Friend of mine almost died a week ago.. RZR PSA

[RiverDave]

Dave if you really believe the tubes in a roll cage should never ever move, you should take a physics class at the jr college. A RZR roll cage is a consumable item. The whole vehicle is designed to shed parts like crumple zones in a wreck.

You have no helmet, shitty seatbelts that are not placed correctly, flat seats, a shitty cage that is too close to your head and body made from shitty material, nothing holding your head or neck and want to roll over at 40-50 mph in a 2000 lb vehicle and expect a crash structure not to move and nothing to break? What happens to all that force Dave? Where does it go?

He did get lucky. He would have been better off with a stock cage, with tubes a foot from his head.

I said (sarcasticly I might add) they are building them with crumple zones now?

You said they are..

Now you are changing the conversation in an attempt to argue the thing all the way to the rack storages they junkers will all the sitting on. Lol

Sorry but joe blow cage shop bends some tubes and slaps them on. They are not engineering failure points into them.

To that point to my knowledge I don’t even believe Polaris is crash testing them either.

None of this shit is actually “tested” until it’s tested if ya know what I’m saying.

 

[LargeOrangeFont]

Ballpark, what does insurance on one of these cost? What would it cover?

Mine is $200 for a year, and includes insurance for driving on AZ streets. It is insured for stock FMV for replacement which is probably $18K. If I wanted to insure all the "upgrades" it was close to $600.

I have just under $20K total into the car including upgrades.

 

[brianwhiteboy]

Pfft....you an your roll cages.

Life when it was simpler.

 

[RiverDave]

Pfft....you an your roll cages.

Life when it was simpler.
View attachment 813766

Lol

 

[LargeOrangeFont]

I said (sarcasticly I might add) they are building them with crumple zones now?

You said they are..

Now you are changing the conversation in an attempt to argue the thing all the way to the rack storages they junkers will all he sitting on. Lol

Sorry but joe blow cage shop bends some tubes and slaps them on. They are not engineering failure points into them.

To the point, none of this shit is actually “tested” until it’s tested if ya know what I’m saying.

No Dave, re read what I said. The stock cage has some thought, engineering, and QC into it. It is designed to deform slightly. It HAS to, as there is no support for the roof at the front save for those 2 A pillar tubes. These cars are consumable, and designed as such.

An aftermarket cage does not have any of this designed in. It may break in two, it may not bend at all, who knows. But sure, make it look bad ass and put all the metal right above your head and roll the dice you don't die when it flips over. You don't want all that force going into your body if you aren't properly contained in your SXS (you arent).

I can tell you the the stock cage wont break in half from an impact like that and absorbs some of that impact.

 

[RaceTec]

One thing that a lot of people don't take in consideration is the weld location and then stress concentration at that location. Especially with 4130 it is very brittle in the welded section. That is why you see trophy trucks and such heat treat and aneal critical components then finish machine them after the fact. In applications such as this there is something to be said for mild steel... Yeah you can build a cage of similar strength with lighter weight out of 4130 but there is a give and take there also. The wall thickness looks to be very thin on that cage also, I know that NHRA mandates a material thickness of .083" on 4130? I would guess the A pillar failure is due to the heat affected zone from welding in the brace. Probably a MIG welded 4130 cage? Most importantly, glad your friend is ok!!!

 

[Waffles]

The point of them is cheap / ez / fun.. Put it in fwd and push pedal. Anybody can do it.

They ride incredible with suspension upgrades, and are extremely capable in the dirt / sand / etc.. Without being overly huge they can go almost anywhere.

RD

Cheap? Lmao
What part of buying a 20k+ toy and dumping thousands into it in "upgrades" is cheap? "Upgrades" that give idiots with more money than brains that false sense of security I was talking about to be "able to go almost anywhere". No, thousands in "upgrades" isn't going to help make your overpriced toy go through the hot tub in Moab like crawler, glide through the dunes like a buckshot rail or let you send it like a bj Baldwin trophy truck.

