Rollcage Materials and fab hints

[Merc69]

OK I have not built the cage for PsyOp yet but have built a rail style dune buggy several years ago. Lessons Learned:

Tubing:
ERW - Welded seam tubing- not as expensive as other materials, for low speed rolls more than strong enough.

DOM - Seamless tubing- Expensive stuff- Used is full blown race cars where highspeed crashes happen.

Recommendations:
1.75" for vehicles with factory hard top.

2" for topless or chop tops

Cautions:
Don't use pipe for a cage. Pipe is made for carrying water or other material. Not as structurally sound. Remember you may be risking your life on the ability of your cage. Also do not use square tubing for the care. Not as strong structurally.

I will probbily use DOM for the main hoop and windshield hoop. Then use the ERW for all braces and mounts.

Years ago I bought a neat tool that uses a hole saw to cut the end of the tubing to match the contour of the tubing you are welding to. NOTE: it is the joint that makes the connection strong, welding just holds thing together. The tool was made by JD2. Similar tools are sold by Harbor Freight, Northern Tool and others.

Mounting the cage:
If you are more interested in looks just bolt the cage to the floor and use a larger plate to back up the inside plate. This should be strong enough for a low speed roll over if your floor is solid and you are running a factory hard top.

If you have chopped the top or are thinking about doing this...go direct to the frame.

Geometry/ Frame design:
The biggest thing to remember is that triangles are stronger than squares or parrell bars.

If you can't get a diagonal brace in use gussets to brace the corners.

Other things to think about:
With a full cage make up braced mounts that tie into the cage and mount your seats to the new mounts. This way you will remain inside the cage even if the body seperates from the frame.

Chormemoly steel is way cool but way expensive and very difficult to weld properly. (Ask Tadsal about that.)

Welding:
Tig is way cool but slow and difficult to master and expensive to get set up in. Mig is easy and easy to learn. 110 volt mig rigs can be bought for less than $500.00. Better yet get a 220 volt rig and you will have a wider range of uses.

Bending your tubing:
Use a real bender. They are expensive or if you can make one that will bend without crushing great. Checkout the other thread on this subject.

I am sure there are other things to consider but that is all I can think of at this time. Those who have pics (Rockjeep44, Resilna and others) this would be a great time to chime in. This could be a very cool thread :cool:

[jode]

Originally posted by Merc69:
If you have chopped the top or are thinking about doing this...go direct to the frame.
One thing I have been thinking of (saw this somewhere) is to design the cage as if you were going to simply bolt it to the floor (with some rounded-corner flange-plates at the bottom to sit on the vehicle floor)

THEN

weld up some more flange plates, and mount them on the opposite side of the body from the other flange plates as if you were simply going to sandwich the body. Use a piece of rubber or poly inbetween the plates and the body.

THEN

Either weld those plates to a peice of tubing to goes directly to the frame, or to a peice of tubing that goes through a bushing (like a shackle mount or something) to the frame.

Using this method, you would eliminate the need to have the cage welded DIRECTLY to the frame. Obviously this is a waste of time on non-road rigs, but might help slow down the noise for if you, and it would allow the cage to be removed - just in case.

[racer32]

I have to disagree with the statement about not using pipe for cages. i have built 3 racecar cages out of pipe and never had problem 1 with any of it failng. i've taken some pretty good hits and my bell was rung pretty hard, but the cages stayed together to race many times after that. if you triangulate and construct your cage properly, ther is nothing wrong with using pipe. plus Harbor Freight pipe crushers are waayyy cheaper than tubing benders.

[Merc69]

With pipe you have to run a much thicker wall thickness to achieve the strength you get out of tubing. Most if not all sactioning bodies for racing expressly prohibit the use of pipe. Some go as far as to say only DOM tubing, the size and wall thickness.

As for the Harbor Freight pipe crusher...I would not use one and can recommend that you use one to bend anything other than pipe for plumbing purposes.

The thing to remember is that a rollcage is a piece of safety equipment. If your head is only worth $20.00 then use a $20.00 helmet.

I have gone as far as putting a 5 point harness in the dune buggy and in PsyOp. A little more expensive but I have see home brewed solutions fail. Cages or safety belts.

[ September 26, 2003, 12:32 PM: Message edited by: Merc69 ]

[Merc69]

Jode

That would be considered going directly to the frame. Just remember to use grade 8 bolts and make the two plates different sizes. If you use the same size you have what the racers call a cookie cutter. In an impact that would place the right amount of stress the two pieces of metal would shear the body metal and could increase the potential for hurting.

If I remember correctly Andrew or Frank in Norway did something simmilar.

[racer32]

Merc-
i'm not trying to argue here, just exchange ideas. i realize that pipe has to have heavier walls to have the same strength as tube. cage rules vary from track to track and usually the higher end cars (late models, sprint cars etc..)
are required to use tube only but for hobby stock level classes, pipe is fine. there are 2 local tracks here and 3 others within 2 hours that all allow pipe for the lower end classes. like i said, if your cage is designed properly and has good welds, pipe should work fine. yes it will weigh more, but it will be cheaper and the benders are cheaper too. if you are building a cage for a desert race truck then by all means, use expensive tube and expensive benders. For most weekend 4x4 guys like us, a pipe cage is plenty...

peace :D

[Merc69]

None taken...this is to exchange ideas. I have been around the SCCA guys for many years, younger brother and dad. The local drag guys all use tube and the circle track guys are also required to use the tubing.

