BMWs

peasant

You can retrieve a RWD break because the solution is to give it power, which has a chance of getting grip

Giving power does not give you grip, RWD or no RWD. Giving power means feeding more force down to the tyres which already have lost grip, so they will not be able to transfer more power and will certainly not "produce" grip out of nowhere ...they'll spin just more.

The situation that you are describing is a different scenario.
When you drive into a tight bend, your front wheels are the first to experience outward pressure, the rear ones are still going straight ahead. At the mid point of the bend, your front wheels are already pointing straight again and experience no sideward forces, while your rear wheels are being pushed to the outside.
They still have grip, though ... your arse-meter tells you that the back of the car is pushing to the outside of the bend, you may think that your tyres are slipping (and they may be slightly) but basically they still have grip.

If you apply power now, you accelerate out of the bend, into the straight line that your front wheels are already in and you get a nice tucking-in effect.

That is the joy of RWD ...but it is not "catching" a sliding RWD car by applying power.

Once the rear wheels properly spin out of control you cannot catch them.
Once the static friction of the tyre surface on the road is lost and turns into gliding friction ...you're f*cked.

unkel

colm_mcm wrote:

definately agree with you about european COTY, although, I must add that most of the cars deserved the title, either because they set new standards, did something differently, or weren't as dire as the rest of the new cars in a particular year!

Agree and I appreciate most of the cars that have won it over the years

colm_mcm wrote:

there were a few that I thought didn't really deserve the title

I've not got an informed opinion on '06 or '07 but the one car that didn't deserve the title imho was the Prius in '05. Too much accolade too late

A more serious criticism is that the award goes to a certain make/model regardless of the engine range. An engine can be more important in the innovation scheme of things than the make/model of a car sometimes. How about the FIAT JTD, the world's first common rail diesel. Or one step up, how about BMW diesels?

Anyway that's getting back on the BMW topic:

cancan wrote:

Handbags for men really

LOL

Maybe you should google a bit more for scientific studies about car drivers and their social / sexual life. You might find some interesting results

dahamsta

peasant wrote:

Giving power does not give you grip

I didn't say it will give you grip, I said it will give you a chance of getting grip. When you're sliding down a hill, do you stand still or scrabble for grip?

peasant

dahamsta wrote:

Is it just me or is the percentage of people incapable of actually reading posts growing exponentially on Boards.ie.

I didn't say it will give you grip, I said it will give you a chance of getting grip. When you're sliding down a hill, do you instinctually stand still or scrabble for grip? Want to guess why your body tells you to do that?

I am well capable of reading ...I am also capable of understanding basic physics.

The coefficient for static friction is higher than that for gliding friction.
A tyre gripping the road surface can transfer a maximum force of X onto the road / back from the road.
X would be the applied power and centrifugal forces etc

When you now overstep the limit and reduce X (static) to the significantly smaller Y (gliding) you need to remove force out of the equasion not add to it on order to regain grip.

Simple really.

Why do you think a car with rolling tyres under full breaking on a dry road stops in a shorter distance than one with blocked, squealing tyres?

dahamsta

By your logic, drag racing would consist of men with hardcore tyresmoke addictions sitting in drag cars at the christmas tree and waving at each other. Granted most of them do actually fit in that category anyway, but when the christmas tree turns green, they take off down the track like shít off a stick. Why? Because after spinning the tyres off the line they eventually get - get this - grip.

http://www.youtube.com/watch?v=C_qXP45OPRQ

maidhc

dahamsta wrote:

Because after spinning the tyres off the line they eventually get - get this - grip.

My physics knowledge is limited to the leaving cert, but I think peasant is referring to the grip a car has to counter the centrifugal force of going around a bend, not to take off at the lights.

If you try driving through a muddy field you will see exactly what peasant refers to. If you put the boot down in first you wont move an inch, but if you ease off in second you will move.

AFAIK dragsters melt rubber onto the road first, let it cool, and then make a launch, I could be wrong on that though.

Elessar

Wow, i wasnt expecting such a big turnout in the thread! So the general consensus is? If I had the money for a 2nd hand beamer, should I get one, go audi or a top of the line ford/toyota?