 

[LargeOrangeFont]

I think both of you have some points but the reality is the rest of the car should crumple, not so much in the passenger compartment. Same thing on a production vehicle. The body and everything around it should crumple and collapse but not the passenger compartment. Give a little is fine, fail like this one or fully collapse? No! Two different things. This is one of the things that made me nervous in the two accidents my wife has been in recently (both 100% not her fault). The 14 fourrunner was in full collapse just in front of the driver / passenger seat. Not where you want things folding up if you like your feet and legs..... The Nissan Rouge that hit her the second time put the engine into the passenger compartment with the driver. Crumple zones, yes, a good thing. Passenger compartment should not be folding rapidly, bending and deforming modestly is OK, collapsing or major intrusion is not.

We all cant drive tanks.. bad things are going to happen in an accident.

Look at BB500s stock cage, vs the aftermarket one that broke in half, now ask yourself.. do you expect the structure of an 1800# vehicle to not crumple and shed parts in a fast rollover. You have to expect something to give at 50+ mph.. or just drive a 3000# SXS with an indestructible roll structure that is slow lol.

This one looks like it landed on the windsheild/roof. so now all you have protecting you from impact is tubing.. do you want the tubing closer to further from your head? Do you want less tubing to just snap uncontrolled closer to your head, or more tubing that might be bending and taking up some of that force, further away from your head.

I realize that is not a choice anyone wants to make, but one sounds better than the other.

 

[Wizard29]

Polaris actually has millions of dollars for R&D in the budget. I fixed your quote above.

What you are looking for is not really possible in a recreational SXS. You'd really want to do a frame off build with a real race cage, which is what the race SXS guys do.

Additionally why would you put (bolt) a stiff cage on a recreational chassis that flexes? It is not going to help much of anything. Again, not all aftermarket cages are bad, but not all aftermarket cages are good either.

I'm referring to aftermarket cages such as the one in Dave's original post. If the garage guys can't get the engineering right, I'd rather have them make it so it doesn't bend at all.

Stock cages do have the R&D budgets behind them, but even so I've seen a lot of them react in ways that aren't ideal. Way too much bending for comfort.

 

[Skinny Tire AH]

Yet people drive them like theyre BJ Baldwin in a Recoil flick.

Thats why i wont buy one. Ive driven my friends, and the false sense of security they give is fucking terrifying.

THIS!!!! You can go from hero, to making your wife a widow and your kids orphans in a heartbeat.

I feel exactly how you do. I have been with friends also and they scare the shit out of me.

I drive mine like its a big quad with 4 seats....because that's exactly what it is.

 

[LargeOrangeFont]

Cheap? Lmao
What part of buying a 20k+ toy and dumping thousands into it in "upgrades" is cheap? "Upgrades" that give idiots with more money than brains that false sense of security I was talking about to be "able to go almost anywhere". No, thousands in "upgrades" isn't going to help make your overpriced toy go through the hot tub in Moab like crawler or glide through the dunes like a buckshot rail.

But it is 1/5 the price, and I can finance it

We have this same conversation about stupid boaters, stupid people towing, it is just a fact of life... most people are dumb. Just stay out of their way

 

[rivermobster]

Lets go for a ride then My 1800 lb 120HP turd is actually really astounding, and tons of fun.

My Z400 has triple rate shocks, long travel suspension, a Scott's stablizer, lots of money in wheels and tires.

But it's still a quad. Even though it rides and handles Great for a quad and has the power to smoke anything in it's class, I still wouldn't call it incredible.

I'm sure your SxS is built the same way, but it's far from an incredible ride.

We were in my friends Revenge car on the original wash road one day long ago. He was running about 70-80 mph, over probably 2ft whoops, I had a drink in one hand and didn't spill a drop.

THAT was an incredible ride.

Thanks for the offer. : thumbup:

 

[LargeOrangeFont]

I'm referring to aftermarket cages such as the one in Dave's original post. If the garage guys can't get the engineering right, I'd rather have them make it so it doesn't bend at all.

Stock cages do have the R&D budgets behind them, but even so I've seen a lot of them react in ways that aren't ideal. Way too much bending for comfort.