I was not aware the local level tracks were allowing pipe. I will concede the fact that in a slow motion rollover pipe may work just fine. Just my experience is that tubing (ERW) is not that much more expensive than pipe and a whole lot lighter.

The bender was a long term investment for me...besides I like to build things.

I will never take offence at what someone else has to say as long as it is ment to inform and share ideas or experiences.

[tomd]

All the circle track classes here require tube, the rules specifically state no pipe...

and the

"Years ago I bought a neat tool that uses a hole saw to cut the end of the tubing to match the contour of the tubing you are welding to. NOTE: it is the joint that makes the connection strong, welding just holds thing together. The tool was made by JD2. Similar tools are sold by Harbor Freight, Northern Tool and others."

is what i've heard called a tube notcher...

[blt2krl]

I would use pipe for an exo-cage and rock sliders.

[jode]

Originally posted by blt2krl:
I would use pipe for an exo-cage and rock sliders.I would venture to say that pipe is better for rocksliders than tubing due to the aforementioned thicker walls.

Racer - doesn't your modified HF crusher bend tubing pretty good?

Originally posted by Merc69:
If I remember correctly Andrew or Frank in Norway did something simmilar.That's cause he is "the man!"

[racer32]

yeah the tubing bender i'm gonna share with you guys will do 1.75" o.d. tubing. it does put a nice bend in the tube. i built my last racecar cage out of 1.75" .095 wall tube. that's the limitation of my tube bender though. i built one die for that size of tube and never had a need to bend any more tube. one more thing you need to have on a good cage is GUSSETS. i think everyone will agree on that. all major intersections of a cage should have em.
here's a couple of pics of the bends:

http://myweb.cableone.net/irace32/cage1.jpg
http://myweb.cableone.net/irace32/cage3.jpg
http://myweb.cableone.net/irace32/cage2.jpg

[Merc69]

Racer...looks good. I agree with gussets and diagonal braces where ever possible.

[Merc69]

The .095 wall tubing you were using...what style of racing are you doing? I know SCCA requires like .120 DOM.

Looks real strong and I bet it will take a real hard hit and not bend. I always liked the style of door guards you made. Just don't think I will use them in PsyOp though.

[Tad]

Looks very nice racer32, I'm impressed.

[racer32]

thanks tad! that means a lot coming from someone who teaches how to build stuff for a living.. :cool:

merc-
the car was built for a local track in the "Future Stock" class. basically a stock 4 cylinder class with pintos, mustang 2's and mustang 3's, monzas etc....
here's an excerpt from our rule book:

....all cage bars must be a minimum 1 3/4” OD - .090 wall thickness tube, or 1 1/4” schedule 40 pipe. No Galvanized, exhaust pipe, or screw couplings allowed. Minimum of one (1) 1” OD bar or tube mandatory in windshield area.....

[ September 28, 2003, 10:23 PM: Message edited by: racer32 ]

[Rhino Racer]

Nice cage racer32.

Is it necessary to cut the top off a Cherokee to build a tight fitting cage?

[Midnightwagon]

UHM WELL TO BUILD A TIGHT FITTING CAGE WITH THE TOP ON WOULD BE VERY VERY DIFFICULT BECAUSE OF THE FACT IN TRYING (OOPS CAPS LOCK AGAIN) to weld the seams on the top of the cage in between the roof and the top of the cage it is next to impossible to weld that with a "tight" fitting cage unless you can build one that will slide in the cherokee after you build it, wich in its own would be a fairly difficult job itself.
Jeremy

[Jethro]

Racer are you competing in I.M.C.A. sanctioned competition?

[racer32]

gcvfd975 -
no my class is not I.M.C.A sanctioned. we run local rules. Twin Falls is a NASCAR sactioned track though..

[Jethro]

o okay sorry for the disrupton class can return to it's regular learning on rollcages.....

[ October 07, 2003, 11:21 AM: Message edited by: gcvfd975 ]

[racer32]

did you have something you wanted to share with the group?

[millertime]

How much does a roll cage usually weight? Im talkin full on the works cage.

[tuck]

that's a good question, obviously it depends on material and design... but ballpark figures would be good..

anyone know how much tubing generally goes into a cage for a rig the size of an fsj?

[seadog]

What size tubing would I need for axle trusses that later in the future I would connect some links too?Cant see spending big money on a good bender for a project like this.Would a HB crusher bend a couple pieces of tubing to do this?

[seadog]

I would also like to make some front and rear prerunner bars that could be fabbed from pipe as they wont be in use for anything except to hold lights.

[tuck]

2" .120 wall, 1.75" 1.20 wall, 1.5" sch40 are all about 2lbs/foot..

100ft of tubing in a cage would be 200-250lbs.. but I'm not sure how much tubing it takes...

[racer32]

i used 120 ft of tube for my racecar and a pinto is a lot smaller than a wag...

of course you dont need door bars in your jeep like my racecar does :D

[ October 30, 2003, 12:11 PM: Message edited by: racer32 ]

[Big C.]

Is it possible to do a roll frame in a J10 and leave room to fit the camper? Or does it have to be above the cab?
C.