Raptor Frame bent
07-05-2011, 01:15 PM
#31
Senior Member
I think it's driver error. Professional drivers would slow down before hitting those bumps, and would have done a pre-run before the high speed run so they'd know where the bumps and boulders are.
Remember, the F-150 Ecoboost that ran in the Baja race broke a wheel bearing on a boulder - even with an almost unlimited budget and racing parts, off-roading will still break things.
Page 17 of the manual gives Ford's instructions for using the Raptor in a Baja event - page 18 includes instructions to pre-run the course before going at full speed.
http://www.motorcraftservice.com/pub.../11f12rp1e.pdf
Remember, the F-150 Ecoboost that ran in the Baja race broke a wheel bearing on a boulder - even with an almost unlimited budget and racing parts, off-roading will still break things.
Page 17 of the manual gives Ford's instructions for using the Raptor in a Baja event - page 18 includes instructions to pre-run the course before going at full speed.
http://www.motorcraftservice.com/pub.../11f12rp1e.pdf
07-05-2011, 02:31 PM
#32
He backed up his explanation and how he came to his numbers. Please explain to us the physics of how hitting a bump works if you are going to call it bull.
I'm not saying you are wrong, but if this guy is full of crap, I'd like to read how and why as opposed to a blanket "that is absurd math"
I'm not saying you are wrong, but if this guy is full of crap, I'd like to read how and why as opposed to a blanket "that is absurd math"
First Absurdity: Assuming that the body does not lift when the wheel rises.
eg: " the truck vertical motion for another small fraction of an inch (no time to respond), and the rest? It all goes into deforming the frame by 1"-2".
Here he assumes the truck suspension is compressing against an immovable point. It is not. As the axle rises, so does the truck body. That's where the extra force/energy/motion goes!
Springs and shocks somewhat decouple the wheels/axle from the frame/body, but they are still connected. Everybody has bottomed out their suspension at some point, even in a street car. After the shocks fully compress (damped by the shocks), you hit a rubber bump stop to soften the metal on metal blow, then the body rises quickly, without the softening effect of the springs/shocks. It's a lot of energy, but nowhere near what is claimed, largely because the body is already accelerating upwards at nearly the wheel rate once the bump stops are reached.
eg: "The bottom of the tire has to move up 12" in .0166 seconds. this is an average speed of 60.24 ft/s"
Run your bicycle with no suspension travel at all into a straight 6" curb. Ouch!
Now make a ramp two feet long onto that 6" curb. Barely notice it.
A kicker is somewhat in between... Not long enough of a ramp to remove the harshness of the bump, but nowhere near the impact of straight wall. The ramp begins the upward acceleration of the wheel/axle/suspension/body much more gently, then gradually applies more acceleration. My guess is that the kicker has as much run as rise, and is a 45 degree angle. Still a very harsh bump, but much different than running into a wall!
Last edited by pfbz; 07-05-2011 at 02:36 PM.
07-05-2011, 02:41 PM
#33
First Tiger of G.R.O.S.S.
You may have to go to the thread and read both his posts. He made the assumption that the kicker was 12" high, and the length of a wheel. He then subtracted an amount for the approach height of the wheel and absorption.
So, he did touch on that.
As far as the "immovable frame" I think he was referring to the amount of Inertia the frame/truck would have when hitting that bump and what force would be needed in order to overcome that force.
So if you have 6k lb truck moving a direction, changing the direction of the backend of that truck to move up so many inches in so many seconds would be so much force... which is where I think he was getting it.
Anyways... I am no math whiz, for sure, but there are a lot of unknown factors since the guy didn't get out and measure the height of the kicker, the length of the approach, the descent side or those kind of details, so those numbers would have to be guesstimated.
What I appreciated about the post was the understanding of the difference between pre-loaded suspension handling a sudden large bump in the road versus a more gradual ramp, leaving the ground where the suspension then can fully extend, and then a gradual decline on the following side.
So, he did touch on that.
As far as the "immovable frame" I think he was referring to the amount of Inertia the frame/truck would have when hitting that bump and what force would be needed in order to overcome that force.
So if you have 6k lb truck moving a direction, changing the direction of the backend of that truck to move up so many inches in so many seconds would be so much force... which is where I think he was getting it.
Anyways... I am no math whiz, for sure, but there are a lot of unknown factors since the guy didn't get out and measure the height of the kicker, the length of the approach, the descent side or those kind of details, so those numbers would have to be guesstimated.
What I appreciated about the post was the understanding of the difference between pre-loaded suspension handling a sudden large bump in the road versus a more gradual ramp, leaving the ground where the suspension then can fully extend, and then a gradual decline on the following side.
07-05-2011, 03:33 PM
#34
Senior Member
I agree with Hobbes on this and the other guy.
The guy in the video is "over running" his suspension. These are stock fox shocks with valving that is a comprimise between street and offroad, if they were adjustable then it may not be as bad. The compression and rebound are set and cant be changed, if you hit a bump at speed that is faster than a shock can react and move its fluid, it in essense locks up which then transmits its forces elsewhere.
Also it is not absurd to have the suspension travel up while the body travels down, go watch any truck or motocrosser jump!
Also, if you hit a kicker at 10 mph, sure it wont be as bad as if it were squared but hit it at 80 and I bet you would notice it a WHOLE lot more!
The guy in the video is "over running" his suspension. These are stock fox shocks with valving that is a comprimise between street and offroad, if they were adjustable then it may not be as bad. The compression and rebound are set and cant be changed, if you hit a bump at speed that is faster than a shock can react and move its fluid, it in essense locks up which then transmits its forces elsewhere.
