BMW questions :)

[Howard]

I meant any other RWD car drivers really <3


5Lab I'm looking at you!!

[Konan555]

The greatest Sierra shaped menace...... the 19 year old Sierra GT owner.

Give them a wide berth if it's raining and there's roundabouts.

[schmunk]

To be hounest, I don't see many on the road now. Graduated to vectras on mondeos from what I've seen.

True, M/N reg Mondeos are pretty popular with that crowd now...

[5lab]

hey.. the only thing htat oversteer made me drive a car into was a wooden pole. that was my fault really, it was cos i overcorrected the oversteer. oops

rwd is good fun, but if you use traction control then it has no *real* advantage over fwd in the average (~150bhp) powered car. above that it does make launching off the line a bit easier..

they've moved onto vectras etc with good reason - you can get a 7 year old mondeo for £800- which would probably provide trouble-free motoring for a good 5 or 6 years.. makes sense imo

[Konan555]

I never found a Volvo 340 that easy to catch on the oversteer, very much a 'nope, I'm spinning now weeeeee'

So well done you for correcting it at all

[5lab]

the facts remain the same - front wheels steer and rear provide power. This allowes for the grip at the front to worry about cornering and not accelerating.

tbh, thats a well quoted thing and complete nonsense. both sets of wheels do steering. if you try to drive round a corner with castors instead of back wheels on a fwd car, you'd see that for yourself.. fwd is safer when you overstep the limits, and the limits of the two are pretty near each other..

I never found a Volvo 340 that easy to catch on the oversteer, very much a 'nope, I'm spinning now weeeeee'

So well done you for correcting it at all

ta its alot easier with some weight in the car and some speed behind you. due to the short wheel base, its not the easiest car, but if you're doing 40-odd you can hold it nicely for 3 or 4 seconds, and i'm no expert

small roundabouts cna be interesting - i remember one time having to do a complete loop cos i'd missed my exit (couldnt recover quick enough)..

[dkmech]

tbh, thats a well quoted thing and complete nonsense. both sets of wheels do steering. if you try to drive round a corner with castors instead of back wheels on a fwd car, you'd see that for yourself.. fwd is safer when you overstep the limits, and the limits of the two are pretty near each other..

I may be wrong, but i think that during cornering (at the start of changing direction rather than just going round in a circle at constant speed) the loads on fronts and rears are going to be very different. Rears just follow where the fronts lead. The fronts must overcome the inertia and wrestle the car to go in a different direction.

Also in a front wheel drive car the vector of the propulsion force, being aligned with the front wheels points to the outside of the trajectory you are trying to follow and you get understeer (yes you can point the wheels sharper into the corner and get the desired line but thats not the point).

I think even with traction control on and a not too powerful car the differences between the handling of a front and rear wheel drive car will be quite significant. To a trained driver at least (like a racing driver, rather than a trained hgv driver, no offence to hgv folk).
I'd like to hear Zak say something here. Or we need someone with a car with 4wd where u can lock each axle at will to test things while going at the same speed and holding the throttle at the same position.

[Konan555]

Or we need someone with a car with 4wd where u can lock each axle at will to test things while going at the same speed and holding the throttle at the same position.

Do what?

[5lab]

I may be wrong, but i think that during cornering (at the start of changing direction rather than just going round in a circle at constant speed) the loads on fronts and rears are going to be very different. Rears just follow where the fronts lead. The fronts must overcome the inertia and wrestle the car to go in a different direction.

you are wrong i'm afraid, hence how rear tyres wear out (albeit slower) on a fwd car. both sets of wheels take the cornering load. the rears do follow the fronts, but in doing so they produce cornering force. i dont know the physics well enough to explain, but basically if you had 50:50 weight distrobution, and went round a corner with no throttle, the front and rear tyres would wear exactly evenly.

Also in a front wheel drive car the vector of the propulsion force, being aligned with the front wheels points to the outside of the trajectory you are trying to follow and you get understeer (yes you can point the wheels sharper into the corner and get the desired line but thats not the point).

err i can see what you're getting at, but if this was the case then rear drive cars would handle worse, which they dont.. umm anyone else wanna explain??

I think even with traction control on and a not too powerful car the differences between the handling of a front and rear wheel drive car will be quite significant. To a trained driver at least (like a racing driver, rather than a trained hgv driver, no offence to hgv folk).
I'd like to hear Zak say something here. Or we need someone with a car with 4wd where u can lock each axle at will to test things while going at the same speed and holding the throttle at the same position.

again i can see what you're getting at. read thru this all the way, and it might help explain stuff to you.. http://www.autozine.org/technical_sc...handling_1.htm

[DaBeeeenster]

Wow, generalising againsts everyone who drives a particular type of car is *so* cool.

