Roll cage design/half topless
- Thread starter drbobxj
- Start date
- Location
- Port Orchard, WA
cool
i would have bent the pieces to alow for more room in the back, and mounted the spare differently - but id bet that we have different uses for our XJ's....
Consider an X behind the driver/passenger - that will prevent the whole structure from coming down on you...
what is it attached to at the frame end?
what is the material?
how is it welded? - looks like a flux core mig with no gas...
i would have bent the pieces to alow for more room in the back, and mounted the spare differently - but id bet that we have different uses for our XJ's....
Consider an X behind the driver/passenger - that will prevent the whole structure from coming down on you...
what is it attached to at the frame end?
what is the material?
how is it welded? - looks like a flux core mig with no gas...
TrailHunter
NAXJA Member #1309
- Location
- Red Bluff, CA
I'm concerned about the bpilar not meeting the top in a node. If it goes on it's roof it might colapse the outter sides of the the roof where it connects to the b-pilar.
Rev Den
NAXJA Forum User
- Location
- Plainfield, IL
Connect to roof, triangle behind seats, plates where cage connects to back floor.
Just a start.
Rev
Just a start.
Rev
Dookie
NAXJA Forum User
- Location
- Shore-town, WA
no offense - seriously - but i would feel VERY unsafe in that.
as stated, i think you need a LOT more triangulation in it.
as stated, i think you need a LOT more triangulation in it.
Yeah, I plan on adding a few triangles. also under the floor with tubing along the subframe.
And Yes its flux core mig with no gas.. is that a bad thing?? I'm poor and this is the first time doing something like this.
I have used flux with other stuff never had a problem.. but if you know of something please tell me.
tubing is 1.5x.120 HREW
And Yes its flux core mig with no gas.. is that a bad thing?? I'm poor and this is the first time doing something like this.
I have used flux with other stuff never had a problem.. but if you know of something please tell me.
tubing is 1.5x.120 HREW
Roxtar
NAXJA Forum User
- Location
- NW Indiana-Chicago area
Flux core is fine. Your tube choice is fine.
2X on what Rev said.
It's a nice start but needs more work.
You need diagonal tube bracing ("X" pattern) behind the seat and probably to the back.
Long tube lengths without bracing is a no no.
Also, any place where tube connects to the floor you NEED to put "pads" in place, 5"or so square pieces of 1/8"-3/16" plate welded between the floor and the tube.
Otherwise you WILL just push the legs right through the thin XJ floor.
2X on what Rev said.
It's a nice start but needs more work.
You need diagonal tube bracing ("X" pattern) behind the seat and probably to the back.
Long tube lengths without bracing is a no no.
Also, any place where tube connects to the floor you NEED to put "pads" in place, 5"or so square pieces of 1/8"-3/16" plate welded between the floor and the tube.
Otherwise you WILL just push the legs right through the thin XJ floor.
- Location
- Desert Beach So Cal
TrailHunter said:
Good advice.
This is critical, as the vertical B-pillar strut as installed will not hold up the halo in a roof impact. It is more likely to bend or punch through the back of the halo. The halo bar between the pillar and halo edge will work more like a hinge, considering the leverage distance you have provided between the halo edge and the B-pillar connection. You have designed-in a tube prone to fail (the rear bar of the halo & b-pillar) during an impact because the point load on the B-pillar places the halo bar in bending and isolates the load on the single B-pillar (rather than sharing the load between both B-pillars and front/read down-bars).
(Best) Redesign the B-pillar to attach at a node vertically under the halo side bars. Use 1.75/.120 wall or larger tube for the B-pillar. A diagional or x-brace in the B-pillar will add considerable torsional resistance.
