SUV rollover

Alright… i’ve debated asking this question given the certain anti-suv fetish some people have here. But I am really curious. One thing that people say are evil about SUV’s is that they tip over easily. My question is this, how much easier will my Chevy Blazer tip over then any other truck or minivan and why? If in fact its actually true.

Your Blazer is unlikely to tip over if it is driven correctly. Take the time to learn how to drive a vehicle with a high CG, and remember that it is not a sedan.

Rate your suv here

A vehicle’s tendency to roll over has to do with several factors, including vertical center of gravity, track (distance between left and right tires), tire friction coefficient and suspension travel & settings.

An SUV has a high center of gravity (relative to its track) and a soft suspension, which give it a tendency to lean over in a turn, increasing the chance of rollover.

Minivans aren’t as likely to roll because their center of gravity is generally lower (less suspension travel allows the vehicle to be closer to the ground) and their suspension is generally stiffer, reducing vehicle lean in turns.

Formula 1 race cars are almost impossible to roll over.

The DOT has published formulas to calculate how easy a vehicle turns over. IIRC, the easiest vehicle to turn over is a Toyota Echo, of all things.

Well that’s only because it weighs next to nothing, no doubt.

Kamandi - I do wonder how many g’s an F1 car would have to pull in a turn to turn over. Any idea? Like a million?

The NHTSA’s New Car Assessment Program gives the Toyota Echo 4 out of 5 stars in rollover tests. The Ford Explorer gets 2 out of 5 stars.

Hmm. I stand corrected. I could have sworn that the article I read (which even published the formula) said that the Echo would be more likely to rollover than anything else.

Man… according to the tests in those links my car is very likely to roll over and has the worst crash resistance… WHOOO… good thing I like adrinalyn… :rolleyes:

Still love my lil truck though.

If you’re referring to the F-1 racers, I think it’s more due to the fact that they create a partial vacuum beneath the car while it’s racing. So rolling an F-1 over would involve getting the car to stop sucking at the ground, as it were.

In 1990 the McLaren team did published some detailed research into the amounts of downforce which was generated by their F1 car at varying speeds with varying wing angles. They were quite keen on demonstrating their state of the art understanding of aerodynamics etc.

For some strange reason, F1 has traditionally referred to 185mph as a golden number - not 200mph or 210mph or 175mph but 185mph - go figure? Anyways, McLaren calculated the following. At 185mph in “Monza” trim, fully 92% of every horsepower produced was spent overcoming wind resistance - such is the degree of downforce produced by an F1 car’s wings.

It’s worth noting that these figures were published at a time when F1’s rear wings were still allowed to be 100cm off the ground. Following Ayrtton Senna’s death in 1994, the maximum height of an F1’s rear wing was lowered to 90cm in a bid to reduce downforce - it worked for about 9 months I’m told.

Nonetheless - back to the original specs… McLaren calculated that at 72mph in “Monaco” trim, their F1 car was generating 750lbs of downforce - enough to drive the car upside down on your ceiling. At 185mph the car was generating 3,200lbs of downforce - enough to pull upwards of 4.5g’s in lateral grip.

Indeed, the wing’s generate such wind resistance that to lift off the throttle at 185mph causes the car to retard in speed at over -1.2g’s - without even touching the breaks.

Obviously, in the context of the original post, such downforce renders the discussion of what an F1 cars true centre of gravity really is - but it’s an interesting thing to calculate nonetheless.

And the reality is that by about 1997 onwards, the F1 field in general has actually reached negative centre of gravity - that is - due to advance in gearbox casings and engine block design and monocoque design, the centre of gravity on a current F1 car is actually LOWER than the car’s axle height - which in effect means that thru corner’s now it actually wants to lean INTO a corner like motorcycle - which I personally reckon is a remarkable thing.

