Cheapest Method Of Uprated Handling

[Yumma]

Hi, I have had my T Sport for a year or so now and while I love it I recnetly bought a RWD summer car and all of a sudden the T Sport is feeling a bit nose heavy, understeery and lacking in traction. Obviously there are significant differences between FWD & RWD cars which I fully accept and the T Sport is damn quick down a twisty B road and does handle very well. But I'd love to get it all feeling more positive and grippy, plus any added stability and improved traction would be welcome too.

What do you rate without spending a fortune. Has anyone lowered their car and does this help or does it upset the handling by causing the car to bounce and skip over uneven surface? I was looking at Springs by Tein, Spax and TTE (Actually made by Eibach for Toyota TTE) do you rate these or are ther better ways to improve the handling for under £200?

By the way I am running the car on top quality Dunlop SP Sport 01 Fast Response tyres all round and ther is little scope for improvement on the rubber front. Also Toyota recently replaced my bushes and gaiters for me so little scope for improvement there either.

What do you guys and girls rate?

Many thanks

Yumma

[cfc1]

In not any particular order, but when all are fitted you will find a big difference...

!6" wheels with 195/45x16 Toyo tyres

Tien or TTE lowering springs

Uprated anti-roll bars (sway bars) front and rear... Whiteline are good (if you can only afford one set at a time do the rear bar first)

Out of this lot I think you might find the anti-roll bars will give you the best improvement.. but will be better if you can do it all.

[gar]

or a set of stabilisers

[Raeman]

In not any particular order, but when all are fitted you will find a big difference...

!6" wheels with 195/45x16 Toyo tyres

Tien or TTE lowering springs

Uprated anti-roll bars (sway bars) front and rear... Whiteline are good (if you can only afford one set at a time do the rear bar first)

Out of this lot I think you might find the anti-roll bars will give you the best improvement.. but will be better if you can do it all.

Why would 16" wheels make a bigger diference, when the car is designed to take 15" wheels?

Not arguing, just curious.

[z-tune-z2]

Any idea how much it would cost to have a garage to install the new springs and strut braces? I haven't the foggiest on how to do it properly myself! Wouldn't trust myself with such tasks either!

[cfc1]

Why would 16" wheels make a bigger diference, when the car is designed to take 15" wheels?

Not arguing, just curious.

When you fit bigger wheels you need to lower the profile of the tyre to keep the same rolling radius, a lower profile tyre won't flex as much which will make the car more stable with a better contact patch on the road, also normally when fitting lower profile tyres in most cases you end up with a slightly wider tyre, this makes the contact patch bigger creating more grip.

I will also point out why I said I would do the rear bar first if I could only do them one at a time.

Swaybars.. or Anti-Roll bars as they are called in the UK (Swaybars is the Aussie name).. link the 2 corners of the suspension together.. when you corner, and your car tries to go down on one side, the car resists this rolling tendancy (bodyroll).

Most cars are designed to slightly understeer.. as this is easier for the average driver to cope with, rather than having oversteer where the back end can step out and catch you by surprise.

The stiffness in the rear is increased, which loads the rear wheels uneavenly and reduces their grip a little, this allows the front to be more evenly loaded and gives a lot more front end grip. Remember.. it's the front that steers the car.

A rear anti-roll bar on a FWD car will give better traction through the car and generally reduce understeer.

Also.. on a car that has been lowered quite a bit (more than 30mm) an uprated rollbar will stop the suspension from bottoming out.. ever seen a lowered car "bounce" round corners and bends?.. this is because of the bodyroll. the car leans over and compresses the suspension, then when the car hits undulations and bumps in the road, the wheel leaves the ground and the car looses grips because it has ran out of suspension travel. an uprated antiroll bar goes a long way of preventing this and keeps the suspension working as it should be.

This must be one of the best mods you can do to improove the handling of your car, and i would (after speeking to Yob Geevers of Whiteline UK on many occassions) highly recommend getting them before lowering a car.

[Johan007]

a lower profile tyre won't flex as much which will make the car more stable

Yes it feels more stable but you could just as easily increase the PSI on high performance tyre as long as the tyre is soft. Will not improve lap times on the track and (unless they over-heat... extreemly rare).

with a better contact patch on the road,

also normally when fitting lower profile tyres in most cases you end up with a slightly wider tyre, this makes the contact patch bigger creating more grip.

Not true, wider tyres gives you the same contact patch. Again contact patch depends on PSI and weight of the car (Simple physics really). In the bends it is the side walls that grip and again this is down to PSI and weight not tyre.

The truth is high profile tyres are a con and offer little or no performance benefit though the car will feel better becuase the side wall is more stable. Bit it also means you are less likely to splash out on top spec tyres like Eagle F1's because they get pricey.

I agree that they are more dangerouse on roads where you get pot holes.

What do you rate without spending a fortune.

Nothing though you could try increasing PSI to load levels. Will make it more responsive and fun but you will lose grip.