(lessor fix) Add a brace to tie-in the B-pillar to the outer edge of the halo, like your halo corner brace, but to brace the B-pillar vertically with the halo (better than what you have). A roof impact will yhen bend the B-pillar rather than the halo, unless you add a horizontal B-pillar cross bar between the bottom node of the two braces (to make any impact transfer and share the load between the two B-pillars). Making the B-pillar corner of these braces the top node of an X-brace in the B-pillar will gain back the strength lost compared to the "best" design, but with a lot more weight.
A little help from SCORE International:
********
As of January 1, 2006 replace rules in the Score International 2003-2006 Off-Road racing Rules and Regulations page number 29 (Vehicle Safety Equipment) through page 32.
VEHICLE SAFETY EQUIPMENT
CR33 ROLL CAGES
All vehicles in competition except Motorcycles and ATV’s must be equipped with a roll cage. Minimum design and tubing size based on seamless 4130 chromoly tubing or ASTM 1018/1026 CDS/DOM. No aluminum or other non-ferrous material permitted.
Material
Material for roll cage construction must be 4130 chromoly tubing or ASTM 1018/1026 CDS/DOM
All welding must be of the highest quality with full penetration and no undercutting of the parent metal. All welds shall conform to the American Welding Society D1.1, Structural Welding Code, Chapter 10, Tubular Structures and Standards for the material used (see AWS.Org). It is strongly recommended that the welder inspect all welds using Magnaflux™, die-penitent, or other effective methods.
All tubes must be welded 360-degrees around the circumference of the tube.
No oxy-acetylene brazing or welding allowed. Good external appearance of a weld does not necessarily guarantee its quality; poor looking welds are never a sign of good workmanship.
None of the tubing may show any signs of crimping or wall failure. All bends must be mandrel type. The center radius of the bends may not be less than three (3) times the outside diameter of the roll cage tubing.
It must be emphasized that the use of heat-treated or high carbon steels may cause problems and that bad fabrication may result in a decrease in strength (caused by brittle heat-affected zones), inadequate ductility and internal stress.
Roll Cage Tubing Sizes
For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver. Note: There is an allowance of minus 0.010 inches on all tubing thicknesses. Minimum tubing size for the roll cage is:
Up to 2000 lbs.
1.500” x 0.095” CDN/4130/Seamless or ASTM 1018/1026 CDS/DOM
2001 - 2500 lbs.
1.500” x 0.120” CDN/4130/Seamless or ASTM 1018/1026 CDS/DOM
2501 - 3000 lbs.
1.750” x 0.095” CDN/4130/Seamless or ASTM 1018/1026 CDS/DOM
3001 - 4000 lbs.
1.750” x .120” CDN/4130/Seamless or ASTM 1018/1026 CDS/DOM
Over 4000 lbs.
2.000” x 0.120” CDN/4130/Seamless or ASTM 1018/1026 CDS/DOM
Construction Procedures
Cages must be securely mounted to the frame or body and gusseted and braced at all points of intersection. Cab or body mounted cages must not be attached to the body structure by direct welding, but must be bolted through and attached by the use of doubler plates (one on either side) with a minimum thickness of .187”, see Figure 4. Where bolt and nuts are used the bolts shall be at least .375” diameter SAE Grade 8 or equivalent. Roll cage terminal ends must be located to a frame or body structure that will support maximum impact and not shear.
Minimum material dimension requirements for roll cages apply to the following members of the roll cage:
(1) Front and rear hoop
(2) Front and rear interconnecting bars
(3) Rear down braces
(4) Lateral bracing
(5) Elbow and door bars
(6) Lower A-pillar tubes, and lower B-pillar tubes
Roll Cage Design
All roll cages must be constructed with at least one (1) front hoop (top of cage to floor), one (1) rear hoop(top of cage to floor), two (2) interconnecting top bars, two (2) rear down braces and one (1) diagonal brace and necessary gussets, see Figure 1. If front and/or rear hoop terminate at elbow/door bar, lower A-pillar and/or B-pillar must be made of same tubing size as roll cage. Centerlines of all required tubes must converge at intersections.
