Suspension and braking

Upto a point, it helps the braking by keeping the car following it's course, and doesn't upset things instead of bouncing and wobbling arround like a jelly. Too soft or two firm the suspension will allow the wheels to leave the ground, and if this while braking you lose braking force.

Same with tyres. Two narrow or two wide will affect the braking. Too Narrow and the braking force will lock the wheels due to not enough contact, usually heavy car skinny tyres.

Too wide and the brakes will lock because while there is enough contact (say on a smaller lighter car) the down force of the car is spread over too large an area to provide enough friction to prevent the brakes locking.

Also too much brake power can have similar effect (brakes over powering the available friction provided by the tyres). Best thing to do is see what the motorsport guys use (Something like the Ka rally cup guys). Think about toning it down for the road.

It helps by reducing the transfer of weight onto the front end. Anti- Dive kits do the same thing.

I'm not thinking of putting 235s on just yet. I reckon 195s (comes with 165s as standard) are about as far as I'd go.

It looks like they stick with fairly standard vented disks and use mintex pads. My problem is that I've got the solid discs, so I'll need new calipers / disks / pads anyway.

How do these work? It's obviously better to have some braking coming from the back end as well as the front. Being FWD and normally one up, the Ka is pretty front heavy anyway. Dive makes things worse, giving a light back end under heavy braking.

too hard and it will jump and bounce like a crack head and the brakes will be worse a little stiffer will help but you also have to make sure that the rears don't lock up as all the weight, while being transferred to the front, won't make it too light at the back bunny hopping golf type happening and stuff like that may be what it'll look like

some come with vents at the front and some don't try to stay within a sensible size and you'll notice the effect it has will be quite remarkable :) S2 rs turbo's will be fine (same size calipers and all the granadas and same size discs as all the dohc sierras to keep costs down) but you may have to look into swapping master cylinders and servos from a car with the vents if you don't have them

but then again, some people like to keep their small discs and calipers and just switch pads :)

A little stiffer is what I was thinking. I don't enjoy having my bollocks shaken off.

Indeed. I think the brake bias valve might be different on the vented disc Ka.

I'll look into that if I ever get round to doing the brakes.

I reckon that's what I'll do when I next knacker the pads, and then if that's not enough, swap to new calipers / discs etc.

That doesn't quite sound right :P.

LOL!!!!!!!!!!!

That would defy the laws of physics.

Paul

On the Capri it moves the front anti-roll bar down an inch or so.

No. The firmer your suspension, the less time your tyres spend in contact with an average bumpy UK road, hence the less grip they give, and the slower you stop.

Agreed. Wider provides more grip in the dry.

This is no bad thing though. On a FWD, front-engined car, the front wheels do almost all of the braking, so A: they need as much grip (weight) as they can get, and B: it doesn't matter if the rears almost leave the road.

Not an option for Doki - his discs aren't even vented !

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Nope, not always. The load pressing down is spread over a larger contact patch. That is why a tea tray will slide across ice, and an iceskate will hold in one place (relatively) until you move. The downforce on the skate causes it to bite into the ice and it grips. Same downforce on a tea tray doesn't cause it to bite in as far (it appears not at all) and so it slides off.

Same with a Ski and a Snow shoe on powder snow. The Surface area of the snow shoe allows it to spread the downforce, and sit ontop of the snow, the ski concentrates it, so it sinks in.

Now compare that to a tyre. Wider equals larger contact patch. Go too big with the contact patch, and the weight of the car isn't pushed onto the tarmac with as much force as it would be with an ideal size tyre for the weight of the car.

The mechanism is somewhat different - when you apply pressure to ice, you reduce the freezing point, and so the ice melts, and, in your example, the ice-skate blade sinks into the ice, hence it sits in a groove, which causes a resistance to movement that has nothing to do with friction.

However, when you apply pressure to tarmac, it doesn't melt, so the friction is simply that characteristic of the interface between tarmac and rubber. To a first-order approximation, the contact area makes no difference to the coefficient of friction, however in reality, as the pressure increases, the coefficient of friction drops, and it is for this reason that bigger tyres give more grip. In summary, a larger contact area will give better grip in all conditions for which the tyre is in full contact with the road.

Of course, what you say is perfectly driving on ice and snow.

Don't forget that the tyre is rotating, rather than sliding. It's a completely different set of equations, not just the basic F=uR.

maybe he should swap to some vented discs then :) straight forward improvement with strand parts :)

That would defy the laws of physics.

the wider the tyre, the les load it has on it at any given pint when compared to a narrower tyre so the loads it can see will be greater for the same corner/braking/traction scenario in the dry this won't matter as much as it will mean that you have to put more effort into breaking traction on teh pull away and the clutch gets a hammering and the brakes have less work to do as they are doing the same thing but using more rubber to slow down in the wet the bigger contact area means that there is a increased chance of there not being enough wieght over the axle to provide sufficient grip in both power (less wieght on the car at the front assuming we are talking baout a front wheel drive car here) and too much contact area so you get more water/ice/snow lifting the tyre off the tarmac not good

Paul