This is like saying cowl shake in a convertible mustang is a safety feature

I am going to have to disagree with this one. The structure of modern cars is good enough that any design in relation to the car's stability due to chassis flex is nominal. It would be even more unnoticeable in wet conditions as transitory loads are even less. Perhaps by throwing a cage into an 80s Chrysler LeBaron might have a profound effect but caging an Evo is different. If anything it allows the suspension to work as designed and helps keep the car on the road.

 

How would adding something into a car after all the design work has been done help make it do what it was designed to?

If the car had been designed with a cage in it, I could understand what you are saying. But the car was not designed that way, so the suspension was designed to function the way that the car is built.

Chassis flex in a uniboody car and cowl shake in a body over frame car are totally unrelated.

Transitory loads are reduced in wet or slick conditions, since the rubber on the tires is not sticking to the road the same as it would in dry conditions. Something has to absorb the extra load, or the car would try to put down more than the tires can handle in the conditions. By stiffening the car to the point of almost no flex at all, it will handle more like a go-kart, which, if you've ever driven on a slick surface, is more prone to spinning out.

As far as the "The structure of modern cars is good enough that any design in relation to the car's stability due to chassis flex is nominal." You just agreed with me completely. From what you just said, it seems you are agreeing that the chassis flex is designed for stability. If you mean it in another way, please reword your response in a way that more specifically zones in as to the concept you are speaking of.

 

He's talking about caging an evo. The whole point of tuning is doing what the factory did but better. Why do we turbo our cars? Because we want it to be more powerful than it was from the factory. I don't know anyone that would put a roll cage or even a roll bar in a car that was stock suspension wise, at least not a lancer. Plenty of rally cars have cages (hell all have cages) yet they have no problem maintaining control on dirt, snow or ice.

 

well... their suspension and their skills are honed for that kind of driving. If I left my car dropped and as stiff as it is. Then tried to drive it in snow next winter, due to the stiffer car im sure it would spin out much easier. Im also not skilled at controlling it, nor is the car set up for it. Just a thought on that side.

 

I understand that he is talking about putting a cage in an Evo, however, nothing was said about having an aftermarket suspension. He said that it helped the suspension to do what it was designed to. If the statement had read that it helped an aftermarket suspension do what it was designed to do, I would still have questioned this, because most aftermarket suspensions are not designed in a car with a roll cage.

Rally cars also have professional rally drivers that slide around corners on a closed course while wearing helmets. None of these elements enter into the conversation of caging a street car.

Rally cars are extensively reworked, and are more like a custom built creation than the cars that they look like. As with NASCAR, which was brought up earlier, because those cars are basically just a giant roll cage with a thin metal body and designed specifically for race use. The cage in both cases is actually integrated into the chassis in some way or another, and used in conjunction with other equipment. They are also used on closed courses, not driven every day on the roads.

I understand what the point of tuning is, and it is to make you machine funtion better for what you use it for. However, if your use is back and fourth to work, school, or just driving around town, a cage is not a wise idea. If it is used for the same purpose, but occassionally sees track use, the ideal situation would be to have a bolt-in cage that you put in when you get to the track, and also disable the factory safety features. On a track, a roll cage becomes a totally different tool that on the street.

 

I agree, and as I said earlier I would never condone caging a street car. I think if you occasionally track the car, a roll bar is a far better option.

 

I agree with no bar in a streetcar is the way to go.

What kills drivers the most, is the top of the windshield, when their head hits that and snaps their neck. If you get "T" boned from the drivers side, your head leaves the confines of the car, and hits the "Vehicle" that hit you. With either scenario, a roll bar offers no help. "T" bone with a cage, your head might not bust the window and strike the other vehicle, but it will now accelerate faster (your head) to strike the top of the door...........same result.

If you compare the crashes from Indy cars/Nascar from 30 years ago, you can see that they tried to make the cars like"TANKS", so they can crash hard, and race another day. USUALLY at the expense of the racedrivers lives. They learned that energy dissipation is what saves drivers. The worse the car blows apart on impact, the better the driver fares, and vice versa. I say you want your UN-helmeted head, as far away as possible from any object in the car, and that includes a roll cage. Not to mention your extraction might also be hampered should the cage fold up and trap you in there. Tons of scenarios, but dump the "Cool factor" in favor of a logical factor. Cars now adays, have built in roll "cages" in case of a rollover. This car had NO CAGE, yet the energy dissapation, and the built in crumple zones did their job. Guy walked away. (he is on this site somewhere.) Visually put a roll bar in there, I think he wouldn't have fared well at all. Just my 2c.............Ok, maybe 3c.

