This is why the chevy sonic and wrangler don't kill you in a crash

"themanwithsauce - has as many vehicles as job titles" (themanwithsauce) 05/12/2015 at 11:15 • Filed to: None

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Note - I am not involved in the business of car saefty, but I know physics so I can explain a few things. If For_Sweden or anyone else involved could please chime in and clarify/add, this is important to share. Please don’t make judgements on safety on misconceptions and falsehoods. Educate and share with family who make car buying decisions on safety.

So let’s tackle two of these rumors for now and if anyone else can chime in with others please do so.

EDIT : Yes, I know about crumple zones. Yes they are necessary. But this is meant to kill the “Small cars are tin cans in terms of safety” argument.

1) “Small cars suck in a crash” - No. Actually. Small cars should do BETTER than larger SUVs and vans by virtue of having shorter lengths of beams and whatnot. I’m butchering this because I don’t remember the technical phrases but hopefully I can get the point across. In a crash, a long, unsupported length of metal will crumple and bend easily. To test this yourself - get a decently thick dowel rod but one you could still snap in half if you gave it a moderate amount of force. Saw off 1/5 of the rod. Take the longer piece and break it by hand. Easy, no? Now try it on the shorter rod. You find it next to impossible, correct? You cannot apply the force on the shorter road efficiently and you don’t get the free torque boost from the long lever arm of the other rod. Compacts and sedans can use these same principles for crash safety. This is why minivans have historically been some of the most unsafe vehicles in a crash and why a saab 900 seems like it could take a tank shot. Smaller openings + shorter lengths of steel that are of similar thickness = much more deformation resistant crash structure. The more holes, the bigger the holes, and the fewer supports and braces to reduce the “length” of things, the more “unsafe” a design will be from the start. You can overcome these with better materials and “smarter” engineering, and all cars on sale in the USA do this, but it is easier with tighter dimensions.

2) The Wrangler - It’s weird how a vehicle could still be sold today with removeable doors and an uncovered roof right? Yet it still has to pass the same safety tests as every other vehicle. I don’t think it is the safest vehicle on the road by a long shot, but to get it to pass everything, the chassis and body that is there? It is undoubtedly made of some of the strongest designs and materials in the world. Coincidentally, this also means it can shrug off rocks and boulders when off road. This is part of how it !!!error: Indecipherable SUB-paragraph formatting!!! when compared to other SUVs perceived to be “safer”. What is really getting stressed there? The A-pillar. And I bet the Wrangler has one of the best in the world.

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davesaddiction @ opposite-lock.com > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 11:20

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The Jeep did better in the test because it glanced off the barrier (because of its fender design) instead of taking the full force of the collision.

themanwithsauce - has as many vehicles as job titles > davesaddiction @ opposite-lock.com 05/12/2015 at 11:22

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I couldn’t see the whole crash, but my point still stands - the jeep is basically a driveable rollcage. And that’s one hell of a fender to be able to deflect a 3500lb SUV with just a few pounds of what, plastic and sheet steel?

TJDMAX > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 11:25

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You are correct with the first point. However trucks and SUV’s tend to still be a body on chassis design where as most sedans and small cars now a days are unibody design. When you have a chassis yes the main frame rails are longer but there are also more cross members and such to strengthen the beams.

Secondly, the Wrangler is able to pass the tests because doors don’t add much rigidity to the vehicle. The floor and roof are what really tie the structure together and the Wrangler is built with a roll cage (not a great one but it is one none the less) from the factory that ties the body together. The fact that the doors can come off doesn’t really change the safety in terms of front end collision protection. So the Wrangler isn’t made out of any special material, i have worked on many JK’s designing suspension systems and i can attest that its just a standard steel frame and body. Nothing special.

themanwithsauce - has as many vehicles as job titles > TJDMAX 05/12/2015 at 11:29

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I agree that the SUVs and even modern minivans are very safe but I was more trying to dispel the “small car is bad in a crash” myth because physics alone says otherwise, let alone engineering.

And yes, you are correct, I was sorta roundabout saying the wrangler is a rollcage with an engine which is why it passes the tests. I’m actually impressed it isn’t made with some of that “ultra strength alloy steel” or whatever, but I knew the pillars and frame construction were meant to take a beating.

TJDMAX > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 11:43

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Fair enough. The logic is definitely there. When you have a tighter smaller construction (like a small car) you can dissipate the forces quicker and the structure is stronger. The misconception also comes from an inertia standpoint. If a small car gets hit by a big car the small car is going to take the majority of the force and thus the occupants will take more of an impact. The big vehicle won’t slow down as quickly so the force will be less. If that makes sense.

themanwithsauce - has as many vehicles as job titles > TJDMAX 05/12/2015 at 11:46

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Oh yeah, the momentum argument.....Fuck, I don’t crash enough cars to know how to eradicate stupid but preserve caution cause there is something there about longer, wider cars being stable or something.......My college had a crash lab and we used to do this stuff as a course but I didn’t take it cause it required some mechanical course I hadn’t taken yet. It was going to be a physics elective. I wish I had taken it.

yamahog > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 12:16

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You want adequate crumple zones in your car, or you will become the crumple zone and absorb all that energy.

Honestly the biggest difference-maker in the cars El_Uly posted is probably when they were designed. The small overlap has very recently gained more significance, and so newer platforms are engineered with that criteria in mind, and older crap like the Journey are still getting #wrekt. For example, the 15MY Chargers/Challengers/300s had to be upgraded to pass this test.

dogisbadob > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 12:46

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Actually, the Wrangler doesn’t even have an A-pillar. The windshield still folds down

LuczOr > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 12:47

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WOAH, WOAH, point 1 is absolutely wrong. Rigid cars transfer all the energy of an accident to the passenger while cars with crumple zones (aka design-intended weak spots) absorb the crash energy. This is a simulation of a front impact on the frame of the new Ford F-150.

You can clearly see the intentionally designed weaknesses in the frame absorbing energy. If the frame had been designed by a fucking caveman to be “next to impossible” to bend, all the crash energy gets transferred into the cab of the truck and subsequently into the sack of meat in the seat.

You may know basic physics, but you don’t seem to understand multibody dynamics and energy absorption. That’s called applied engineering.

themanwithsauce - has as many vehicles as job titles > LuczOr 05/12/2015 at 12:51

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And I never said you don’t want crumple zones. At all. But people seem surprised that these subcompacts don’t accordion when they hit a wall and my point is that it’s actually very easy to not make the passenger compartment do that. TO include all about energy distribution/dispersion/diffusion/whatever and crumple zones and everything else would make this 10x longer.

themanwithsauce - has as many vehicles as job titles > dogisbadob 05/12/2015 at 12:51

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........wut.........

Okay what is a wrangler made of?

themanwithsauce - has as many vehicles as job titles > dogisbadob 05/12/2015 at 12:52

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And follow up question - I know there has to be some sort of main support/structure between the front wheels and the passenger compartment. Would that still be called or considered a pillar? Or is that just all called the firewall or bulkhead?

themanwithsauce - has as many vehicles as job titles > yamahog 05/12/2015 at 12:57

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Oh you definitely want crumple zones......you just don’t want the structure around you to crumple. This is what I was seeing in cmments on these safety videos - “Whoah?!?!?! The subcompact is still mostly intact?!?!?!” as if they thought it was still legal to sell a small car that flattens into a pancake when in a crash.....Ever see the old minivan tests? The crumple zone included the rear benches, even if hit in the front. But it is easy to make the passenger area of a small car be very sturdy in the event of a crash. This makes it that much easier to then design your crumple zone and control the energy and forces and whatnot.

dogisbadob > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 12:58

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Honestly, I’m not sure, but leaning towards not considering it a pillar, much in the same way that some coupes lack a B-pillar. You’re probably right, most likely part of the bulkhead or firewall

themanwithsauce - has as many vehicles as job titles > dogisbadob 05/12/2015 at 13:00

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Hmmmm......but they tested the wrangler with that support up. I think it might still be capable of providing frame stiffness. In that case, it is part of the crash structure, technically. So it might still be a pillar in some way?

dogisbadob > themanwithsauce - has as many vehicles as job titles 05/12/2015 at 14:31

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Maybe. The windshield seems to start folding in the crash video. I don’t know if you’ve watched it, but that’s what it looks like to me. Tell me what you think.

themanwithsauce - has as many vehicles as job titles > dogisbadob 05/12/2015 at 14:38

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Work is blocking YouTube. I saw a few moments after contact then the firewall woke up.... I saw the pictures though