Parker. They are very close to the way I'll be running mine.

    Also, a question for Grim or anyone else that wants to jump in. If you don't put some kind of diagonal bracing in the cage, what ultimately keeps the whole cage from flopping sideways if you roll hard on your side??

    The best solution I can see is some kind of removeable diagonal braces for the main hoop and rear hoop (in a 6 pt) that lock in but are removeable.

    Anyone?

    Brian
    89KBlazer
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well nothing but the strength of the tube and the welds....that's the problem. I went with a 17/8 tube for that very reason to make it as ridgid as possible. I only have my rear section in and the front hoop will not be in for a few more weeks. Even with out the cross brace it has stiffend the truck up conciderably. Most of my bed flex is gone. I also replaced my tail pan with a very heavy duty tail pan made out of C channel that the rear legs of the cage sit on.
    Like I pointed out its going to be a give take. You can put the cross braces in but it will make entry into the rear difficult and in my instance with 2 kids I had to leave it out. As for a removable brace...Well you could do that but where it really comes into play is not bending at the T intersections of the side bars. Making it that ridgid and removable is going to be difficult. Also poping it out every time you stop to let the kids in and out would be a hassle. I have been known to sleep in my truck when I'm wheeling without the family. My front seats fully recline and cross bars again would not alow me to recline them.You also need to look at how your using the truck. I rock crawl and on the trail where I'm most likly to roll I'm running maybe 10mph My impact force will be reasonably low. 95% of the possiblility of my cage coming into play is laying over on the side in a slow roll. If I did high speed running I would be much more concerned because the impact would be many times higher than the roll I'm likly to encounter in my truck.
    Now I do plan on doing some gusseting as well as using some 1-1.24 tube at a few of the major bends where the weakest areas are. they will be placed so they will double as grab handles. Just need to evaluate what your needs are. If you never have rear seat passengers then the cross bar is not going to be as much of a hassle to live with and you can add it and 4 point harnesses. To be quite honest my bigest reason for a cage wasn't the front passengers is was my rear passengers (my 2 daughters). In that case I don't like the way the cage on the truck in the link is made. it has no top cross bar in the back to tie the 2 sides together so it has a much higher chance of folding. I'm sure the owner of that truck had some good reason for for going that brace and it appears he concentrated on the front and I feel it's very safe cage for the front passenger. He probably doesnt have rear passengers often since he has a cross bar behind the front seats. That other bar being missing would make it far easier for the rear seat passengers to get in from the back of the truck. It would also allow him to carry over sized tall loads if needed. I'm sure the owner has a valid reason for electing not to install that cross bar. Like I said My girls ride in tha back so that bar was VERY important to be there. Now my upper bars also extend back farther so that cross bar does not cause a head room issue. My cage is VERY close to the same as the cage on the green truck. I however don't have the diagnal bars on the rear legs, I do have a upper cross bar and no bar behind the front seats. I didn't mount my seats to the cage in the same way either but my seats are in a round about way mounted to the cage from below the truck (see the link to my site and see the sub frame for my floors...cage bolts to that). My front legs are identical to the Green K5's. You would think they were made side by side. I'm still working on some over head bars trying to mount the Stereo and CB up there.
    Regardless as long as it's bolted to a solid floor and the welds are good I feel that the cage is far stronger than the metal hard top and much less likly to fold providing a great deal more strenght.
    I have some pictures taken of my cage and I'll try to get them developed and posted soon so you can see how I did my cage to suit my needs. I looked at quite a few cages trying to figure out how I wanted mine and I'm pleased with the end result. Cage is a major project and you are far better asking a lot of questions and looking a a lot of cages to get a real idea of how you want yours. I would pay some real attention to a few points. The front legs and where you tie them into the hoop are very imprtant. There is a post showing a 74 with the cage going through the dash. I like that a Lot! but I don't like where he tied into the hoop. He joins the hoop above the bend. This makes the front of the cage slop down and personaly I feel it looks strange. I also think that it will interfer with head room and your more lilkly to hit your head on it. Now look at the Green truck. He tied in at the radius of the bend just like I did. the cage looks level and it moved that bar out to the side giving better head room. I'm a tall guy and that played a big part in my design. I also raised my driver seat some when I put my truck together. My seat sits about 3 inches higher than stock to give me a better veiw over the hood when wheeling. With the hard top on that bar is dead level with the window opening and just above it so it does not interfer with visablility and tight enough to the outside you almost don't notice it's there. One thing I did was mock up my bar placement around my head with a peice of card board tube. I then moved around trying to see where I could place it that I was least likly to bang my head on it. That point seemed to work best and I ended up with a simular cage to the Green truck as a result.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  5. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Grim