Edit: I really like german cars, so I'd prefer to stick to them!

peasant

dahamsta wrote:

By your logic, drag racing would consist of men with hardcore tyresmoke addictions sitting in drag cars at the christmas tree and waving at each other. Granted most of them do actually fit in that category anyway, but when the christmas tree turns green, they take off down the track like shít off a stick. Why? Because after spinning the tyres off the line they eventually get - get this - grip.

Ok, let's do a little theoretical excecise here.
Lets assume that a tyre has enough grip to transfer 200 bhp worth of power onto the road.

Lets start with your dragster first. Lets assume it has 300bhp worth of power to send to every tyre. Your man floors it, tyres spin. But even spinning tyres can still transfer power, just not as much ..let's say 150 bhp worth. So even though the tyres spin, the dragster moves forward. As it does so it gains momentum and shifts its weight backwards. That weight shift creates downforce on the tyre and all of a sudden it can transfer 200 bhp (still spinning, because 300 bhp are applied), momentum grows, dowforce grows until your tyre can transfer the full 300 bhp and tyres stop spinning. And if your man just eases off the throttle for a little bit just after the start, they stop spinning even quicker.

Now lets look at your road car going out of control. That car also has 300 BHP but only 150 go to each tyre ...so youre grand, grip at all times.

Now youre going into a bend at 2/3 full throttle. 100 bhp going to the tyre in force from the engine but another 100 bhp worth of force are needed to counteract the centrifugal force and momentum that wants your car to keep going straight. So you're on the point of loosing it. If the bend now tightens slightly, all of a sudden you have a centrifugal force/momentum that has increased to the equivalent of 150 bhp. 100 + 150 = 250 ...grip is lost, your tyre spins. It can now only transfer 150 bhp worth of force. No matter how much power you add by flooring the throttle, you're not getting grip back.

Force has to be removed out of the equasion ...either by pointing the car straight or by easing off the gas.


Of course all this is over-simplyfied and the figures are inaccurate and several contributing factors have been omitted ...but you get the picture ...I hope.

Because telling people to floor it once their car loses grip is NOT good advice.

cancan

dahamsta wrote:

When the front end on a FWD car breaks loose, you're going into the wall.

They are helpless too. Understeer is not just a FWD thing. A point of no return in either is just as hopeless. If the front has no grip, power or lack thereof is not going to make any difference.

Regarding the study done on sexual habits of various brands, given the amount of 316 drivers who consider their car the ultimate driving machines, it was generally considered that their liklihood to fudge the truth was most prevalent among those same photocopier salesmen.

BMW drivers were considered to believe that they were having more jiggy jiggy that they actually were!

dahamsta

I'm sorry, we're going to have to differ on this. I've driven FWD and RWD cars, I've lost grip in both, and in the ten minutes I've spent trying to reverse the FWD car out the ditch, the RWD has gone six miles down the road. Real-world situations with factors like tyre quality, travelling distance (tyre warmth), road quality, weather, etc, etc, just isn't the same as a simple, strict physical model with 2-3 factors. I drive on a road, not in a lab.

adam

endplate

@ peasant


Driving in the wet with bald tyres. That can cause a lot of spins too

peasant

just to explain what endplate is smiling at ...

there was a post of mine, which I deleted because it was probably a bit too personal.

Seth Brundle

right then - to kind of summarise
BMWs are liked by some and not by others. Some buy them purely for show whilse others have different reasons for them.
They may or may not be better than a higher powered lexus.
They are RWD which may or may not be better than FWD and RWD may or may not be easier to control out of a slide.
Can we close this thread now?

dahamsta

kbannon wrote:

Can we close this thread now?

Why would you want to close it? The discussion has been argumentative but not disruptive, and some points have actually been quite interesting, even occasionally amusing. Has someone broken an unwritten Boards rule or something?

maidhc

dahamsta wrote:

Why would you want to close it? The discussion has been argumentative but not disruptive, and some points have actually been quite interesting, even occasionally amusing. Has someone broken an unwritten Boards rule or something?

Indeed.

Thread is no better or worse than any other "what is your favourite car" threads. Objectivty in such threads is impossible, and this one has been a hell of a lot more successful than the Renault/Alfa ones!

Seth Brundle

True but it has gone way off topic!
I'll leave it for another while anyhow.