Ok so hopefully this isn't as stupid a question as the title makes it seem, and I get some sensible answers.

Basically, I currently have a Seat Ibiza. So a small-ish hatchback. It currently has poly bushes, kw v3 suspension, new ARBS, strut braces blah blah blah. And it handles reasonably well.

I used to have a 306 gti-6 and standard, it probably out handled my Ibiza at the moment.

Everyone knows Clios handle really well out the box too.

So whats the reasoning. They're all small-ish hatchbacks with a (generally) similar suspension set up. So what makes them so different to drive? From what I've seen, its not spring and shock rates, its not bushes etc.

Is it smaller wheels (Stupid big brakes need stupid big 17s to clear them), is it the chassis (and if it is, what about the chassis is it) or am I just oversimplifying and its a combination of all those things.

 

There made up of totally different parts the weights / chassis are different the hole cars geometry will be different to the next lol thats like asking why dose an apple taste different to a mars bar

 

Using a 172 and my Ibiza as an example - the weights are within kg of each other and geometry is adjustable.

I'm pretty sure me changing the geo to that of a clio won;t make it handle the same (trust me it won't - I've tried a lot of geo set ups)

How is the chassis so different that it makes that much of a difference? They're roughly the same weight, width, length and height. Theres stiffness, but is mine worse because it's stiffer - then why do people add bits to make the cars stiffer.

Personally I think its nothing like an apple tasting different to a mars bar, but thats for your well thought out, informed answer

 

Tires make a difference.

 

You have to remember things like the castor and camber angle. For example the front hubs on a 3dr cossie has different geometry to 2wd saph front hubs. The 3dr hubs give better turn in but less stable. So there are small things that will differ from car to car depending on what the designers wanted the car to drive like.

 

I deliberately didn;t mention tyres because they're so easily changed, but I agree they make the biggest single difference on my car.

I understand that those things are different, but they're also fairly easy to adjust. And adjusting them alone won;t make one car handle like another.



I'm also aware that handling is very much subjective. And I'd imagine that both cars will actually have very similar grip levels. Its just that in one, you feel like your going to die at every corner, and the other feels very safe at the same speeds

 

Theres far too many factors that make them different there totally different cars like the wheel base length its width (roughly the same could make a massive differece to the way it handles lol) its centre of gravity there is proberly a list as long as my arm

 

Well proberly that list is what I'm looking for then

 

There just plain and simply different...

Weight
Geometry
Shape

All have different effect's on physics.

 

Many many many books have been written about vehicle dynamics. It's an enormous subject.

There are countless factors that will influence vehicle behaviour.

The list is literally as long as your arm. Every aspect of the vehicles design can influence its handling really, from weight distribution and centre of gravity, suspension geometry, which is a hugely complex area on it's own, steering geometry.

Things like the static ride height, camber, caster and toe angles are only a tiny part of it to be honest.

You could take two cars of similar weight, wheelbase, track, and set their ride heights the same, set camber, caster, toe and ride height/damping exactly the same, but they'd still handle different, because the suspension geometry will still be different, so as the suspension compresses, it will have a different effect on wheel position to the other car. Then you've got things like roll moment and things to consider, as no two cars have their centre of gravity in the same place.

There's some good books out there on the subject, but it's massive, and some of it is a bit of a mindfuck unless you're an engineering maths genius

 

steering wheel position is a major different
just because it feels different can be just feel

also steering ratios brakes confidence it it going round that corner all change your driving and thus how teh car feels

if the clutch pedal is badly placed you will be paying mor attention to that than th next corner and you can over run, etc etc etc if all little cars were the same it would be a boring place to live
i liek to think when they design a car they think 'how can we make this better than XXXX car' but i expect its more likely they say how cheap can we get the hubs made and how can it be done cheaper

 

Weight distribution, base suspension settings (caster/camber etc) are the obvious ones.
But even if you say take a corsa and set the geometry to exactly the same as a clio (Ive had a clio and a corsa both running on EXACTLY the same geometry front and incredibally similar rear) it still wont handle anywhere near as well.

The way that the arms are located plays a massive part, as it changes how things alter when the car leans or brakes etc.
A key one different between the clio and corsa b for example is how toe changes during compression. If you compress the suspension on the clio, the toe doesnt change much, but on the corsa it does, so when you turn into a bend and the car rolls the change in suspension settings on the corsa hinders it from cornering as well.

Massively complicated subject though and one I only have a very basic knnowledge of TBH


My corsa xe and clio 172 are very very similar on paper, similar weight, not massively different weight distribution (corsa slightly more nose heavy but no a huge amount), they have same wheelbase and track more or less, static suspension settings are the same.

Its only really the things like steering arm location and bottom arm setup that make such a huge difference to the way they each handle. And sadly that is just about the most difficult thing to change on a car really! Easier to put a different engine in or whatever than start trying to alter the location of the rack and the type of bottom arm setup used etc.

 

More importantly, why do cars that were judged as great handlers back in the day by the press etc suddenly become terrible handlers ( compared to cars they were perceived as being better or equivalent to in terms of handling ) 20 years later.......??

 

What you've said is kinda what I was getting at. My car isn;t particularly far off a clio in shape/size/weight etc, yet even with a fortune spent on suspension and varying geometry changes, its still not as good.

Dynamic changes isn;t something I had thought about TBH, but obviously thats going to matter.

Just to point out too - I don;t really want to go changing stuff to make my car handle as well as another car. I was just purely wondering why it didn;t when at the end of the day, they're all basically the same.

Anyone know any good books to read on it?

 

Ps

Another good example is a rwd saph and a 3 door.

Swap the hubs off the 3 door onto the saph and it handles better.

Even though afterwards you have:
exactly the same toe
exactly the same camber
exactly the same caster
exactly the same weight distribution
exactly the same suspension rates (dampers / springs etc)

Just purely down to the geometry of the steering arms on the 3 door hub.


Mike Rainbird would be a good one to ask about the exact differences for that example as in my case I started with the better 3 door ones so have had no reason to put them side by side and compare the exact differences etc. But I do know its a well renowned fact it makes a significant difference.

 

Pps

A big percentage of what I know about suspension geometry I learnt from Alistiar Olsen on here, not sure how far "Killie" you have on your location is from Oban in scotland but if you are near by you should take him out for a pint and a chat

 

^^^^ did they have the same tires on em ^^^^

 

Its miles away. Your probably closer

 

I think this is what Massivewangerswas alluding too also...

 

Yes, literally the same tyres, I dont just mean same make, I mean the actual ones, as I have made up adaptors to allow me to run all my vauxhall track wheels on the renaults.

 

Well you'd still be better seeing him, simply because he knows FAR more than me!

 

once geomatry is within a knats cock its all about feel. feel instills confidence which in turn creates quicker speeds. so, hen a seat and clio are on a par hp wise and have equal setup's you will probably be quicker in the clio as its feedback gives you confidence and as you have said feels as though it handles better. tyres though are the single biggest thing when pressing on a bit wether it be a car/bike

 

This book is as basic as they come, but might help you get your head around some of the concepts involved. It's main focus is single seater type cars, but it does cover bits and pieces on saloon cars too. It's not hugely scientific in many ways, but does put it into more simple terms: http://www.amazon.co.uk/Competition-...3622198&sr=1-1

These two are considered to be the bibles of vehicle dynamics by many:

http://www.amazon.co.uk/Fundamentals.../dp/1560911999

http://www.amazon.co.uk/Race-Vehicle...3622244&sr=1-1

Light reading they are not, but if you want to see what really goes in to the thinking behind vehicle suspension, they'll give you some ideas.