Has anyone put a roll cage inside the cab of their truck? I'd like to make one and have a few questions. First, it's a 78 F150 4x4 reg. cab. I don't want a fancy one, just something to keep my head from gettin' crushed if I tip it over.

For the most part, it will be a rectangle around the ceiling of the cab with 4 legs in the corners and possibly an X behind the seat. Perhaps a horizontal member across the front as well, I just don't know where.

How would you mount this to the truck? To the floor of the cab or through to the frame? The cab sits on rubber bushings so if it were mounted to the frame, it would move seperately from the cab. However, the floor of the cab isn't all that strong.

Also, if I put a horizontal bar across the front, should I put it under the dash or on top?

Any advice would be greatly appreciated.

Kevin K.

 

For a roll bar or cage to really do it's job, you must weld it to the frame. Better yet is to whole saw the frame, drop the pipe through and it weld on the top and bottom of the frame. Door bars would ad extra strenth also, but would be a pain to climb over all the time. Depending on if your going to cut the dash so you can fit the pipe tighter to the firewall would more or less dictate where you would put the front cross bar. Bending a custom cage will be a PITA if you don't plan on modifying your dash.

 

Yeti is correct, however if you don't plan on cartwheels (yeah, I know-like anyone does!) and want it as a "just-in-case" type thing, you would make plates as large as you can fit with the down tube welded to the inside plate, to "pinch" the floor and bolt thru these and the floor to give the support it needs in a tip over. Won't prevent damage to the cab, but should keep everything off the noggin'. Personally, I thought this would be the way to go for me-mild to moderate wheelin', I could just see my cab mounts letting loose and the cab sliding around on the cage. Just a little more food for thought as it were!

 

[updated:LAST EDITED ON 06-Aug-02 AT 05:43 PM (EST)]Thanks guys.

That's actually what I was thinking I would do if I cant find a solid cab. Kinda sandwich the floor between steel plates. I'd like to extend the plate over to the cab mount if I can and have the mount bolt go thru the plate.

Then again, I suppose I could go to the frame since the cab doesn't move THAT much?

Now I just have to get the tubing and I'm ready to go.


Thanks again!

K.

 

Only one thing to suggest, take your truck out and put the twist to it, you'll see how much the cab actually moves on the bushings. I figure this helps when doin' the rocks by allowing the frame to take some of the twisting, keeping the tires planted and takin' stress off the mounts. I have poly bushings and no body lift and mine move at least 1/2" or better corner to corner. Of course it depends on your type of wheelin'. Just more food for thought! Let me know how you make out with this-you can be the test mule! But really, if it works out well, I'd like to try the same in our '79. I have corbeau buckets, so it should be easier than with the bench-more room in the rear corners, we have to keep the stock shoulder belts for PA insp. (have 4 point harnesses but not legal for the street here-go figure!?!), so let me know if they have to be removed or relocated when you do yours. Thanks, Chuck

 

What I am doing for my truck is removing the bed, moving it back three inches, and installing a halo rollbar that extends to over the cab roof and mounts to 1/4 channel bolted to the frame. I might put pressure treated in the channel to provide a little more resistance and "give" in a roll over when bolted to the frame.

 

If you weld the cage directly to the frame you will pick up all of the vibration and noise that is normally soaked up by the rubber body mounts - not something you want on a daily driven vehicle. It will drive most people crazy. The solution to this is simple. Tie the cage to the frame by running a urethane bushing beneath the floor of the cab at each point just before it attaches to the frame itself. This will reduce much of the noise and vibration but may still be annoying. A properly designed and built cage utilizing the bushings will still be plenty strong for most street vehicles. Remember that triangles are stronger than squares or circles when working with cage designs. The more triangles the better. In a severe roll over a simple hoop style cage might not be enough protection to prevent the cab from collapsing.

If you mount the cage to the floor it will only be as strong as the floor itself. Never use two plates of the same size to anchor your cage as in a rollover the loads will actually turn those plates into metal shears. Make either the upper or lower plate a different size to help prevent just tearing the metal cab floor apart.

Another option is to run floor bars that tie it all together - that way as long as you stay within the confines of the cage it will protect you.

Material selection, the method used to bend the material, and the welding method is all critical to a good cage. There have been a few cases where people have been impaled and killed by bad roll cage design... people that would've survived if they had no cage at all. If you are building it out of mild steel it better be DOM and make sure it's .120" wall. Don't go for any of that seamed junk either. Running a 4130 material is more expensive but you can either reduce wall thickness or diameter and maintain a similar strength to regular DOM. When all else fails look to a racing sanctioning body for guidelines. If it's good enough for NHRA, IHRA or SCORE it should be good enough for you.

Last but not least. Having just a roll cage tied into the frame in four points will create a bunch of centralized stress when the frame tries to flex. Without beefing up other areas of the frame those points may tear as the frame rails try to twist. What generally happens is the front and rear try to flex but the middle with the cage becomes super rigid. Search around the net for articles on desert racing trucks that have been built from the ground up - some of those articles contain photos that will give you a good idea of the right way to do things.