UK-POLOS.NET - THE VW Polo Forum

Admittedly I have car from my old leon that rides on much bigger and fatter tyres but GTi feels very light going into corners. The guy sold the car we new but cheap tyres, do you think that a better make such as goodyear will improve the handling or do I need to get power steering adjusted / car lowered to imrpove response ?

Still enoying the new car, not so happy with the quoted £650 to make my paintwork look like new !

Neil

tyre mean so much really they do think of the weight of any car, and then think whats the point of having all this power if i cant get it on to the tarmac, thus equaling quality of tyres plays pretty much the most important part of handling its where the car meets the road, and the average area each tyre has contact with the road is a man hand span, so all that power and going in to corners you have at most 4 hands worth of rubber stopping you from hitting that post, lol tyres are pretty overlooked i would say, very important lol excuse tha essay + lowering the car will obviously help the handling and stop the body roll in to and out of corners

As PoloCornwall says, quite simply the higher-quality your tyres are, the more grip and better handling you will have and lowering will certainly help matters as it will reduce the body roll considerably plus lower your centre of gravity

What's up with your paintwork?

Loweing dosnt effect handling, or the centre of gravity. Its the stiffer springs that do

Bought car two weeks ago fairly cheap at sub £5k,but paintwork needs attention to remove :-

1, Two keylines to pass rear quarter + very slight ding.
2, Peppered Bonnet (only down to white base laser), but quite heavy.
3, Surface blemishes on drivers door and rear quarter.

Best paintwork price so far is £650 to basicall remove all dings and respray half of car + bake in over. Not a bad deal and prob. worth doing as I want to keep the car for two years +.

Still pleased with the car, it may not be as fast as the Leon, but certainly appears to be better built, like the way the hatch thuds when closing it !

Might be worth looking at how much a full respray would cost

stuart_hatch wrote:Loweing dosnt effect handling, or the centre of gravity. Its the stiffer springs that do

If you lower anything closer to the floor it will effect the centre of gravity as its getting closer to the floor?

PoloCornwall wrote:

stuart_hatch wrote:Loweing dosnt effect handling, or the centre of gravity. Its the stiffer springs that do

If you lower anything closer to the floor it will effect the centre of gravity as its getting closer to the floor?

See that's what I understood to be the case too

stuart_hatch wrote:Loweing dosnt effect handling, or the centre of gravity. Its the stiffer springs that do

compare a van and a car with the same springs. the van's c of g is so high it's ridiculous - so cornering has a bigger moment because the c of g is so high compared to the roll-centre of the car.

if you had the c of g in-line with the roll centre, you would have much less moment when cornering. so lowering helps in that case.

edit: you can lower too much, effectively increasing the distance between the c of g and the roll-centre, so the car can roll MORE if you lower too much.

If you want improved handling, lowering is not the way to go. If you want it for just looks, and dont care about handling at all, go ahead.

The reasons are as follows:

Many poeple mistakenly believe that lowering the car reduces body roll due to a lower centre of gravity. In reality this is very rarely the case. This is due to something called the roll centre of a car. If you dont change the roll centre, the centre of gravity change makes no difference. Heres a simplistic example of why lowering doesnt affect body roll...

imagine you have a regular house brick, sat on another housebrick made from jelly, all sat on two planks of wood, all one on top of the other. If you push the top house brick to one side it will roll over a certain amount. Now remove one of the planks of wood and push the top brick with the same force. It will roll over exactly the same amount even though the whole contraption is lower.

So why do lower cars seem to have less body roll then, the answer is that lowering springs are a little stiffer, nothing else. So to improve body roll you may as well just get stiffer, not lower springs.

Now lets think about suspension travel. UK roads are bumpy, and youd be surprised how much the suspension moves around. You need a suspension setup that is suited to these roads. If you look at the tarmac spec rally polos, they actually have totally std ride height. Not cos of the rules, but cos it works best. Shorter suspension travel means the car will bottom out over larger bumps and cause a loss of control.

This effect is compounded by the fact that if you reduce the suspension travel by lowering the car, you have invariably fitted much stiffer springs, which will prevent the suspension from being able to soak up smaller lumps and bumps. So you come flying into a bumpy corner and your overly stiff suspension just skips over the bumps, making the tyre lose contact with the road and sending you into a hedge. Whereas a std set up would have sent you through there no problems.