Lets also mention the DANGERS of 5 point seatbelts in streetcars, the SUBMARINING and lacerating of livers and aortas, which can kill FAST, in minor accidents. Go 3 point ONLY in your street cars. 6 point MINIMUM in racing applications. Save your A$$.

 

good points. That is quite the hit that evo took... wow

 

Isn’t this what modification is all about?

This is assuming that the design is optimum which is a really big assumption.

Not really. It was just an extreme example to make a point

??? Transitory loads are reduced so something has to absorb the extra load? (paraphrase)
By stiffening the car’s chassis you allow the suspension and tires to do their jobs. Even if some chassis flex is designed in to the suspension design do you really believe that a cage can actually increases stiffness enough to produce a handling problem? This is especially significant as you mention poor weather conditions where the stiffness of the chassis would have a lesser effect and not a greater one. How does a kart have anythign do do with this? We are still talking about stock suspension.

I did not agree with you. Sorry If I was unclear. My point was how much structure can actually be added by a cage so that it reduces chassis flex beyond the design and ability of the suspension? It would have to be a very soft chassis.


I agree that a cage might not necessarily improve the stock handling of a car but it is not a good argument to claim that it can adversely affect it – especially in wet conditions when the car’s dependence on the chassis structure is actually reduced.

 

Modification is about changing systems to make them work better together. As another member stated, who in their right mind would cage a car with a stock suspension?

No assumption was made about the design being the best it could be or not. All that I was saying is that the systems were designed to interact with each other in the best way possible. By changing the way that one system functions, you will change the way another functions.

Why go to such extremes with you examples that it goes to be something totally unrelated? At such point that somebody does that, the conversation goes from intelligent to complete BS, as is the case with alot of others on this topic.

The weight is still going to attempt to transition from front to rear or side to side the same it would with the throttle or steering input that you give it. Factory chassis are designed in such a way that you may not get the most performance out of it in optimal conditions, but will still remain safe in poor conditions.

The example of a go-kart was used because that is the easiest thing that everybody should be able to relate to that will have that kind of behavior. Suspension on a go-kart is about the stiffest you will find, as well as the chassis. This is because of their small size and lack of suspension (in most cases). They will handle like a dream, ride like crap, and spin out very easy or dirt, water, or ice. Which, when you stiffen the suspension and chassis on a car, will also be the case.

Again, as explained, the suspension is designed to function to it's safest potential with the factory chassis. When the chassis is stiffened, you may increase performance but this will be at the expense of safety. Face it, even though you may think your EVO is a race car, it is still just a street car.

Let me give you an example with this one... take a bone stock car, no modifications (I'm sure you can find one somewhere) and drive it around a road that you are familiar with in bad weather and have somebody video tape the speedometer and how the car handles on the road. Now, take the exact same car and have them put a roll cage in it to get the car nice and stiff (you can leave the stock suspension or modify to a stiffer setup, I don't care either way) and take it down the same road in the same conditions with somebody taping again. Replay the tapes side by side and you will notice that you have to slow down more in the modified car to take the corners than you do in the stock one. That is the negative effect during bad weather. I have experienced this first hand. All the theory and method you can possibly explain will not lead you to expect this, but it will happen.

When coupled with the original systems on the vehicle, a cage will alter the funtions to a point in which they are not designed to handle. Every modification that you do will be at the expense of something else. Suspension and chassis stiffening will improve handling in good conditions, but will make the car a more harsh ride and much less predictable on slick surfaces. Power adders will make the car faster or quicker, but at the expense of reliability and longevity. That is the bottom line on modifying. Unfortunately, we all pay the price to play.

 

I do believe we are straying from the purpose of this thread.

Please understand that I do not think a cage is appropriate for a street car – it is not. I however, do believe that your theory that the increased structure a cage can provide will have an adverse effect on suspension dynamics is flawed.

For a cage to have any effect there would have to be a great deal of chassis flex engineered into the suspension. This is simply not the case with modern cars and the effects of adding a cage would be so nominal in this regard it is truly not worth mentioning. In the wet, on dirt or ice the loads the chassis is under would be even less, hence less dependence on the chassis.

After contemplating your example comparing 2 cars with cages and suspension changes I believe I understand where you are drawing your conclusions from. You are completely correct that a significantly stiffer suspension will result is less wet weather grip – this is very basic. A softer suspension, within reason, is faster in the wet. For a cage to have a noticeable effect it would have to be attached to a car with the structural integrity of a box of Kleenex.

Note: Please don’t assume to know how I perceive the Evo. I am well aware that it is a street car – albeit a very good one