Link:
http://www.leftlanenews.com/2006/07/...eet-the-press/

by the way, am I the only one shocked by how the GT500 dives under hard braking ? There is something not quite right there...

Opinions ? Feedback ?

 

Suspension tuning, an iron block motor, and forward weight bias...based on everything we have seen and read about this car, I would not be surprised during a hard stop to see this. It is what it is.

 

I'd be less concerned with the dive during breaking, and more interested in the actual stopping distance. That's what really matters, after all.

 

I understand, but don't you think it's quite extreme ? I never seen anything like this before in any car.

 

Nope...

My '96 Cobra used to nose dive like that when I autocrossed it. It had progressive rate springs which took a bit before they set. It was a comfy ride but definitely a lot of lean.

 

A "classic" modern Mustang trait, given how nose-heavy the car is. Probably also a result of the front strut suspension. My '88 5.0LX coupe was pretty bad in this department (similar, if not worse F/R weight distribution than GT500). Very scary in turns.

 

Yeah, I hope no one will have to brake that hard in a curve because I don't know how they'll keep it on the road...

 

Why would it go off the road because of nose dive?

 

It wouldn't, necessarily. But it will ramp up your understeeer so badly that it's likely to cause the front-end of the vehicle to have less mechanical grip, and thus become unable to follow the trajectory in the corner.

Depends upon the driver, but as the automotive journalists have already said, you want to brake in a straight line with this beast BEFORE hitting the corner, THEN accelerate out of the apex.

 

Well, keep in mind he also talked about testing the brakes at high speeds like 70mph. I'd expect the nose to dive pretty severly at that rate of speed.

Ford could dial in a little more brake bias toward the rear. This could reduce the nose dive a little.

You have that backwards. The weight transfer from hard breaking will substantially increase the front tire grip as the nose dives down. This will give incredible grip in the front while making the rear tires loose grip. This is called over steer. When the front tires out drive the rear tires the rear will break loose and the car's rear-end will come around on you in a corner.

 

Have to disagree with you here. While I will concede that front tire grip will increase, the inertia that is being overcome by the hard breaking will still cause the car to understeer if you happen to be turning the wheels and trying to steer...all simultaneously. The grip will not overcome the momentum. Oversteer happens when the rear tires exceed the limits of their lateral traction during a cornering situation before the front tires do - such as accelerating too hard out of the apex of that corner I discussed above - thus causing the rear of the vehicle to head towards the outside of the corner.

Another way to think of it is that ploughing with high inertia will lead to understeer...whereas squatting (hard acceleration) in a corner can lead to oversteer

 

From my personal experience and what I have read on the subject, you both got good points.

Oversteer in a curve with a rwd vehicle can generally be caused by:
1 - accelerating: applying too much power. The rear tires simply can't cope with it and the car rear end will start sliding out.
2 - braking hard: weight will be transferred abruptly to the front side of the vehicle, increasing traction in the front tires but dramatically decreasing traction in the rear ones making it very easy for them to lock up completely (even though nowadays with ABS, trac control, dsc, esp, etc. etc., it's more difficult for this to happen).

In a car like the GT500 with its weight, weight distribution and the way it dives when under hard braking, overshooting a curve (and I am not talking overshooting it big time, because in such an occasion any car won't be able to stay on the road, but I am instead talking mildly overshooting it) could be absolutely lethal.
There are cars and cars, some are more forgiving in a curve when you either accelerate hard or brake hard and I believe the GT500 is not one of them, from what I can see on that video.
Planning ahead for a curve, I feel will be paramount with this car.
I hope whoever will buy a car like this, will keep this in mind...

 

In most cases, the ABS should kick in if someone is jamming the brakes in a quick (panic) slowdown before entering a corner. That will help reduce the likelihood of "flying off the road". The ABS has saved me a number of time in autocross with the front-heavy Mach.

However, as mentioned above, depending on what you are doing when you are in the turn (braking and turning OR accelerating and turning), the car would most likely already be unbalanced, resulting in either the understeering or oversteering condition.

If one is driving like that on public roads, one should most likely be on a track anyway.

To the inquiry at hand, that much dive, while not optimum for a tight track and disconcerting when seen or felt, is indicative of street tuning and the front/rear weight distribution.

The amount of power and torque is what will be tricky for sure to manage.

 

that was an awesome vid!

 

ya, i was actually coming onto TMS to post about this vid and put up this screen shot. So yea... you weren't the only one that noticed that crazy diving. I think this shot makes it look like its got HUGE rear wheels, which is pretty **** funny.