But those guys have $0 in R&D. That cage didn't bend at all.. it just broke

 

[riverroyal]

Horrible design on the front windshield area. The cage created its own weak spot with the cross tube. For one it directed all the stress that area. Next the welds there soften the steel creating a weak spot. It would have been stronger without the bar. Doesnt matter the material or weld skill, although the amount of metal within that weld is too much. A simple TIG pass would have kept the metal cooler and less annealed.
Hope the guy has full recovery!
Chose your cage wisely or leave it stock

k.

 

[rrrr]

Is anyone making frame copies constructed with 4130 tubing? If it's jigged correctly and the attachment points are the same, it doesn't appear swapping over the components would be a big deal.

 

[LargeOrangeFont]

My Z400 has triple rate shocks, long travel suspension, a Scott's stablizer, lots of money in wheels and tires.

But it's still a quad. Even though it rides and handles Great for a quad and has the power to smoke anything in it's class, I still wouldn't call it incredible.

I'm sure your SxS is built the same way, but it's far from an incredible ride.

We were in my friends Revenge car on the original wash road one day long ago. He was running about 70-80 mph, over probably 2ft whoops, I had a drink in one hand and didn't spill a drop.

THAT was an incredible ride.

Thanks for the offer. : thumbup:

What makes them unique is the versatility.. not necessarily the speed. They are not the best at anyone thing, but they can do almost anything and go about anywhere. It is like a rally car, a rock crawler and a miata all rolled into one. I can go climb up a dry waterfall, then blast down a wash with 1 foot whoops at 50+, then fly through a technical trail with switchbacks sweepers and hairpins hanging it out like a rally car.

No its not going to wheelie at 100MPH in the sand, no its not going to blast through 3 foot whoops at 60, or climb up some sheer rock face, but I can do a little of all of that with one vehicle.

 

[gqchris]

That's why I always wear a helmet and if you're in my car you will also wear a helmet or no ride! I may not look "cool" but then again I'm not "cool" anyways.

Guess id be walking then.

 

[LargeOrangeFont]

Is anyone making frame copies constructed with 4130 tubing? If it's jigged correctly and the attachment points are the same, it doesn't appear swapping over the components would be a big deal.

At that point just buy a purpose built car...

Keep i mind these are designed to be crated and shipped for delivery. Most of them have the cage bolted to the frame.

 

[mjc]

You incident actually is why I have not bothered with an aftermarket cage.

It's almost as if Polaris tested the factory cage because they know they would be liable if the cages just broke in half on every rollover.

I immediately thought of your rollover when I saw this one.. looks like a similar impact at a similar speed.

That is my thought I know the factory has to do tested to get things approved to sell and deal with liability. Do any of these aftermarket people do any testing on the replacement cages? I doubt if any are tested like the factory does.

 

[rrrr]

Horrible design on the front windshield area. The cage created its own weak spot with the cross tube. For one it directed all the stress that area. Next the welds there soften the steel creating a weak spot. It would have been stronger without the bar. Doesnt matter the material or weld skill, although the amount of metal within that weld is too much. A simple TIG pass would have kept the metal cooler and less annealed.
Hope the guy has full recovery!
Chose your cage wisely or leave it stock View attachment 813771 k.

It wouldn't be popular, but a cage with a properly located downtube is what's needed for the loads that caused the failure. Without the welded in support, I think the cage would have folded at the bend just as easily.

 

[Flying_Lavey]

The more I look at this, and the fact the other side failed in the exact same fashion and location....

It almost looks like the down tubes were welded with a butt joint (don't know the welding term).

Anyone else see the same thing? View attachment 813696

That was my first thought as well. Pretty consistent break on both sides. From the back to that joint, about a 10-foot stick. And no Spud.
The Chinese steel comment is right on also.
Never seen a cage tear like that, doesn't mean it couldn't happen. With that handhold causing a stress point. With that said as sheared off as that tube was, I would expect some structural degradation in that handhold.

