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why 4x4 vehicles have nose down "no exception" ??

8.4K views 39 replies 21 participants last post by  _Bacchus_  
#1 ·
some believe that nose down on 4x4 vehicles are just a manufacturer error
other's believes it's just for car aerodynamic
but after thinking it's gotta be a greater reason for that, otherwise the factory would do a recalling process.

yesterday someone posted on facebook about jeep wrangler flipped over 45 degree "more or less" small rock ramp .. i got stunned !! i mean how is that even possible with these amazing mods he added ??
after replaying that video more than 10 times, i noticed in the first seconds of the video the front wheel height match the rear wheel height "and maybe little higher"
after it flipped over, the wheels in front much higher than the rear wheels.

so it come's to me !! it's not just about vehicle aerodynamics !! it is also about physics and vehicle handling.

look at this picture :



this picture of a car had it's nose up by whatever of coils spacers etc.
regardless about how cool it looks when we do that, it fails on hard off road
now this picture is too long to explain but the bottom line is this :

as long (Fmg"sin") is a lot smaller than (Fmg"cos") on any ramp , your ok.

knowing that (Fmg"sin") increases by hard pressing on gas pedal, high ramp angle and the type of suspension you have .. more harder suspension more better and safer to climb.
and (Fmg"cos") increases by car momentum and nose down low ramp angle

that's why the reason of the nose down and you should never change it with spacer nor coils neither front lift kit if you want to offroad with it.

want to get your vehicle higher ??
buy a full off road suspension kit from trusted company
 
#8 ·
Its A Heep... I Mean Jeep Thing lol
 
#9 ·
"Level" at stock height is what I said. Lets break down the differences; Video 1 we have a highly modified jeep on high traction slick rock with a driver that thinks full throttle is the way to get up the hill. Video 2 is a stock height leveled jeep on a smaller degree of incline in loose soil and being driven by someone that may not be capable of full throttle.

Completely differing circumstances but I believe your point of nose rake has nothing to do with why Jeep number one flipped and jeep number two didnt.

This is still a great topic to debate though.
 
#18 ·
The momentum when turning relates directly to the height of the center of mass and the weight. If the vehicle is heavier in the front, by lowering the front a bit, momentum generated in turns by the back and the front of the vehicle become more similar. Greater momentum in the front than the back can cause the vehicle to lose front traction faster in the front tires than the back tires. Just for this reason, I would make the front a little lower than the back.
 
#19 ·
Properly aimed headlights on an unloaded vehicle will still point up when you load the rear down unless they're auto/manual leveling lights, so that reasoning doesn't work in my head. Also, I find it hard to believe manufacturers would design their vehicles this way when 99% of the miles driven on these vehicles won't be loaded enough to ride level. If the intention was to have the vehicle loaded down, why are the rear suspension links, sway bar links, drive angles, etc. designed at ideal angles for an unloaded vehicle? If a manufacturer is worried about the rear squatting too much under load, go with a progressive rate spring designed for comfort and heavy loads.
 
#22 ·
some believe that nose down on 4x4 vehicles are just a manufacturer error
other's believes it's just for car aerodynamic
but after thinking it's gotta be a greater reason for that, otherwise the factory would do a recalling process.

yesterday someone posted on facebook about jeep wrangler flipped over 45 degree "more or less" small rock ramp .. i got stunned !! i mean how is that even possible with these amazing mods he added ??
after replaying that video more than 10 times, i noticed in the first seconds of the video the front wheel height match the rear wheel height "and maybe little higher"
after it flipped over, the wheels in front much higher than the rear wheels.

so it come's to me !! it's not just about vehicle aerodynamics !! it is also about physics and vehicle handling.

look at this picture :

View attachment 303817

this picture of a car had it's nose up by whatever of coils spacers etc.
regardless about how cool it looks when we do that, it fails on hard off road
now this picture is too long to explain but the bottom line is this :

as long (Fmg"sin") is a lot smaller than (Fmg"cos") on any ramp , your ok.

knowing that (Fmg"sin") increases by hard pressing on gas pedal, high ramp angle and the type of suspension you have .. more harder suspension more better and safer to climb.
and (Fmg"cos") increases by car momentum and nose down low ramp angle

that's why the reason of the nose down and you should never change it with spacer nor coils neither front lift kit if you want to offroad with it.

want to get your vehicle higher ??
buy a full off road suspension kit from trusted company
To cause the vehicle to flip you have to move the center of mass behind the rear axle to flip backward, or in front of the front axle to flip forward. Lifting the vehicle moves the center of mass upwards and reduces the angle required to get the center of mass over the axles.

What happened in that video as others have stated is purely due to horrible throttle control. You can see that it only starts to flip once he has throttled it close to 90 degrees. No amount of drop in the front end was going to save that guy:smile
 
#23 ·
The coefficient of the center of gravitational rollover is inversely rooted the 5th derivative of sin(of the driver's intoxication level) :cheers:
 
#25 ·
You're wackadoo!!! Please explain ye answer :)

Because I know you know that I know you know :cheers:
 
#32 ·
flipping over is more complicated than looking at your car as a simplified point object.
flipping over has something to do with torque because flipping over is a rotating motion.
going down hill and you have short wheelbase and very light in the back, you are going to start rotating forward if you brake hard enough if torque is strong enough to lift the back end.
same with uphill, if your front is light and you have too much throttle you flipping backwards.
long wheelbase is better than short wheelbase, lower car is better than higher car.