Hrew Vs. Dom

I have a 75 CJ5 w/ a glass tub. Anticipate moderate at most wheeling, mostly mud and not alot of rock crawling. Probably 95% on lined roads though. Had planned on adding a front hoop and spacer bars to the factory bar with welded tie-ins to the frame front and back. What are people's thoughts on that plan vs. on starting over with a 6 point DOM cage ($$$) still tied in everywhere. Safety is always nice but is that a good spend and how much safety am I really buying?

 

With the glass tub, I’d consider how you tie the cage into the frame to be more important than which tubing you use.

That being said, HREW vs. DOM is one of those debates that could go on for pages, and it would still come down to opinion in the end. Yes, DOM is somewhat stronger. And more expensive. Is the extra price worth it? I’ve seen articles that talk about HREW being single-use; It’ll save your life once, but it’ll be trash afterwards. My old racer’s cage is HREW, and that thing has violently been flipped on its roof many times. It’s a little twisted up and under some tension, but I still trust it with my life.

I made my last cage from DOM, mainly because it doesn’t have the cross-bracing that the racer has, so the extra strength was welcome.

Personally, I’m in the “anything is better than nothing” camp. I flipped a bone stock 2a when I was a kid. I watched the tiny corner of the windshield frame support the weight of the Jeep and keep it from crushing me.

On the other hand, in the motorcycle world, a $5 helmet for a $5 head....

 

Anybody know what my OEM rear is made of on a 75 CJ5? I Assume it's HREW. What else could it be?

 

IMO, it all depends on how you use it and what you expect. If you expect to roll, for example, a comp rig or a drag car, put the $$$ DOM into the cage.

If not, if its just for a “what if” situation - HREW is fine, if its engineered with some good nodes, welds and triangulation support.

 

You should go with dom. I have a 6 point hrew cage thats 2" with a 1/8" wall. Luckily i haven't tested how it holds up in a crash. Imo hrew is fine for how i use my jeep but i dont expectit to survive a high speed roll over. Other than spending a little more money up front for the dom there aren't any negatives for going dom and the peace of mind would be worth it. Several of us have 6 point prebent cage kits from extremecustomparts. They come i hrew as standard but you can upgrade to dom.

 

Lots of first-hand experience in this thread:
Roll cage material question

 

Just to muddy the waters NHRA spec's call for 1.75"OD x .118" T DOM or 1.5" OD x .083" wall Chrome Moly

My dad built his out of sch 80 2" Steam Pipe with Large sweeping corners all welded to 1/4" boiler plate that covered the whole top of the wheel house. Only test was laying it over on its side at 0mph and I'm sure the 3A windshield frame stopped it before the Roll bar ever touched the ground. Took me about 3 hours of screwing around to get the Windshield frame perfectly square again.

 

Compromise with a main hoop of 1.75” and all other surrounding cage of 1.5” .120 wall tube, welded by a competent welder. If you roll your Jeep you won’t know the difference between chromo, dom or mild steel. Chances are if you roll hard... your Jeep will be totaled..... not uprighted and speeding off to be wrecked again. Most Jeeps are weekend drivers and ice cream runners.... not competition vehicles. Competition vehicles see far greater stress on a regular basis, than anyone here’s street legal Jeep ever will. Cromo is pointless unless you are going to tig weld it.
As far as tubing size, try gripping various sizes of tubing. If you have kids, nieces/ nephews they won’t appreciate larger tubing. 1.5” tube can be bent into tighter radius, is easier to grab and hold on to and takes up less space in a tight Jeep.
whatever you do, don’t use pipe of any schedule......

 

Raced for SCORE years ago, here are their rules. I am using 1.750” x .120” DOM with the windshield, middle and rear hoops all going to frame.
My wife, kids, and grandkids one day may benefit. Octatiel Wells, Glamis dunes, Devils Playground dunes are all within 2-3 hours.

Courtesy of SCORE
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 double 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) Lateralbracing
(5) Elbowanddoorbars
(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), or two (2) lateral hoops, 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. Upper main, front, rear, and lateral roll bar hoops must be made in one piece without joints. Centerlines of all required tubes must converge at intersections.

Dennis

 

That was a good read. Lots of info.