The Swerve test and homologation

[Alex Roux]

Guys

I am sure some of you surf the various forums frequently enough to have come to this post on the Fortuner.
http://www.4x4community.co.za/forum/sho ... p?t=126621
At least on the Patrol forum one can be biased without too much backlash of opposing views!

I have always contended that modern 4x4s roll due to lighter chassis, hence higher centre of gravity, harder suspension suited for tarmac, and lastly, driver error. More Fortuners (an lets face it, there are many) means more rollovers. Thats that. Nothing special about the Fortuner being more susceptible to rollovers. The above link to a debate suggest otherwise, but thats not my point.

I am wondering though how the factory spec Patrol would do in the "swerve test" and more importantly, how will they perform with our suspension mods?...
Yes we are wide, and yes we are very heavy at the bottom, but can I sleep easy at night?

Alex

[Peter Vee]

Alex I had to execute a dramatic braking move with a c4cerius swerve to avoid a P.B who pulled out in front of my oncoming Patrol and offroad trailer... was only doing approx 80kmph... was scary and I would not want to attempt it again... but heck I am here typing this.

Methinks the heavier chassis and anchor at the back helped keep things upright.

Cheers Peter

[Alex Roux]

Scary photo, hence the topic

This is what happened to a good friend of mine on the Stilbaai / Vermaaklikheid dirt road about 10 days ago.
His back fractrued but no permanent damage. Kids were fine, miraculously.

Cruiser.jpg (57.19 KiB) Viewed 4247 times

[Bruin Beer]

For a moment I was afraid it depicted a Patrol.
Than the Lord they were alive.

[ricster]

That is a scary one !!!!!

[Peter Connan]

Alex, I am glad your buddy and his family survived.

there are obviously a large number of factors influencing a vehicle's performance in a swerve test.

I would tend to group them into two cetegories. The first can be named "rollover angle" and includes all the factors that determine a vehicle's rollover angle in a static position, mostly being the track width and centre of gravity height, but also influenced by suspension stiffness, tire sidewall height and pressure and a number of other small factors.

These are fairly obvious, and we must always remember that these are 4x4's and not sports cars.

The other less obvious category could perhaps be named "directional stability", but what is really important here is how easily a vehicle will oversteer.

I believe that a great majority of rollover incedents have more to do with this factor than with the vehicle's ultimate centre of gravity or "rollover angle" as described above. Because when a vehicle is oversteering and hits any obstacle with a tire sidewall, it will turn over much more easily. I have even seen a very wide and low sports car rolling after sliding into a curb.

I firmly believe this is the factor mostly influencing the Frotuner's reputation, as several people have remarked to me that these things are virtually uncontrollable on a wet road. I suspect the full-time 4wd with torsen LSD in the centre diff affects this, but wheelbase is also a significant factor here, and this vehicle has a relatively short wheelbase.

Your friend's cruiser also has (had?) a significantly shorter wheelbase than the Patrol.

Other factors influencing this are suspension stiffness (here stiffer rear suspension and particularly badly matched shocks can be detrimental), tire flexibilty and sidewall height etc.

Fortunately you have to severly taunt a Patrol to get it to oversteer, but I am sure a good advanced driver's course can significantly improve your safety in this situation.

[Alex Roux]

Hi Peter

Helpful thanks. My friend is now upgrading to a Prado III...
I told him, Prado III is ugly and expensive. But I also do not know of dissatisfied Prado III owners...

I think I need to go on one of them driving courses. You cannot overland in Southern Africa without a significant amount of dirt road. And it would not have been as much fun if all were tarmac anyway.

[Gerrit Loubser]

Excellent post, PeterC

I agree that the Y60/Y61 Patrols actually have very benign handling for such monstrous vehicles. The long wheelbase does help here.

The 76 Series Cruiser in the picture above has a wheel base of 2730 mm compared to the Patrol's 2970 mm (Patrol's wheelbase is about 9% longer).

I firmly believe this is the factor mostly influencing the Frotuner's reputation, as several people have remarked to me that these things are virtually uncontrollable on a wet road. I suspect the full-time 4wd with torsen LSD in the centre diff affects this, but wheelbase is also a significant factor here, and this vehicle has a relatively short wheelbase.

I doubt whether we will ever know exactly what the root cause was of the early Tunas' propensity for misbehaving, but I doubt whether the Torsen center diff is the culprit (this issue also affected the 4x2 versions). My pet theory has revolved around inaccurate rear axle location (due to the fact that the springs are attached tot the trailing arms and not to the axle directly, thus requiring large bushes that limit flex excessively unless they are made quite soft) in combination with tyres with low lateral stiffness and cheap shock absorbers. When the Tuna was updated Toyota changed the tyres (to A/T tyres with stiffer sidewalls and specified lower profile tyres) and added electronic stability control. There are different numbers in the Toyota parts system for the shock absorbers now as well...

[Peter Connan]

I didn't realize that the springs are located on the trailing arms, and your theory makes a lot of sense. I am not totally happy with my torsen diff theory, as that should really encourage understeer under most conditions.

However, I recently read a thread on another forum (not the big one alluded to before) of a guy who recently bought a brand-new fortuner. He was very happy with the vehicle untill he recently drove it on a wet dirt road, and he says that even at speeds as low as 30km/h it was continually trying to swop ends. Several bakkies passed him at speeds more than double what he was doing without trouble. So it would seem to me that Toyota possibly still haven't really solved the problem either?

[dieselfan]

Hi Peter

Helpful thanks. My friend is now upgrading to a Prado III...
I told him, Prado III is ugly and expensive. But I also do not know of dissatisfied Prado III owners...

I think I need to go on one of them driving courses. You cannot overland in Southern Africa without a significant amount of dirt road. And it would not have been as much fun if all were tarmac anyway.

Both my neighbours were the biggest Toy fans. The now EX Toy fan had two hiluxes max km was around 40k km within 18 months, first one had gearbox issues second one (Legend 40) clutch buggered up with towing his boat... illegally too. He bought the Prado 3. Two months later his rear air suspension, Prado only has rear, collapsed in Moz.

He now has a Ford Ranger and loves it.

As for the roll overs, perhaps more common BUT EVERY single trip (>500km) I've been on over the last 5 years I've seen atleast ONE hilux / fortuner rolled. My sister has one and hates it, but her hubby loves it and says he just won't swerve.

When I went to Toyota the salesman said the newer "sorted" models were raised and had VDC fitted - Yup higher.

Peter hows the Tritons wheel base compared to the Hilux, neither the Navara nor Triton failed the moose test?

We must also consider the fact that in most of Europe Hiluxes are purely for delivery, no pax, and Fortuners aren't even sold.

Then recall also how the Prado 3 was "banned" in the USA and sales halted for weeks as they were rolling over after launch. Toyota couldn't find out what the prob was, then a local Mag explained weight distribution of the driver and tank...Toy SA said no worries our drivers sit on the right.