One thing that a lot of people don't take in consideration is the weld location and then stress concentration at that location. Especially with 4130 it is very brittle in the welded section. That is why you see trophy trucks and such heat treat and aneal critical components then finish machine them after the fact. In applications such as this there is something to be said for mild steel... Yeah you can build a cage of similar strength with lighter weight out of 4130 but there is a give and take there also. The wall thickness looks to be very thin on that cage also, I know that NHRA mandates a material thickness of .083" on 4130? I would guess the A pillar failure is due to the heat affected zone from welding in the brace. Probably a MIG welded 4130 cage? Most importantly, glad your friend is ok!!!

Horrible design on the front windshield area. The cage created its own weak spot with the cross tube. For one it directed all the stress that area. Next the welds there soften the steel creating a weak spot. It would have been stronger without the bar. Doesnt matter the material or weld skill, although the amount of metal within that weld is too much. A simple TIG pass would have kept the metal cooler and less annealed.
Hope the guy has full recovery!
Chose your cage wisely or leave it stock View attachment 813771 k.

Racetec and riverroyal beat me to it. I HIGHLY doubt the main hoop was extended at that point. I bet it was an issue caused by the welding process heating the metal and effectively annealing it in a hyper critical area. (A pillar to Halo juncture point is probably the most critical point of the structure).

Sent from my LM-G710VM using Tapatalk

 

[LargeOrangeFont]

Guess id be walking then.

Me too.

Although for anything more than the recreational stuff, or a long ride with the "guys", I do have a helmet.

 

[Racey]

I've seen it break, but not like that either. It does not even look like it bent at the break, but who knows. We are just armchair experts without really looking at everything and knowing how it wrecked.

My Guess would be that either/or a combination of 1) too thin of tubing for the long A pillar span, and 2) that handle welded between the A pillar and Roof beam actually weakened the cage, The weld there sugared the inside of the tubing as it is not back purged, that sugaring created an inclusion that became the failure point when it became the focus of a stress concentration. The thinner the tubing wall the more pronounced the sugaring will be on the back side of the weld.

Glad your friend is alive and hope is recovers. As a driver or passenger in these things you have to remind yourself that the cage does not make you invincible. Everything has it's limits.

Edit: Just for clarification nobody needs to be back purging the entire tube structure when welding it, and i was not saying it should be, that's just ridiculous and overboard. But as a welder sugaring should be taken into consideration, your wall thicknesses, joint preps, and weld temps should be selected with it in mind. Many times i will just braze noncritical pieces with SILBRZ as it does a fine job of holding things in place with minimal heat input. And we don't know how bad that impact was and at what speed, i was only speaking as to the WHY of the tube breaking exactly at that point, not if that was acceptable or not. Remember a RZR is not designed with a 'Roll Cage' it is a 'Roll Over Protection System' They are not the same thing, look at rrrr's posts with the land speed racers, that is a true cage, a Trophy Truck, or Buggy with a SCORE tag is also a cage (to a lesser extent) but these SXS's really don't have them by nature of their construction, it's all attached to cheesy stuff under the plastics by comparison.

 

[Sandlord]

The stock cage would have done the same thing except likely wouldn’t have snapped as it’s mild steel therefore less carbon than chromoly. It would have bent instead

good point, properly annealed chromoly would have likely bent too. chromoly that has been welded, if not properly cooled or annealed, loses malablity and become brittle or more likely to break than bend.

 

[rrrr]

At that point just buy a purpose built car...

Keep i mind these are designed to be crated and shipped for delivery. Most of them have the cage bolted to the frame.

That makes sense. How much does a sand car with comparable performance cost? I think a turbocharged Rotax 914 would be a good engine for that, they put out 125 HP.

 

[gqchris]

I know from the first 2 minutes of a ride with some one that:
a: Am I tapping out?
b: Am I getting back in?

There are always going to be idiots. I have ridden with members on here that are like minded and I would trust my daughter in the back. I include camping as well, because idiots in a camp can turn shit upside down quick also.