[cfc1]

also normally when fitting lower profile tyres in most cases you end up with a slightly wider tyre, this makes the contact patch bigger creating more grip.

Not true, wider tyres gives you the same contact patch.

I was trying to keep things simple (without purposely misleading anyone) by trying to explain it in laymans terms, most people would agree that wider, lower profile and larger diameter tyres give better grip. It is down to the contact patch but, as you have said.. it's not it's size, it is in actual fact it's shape. There are other factors that come into it aswell though, rubber compound, heat and tyre load. It gets very confusing to explain it in simple terms to someone who doesn't understand the physics behind it so I'll leave it to someone else....

If there's one question guaranteed to promote argument and counter argument, it's this : do wide tyres give me better grip?

Fat tyres look good. In fact they look stonkingly good. In the dry they are mercilessly full of grip. In the wet, you might want to make sure your insurance is paid up, especially if you're in a rear-wheel-drive car. Contrary to what you might think (and to what I used to think), bigger contact patch does not necessarily mean increased grip. Better yet, fatter tyres do not mean bigger contact patch. Confused? Check it out:

Pressure=weight/area.

That's about as simple a physics equation as you can get. For the general case of most car tyres travelling on a road, it works pretty well. Let me explain. Let's say you've got some regular tyres, as supplied with your car. They're inflated to 30psi and your car weighs 1500Kg. Roughly speaking, each tyre is taking about a quarter of your car's weight - in this case 375Kg. In metric, 30psi is about 2.11Kg/cm².

By that formula, the area of your contact patch is going to be roughly 375 / 2.11 = 177.7cm² (weight divided by pressure)

Let's say your standard tyres are 185/65R14 - a good middle-ground, factory-fit tyre. That means the tread width is 18.5cm side to side. So your contact patch with all these variables is going to be about 177.7cm² / 18.5, which is 9.8cm. Your contact patch is a rectangle 18.5cm across the width of the tyre by 9.8cm front-to-back where it sits 'flat' on the road.

Still with me? Great. You've taken your car to the tyre dealer and with the help of my tyre calculator, figured out that you can get some s****y 225/50R15 tyres. You polish up the 15inch rims, get the tyres fitted and drive off. Let's look at the equation again. The weight of your car bearing down on the wheels hasn't changed. The PSI in the tyres is going to be about the same. If those two variables haven't changed, then your contact patch is still going to be the same : 177.7cm²

However you now have wider tyres - the tread width is now 22.5cm instead of 18.5cm. The same contact patch but with wider tyres means a narrower contact area front-to-back. In this example, it becomes 177.7cm² / 22.5, which is 7.8cm.

Imagine driving on to a glass road and looking up underneath your tyres. This is the example contact patch (in red) for the situation I explained above. The narrower tyre has a longer, thinner contact patch. The fatter tyre has a shorter, wider contact patch, but the area is the same on both.

And there is your 'eureka' moment. Overall, the area of your contact patch has remained more or less the same. But by putting wider tyres on, the shape of the contact patch has changed. Actually, the contact patch is really a squashed oval rather than a rectangle, but for the sake of simplicity on this site, I've illustrated it as a rectangle - it makes the concept a little easier to understand. So has the penny dropped? I'll assume it has. So now you understand that it makes no difference to the contact patch, this leads us on nicely to the sticky topic of grip.

The area of the contact patch does not affect the actual grip of the tyre. The things that do affect grip are the coefficient of friction of the rubber compound and the load on the tyre. As far as friction is concerned, the formula is relatively simple - F=uN, where F is the frictional force, N is the Normal force for the surfaces being pressed together and u is the coefficient of friction. In the case of a tyre, the Normal force basically stays the same - mass of the car multiplied by gravity. The coefficient of friction also remains unchanged because it's dependent on the two surfaces - in this case the road and the tyre's rubber.

The coefficient of friction is in part determined by the rubber compound's ability to 'key' with the road surface at a microscopic level.

This explains why you can slide in a corner if you change road surface - for example going from a rough road to a smooth road, or a road surface covered in rain and diesel (a motorcyclist's pet peeve). The slide happens because the coefficient of friction has changed.

So do wider tyres give better grip?

If the contact patch remains the same size and the coefficient of friction and frictional force remain the same, then surely there is no difference in performance between narrow and wide tyres? Well there is but it has a lot to do with heat transfer. With a narrow tyre, the contact patch takes up more of the circumference of the tyre so for any given rotation, the sidewall has to compress more to get the contact patch on to the road. Deforming the tyre creates heat. With a longer contact patch and more sidewall deformation, the tyre spends proportionately less time cooling off than a wider tyre which has a shorter contact patch and less sidewall deformation. Why does this matter? Well because the narrower tyre has less capacity for cooling off, it needs to be made of a harder rubber compound in order to better resist heating in the first place. The harder compound has less mechanical keying and a lower coefficient of friction. The wider tyres are typically made of softer compounds with greater mechanical keying and a higher coefficient of friction. And voila - wider tyres = better grip. But not for the reasons we all thought.