Any vehicle that is not provided with stock steel doors for its driver and co-driver must be equipped with sidebars, at least one on each side that will protect the occupants from the side. These bars must be parallel to the ground (or as close to parallel as is practical) and be located vertically in relation to the occupants to provide maximum protection without causing undue difficulty in entering or exiting the vehicle. The sidebars must be formed of tubing of the same material and dimensions as the roll cage itself and must be securely attached to the cage’s front and rear members. Additional side tubes may be required to limit cockpit intrusion, these additional tubes must be of the same size tubing as the roll cage. Tubes must be placed in such a manner as to limit openings adjacent to the occupants. Maximum opening size in this area is limited to 370 square inches.
All roll cage bars must be at least 3” in any direction from the driver and co-driver’s helmets while they are in their normal driving positions.
Gussets must be installed at all main intersections on the main cage including diagonal and rear down braces, and where single weld fractures can affect driver’s safety. Gussets may be constructed of .125” X 3” X 3” flat plate, split, formed and welded corner tubing, or tubing gussets the same thickness as the main cage material, see Figure 2 and Figure 3. Rear down braces and diagonal braces must angle no less than 30 degrees from vertical.
An inspection hole of at least .187” diameter must be drilled in a non-critical area of the roll bar hoop to facilitate verification of wall thickness. It is the prerogative of SCORE to drill a second hole if deemed necessary.
Any cage or chassis that has been built after January 1, 2006 must be identified by means of an identification plate affixed to it by the manufacturer; this identification plate must be neither copied nor moved (i.e. embedded, engraved or self destroying sticker). The identification plate must bear the name of the manufacturer, a serial number, and the date of manufacturer.
Head/neck restraints designed to prevent whiplash are required on all vehicles. These restraints must be a headrest of approximately 36 square inches, with a resilient padding at least 2” thick. Any portion of the roll bar or bracing which might come in contact with the helmet must be padded.
Roll Cage and Vehicle Annual Inspection
All vehicles must have their cages approved prior to racing in a score event. The inspection will be preformed at the Score Technical office. After passing inspection and paying Inspection fees all vehicles will receive a Score I.D. tag that is to remain with the vehicle at all times. If tag is removed or lost vehicle must be re-inspected and retagged. Any modification to an approved cage may render its approval invalid, and may need to be re-approved. All repairs to a roll cage damaged after an accident must be re-approved by SCORE International.
All vehicles built before January 1, 2006 may be required to have an inspection every six months.
********
HTH?
Ed, since you seem to be very knowledgable of cage design...
I see a lot of gussets made of steel plate. The SCORE rules you just posted even require .125" plate for gussets.
I came across a theory recently that suggested that a gusset designed properly should not be rigid like a plate, but should rather allow for some "elasticity" to promote impact absorbing qualities. This would suggest the use of a bent tube as a gusset instead of a plate or straight tube.
What are your thoughts?
TIA
I see a lot of gussets made of steel plate. The SCORE rules you just posted even require .125" plate for gussets.
I came across a theory recently that suggested that a gusset designed properly should not be rigid like a plate, but should rather allow for some "elasticity" to promote impact absorbing qualities. This would suggest the use of a bent tube as a gusset instead of a plate or straight tube.
What are your thoughts?
TIA
- Location
- Desert Beach So Cal
Dirk Pitt said:
The goal of the gusset is to add weld inches to the node connection, the primary goal is not to add stiffness. The intent is to improve the tube connection and remove the stress concentration at the weld bead fillet. A plate adds weld inches and it places a weld bead parallel to the tension load on the tube (along the tube, not perpendicular to the tube at the junction).
The tube outside the junction and gusset node is still elastic, but the tube junction remains rigid. The goal is to keep the manufactured junction free of fatigue stress (free of elastic bending and stress concentration).