Generally, once I spot fuckery, I dont continue to hang with those folks. And yes, there is dumb asses on this board also. I have been dropped off on beach with a member after a boat ride. I Tapped out. Dude drove like a fuckstick. Trimmed all the way up to tail wagging because Magic told him the delta pad is the sweet spot! Took Zero criticism when I tried to help him out.

 

[LargeOrangeFont]

That makes sense. How much does a sand car with comparable performance cost? I think a turbocharged Rotax 914 would be a good engine for that, they put out 125 HP.

$40k-$60K probably similar to what people have in their higher end SXS builds. If you are looking at used sand cars you can get something very capable for new RZR money.

 

[RiverDave]

Racetec and riverroyal beat me to it. I HIGHLY doubt the main hoop was extended at that point. I bet it was an issue caused by the welding process heating the metal and effectively annealing it in a hyper critical area. (A pillar to Halo juncture point is probably the most critical point of the structure).

Sent from my LM-G710VM using Tapatalk

This.. the grab handle is added afterwards in everyone I have seen

 

[RiverDave]

$40k-$60K probably similar to what people have in their higher end SXS builds. If you are looking at used sand cars you can get something very capable for new RZR money.

Approaching 60.

Pick it up Friday! .

(Won’t fold like laundry)

 

[LargeOrangeFont]

I know from the first 2 minutes of a ride with some one that:
a: Am I tapping out?
b: Am I getting back in?

There are always going to be idiots. I have ridden with members on here that are like minded and I would trust my daughter in the back. I include camping as well, because idiots in a camp can turn shit upside down quick also.

Generally, once I spot fuckery, I dont continue to hang with those folks. And yes, there is dumb asses on this board also. I have been dropped off on beach with a member after a boat ride. I Tapped out. Dude drove like a fuckstick. Trimmed all the way up to tail wagging because Magic told him the delta pad is the sweet spot! Took Zero criticism when I tried to help him out.

So is this why you jumped out of my RZR at 40MPH at 1AM with the coyotes howling nearby?

 

[LargeOrangeFont]

Approaching 60.

Pick it up Friday! .

(Won’t fold like laundry)

View attachment 813780 View attachment 813781 View attachment 813782 View attachment 813783

Looks great. Just don't land it on its windshield and it should last forever. Those guys appear to do very good work that is well thought out.

To your point, that windshield area is going to be stronger than stock.

 

[Flying_Lavey]

It wouldn't be popular, but a cage with a properly located downtube is what's needed for the loads that caused the failure. Without the welded in support, I think the cage would have folded at the bend just as easily.

Honestly, I doubt it. Look at the rest of the cage.... It's really not deformed much at all. Once those tubes broke, the rest of the cage took ALL the stresses put into it and they still look good.

I do agree though that better bracing across the front end of the cage would be MUCH better.

Sent from my LM-G710VM using Tapatalk

 

[riverroyal]

I found a good example of stock cage engineering. The material is thin, Im not saying it wont fold. But you can see how stress area's have the forces extended over long lengths.

 

[Riverfamlee]

So no one has ever been hurt or killed in a purpose built car? Only sxs’s I guess

 

[2Driver]

So how does the average guy shop for a robust tested crash proof cage? Talk's cheap and everyone will give you “ ours are over built... it’s the same design as a class 10 buggy”.

I suppose the top criteria for some shoppers is, will it make my RZR look like a Penhall buggy and how many LED light brackets can you fit on it.

 

[Joker]

Reason #150 not to waste my money on a souped up golf cart.

 

[gqchris]

So is this why you jumped out of my RZR at 40MPH at 1AM with the coyotes howling nearby?

HAHA!! That was a great ride. NO jumping out here.

Headed to Barstow this weekend. My Dad is coming from Tennessee!

 

[rivermobster]

Approaching 60.

Pick it up Friday! .

(Won’t fold like laundry)

View attachment 813780 View attachment 813781 View attachment 813782 View attachment 813783

So 60k is your idea of cheap?

:bowdown:

Be careful in that thing.

 

[Bpracing1127]

River royal and sandlord have it right like i do. The design and how the cage was build was crap. You would have been off in a stock cage in this particular accident.

no sxs cage mfg is annealing their cage to keep the proper metallurgy in the tubes.

that being said don’t drive past your or the machine limits and you will live

 

[Bpracing1127]

HAHA!! That was a great ride. NO jumping out here.