Then theres the suspension geometry. The polo suspension is designed to be set at a certain geometry, and as the suspension is compressed, this changes, deliberately, and is all designed to work together to make the car handle properly. By lowering you mess around with this geometry and risk adversely affecting the handling even more.

Also it commonly seen that a lowered polo tends to sit 'flatter' than the std 'arse in the air' stance. This means the car tends to understeer more.

stuart_hatch wrote:This is due to something called the roll centre of a car. If you dont change the roll centre, the centre of gravity change makes no difference.

edit: if this sounds arsey - it's not supposed to!

i agree with what you are saying about the design of the geometry and so on, but that quote is wrong. it's the gap between the roll centre and the c of g that causes the body to roll due to a moment being set up between the two when you corner. if you lower the c of g to match the roll centre, you will get zero roll no matter what your springs are made of.

however you are right about the suspension geometry, lowering often lowers the roll centre too much - and therefore the gap between the two can increase - causing more roll.

i'm not saying that the gap increases or decreases when you lower a polo - and less body roll is mostly down to the springs as you say. I'm just pointing out that the lower c of g may reduce body roll in the case where it lowers the gap between the roll centre and c of g.

the design of the polo does not place a priority on body roll, I am pretty sure that lowering the car and keeping the same spring rate would reduce body roll even though the suspension geometry changes.

this is a good article expaining why lowering may increase body roll

http://e30m3performance.com/myths/Weigh ... nsfer2.htm

and the first page shows the right reasons to lower a car (reduced weight transer)

http://e30m3performance.com/myths/Weigh ... ansfer.htm

stuart_hatch wrote:If you want improved handling, lowering is not the way to go. If you want it for just looks, and dont care about handling at all, go ahead.

The reasons are as follows:

Many poeple mistakenly believe that lowering the car reduces body roll due to a lower centre of gravity. In reality this is very rarely the case. This is due to something called the roll centre of a car. If you dont change the roll centre, the centre of gravity change makes no difference. Heres a simplistic example of why lowering doesnt affect body roll...

imagine you have a regular house brick, sat on another housebrick made from jelly, all sat on two planks of wood, all one on top of the other. If you push the top house brick to one side it will roll over a certain amount. Now remove one of the planks of wood and push the top brick with the same force. It will roll over exactly the same amount even though the whole contraption is lower.

So why do lower cars seem to have less body roll then, the answer is that lowering springs are a little stiffer, nothing else. So to improve body roll you may as well just get stiffer, not lower springs.

Now lets think about suspension travel. UK roads are bumpy, and youd be surprised how much the suspension moves around. You need a suspension setup that is suited to these roads. If you look at the tarmac spec rally polos, they actually have totally std ride height. Not cos of the rules, but cos it works best. Shorter suspension travel means the car will bottom out over larger bumps and cause a loss of control.

This effect is compounded by the fact that if you reduce the suspension travel by lowering the car, you have invariably fitted much stiffer springs, which will prevent the suspension from being able to soak up smaller lumps and bumps. So you come flying into a bumpy corner and your overly stiff suspension just skips over the bumps, making the tyre lose contact with the road and sending you into a hedge. Whereas a std set up would have sent you through there no problems.

Then theres the suspension geometry. The polo suspension is designed to be set at a certain geometry, and as the suspension is compressed, this changes, deliberately, and is all designed to work together to make the car handle properly. By lowering you mess around with this geometry and risk adversely affecting the handling even more.

Also it commonly seen that a lowered polo tends to sit 'flatter' than the std 'arse in the air' stance. This means the car tends to understeer more.

yea you are right in a way, but you contridicted yourself by saying it does help ( a bit ) and your right about geometry thats why after lowering you should always take your car to have camber/caster tracking etc.. i agree about alot of the big drops are just to do with looks but its physics mate, the lower you are to the ground the less lightly you are to roll/body roll, ever tryed to flip a racing go cart? it wont happen their about a mm of the ground i mean they dont have suspension, but you would be more likely to roll a polo without suspension with a higher c of g than you would a go kart with no suspenion which pretty much touches the floor

(again if i sound like i having ago i aint) hehe

i gets ya, not a thing that bothers me anyway, im on colilovers

People beleive that lowering reduces body roll because the springs are always shorter, and shorter springs mean less room for flexing and therefor to allow for shorter springs you reduce the area in which the springs can compress meaning that the car in theory cannot roll as much. If the springs do not move much it means that the car will not roll as much.