Clear as mud?
tHanks,
Ok, I know the b-piller was not to good but wanted to hit the subframe. And I will be adding plates under the jeep at each tube hitting the floor. Also I was thinking of running tube on the inside floor between each tube??? Not sure if that would help any?
How is this for more:
just to put a note in Im not racing or anything like that.. and this is just the start.
Ok, I know the b-piller was not to good but wanted to hit the subframe. And I will be adding plates under the jeep at each tube hitting the floor. Also I was thinking of running tube on the inside floor between each tube??? Not sure if that would help any?
How is this for more:
just to put a note in Im not racing or anything like that.. and this is just the start.
- Location
- Port Orchard, WA
drbobxj said:Here is a pic of what I was saying about running tube along the floor:
idealy - you want the seats and harnesses to mount to the cage so that in a roll - the entire cage is self suficient and can be torn from the rest of the body and have the passengers be ok...
that said - i have no expierence in any of this..
- Location
- Desert Beach So Cal
If you want the most enhancement for your effort add the yellow B-pillar x-brace in your rendering, and run the top ends all the way out to the halo. From the halo, run to the opposite lower B-pillar corner, and cross the halo end vertical B-pillar (weld to the x-brace diagional). Each x-brace diagional will have a bar between the halo and B-pillar, and the B-pillar and frame.
The extra x-brace on the rear down bars is not needed (blue X, as long as you have an x-brace somewhere, and in the B-pillar plane behind the seat-back is best).
Body panel attachment plates should be 3/16" or thicker, and of a different size top and bottom sandwich of the body sheetmetal. The tube plate should be BOLTED through the body with washers on both sides of the panel attachment.
The .120 wall cage tube should be welded to the .188 plate on the tube side body attachment face plate. The tube side plate should be BOLTED, not welded, to the body (the opposite side backing plate can be welded to the body). Four 3/8 bolts minimum per plate.
The goal is to have a puncture resistant plate welded to the tube end that will not puncture the sheetmetal in an impact. The backing plate needs to be a different size from the tube/face plate to reduce potential shear stress concentration around the sandwich plates perimeter. The bolted junction allows for energy to be expended, stretching the sheetmetal, before tearing the unitbody (it also protects the unitbody sheetmetal from weldheat embrittlement).
If you have the lower B-pillar junction at the unit frame, the tube/face plate needs to be located on top of the frame rails, and wide enough to allow you to bolt down through the body and capture the unit frame flange with the underside washers (and/or underside backing plates).
The tube rails above the frame, like in the photo's doorsill bars, fully cage the occupant space, and work like long tube/face plates to spread out an impact between the body and cage. If you want a good seat mount the lower sill bars provide an excellent place to tie in a seat bracket subframe.
Tube/face plates are the recommended way to attach a tube junction to a sheetmetal structure, but anything you do to enhance the unitbody will be an improvement. Welding the tube/face plates to the body is better than having no face plate and no puncture resistance.
It's hard to be critical when the cage duty is not competition and nearly anything you add in protection is a benefit (even the SCH 40 pipe: cough, cough, cough: but tube provides a cheap quality control insurance improvement).
If you cut out and weld in new B-pillars that start at the top of the halo and angle or have a bend down to the same floor location as currently used, you only need a single diagional B-pillar plane brace (top behind the driver head top node and bottom at the opposite floor node). Sometimes it's easier to cut and redesign the problem area. A second diagional (x-brace) will protect a passenger (if it is a goal).
Overall the cage is a good design except for the top of the B-pillar.
The extra x-brace on the rear down bars is not needed (blue X, as long as you have an x-brace somewhere, and in the B-pillar plane behind the seat-back is best).
Body panel attachment plates should be 3/16" or thicker, and of a different size top and bottom sandwich of the body sheetmetal. The tube plate should be BOLTED through the body with washers on both sides of the panel attachment.