Also it is not absurd to have the suspension travel up while the body travels down, go watch any truck or motocrosser jump!
Also, if you hit a kicker at 10 mph, sure it wont be as bad as if it were squared but hit it at 80 and I bet you would notice it a WHOLE lot more!
07-05-2011, 04:44 PM
#35
This is the result of idiots driving trucks. Hellooooo, the raptor IS NOT A BAJA RACER. Ford's Baja racer is not an F150 with springs and suspension "tuning". Its a purpose built off road frame with some f150 "components" (mostly if not entirely the engine). The raptor has "more off road" ability than an FX4 but its not an "off road racing" worthy vehicle, the bent frames are just a predictable result.
If any of the morons that damage their trucks in this way had any military expirience they would understand. Military vehicles are rated for all conditions, ergo, a five ton truck means five tons off road, on road the capacity almost triples. Commercial vehicles are exactly the opposite, they are rated for their maximum on road capacity, off road capacity is at best one third of their "rated" capacity.
BTW Ford offers the strongest fully boxed ladder frame in the industry, the dummy that wrote the article doesn't even understand what fully boxed means. If you had taken a pickup by any other manufacturer and put it through the same sort of abuse it probably would have ended as scrap.
Willingly, or not, Ford......
If any of the morons that damage their trucks in this way had any military expirience they would understand. Military vehicles are rated for all conditions, ergo, a five ton truck means five tons off road, on road the capacity almost triples. Commercial vehicles are exactly the opposite, they are rated for their maximum on road capacity, off road capacity is at best one third of their "rated" capacity.
BTW Ford offers the strongest fully boxed ladder frame in the industry, the dummy that wrote the article doesn't even understand what fully boxed means. If you had taken a pickup by any other manufacturer and put it through the same sort of abuse it probably would have ended as scrap.
Willingly, or not, Ford......
I would be surprised if Ford didn't have some sort of warranty monitoring software in the ECU that can detect extreme G's that may or may not void warranty.
07-05-2011, 04:56 PM
#36
Senior Member
hmmm...well i guess thats a lesson in using your daily driver as an offroad vehicle. of course stuff is going to break you are driving on ****ty terrain as opposed to asphalt.
now that being said, i really hope Ford does something about this to add strength and support for future models. they do advertise the raptor as an ultimate offroad vehicle with 100+mph capabilities in 4wd and this seems like a semi-widespread problem.
oh well...im happy with my lariat
now that being said, i really hope Ford does something about this to add strength and support for future models. they do advertise the raptor as an ultimate offroad vehicle with 100+mph capabilities in 4wd and this seems like a semi-widespread problem.
oh well...im happy with my lariat
07-05-2011, 06:38 PM
#38
I am betting that almost everyone who thinks he "abused" the vehicle has no real experience with high speed desert riding, moto or truck.
I absolutely agree that a stock Raptor isn't close to being able to handle race-type offroad conditions, but what that video shows isn't even close to abuse or race-pace in my book, nor is the course anywhere close to what you would experience in race conditions.
I absolutely agree that a stock Raptor isn't close to being able to handle race-type offroad conditions, but what that video shows isn't even close to abuse or race-pace in my book, nor is the course anywhere close to what you would experience in race conditions.
07-05-2011, 07:30 PM
#39
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07-05-2011, 07:39 PM
#40
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From an engineering standpoint if you are designing an "offroad" truck you have to do you due diligence to discover the weakest points in your design and reinforce them if necessary. The frames are designed to bend under extreme forces, like an accident, for added safety. However you can't design an offroad truck with a frame that can be bent by the axle then landing. The frame should have been reinforced in the area of the suspension and the axle to keep it from bending when the truck is landing. Also, if you were designing the weaker point of the two, the axle should bend before the frame does. The axle can be replaced relatively cheaply, but the truck is scrapped when the frame is bent. Seems to be like an oversight by fords engineers, or maybe with "professional" drivers who pre-drive a course before going all out these drivers landed on a downslope softly, and the problem never presented itself.
As in both video posts on the 2nd page of this thread the most force is exerted on the rear wheels when the truck goes airborne and the front comes down first causing the rear wheels to whip down. The black raptor on the jump. The first landing was rough but the greatest force was clearly delivered when the the truck face planted at the bottom of the jump causing the back of the truck to slam down.
Whether Ford wants to take responsibility for a design error is still to be determined, but if I was sitting there with a bent frame I surely would not have videos of me going over tabletop jumps and not making it.
As for Ford, don't advertise the Raptor as a truck that can fly through the desert at 100 mph and have designed a truck with a weak point in the frame above the rear axle.
Good luck to all you Raptor owners in this fight and I hope Ford does right by you.
As in both video posts on the 2nd page of this thread the most force is exerted on the rear wheels when the truck goes airborne and the front comes down first causing the rear wheels to whip down. The black raptor on the jump. The first landing was rough but the greatest force was clearly delivered when the the truck face planted at the bottom of the jump causing the back of the truck to slam down.
Whether Ford wants to take responsibility for a design error is still to be determined, but if I was sitting there with a bent frame I surely would not have videos of me going over tabletop jumps and not making it.
As for Ford, don't advertise the Raptor as a truck that can fly through the desert at 100 mph and have designed a truck with a weak point in the frame above the rear axle.
Good luck to all you Raptor owners in this fight and I hope Ford does right by you.