So there you have it... sometimes it's better to keep things as simple as possible to get the message over, even if it means being slightly economical with the truth getting technical can confuse people who aren't as technically minded as others.

In the bends it is the side walls that grip and again this is down to PSI and weight not tyre.

Not true.... the rubber compound of the tyre has everything to do with it, as explained above.. "coefficient of friction" and "the rubber compound's ability to 'key' with the road surface"

:P ;)

[Yumma]

CFC you da man! Good work fella; and I thought I was alone in understanding the coefficient of friction after many years skid testing for local authorities and the police.

This guy knows his stuff.

As per the original post me thinks I will go with a rear anti roll bar upgrade and drop it on Tein springs. Ideally I'd like a full suspension kit but cost does not permit. Also the improved suspension, with less roll will help keep a tyres contact patch in contact with the road surface and thus give better grip. I reckon the existing wheel & tyre combi will offer ample grip and I do not wish to affect unspring mass and gyroscopic forces.

Cheers

Yumma

[Johan007]

Sure good accurate post but I have to say that cooling is not really an issue on the road even if your belting it... on the track sometimes yes but not always. In the RGB series these cars have tremendous grip but the control tires are high profile and narrow see http://www.bdnsportscars.com/photos.asp and outlap most super cars on the track. The drivers say that heat is not an issue.

Also the contact patch in the bends is on the edges/walls.

So for the majority of people even on the track, low profile and wider will not go any faster but sure it may feel better! It is not worth the upgrade to 100bhp Yaris and you will be spending more money on rubber. Best and first upgrade would be terbo... if it fits?...does it fit?

[Yumma]

Agree with you over heat and tyre widths etc, the standard tyres are plenty enough for a 106BHP Yaris T Sport.

However a Turbo is one of the last mod's I'd make as they are expensive and as a certain advert once stated 'power is nothing without control'. Best get the handling and braking in check first as this is where most useful gains can be had in the real world, then maybe look at increasing power which will then have you begging for a proper Diff in order to lay the power down and an uprated clutch.

[stantheman1]

Wow, my head really hurts now!

Great post, love all that technical stuff.

[cfc1]

Cooling on tyres isn't really an issue in normal road use.. even with the odd bit of spirited driving, so long as you have the correctly specified tyres fitted to the car in terms of traction, load rating and temperature. When modifying a car to more extremes than most it is wise to do it in the correct way, as has been said "power is nothing without control", if you are planning power modifactions such as turbo's or superchargers you have to ensure other components on the car can handle the extra power etc, components such as the clutch, suspension components (not just springs.. but even less obvious items like drop links) breaks and tyres all have to work together to keep the car under control. I'm not going to say that the tyres are the most important factor but they are the only part of the car that is in contact with the road surface, if you get the tyres wrong you won't get the correct feel of what the car is doing and your setup could be drastically affected.

The other reason 16's would be "better"... well, when we modify our cars we want to show it off to a certain degree, fitting items that can't be seen or where the difference isn't visually noticeable (such as anti-rollbars) doesn't show what you have done, no matter how much an improovement to the handling/driving it makes... fitting a nice new set of wheels will not only compliment your other mods it will also give you something to see for your hard earned spent B)

Cheapest Method Of Uprated Handling, Whats best

As you can see, it really depends on how far you want to go with it, there isn't really a cheap way but there is a correct order to do things, it also depends if you want others to see what you have done.

If you want people to see... lowering springs and a set of wheels and tyres (will give limited improovement in handling but will look and feel better.

If you aren't concerned with the looks side of it.. Uprate the springs and anti-roll bars, there will be a significant difference in handling over springs and tyres.

Fitting the roll bars first will also put you in a better position than most if you wanted to go with coil over suspension instead of springs, go too low and your suspension will bottom out causing bump steer.. anti roll bars will help prevent that happening.

If you do things properly it can mean that you will spend less money in the long run (if you are planning more future mods in the power department) as, in a way, you will be "future proofing" your car as you go along.

[Johan007]

@cfc1 how much more in insurance did it cost to turbo your MR2?

[cfc1]

With ALL my mods declared (see my registry entry in my sig) around 200 extra.. I'm 41 with max no claims.

[Raeman]

Does all depend on the car really, my experience with a mk3 Golf Gti was dreadfull..

I put brand new shocks & springs on it which lowered it about 40mm, and then fitted some 17's, (did look great)

This absolutely ruined the ride totally. The car was virtually undriveable, hitting a cat's eye in the road was like hitting a 6" deep pothole!! :censor:

The thing used to bang and clatter like riding on a skateboard, and as for the handling, well it just made it dangerous.

It used to skip and hop round corners despite the tyres being brand new Yoko's, in the wet the rear used to step out aswell.

As a standard car is was ok, modified it was a shed.

Be carefull before splashing out a lot of money on things that will ruin the car.

If i was to do similar to my Yaris, i think i would replace every bush, then fit coilovers. The 15's with low profile's stick like hell on mine.