The .120 wall cage tube should be welded to the .188 plate on the tube side body attachment face plate. The tube side plate should be BOLTED, not welded, to the body (the opposite side backing plate can be welded to the body). Four 3/8 bolts minimum per plate.
The goal is to have a puncture resistant plate welded to the tube end that will not puncture the sheetmetal in an impact. The backing plate needs to be a different size from the tube/face plate to reduce potential shear stress concentration around the sandwich plates perimeter. The bolted junction allows for energy to be expended, stretching the sheetmetal, before tearing the unitbody (it also protects the unitbody sheetmetal from weldheat embrittlement).
If you have the lower B-pillar junction at the unit frame, the tube/face plate needs to be located on top of the frame rails, and wide enough to allow you to bolt down through the body and capture the unit frame flange with the underside washers (and/or underside backing plates).
The tube rails above the frame, like in the photo's doorsill bars, fully cage the occupant space, and work like long tube/face plates to spread out an impact between the body and cage. If you want a good seat mount the lower sill bars provide an excellent place to tie in a seat bracket subframe.
Tube/face plates are the recommended way to attach a tube junction to a sheetmetal structure, but anything you do to enhance the unitbody will be an improvement. Welding the tube/face plates to the body is better than having no face plate and no puncture resistance.
It's hard to be critical when the cage duty is not competition and nearly anything you add in protection is a benefit (even the SCH 40 pipe: cough, cough, cough: but tube provides a cheap quality control insurance improvement).
If you cut out and weld in new B-pillars that start at the top of the halo and angle or have a bend down to the same floor location as currently used, you only need a single diagional B-pillar plane brace (top behind the driver head top node and bottom at the opposite floor node). Sometimes it's easier to cut and redesign the problem area. A second diagional (x-brace) will protect a passenger (if it is a goal).
Overall the cage is a good design except for the top of the B-pillar.
BrettM
NAXJA Forum User
- Location
- michifornia
very interesting.... with the potential to be very nice...
you're one of the few I've seen endevour(sp?) to building a custom dash, let us know how it goes and post pics. are you keeping the heater?
edit: is it just an optical illusion, or is that bend right behind the B-pillar on the second picture very flattened?
you're one of the few I've seen endevour(sp?) to building a custom dash, let us know how it goes and post pics. are you keeping the heater?
edit: is it just an optical illusion, or is that bend right behind the B-pillar on the second picture very flattened?
XJONABUDGET
NAXJA Member #980
- Location
- Louisville, KY
BrettM said:
i was gonna ask the same, looks scary in the second pic.
ArcticXJ
NAXJA Forum User
- Location
- Anchorage AK
DrBobXJ, your cage looks like its taking shape nicely. I think that its commendable of you to get on here and respectfully accept and incorporate all the advice from those with experience.
Too often someone will post in pride of some lousy peice of spank and ask for criticism, hoping theyll really get praise. Theyll catch a rude awakening and get all defensive and resort to insults and the thread goes to hell.
But thanks for being open minded and listening respectfully to some of these guys. Threads like these are the ones that teach me the most. Kudos. :cheers:
Too often someone will post in pride of some lousy peice of spank and ask for criticism, hoping theyll really get praise. Theyll catch a rude awakening and get all defensive and resort to insults and the thread goes to hell.
But thanks for being open minded and listening respectfully to some of these guys. Threads like these are the ones that teach me the most. Kudos. :cheers:
thanks.. .
Yeah I did a really bad bend in by the b piller... going to fix it.
Do any have some pics of a custom dash I have searched but can't find much...
yeah I like it when people give good replys with how to fix whats wrong or just more info.. I have learned alot from this site...
this is my first time doing anything like this and most ideas have come form here.
Yeah I did a really bad bend in by the b piller... going to fix it.
Do any have some pics of a custom dash I have searched but can't find much...
yeah I like it when people give good replys with how to fix whats wrong or just more info.. I have learned alot from this site...
this is my first time doing anything like this and most ideas have come form here.