Headed to Barstow this weekend. My Dad is coming from Tennessee!

Hmmm might join ya

 

[boatnam2]

I went with a big boy toys cage which is on the lower price scale for a cage, guy has been around building buggies before the SXS rage for quite awhile. A car was sitting there that was junk, insurance deal that was rolled 6 times, cage had a scratch on it and that was good enough for me. Like anything fun and fast, shit can happen.

 

[LowRiver2]

So how does the average guy shop for a robust tested crash proof cage? Talk's cheap and everyone will give you “ ours are over built... it’s the same design as a class 10 buggy”.

I suppose the top criteria for some shoppers is, will it make my RZR look like a Penhall buggy and how many LED light brackets can you fit on it.

no
It’s a piece of equipment.
If a builder has built SCORE reg. Vehicles, sxs’s , they might know a thing or two. If the mfg. can show you pics, customer referrals of owners who rolled their cages and were saved, even better.
The days of a cage keeping you perfectly safe are long gone once sxs’s passed the 100hp mark.
It’s a combination of design, materials and driver common sense, experience,
That keeps one relatively safe.

In shooting the old saying “ $5k in rifle is shit with $5 of training”
Same ideology applies in sxs’s

 

[Waterjunky]

We all cant drive tanks.. bad things are going to happen in an accident.

Look at BB500s stock cage, vs the aftermarket one that broke in half, now ask yourself.. do you expect the structure of an 1800# vehicle to not crumple and shed parts in a fast rollover. You have to expect something to give at 50+ mph.. or just drive a 3000# SXS with an indestructible roll structure that is slow lol.

This one looks like it landed on the windsheild/roof. so now all you have protecting you from impact is tubing.. do you want the tubing closer to further from your head? Do you want less tubing to just snap uncontrolled closer to your head, or more tubing that might be bending and taking up some of that force, further away from your head.

I realize that is not a choice anyone wants to make, but one sounds better than the other.

Just for reference I didn't even enter into the distance from head discussion. At 6'4" this is a real issue for me in all vehicles including when I raced local dirt track years back. I expect nothing to be indestructible. If it is you are not trying hard enough. My point is that there are areas that are fine to collapse / break / shear, and there are areas you only want mild deflection in. Not sure why you are worked up over my statements.........
Engineering a cage is no joke because you cannot definitively estimate the impact energy. As LOF knows, different classes of racing require different cages just for this reason. A slower class on a tight track may never see speeds over 60mph. The cage on this would need to be built differently than the same track in a faster class doing north of a bill. This thought process is just as important in sxs's If you are just out for some fun and want decent protection for you and your family at stock speeds that is one thing. If you are out to run hard in a high HP machine with all the bells and whistles, that is a different level. Both are fun and have a place but need different preparation. Just like in the towing thread, you don't need DRW for 5k trailers and you probably need more than your lifted mall crawler tundra for your 15k 5er. We have all seen both extremes in towing and cages. What do you actually need? depends on what you are planning to do........ People need to use some (un)common sense and have a realistic plan.

None of this changes my statements earlier that the cage shouldn't have cracked like that. bent a little, deformed a little, yes, no worries. Split or totally deformed, NO, bad things happening quickly.

 

[LargeOrangeFont]

HAHA!! That was a great ride. NO jumping out here.

Headed to Barstow this weekend. My Dad is coming from Tennessee!

Have fun out there. I’ll be running my RX7 on AAA speedway or I’d come out too.

