What happens when the front is MUCH narrower than the rear?

[kuehjo]

[ame]http://www.youtube.com/watch?v=6oYKZ8PT_wQ[/ame]

This is way over the top (I'm more a fan of subtle) - but my question is this...
What happens to driveability when the rear is so grossly wider than the front?
I'm sure its a rocket in a straight line, but what happens in the slaloms??

Thanks!!

 

[ydeardorff]

You know I read something about this in my quest to understand suspension. I forget the source.
But it referred to the Porsche 911 as being the best example of a wider rear than front problem.

Although the look of having the wider rear is appealing to the eyes, it makes the handling worse. So does wider than needed tires. If memory serves, it will induce sliding, and front end drift in corners. The Porsche guys actually prefer it as it can cause for a skilled driver, a predictable response in corners that can make corner transitions smoother and faster.

Funny though. Ive been on this forum for 3 years now, and Ive never actually seen that car move under its own power. I too have different appeals to what works and what doesn't on a car. I think he actually had it for sale at one point.

 

[letterman7]

*laugh* That idiot has been trying to sell that for a few years now. He thinks it's the hottest car on the planet, or at least in his little world. And it's all show, of course, still running a basic 1600 if memory serves.

I can't comment too much about what the ratios will do to cornering rates. I would assume that Yaughn is pretty accurate with his assessment though. I guess it comes down to what you want the car to do as to how you'll set it up in the end. Drag races want the wide meats on the rear, corner carvers would want pretty close to all the same size I would think!

 

[ydeardorff]

*laugh* That idiot has been trying to sell that for a few years now. He thinks it's the hottest car on the planet, or at least in his little world. And it's all show, of course, still running a basic 1600 if memory serves.

I can't comment too much about what the ratios will do to cornering rates. I would assume that Yaughn is pretty accurate with his assessment though. I guess it comes down to what you want the car to do as to how you'll set it up in the end. Drag races want the wide meats on the rear, corner carvers would want pretty close to all the same size I would think!

I didnt want to say, but yes Rick, that car looks like a cross between the back to the future delorean, and some post apocalyptic gun runner movie car. None of the additions make any stylistic, or functional sense from a cars perspective. Its like he bought the whole J.C. Whitney catalog and bolted it on there.

 

[delbertinie]

what in the heck are those shoe boxes glassed over the rear wheel arches supposed to accomplish.

I'll bet that guy watches corvette summer over and over and over and over.................................*insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane*

 

[kuehjo]

It just occurred to me - I remember reading about 6 months or so ago - in Motor Trend, or Road & Track (one of those type magazines) about them trying to set up either a 350 or 370 Z car. They DID make the point that that car got the best skid pad results and overall times when they did NOT use a staggered setup - but I think that was referring more to using the same size wheels, front and rear. At the time I took it to mean the rims were all the same - but now I think it was probably not even just diameter, but cross section too...

I should go look at the NSX - I understand those have dedicated tires for all 4 corners...

And I agree with the above assessments - very Mad Max...

 

[Tullio]

A lot of times what happens is that if you put wider tires on the rear then the rear will have more traction. So, your rear has more traction than the front. When you go around a corner too fast, the car will understeer because the front looses traction first.

If you have the same grip on all four tires, then the front and rear will loose traction at the same time and you will go into a 4 wheel slide which is usually easier to control.

This of course can all change depending on the driver and how he goes into a corner.

I have a 350Z with wider (275) on the rear and less wide (255) on the front.

If I just yank the wheel to one side the car will push forward and understeer. However, if I setup the turn properly (setup the suspension prior to entering the turn), it will stick around the corner just like it should. Or, if I am feeling frisky, give it some gas, swing the rear end out and slide that baby right around *rock on*

It also depends of braking. If you are heavily breaking when entering a turn, the weight transfer will move forward and effectively give you front tires more grip because of the dynamic weight.

 

[tgidavid]

Tullio has hit the mark on the staggered setup. In a perfect world every car would have a perfect weight ratio of 50/50 front and back and drive like its on rails. Keeping the car 50/50 is just one way of balancing the car. When I drove in the SCCA (autocross solo) with the mr2, balancing the car happened in several ways.

1) using staggered tire setup to either increase or decrease oversteer.
2) changing tire pressure
3) adjusting shock compression/rebound (if you have the option)
4) adjusting swaybar preload (if you had adjustable sway bars)
5) using different brake compounds for front and rear to change brake bias

Obviously you can overdo the stagger setup for handling, but putting a huge tire size in the rear would help in a drag setup.

 

[kuehjo]

Soooo - not to overstate the situation, but in these 2000lb cars that we drive, that are ALREADY too light on the front end - this guy's suspension set-up is PROBABLY jacked up for anything but sheer straight-line acceleration...???



Ok - so what about running staggered RIM sizes??? Like 18" rears and 15" fronts. Is there a good reason to do so, or not to do so? I know it was kind of faddish a few years back, but I mean from a strictly PERFORMANCE perspective - can anyone make an argument why you might want to run lets says 18" rears and 16" fronts?

 

[ydeardorff]

Wheel wells aren't the same size?*laugh*

 

[letterman7]

Here in Pennsylvania it's illegal to run two different size wheels *insane*. Ask Warren... he got busted on his state inspection because of a 1" discrepancy.

 

[Tullio]

You can't really make a blanket statement saying if different wheels make a difference, good or bad.

It all depends. Different wheels can mean (but doesn't always mean) different weight and different sidewall height of the tire. Now you start getting into sprung weight vs unsprung weight.

How tall the sidewall of the tire is changes everything.

The Porsche Carrera GT runs stock 19's in the front and 20's in the back if I remember correctly.

Basically, handling, performance and drivability are effected by so many aspects and they all play off one another.

Did you know that Formula 1 suspensions systems are designed with the compression and rebound of the tires in mind?

 

[RazrRob]

If memory serves me right he was trying to sell his car a quite a few months ago for $40000.

What im trying to get an idea on is?

How in is right mind can he justify selling the car for that price when it looks like utter crap with everything that has been done to it.

*insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane**insane*

Even his other car that he has as a video in his youtube section that is suppost to look like a an original batmobile is far from looking anywhere similar.

This guy really knows how to make people not want to buy his car as well as hurtful to look at.