Idiots drive all sorts of cars, people notice them in BMW's becuase they've filled their head with jealously.

No, sorry, that's not the case. Most people that drive beemers really are muppets.

[Fox]

Only in the same way that everyone who drives a Saxo is a chav, everyone who drives a Mondeo is a rep, everyone who drives a Panda is a hippy, everyone who drives a VW has delusions of granduer and everyone who drives a Saab in a dentist.

Stereotyping... great.

[schmunk]

Only in the same way that everyone who drives a Saxo is a chav, everyone who drives a Mondeo is a rep, everyone who drives a Panda is a hippy, everyone who drives a VW has delusions of granduer and everyone who drives a Saab in a dentist.

Stereotyping... great.

Commie pinko liberal...

[Konan555]

Bang on Fox

[dkmech]

I may be wrong, but i think that during cornering (at the start of changing direction rather than just going round in a circle at constant speed) the loads on fronts and rears are going to be very different. Rears just follow where the fronts lead. The fronts must overcome the inertia and wrestle the car to go in a different direction.

you are wrong i'm afraid, hence how rear tyres wear out (albeit slower) on a fwd car. both sets of wheels take the cornering load. the rears do follow the fronts, but in doing so they produce cornering force. i dont know the physics well enough to explain, but basically if you had 50:50 weight distrobution, and went round a corner with no throttle, the front and rear tyres would wear exactly evenly.

If you read what i said i was specifically referring not to going round the corner with no throttle, but to going into the corner.

err i can see what you're getting at, but if this was the case then rear drive cars would handle worse, which they dont.. umm anyone else wanna explain??
again i can see what you're getting at. read thru this all the way, and it might help explain stuff to you.. http://www.autozine.org/technical_sc...handling_1.htm

My previous explanation about steering loads and propulsion loads being shared by the tyre may be incorrect, but the main point is that an equally well set up rwd car should have an advantage over a fwd car even if the engine is not very powerful or the traction control is on. RWD doesn't just come in when you want to do donuts or to severely oversteer out of the corners.

Power Oversteer and Lift-off Oversteer
The more tractive force we apply, the larger slip angle is created in the driving wheel. Therefore, for the RWD cars, we can use the throttle to control the degree of oversteer. When the car is entering a corner too fast and seems likely to run wide, we can correct its direction by increasing the throttle (not to do this before reaching the mid corner !), then the car oversteers. If we find the correction is too much, we can ease the throttle and let the car returns to neutral steer or even mild understeer, depends on the suspension design and weight distribution.
Only RWD cars or rear-biased 4WD cars can do this ! In the same situation, the driver in a FWD car has nothing to do other than easing the throttle, slow down the car thus reduce the centrifugal force, and hope the car can overcome the corner. There are many disadvantages :


You lose time during slow down.
You lose engine rev during slow down, thus the engine takes longer to rise back to the useful power band once you exit the corner.
Very often, if you miscalculate, you are unlikely to have sufficient road ahead for you to slow down, especially in tight corner.
.
Therefore we always say RWD car is superior than FWD car in handling. There are, however, some well-sorted front-driver (especially some GTi) can play "lift-off oversteer", which is actually the reverse of "power oversteer" - a degree of permanent oversteer is built into the car but is only accessible when the car is pushing to the limit and with throttle disengaged. Step down the throttle again will reduce the oversteer and even back to understeer. Anyway, obviously this is still not as controllable as "power oversteer". While power oversteer can extract a lot of oversteer - actually depends on throttle - lift-off oversteer is rather limited, simply because it is impossible to build a lot of permanent oversteer to the chassis without deteriorating handling in lower speed or straight line.
Once again I have to emphasis that the power oversteer must be highly controllable by the driver, otherwise the car may lose control and spun. To make a good power oversteer car, the secret is to match the power and cornering limit perfectly at the speed concerned. If the cornering limit exceeded the power, the rear wheels will grip hard and refuse to slip. In contrast, if the cornering limit is too low or the engine torque is too high at the speed concerned, the rear end will slide severely once the throttle is pressed. Therefore, the cornering limit must be set at a level where the engine output, at the speed and road we normally want the car to power oversteer, has just sufficient power to exceed. To implement it , choose a suitable set of tyres, applying suitable amount of downforce and an adequate front / rear weight distribution is very crucial.

[gobbo]

Althought it is stereotyping, you have to admit, sometimes it is very ammusing: