Would rock sliders help in an accident?
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A friend of mine drives a Jeep Rubicon with sliders. He was t-boned right at the driver's side door.
The slider bent up, but stayed attached to the frame, which got very bent out of shape as you can imagine. The rigidity of the slider seemed to transfer a lot of the impact from the side of the vehicle to the frame instead of into his body, which was great. It was so effective that he slammed his head into the side window and got a concussion.
Edit: I'd imagine it depends on what kind of vehicle you're in, what hits you, and the dynamics of the impact (speed, angle, etc.). Key thing to remember is that vehicle makers design a vehicle with crashes in mind. Slapping a huge steel rock slider on the vehicle and bolting it directly into the frame is going to alter the crash dynamics.
The slider bent up, but stayed attached to the frame, which got very bent out of shape as you can imagine. The rigidity of the slider seemed to transfer a lot of the impact from the side of the vehicle to the frame instead of into his body, which was great. It was so effective that he slammed his head into the side window and got a concussion.
Edit: I'd imagine it depends on what kind of vehicle you're in, what hits you, and the dynamics of the impact (speed, angle, etc.). Key thing to remember is that vehicle makers design a vehicle with crashes in mind. Slapping a huge steel rock slider on the vehicle and bolting it directly into the frame is going to alter the crash dynamics.
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Jhalko
New member
Curious if he had side airbags and if they went off? It sounds like no but just checking.
honda250xtitan
New member
hahaha seriously.
Jeremy556
New member
Totally depends on the circumstances.
Small car, low speed impact - rock sliders destroy the car and result in probably no damage to 4runner.
Large vehicle and/or high speed impact - rock sliders transfer energy directly into the frame that would have been absorbed by the body, resulting in more damage and increased injury to 4runner occupants.
Small car, low speed impact - rock sliders destroy the car and result in probably no damage to 4runner.
Large vehicle and/or high speed impact - rock sliders transfer energy directly into the frame that would have been absorbed by the body, resulting in more damage and increased injury to 4runner occupants.
I disagree and would like to know how you arrived at this conclusion. More steel is more steel, and the car with the most steel wins in all cases by transferring all of the injuries to the occupants of the car with the least steel. Crash tests showing cars hitting completely solid walls do not reflect reality in an accident as it is unlikely that a solid concrete cube is what people will be crashing into.
For instance, I was rear ended by a 2017 ford sedan going around 50mph last year, nothing happened to my rear bumper or my frame at all, though the sedan crumpled up like a tin can all the way to the passenger cabin. All of the injuries and damage was simply transferred to the plastic car and its occupants while I actually drove away from the accident to buy a can of spray paint to get the ugly ford paint off my bumper. Granted, I knew that I was going to be wheeling hard, so I had a metal shop brace my rear frame with 5/16" plate on top of having a 220lb steel rear bumper.
In a T-bone accident, most of the ratings are based on cabin intrusion, or more commonly: "the amount of steel in the door." Less steel = more death. By adding sliders, you are adding a layer of steel that can cushion the impact simply by being farther from the car-- for simplicity, if you imagine the maxima and minima of this situation you can have a better grasp on the smaller effects. lets say you wanted the ultimate side impact protection for your car, welding sliders that stick out 100 feet would definitely prevent someone from ever getting to your head in an accident and allow the steel to deform enough to prevent you from being injured. conversely, if you removed all of the steel and only had a single piece of sheetmetal between your head and an oncoming car, the single piece of sheetmetal would not have any distance to deform and you would die.
I would like to refer to the below IIHS data, which states unequivocally that cars with more weight cause more death to occupants of cars with less weight, while the deaths per thousand of the occupants of cars with more weight are vastly lower.
Driver death rates vary widely by model
Specifically, the following data shows that the 2003+ 4runner is incredibly safe (for people inside it) If you hit one with another car, you die, while the 4runner occupants have little to no injury. I personally believe this is because the 4runners fully boxed frames simply bash the unibody cars and their occupants into a pulp in an accident.
http://www.informedforlife.org/demos/FCKeditor/UserFiles/File/DEathRatescombined1994to2004alpha.pdf
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1engineer
Moderator
I don't know where to begin with this post. It's like you are mixing and matching physics and outcomes, which is illegal to break the law of physics in all 50 states and pretty much in the whole universe.
First [MENTION=78273]Jeremy556[/MENTION] arrived at the conclusion he did because he is correct and understands physics, and he followed the laws. You are wrong because you didn't.
Mass COULD win in specific cases, although mass is not just "more steel" added to the sides of a vehicle. Also, you used the word "all" and nothing is ever "all." For example, If we were in identical vehicles with identical mass going opposite directions and had a head on collision at the exact same speed, the only difference is I was wearing my seatbelt and had functional airbags and you weren't and didn't, who would walk away and who would be carried away? I win and we had the exact same mass.
Now, let's say I was in a Toyota Corolla and you were in a solid steel vehicle with 100% rigidity that weighed 2X what the Corolla weighs. Again, you don't have a seatbelt or airbags. Who will walk away from a 30 mph crash? Me. You would, again, be carried away because you do not have enough strength to support your body mass at 30 mph. You also have no energy absorption (no crumple zones) in that steel vehicle. Sure, you had more mass but so what... that's all you had.
Now let's go to the sliders and what Jeremy told you. Let's say another 4Runner with no sliders hits you broadside in your 4Runner with sliders and skids and one thousand pounds of gear inside. You definitely have more mass and you have that slider so you should be golden right? Wrong. What is going to happen is this:
The 4Runner hits you at 40 mph right in the slider. You are sitting still, so all your extra mass means nothing in the F=MA world because you have no "A." Your slider then transmits all of the force from the impact into the frame rail. What's going to happen to your vehicle? It's going to bend first, both frame and slider, then it's going to move sideways and up (because of friction of the opposite side tires on the road) at right at 40 mph. Your body won't be moving right at that moment, because there is slack in your seatbelt, so you stay in one position while the door glass rushes sideways towards your head at 40 mph. The side airbags pop and save your life but, because of your sliders transmitting pretty much all the energy into one frame rail, you are not only going sideways, you are going to go up and over onto your side and possibly your top and possibly flip completely. That kinetic energy has to be dissipated somehow, and if you didn't have those sliders, the door and inner crash beams would have absorbed the energy and probably left you rocked but still on your wheels. But because you thought sliders were a good idea in a side impact, you are going to go for a hard ride. The guy that hit you in the other 4Runner gets out to see if you are OK as you are hanging upside down, because 4Runner drivers are cool like that. His energy got absorbed while your energy got transmitted for awhile.
Bottom line, if you have more mass then the other vehicle, and you both are using all your safety gear, and you hit head on, and the crumple zones on both vehicles are comparable, THEN the vehicle with the more mass will inflict more damage to the other vehicle. That is a lot of conditions though and rarely does it work out that way.
Bottom line, more mass does not always win and sliders will prevent door dings in a parking lot.
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STX4Runner
New member
cbreze
Member
I never considered my sliders might help any in a side impact collision. Interesting. Alot of factors would be dependent on the outcome for sure, not just having sliders.
I got mine for different reasons. Number one, they look cool! Also make a good step to access the roof. Also have saved me from door dings by inconsiderate jerk Parker's. Good rocker panel side protection when out in the boonies having some fun. Lots of reasons for me to justify getting them.
OP, just do it!
I got mine for different reasons. Number one, they look cool! Also make a good step to access the roof. Also have saved me from door dings by inconsiderate jerk Parker's. Good rocker panel side protection when out in the boonies having some fun. Lots of reasons for me to justify getting them.
OP, just do it!
The sliders would absorb more of the impact that would have otherwise hit the doors, which would get a lot more damaged and intrude upon the interior of the cab and cause more injuries to the occupants. But then again maybe it would cause the occupants to slam around inside more?
Of course the sliders won't do any good if whatever hits you is taller than them so there is that.
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Engineer
New member
[MENTION=122163]duffdog[/MENTION] .....dude.......
Anyways, While I am a young guy and didn't live through the 50s,60s,or 70,s and almost not the 80s I really appreciate the leaps and bounds that car safety has grown. Do I like that they dent with a slight glance, no but I also appreciate the ability to keep the occupants safe. Thank the powers at be for airbags, collapsible steering columns, shoulder belts, ABS, quality rubber compounds etc etc
Back on topic, As already stated the point to which sliders will help or hurt is situationally dependent. I would never buy them thinking they are going to help in an accident but hey a mans gotta do what a mans gotta do
Anyways, While I am a young guy and didn't live through the 50s,60s,or 70,s and almost not the 80s I really appreciate the leaps and bounds that car safety has grown. Do I like that they dent with a slight glance, no but I also appreciate the ability to keep the occupants safe. Thank the powers at be for airbags, collapsible steering columns, shoulder belts, ABS, quality rubber compounds etc etc
Back on topic, As already stated the point to which sliders will help or hurt is situationally dependent. I would never buy them thinking they are going to help in an accident but hey a mans gotta do what a mans gotta do
83Mule
New member
Sliders are not solid blocks of steel that don't yield and transfer ALL impact to the frame. There will be some collapse as the intrusion of the other vehicle occurs and THAT is of benefit in decelerating the impact and G forces IMO. I certainly wouldn't worry about Sliders being a detriment to the safety of the Truck.
FattyHunter
Member
I might of gotten lucky, Pilot t-boned me going about 35 mph maybe or less, who knows? RCI bolt on sliders, lifted on 285s. She hit me then reverses and her car died right there. Definitely depends on situation, alignment straight afterwards, no frame or damage to sliders. Pictures in link
https://goo.gl/photos/zJsqGtLUPMJ7uEjTA
https://goo.gl/photos/zJsqGtLUPMJ7uEjTA
You know...
I don't think you are a very good engineer. I would not trust your designs at all.
The point of my post was to specifically illustrate that the vehicles "crumple zones" are NOT equal once you add more high-strength steel to one car. In fact, the vehicle with the most steel tears through the other car as if it wasn't even there. No safety equipment came into play in my accident because my bumper simply destroyed 100% of the ford sedan. Our "crumple zones" were not equal. I have no crumple zone in the rear anymore, if you hit the rear of my truck at sufficient speed you will die and I will suffer no injuries. I dare you to do it... I can give you the information for a person who already tried that.
I actually WAS IN an accident where my speed was zero and the other cars speed was 50mph. I had more steel, therefore I did not sustain any injuries. YES, my 4runner was kicked in the air and flew forward about 30 feet, but it does not change the fact that no structural damage occurred precisely because the design of my rigid bumper transferred 100% of the damage and injury to the wimpier car. I really can't understand how you could argue with this. Additionally, I can't understand why you would even put forth the idea that the concrete IIHS data which states: "cars with more metal mass win in every accident" and claim that it is wrong somehow because you seem to believe that vehicles are somehow evenly matched in accidents. It is statistically unlikely that any two vehicles are ever evenly matched and will share exactly 50% of the damage and injury. The statistical likelyhood of that ever happening is so close to zero that it is disingenuous for you to even mention it as a possibility, being an engineer. Additionally, your supposition that installing sliders would make your car "flip" at any greater predictable likelyhood is supported by no evidence and I doubt someone who actually had the time to model this behavior using FEA would ever publish it as a factual occurence. Again that is extremely disingenuous as an engineer to say that your hypothetical situation which has never been modeled or proven amounts to a statistically likely possibility.
Furthermore-- you disregarding my maxima and minima solutions for why installing more metal can reduce the DeltaV is completely bonkers. How can any rational engineer put forth the idea that if you added your own "crumple zone" onto the side of a car by welding on sliders which did not previously exist, you would INCREASE the DeltaV??? What in the :fish: are you talking about? I would LOVE to see how you modeled that with FEA...
Lets take your example and my example and put them together. I have welded on sliders which stick out 100 feet from the side of my truck. You are going to t-bone me by running into the sliders that stick out 100 feet with another 4runner. Are you telling me that when you hit them, they do not crumple? They would not be absorbing the impact and lowering your velocity? And by the time you get to my truck door panel, your velocity has not changed at all? I can't believe you or any other rational person would suggest this.
Additionally, by extending the point where another vehicle hits the sliders PERPENDICULAR to the direction of a vehicle rollover, the torque required to "flip" the truck is INCREASED making it less statistically likely that the truck would flip over. If the sliders were hit from above or below (in your example a car would have to fall from the sky) then the torque required would DECREASE and make it more statistically likely that the truck would flip. Now how likely would it be for any vehicle to strike the top or bottom of the sliders and cause it to flip? I would hazard a guess that it is pretty unlikely. Most people would agree that a traveling vehicle would strike on the same plane as the target vehicle, causing the slider to deform (first absorbing some impact force) and thus able to transmit LESS force to the truck to flip it over.
It is not me who are violating the laws of physics, but you. Change in velocity is increased with less absorbing material in the same direction as the object is traveling, regardless of what that material is. Should the material be capable of semi-rigid deformation, the velocity energy is transferred to the deformation energy required to bend the material, resulting in the conservation of energy and the decrease in velocity of the original traveling body.
I would trust any car I designed to save my life over any car you designed...
4Reak Show
New member
My sliders have Bedliner on them. Does that help anyone figure out this mess?
Sleeter
New member
Lol....I going to venture out on a limb here and guess that you're not employed in a SME field?
In summary slidders might help is some cases, typically low engergy impacts, but probably won't help in high energy situations.
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