They don’t of course - current F1 cars have less than 2cm of suspension travel and it’s generally conceded that they derive greater amounts of bump compliance thru judicious tyre pressure settings than thru the suspension itself…

I think it’s safe to say that they aren’t comfortable things to drive!

One last thing… if you look at the bottom undertrays of F1 cars from behind - take careful note of the wonderfully desgined upswept tunneling. This is far more important than merely aiding in the creation of downforce you know. Those guys actually do that to shoot dirty air turbulence upwards - way up high 30 or 40ft. And why do they do this? To stop OTHER cars slip streaming behind them. Apparently 10 years ago you could get a tow from 3 car lengths behind. Now you have to be 1 car length or less. Very dangerous stuff and your car overheats pretty quickly at those distances.

F-1 has a center of gravity that is lower than the wheel axels. They will slide before rolling unless the wheels come against something to prevent them for sliding. ( a curb of some sort)

(I was referring to the Echo with the "weighs next to nothing comment.)

Very nice, thorough post, Boo Boo Foo! If the car is generating that much downforce, wouldn’t it calculate out that the effective center of gravity would be below the ground? Thus making it impossible to roll the car over? Brain hurts…

Of course there’s the issue that GusNSpot mentions, relating to tire grip. This is really true of all vehicles, though. If you’ve got bad enough tires, you won’t even be able to roll over an Excursion!

Car and Driver (Magazine TM) about two years ago mentioned that the single most deciding factor in whether or not a vehicle was prone to roll over was whether it had two doors or four doors.

The rollover rate for two door vehicles versus four-door vehicles indicated a gap bigger than any other single vehicle difference.

They implied that if you wanted to make the single biggest reduction in rollovers, and you looked at a list of rolloever trends among vehicles, you would reduce the most rollovers by reducing the number of two-door vehicles.

Just thought I’d toss that into the fray.

Was an explanation offered for the discrepancy? I am curious as to whether it was a comparison of statistics for reported accidents, where the driver and howthe vehicle was driven could have an influence, or some engineering test which discounted everything except the structure of the vehicle.

I was being facetious about the F-1 comment.

As mentioned above by GusNSpot, the car will slide rather than roll, unless it hits an obstacle that flips it over.

Sorry about spawning the hijack, but that was a great post, Boo Boo Foo. Welcome to the SDMB!

This sounds to me like an example of correlation without causation. Adding or removing doors doesn’t directly change a vehicle’s stability in a turn. There are likely other factors involved here.

Kamandi, Go alien,

I agree that it is just a statistic. Obviously, other factors are contributors…like young males between 18-25 driving mostly two door cars…and most likely to drive at excessive speeds, etc…most likely group to cause roll overs.

I guess what they might have been getting at is that you can’t just look at rollover stats in SUVs and blanket-blame SUVs.

Maybe it’s the user, the type of user…the type of use. Maybe it’s the design and these factors hand in hand. But even two door SUVs rollover alot less than four door SUVs.

Maybe you could draw the conclusion that responsible drivers are no more likely to roll an SUV than a sedan. But maybe the SUV rollover data (making SUVs look bad) is a product of the fact that certain types of people have gravitated towards SUVs and tend to drive them in ways that are more aggressive than regular sedans.

Again, it’s all to demonstrate that data (especially when used to say ‘this causes that’) needs to be compiled more thoroughly, while understanding how misleading cause/effect data interpretations can be.

Well, neither of the sites in this thread have tested my car, a Land Rover Discovery II.

As you can see by some of the pictures on this site-

if I am going to roll over, I would like to be in my car! Especially when looking at the damage sustained by Ben & Tommy.

And I always thought that the primary factor in rollovers was how the vehicle was being driven… :smiley:

I know for a fact the Ford Explorer falls over going 10mph.

I also know for a fact the Ford Explorer, while only slightly damaged from falling over, costs over $1000 to repair.

I ALSO know for a fact people like Ford Explorers so much they pay full blue book for a Ford Explorer with a banged up side.