4x4 Action Group

I'm trying to figure out at what angle my vehicle would tip over (sideways).

https://www.omnicalculator.com/physics/car-mass-center

How accurate is this?

Sent from my SM-G975F using Tapatalk

Too many variables. Especially with the terrain & what speed you’re at. What I do know for sure is that it’s roll over angle is far greater than we think.

... I think the vehicles specs reasonably reflect standard vehicles measured limits uder controlled tests
... then it modified by your added accessories and load etc be they roof racks, tents etc and whether loads are secured or slide at extreme angles etc
... and further modified by vehicles trail/terrain predicament & attitude ... typically one would think that two wheels defie pivoting points ahead of tipping though speed and momentum etc will further change the dynamics.
... one would have to make a few simplifying assumptions but ...
... ultimately resolveable to force vectors ...

Hunter4x2 wrote: ↑

Thu Aug 22, 2019 12:37 am

As mentioned in posts, too many variables. What I would do is pack vehicle as if going on holiday, then Jack one side up till vehicle slowly wants to lift off Jack( just 7se ropes to prevent it rolling over, mark that angle and gently put vehicle back on ground. Sounds crude but then imho you would get a true roll over angle for that load at that time.

I remember watching some time back that at one of the 4x4 training schools they had a vehicle thingymajig that you drove your vehicle onto this equipment, it would then tip your vehicle until your one side of the vehicle wheels started to lift. They then measured this tip over angle.


Sent from my SNE-LX1 using Tapatalk

And this is why no manufacturer wants you to buy a 4x4 - because of silly shit like above. Hell, you should be blacklisted on all insurance schemes for that

This is my simple method.
Not 100% correct but gives a reasonable indication
When the COM dot crosses the vertical black line you are going over

Wooky wrote:This is my simple method.
Not 100% correct but gives a reasonable indication

Side slope.jpg

When the COM dot crosses the vertical black line you are going over

How do you calculate COM?

Sent from my SM-G975F using Tapatalk

It's not really calculated and hence not 100% accurate.
Basically the two red dashed lines drawn corner to corner in my photo.
As cars are somewhat "box" like laterally, where the two lines cross is approximately where the COM will be.

It just gives an idea on how well calibrated your "pucker factor" is on side slopes

Wooky wrote:It's not really calculated and hence not 100% accurate.
Basically the two red dashed lines drawn corner to corner in my photo.
As cars are somewhat "box" like laterally, where the two lines cross is approximately where the COM will be.

It just gives an idea on how well calibrated your "pucker factor" is on side slopes [emoji38]

My "pucker factor" is the real issue here!

Any excercises one can do to improve the "O-ring" strength? [emoji1787]

Sent from my SM-G975F using Tapatalk

Side slopes will never be a comfortable place for me

Wooky wrote: ↑

Thu Aug 22, 2019 7:09 am

This is my simple method.
Not 100% correct but gives a reasonable indication

Side slope.jpg

When the COM dot crosses the vertical black line you are going over

That was quite a moment. That's as close to tipping over as I've come since I tipped that very same vehicle on it's side about 25 years ago.

Tip over angle is easy. just move the centre of gravity over either outside tyre edge.

it's not bad, it calculates the centroid of mass at a particular angle but it fails to take into account suspension compression - especially on long travel / low spring rate vehicles, and more so on high COG heavy vehicles. eg 4x4, especially lifted 'overlanders' with all the heavy kak and 140l of jerry cans on the roof.

As the actual slope angle increases , your body roll increases at a greater rate as the low side springs compress, which shifts the COG over the tip point sooner than this simple calculation will estimate.

to be very contrary to the above opinions, there are not enough variables. without spring rates and compression information, this lacks the detail to be really useful...

Apocalypse wrote:Tip over angle is easy. just move the centre of gravity over either outside tyre edge.

it's not bad, it calculates the centroid of mass at a particular angle but it fails to take into account suspension compression - especially on long travel / low spring rate vehicles, and more so on high COG heavy vehicles. eg 4x4, especially lifted 'overlanders' with all the heavy kak and 140l of jerry cans on the roof.

As the actual slope angle increases , your body roll increases at a greater rate as the low side springs compress, which shifts the COG over the tip point sooner than this simple calculation will estimate.

to be very contrary to the above opinions, there are not enough variables. without spring rates and compression information, this lacks the detail to be really useful...

In other words lift it up until it nearly falls over...?

Not the best idea but an easy solution.

Sent from my SM-G975F using Tapatalk

Shane wrote: ↑

Fri Aug 23, 2019 2:07 pm

Apocalypse wrote:Tip over angle is easy. just move the centre of gravity over either outside tyre edge.

it's not bad, it calculates the centroid of mass at a particular angle but it fails to take into account suspension compression - especially on long travel / low spring rate vehicles, and more so on high COG heavy vehicles. eg 4x4, especially lifted 'overlanders' with all the heavy kak and 140l of jerry cans on the roof.

As the actual slope angle increases , your body roll increases at a greater rate as the low side springs compress, which shifts the COG over the tip point sooner than this simple calculation will estimate.

to be very contrary to the above opinions, there are not enough variables. without spring rates and compression information, this lacks the detail to be really useful...

In other words lift it up until it nearly falls over...?

Not the best idea but an easy solution.

Sent from my SM-G975F using Tapatalk

that's fine, but you can't jack it up on the chassis - you need to lift the one side on it's suspension - because the high side springs unload as the centroid shifts to the low side. and then you still haven't worked in dynamic loads, like a bump/bouncee or braking or accelerating.

You can feel when a vehicle is reaching it's tipping point. small movements of your own body mass make for big movements in the body's posture at the tipping point. it 'feels' light.

What I had in mind. With a few good stabilisers to prevent it from toppling over!

... unsprung mass , so often a criticised aspect in vehicle specs, probably a benefical stabilising component in tip-over logic...

... also, at the penultimate stage, the cars full rolling mass would increasingly load the sidewalls of the two pivoting tyres ...
... tubeless tyres would be prone to collapse and provide a final limit-breaker to tip-over ?