    Don't your fingers ever get tired??? [​IMG][​IMG]

    Took some reading and studying the moneypit pics but I got everything you said in you post (I think [​IMG]). In regard to the diagonal braces behind the front seats, I do have the problem of child access. Maybe just adding a couple of removeable's to the rear would help. I plan to have a third hoop across the Blazer like the one shown on moneypit behind the front seats. That way, I can put a couple of diagonals across the hoop that should help fair bit with stiffening the cage laterally, especially since the rear area is my biggest concern with my son riding back there. The only time they'd need to be removed is when carrying large items in the bed of the Blazer.
    With my new boxed tube chassis & the fact that the tail pan is rusted bigtime[​IMG], I'll probably tie the rear hoop to the chassis the same way you did by beefing the tail pan crossmember & tying the cage to it.
    Also like the idea of lifting the seat in the cage. Will definitely be doing that and ditching the weenie base that the seats are currently mounted on.

    Take Care & sorry to steal the post James but it's all relevant to you topic sort of!!

    Brian
    89KBlazer
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    You could also improve stability from side impact by adding a triangulating bar behind the front seats. It could tie into the main loop somewhere around shoulder height and angle down toward the center of the floor leaving a 2' or so open gap between the two braces. This would still allow easy walk through access to the back (down the center) but you would have to give up on reclining seats. I'm sure you could come up with other options. Triangulation is the key to structural rigidity, straight 90 degree cross braces don’t help nearly as much.

    Bad Dog

    85 K30 CUCV, 350 TBI, TH400, NP205, D60/C14, 4.56
    Coming soon: 4" lift, 40" tires, massive cutting, shorter wb and rear overhang.
     
  7. James90

    James90 1/2 ton status

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    thanks guys steve sent my some pic of his cage and I really like it but I have a lot of questions like what did he do with his Parking brake and what kind of stuff did he have to move in side the dash but I guess I need to ask him.

    my blazer is going to be a to seater with 5 points and may be windo nets so I want to run all te bars I can but still want to be abel to work on my dash

    and I wonder how much it would cost to have it go thru the dash

    [​IMG]If you want to run cool
    you got to run on Heavy Heavy Fuel

    <A target="_blank" HREF=http://www.trailblazer90.coloradok5.com>http://www.trailblazer90.coloradok5.com</A>
     
  8. nyyef

    nyyef 1/2 ton status

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    i would like to emphasize what baddog mentioned about triangulation. the key to any rollcage is triangulation. the triangle is the strogest shape around (as a general rule, the less number of sides, the stronger the shape). a good way to check out the rigidity of roll cages is to make a small scale model out of toothpicks. then start applying forces to different sides, simulating a rollover or crash.
    of course, most of us have double duty trucks so something is always better than nothing.

    Knife.
    knife.coloradok5.com
     
  9. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    You can see the triangulation pretty well on a cage S&W Race Cars sells. Just click onto the picture of the cage for the page... <A target="_blank" HREF=http://www.swracecars.com>http://www.swracecars.com</A>. They sell cages 8 and 10 points. But I think I am gonna steal this basic shape of their 10 and have someone in town (or myself make it if I can find a bender and welder to buy) make it for me. [​IMG]

    "Suck Fumes Ford Boy"
    "I love my country, I fear my government"
    "What if the hokey pokey is what it's all about?"
     
  10. Michael

    Michael 1/2 ton status

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    My front tube goes thru the dash and my parking brake will still work. I just moved the "pad" over to the left......I had to cut it off and re-weld it. I have a shot on my site. Email and I'll try to get ya some more detailed shots.

    Michael[​IMG]
    <A target="_blank" HREF=http://www.jmartin.net/parker/goose.htm>http://www.jmartin.net/parker/goose.htm</A>
     
  11. James90

    James90 1/2 ton status

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    thanks Michael

    I sent you an E-mail if you dont get it tell me I am not all that good at this pc stuff

    [​IMG]If you want to run cool
    you got to run on Heavy Heavy Fuel

    <A target="_blank" HREF=http://www.trailblazer90.coloradok5.com>http://www.trailblazer90.coloradok5.com</A>
     

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