We will have to do another ride. The car rides even better now after this last shock change. It’s almost like the chatter bumps no longer exist now

 

[LargeOrangeFont]

Just for reference I didn't even enter into the distance from head discussion. At 6'4" this is a real issue for me in all vehicles including when I raced local dirt track years back. I expect nothing to be indestructible. If it is you are not trying hard enough. My point is that there are areas that are fine to collapse / break / shear, and there are areas you only want mild deflection in. Not sure why you are worked up over my statements.........
Engineering a cage is no joke because you cannot definitively estimate the impact energy. As LOF knows, different classes of racing require different cages just for this reason. A slower class on a tight track may never see speeds over 60mph. The cage on this would need to be built differently than the same track in a faster class doing north of a bill. This thought process is just as important in sxs's If you are just out for some fun and want decent protection for you and your family at stock speeds that is one thing. If you are out to run hard in a high HP machine with all the bells and whistles, that is a different level. Both are fun and have a place but need different preparation. Just like in the towing thread, you don't need DRW for 5k trailers and you probably need more than your lifted mall crawler tundra for your 15k 5er. We have all seen both extremes in towing and cages. What do you actually need? depends on what you are planning to do........ People need to use some (un)common sense and have a realistic plan.

None of this changes my statements earlier that the cage shouldn't have cracked like that. bent a little, deformed a little, yes, no worries. Split or totally deformed, NO, bad things happening quickly.

I’m not worked up, we are in violent agreement, and I’m 6’3 so the struggle is real.

I think my point is if you land a SXS on it’s A pillars at speed the windshield is gonna bend. I don’t think there is enough material or support there to stop that from happening in any recreational cage, stock or otherwise.

And I’m pointing out there is a difference between a racing roll cage in a race car and the “ROPS” cages that are in a SXS, and that is because the use case is different. A race cage is designed to largely not move around the driver and the assumption is you are contained. A SXS mfg does not make the assumption your head and body are contained and the ROPS (cage) is designed around that assumption.

The only reason I’m babbling on about this is because I have a pretty good idea of what goes on when designing these things. One of my good friends did all of this for the Wildcat XX when he worked at Textron.

 

[gqchris]

Hmmm might join ya

That would be awesome. Copper City road trip. Ill shoot you the GPS file, lots of cool sites on the list!

 

[gqchris]

Have fun out there. I’ll be running my RX7 on AAA speedway or I’d come out too.

We will have to do another ride. The car rides even better now after this last shock change. It’s almost like the chatter bumps no longer exist now

Sounds good brotha. Love to see the improvements.

 

[lbhsbz]

One thing that a lot of people don't take in consideration is the weld location and then stress concentration at that location. Especially with 4130 it is very brittle in the welded section. That is why you see trophy trucks and such heat treat and aneal critical components then finish machine them after the fact. In applications such as this there is something to be said for mild steel... Yeah you can build a cage of similar strength with lighter weight out of 4130 but there is a give and take there also. The wall thickness looks to be very thin on that cage also, I know that NHRA mandates a material thickness of .083" on 4130? I would guess the A pillar failure is due to the heat affected zone from welding in the brace. Probably a MIG welded 4130 cage? Most importantly, glad your friend is ok!!!

This. When I was racing, the only reason anyone used chromoly was to save weight, because you were allowed to used .090 wall chromo whereas with mild DOM you'd have to use .120 wall.

Chromoly requires special fillers or post treating in order to create or proper connection, or so simply overdesign the hell out of it such that a whole boatload of reinforcements make up for the shortcomings of less than ideal welding techniques...which add weight and negate the whole Chromo thing anyway.

I built DOM cages for all my race cars, as did everyone else on the track with me.

If that was a chromoly cage, I'd say they either used an inappropriate filler/post treat/technique and created a very week HAZ where the grab handle was welded near the crack, which caused the tube to fail under stress.

 

[rrrr]

I found a good example of stock cage engineering. The material is thin, Im not saying it wont fold. But you can see how stress area's have the forces extended over long lengths.

View attachment 813791 View attachment 813793

That stock cage is a helluva lot stronger than the cage on the crashed vehicle. Properly engineered structures are all about transferring loads, and it's obvious the stock cage's load path is superior in that respect.

 

[lbhsbz]

That stock cage is a helluva lot stronger than the cage on the crashed vehicle. Properly engineered structures are all about transferring loads, and it's obvious the stock cage's load path is superior in that respect.

Agree...those joint reinforcements are designed exactly right.