Can a 1050kg car out brake a 1500+kg r34 gtr?

[lou15x]

Quote by R33:"Now the heaver car will have more weight on the tyres. This means that more braking force can be applied before lock up. Therefore the heavier car is capable of more braking force before reaching its maximum which occurs just before lock up. It is because of the fact the heavier car can apply more force that it will stop quicker."

Dude, i think what you are refering to is pressure....that because of the extra weight, there is more pressure per square inch of the tire's contact patch compared to the lighter car, and hence should be able to apply more force without reaching the grip limit and locking up.

But i think you forgot to factor in that while there is more weight and pressure on the tires to give it an increased grip limit, there is also that extra weight which will overwhelm the grip as well.

Put simply...if what u said were true.....F1 cars would weigh 10 tonnes and wear 175mm tires.... but we dont see that happening dont we?

[dojobi]

I like R33man's theory. It makes total sense to me, but I'm really not qualified to say if it's right or wrong.

Anyway, just to add some more to the topic, I did an advanced driving course with Ian Luff a year or so ago and he said that trucks can generally brake as well as most cars. This is because of the contact area of the tyres to weight ratio.

[Duncan]

I like R33man's theory. It makes total sense to me, but I'm really not qualified to say if it's right or wrong.  

Anyway, just to add some more to the topic, I did an advanced driving course with Ian Luff a year or so ago and he said that trucks can generally brake as well as most cars. This is because of the contact area of the tyres to weight ratio.

and there's a great reason to find a different advanced driving school!

Doughboy gave the right answer in the 3rd post, why are we still talkin about it?

[Sonic]

If the lighter car is a Holden of course it will break quick!

Or if it's a Lotus: Lots Of Trouble Usually Serious

[R31Nismoid]

and there's a great reason to find a different advanced driving school!

not nessasarily.

Your average truck (without the million variables) can brake at approx 75% of what your family sedan can.

so he was sorta right in saying what he did

Maybe not 'as well' but it's not 'too far' off

[Warpspeed]

Very true.........

Surprisingly one of the hardest things to make brake quickly is a motorcycle. High centre of gravity, and short wheelbase. They are awsome in every way except braking capacity. You would not want to lock the front wheel, or go over the handlebars I think.

I have not looked at figures, but I would not be surprised if a top bike could stay with a formula one car in acceleration, but the formula car would kill it for braking.

[Kinks]

Regardless of the brakes the tyres will provide a given coefficient of friction (Cf).

Precisely. As mentioned bigger brakes will only mean that you can stop from a higher speed without fade or multiple times without fade. We're assuming the brakes on both cars are adequately sized for at least 1 100->0km/h stop.

Remember the old adage "brakes stop the wheels, tyres stop the car". Small brakes can lock wheels no problem, your braking is limited by the tyre's adhesion with the road until you reach the point where the brakes start to go off.

As for who will stop first, the heavier car will have a bigger contact patch proportional to its weight. The Cf shouldn't change IMO because at a given point on the contact patch the tyre can only push down on the road with a force equivalent to its internal pressure. So the braking gain of the higher car is related to having a bigger contact patch. I think both cars would be fairly similar really.

[usuckpoo]

Actually this test is rather easy to prove...

do it with your car unloaded....

wait 1/2 hour to make sure the brakes have fully cooled

then do it again with 4 of your heaviest mates on board.

[Busky2k]

More weight means more pressure on the tires, and it does seem logical that they would stop better. However the tyre will be under much more stress and deform more, and thus, traction will not increase in a linear relationship with weight.

Half the reason you dont want body roll around a corner is to help spread the load onto the inside tyre. Sure the outside tire has alot more weight on it, and theoretically should hold the road better as you get more body roll but it gets to a point overloaded and looses traction and it ends up worse!