12-18-2015, 01:09 AM | #23 | |
Private First Class
14
Rep 111
Posts |
Quote:
I'm obviously wrong then, but it was my understanding that the electronic aids were only there as extra protection and not to be relied on because they're not always 100%? When we "race" don't we turn all these electronic aids off anyway? I've never driven fast with ABS. I have an automatic reaction to hit the brake then feather it to get traction. I have a few stories of sticky situations. Traction control, isn't this turned off as it slows you down anyway? To go fast in the M135i we hold down the traction button for 5 seconds to activate the electronic LSD, which turns off all the funky electronics anyway right? Like I said I obviously have a misunderstanding, so keen for you to share your knowledge here. |
|
Appreciate
0
|
12-18-2015, 01:49 AM | #24 |
Brigadier General
266
Rep 3,290
Posts |
Which driving aids to use, depends on your experience. The car is fastest with DSC Off, but that requires the driver to deal with car control. If you are not comfortable with recovering slides at high speed, you might be better off with a safety net. Sport+ will provide some electronic stability, and Sport Mode will give you full DSC. It will hold the car back by braking a bit on the limit.
The ABS system can not be switched off, and you don't really want to. There are also some cornering brake control features that will always be enabled. To go fast, you want to take advantage of the ABS system, and let it regulate all four wheels at the limit when braking for corners. This means stepping hard on the brake pedal, and holding it down. If the corner is suitable for trail braking (going from a fast section to a slow one), you gradually ease off the throttle as you feed in more steering. In some situations the first part of the corner is driven with maximum braking. As a track driving instructor, the two most common rookie mistakes I see, are to not brake hard enough, and to not exploit the full width of the track. Both make it more difficult to make it around the corner. |
Appreciate
1
|
12-18-2015, 09:15 AM | #25 | |
Major
1037
Rep 1,340
Posts |
Quote:
It's just your experience depends on the driving aids you use: driving aids-less as if it were there will lead to a disaster while ignoring the aids available appears inefficient. (That is it looks one should choose the "old school" or "new wave" driving skills "category" and stick to it as the skills are inverse.) |
|
Appreciate
0
|
12-18-2015, 06:37 PM | #26 |
Major
282
Rep 1,491
Posts |
I'm no professional racing driver, but I have built and driven a number of competition cars, mainly for rallying. None of these had any electronic driver aids, so driving fast was always about maintaining controllability. That meant understanding threshold braking, to avoid wheel lock-up (which reduces the driver's ability to steer), as well as various techniques to control understeer/oversteer (handbrake!!). Let me be the first to say I was OK at all of this, but not great - I had lots of fun...and quite a few offs!
The point I was making, which has perhaps been better said by ovekam, is that was then, this is now. These electronic driving aids have all had their genesis (and a great deal of proving) in competition cars. Most modern competition cars do race with ABS operational; in fact, race ABS systems have adjustable threshold systems that enable the driver to accommodate loose gravel roads, wet roads, new tyres (vs worn) and other conditions. The ONE thing you want to maintain above all else when driving a car fast in competition is controllability, and the steering capability that ABS gives the driver under braking, even very hard braking, is central to that control. That's why I recommend everyone take an advanced driving course, or go to one of the BMW Experience days, and try the "lane change under emergency braking" exercise. For anyone trained "the old way", the controllability is sensational. Don't believe me? Then try it, if you can, in a car with no ABS (I've seen people pull the ABS fuse to demonstrate this -- NOT recommended) The same is true of advanced stability and traction control systems, which enhance the controllability of the car when driven on the road, enabling, eg, better cornering by selectively braking rear wheels. When driven on the track, you generally need to play around to find which combination of settings works best for lap times. With each generation of car I've owned since around 2005, I've found I'm leaving more of the systems on (except maybe traction control that kills power when you're trying to accelerate out of a corner ) I've read some tests of the current McLaren, Ferrari and Porsches, that suggest they become almost undrivable with many of the aids turned off.
__________________
BMW F22 M240i; F48 X1 25i, BMW F20 M135i
Peugeot T9 308 GTi 270 Renaultsport Megane 3 Trophy-R, Renault Clio Sport 182. |
Appreciate
0
|
12-19-2015, 04:00 AM | #27 |
Major
220
Rep 1,231
Posts |
Race track vs. public road
As far as driver aids are concerned there are 3 major differences between a closed circuit race track and a public road.
A race track typically has spin-off areas, Armco and maybe even gravel traps and tyre barriers. A public road has 10cm+ kerbstones, trees, telegraph poles, ditches etc. Leaving a racetrack backwards often has only minor consequences.....not so public roads On a race track the surface and available traction are well known....a sighting lap will identify areas of low traction and at least on raceday marshalls will signal oil on the track. On public roads you've no idea what you're going to find around the next corner.....diesel on roundabouts from overfilled cars, sunken manhole covers, slippery white lines, low traction wet tarmac, standing water, wet leaves, mud or something spilled from a lorry....no idea Other drivers on a racetrack are typically experienced and expect other drivers to be going quickly. On public roads almost no one is expecting other vehicles with high speed differentials. Also many drivers seem to entirely lack the ability to keep their car between the lines when driving quickly on a narrow road. Then of course there're trucks and wide loads....nothing like threading your way down a nice winding road to suddenly find a truck or camper van filling the opposite lane and a part of yours What all this means is that a track driver has a much easier time....knows what the available traction is, can plan entry and exit lines, has spin-off areas to catch his mistakes and most importantly, doesn't have cars and truck coming the other way. So what does this mean for driver aids? On track, driver aids are there mainly to catch driver errors when he/she steps over 100%......push too hard, accelerate too quickly, brake too hard and a driver aid will step in and correct. Back off the driver aids and you'll feel the car moving around more underneath you and you'll need to be more careful and refined with your driver inputs. Make a mistake and whoops, the scenery's spinning and there's lots of noise and smoke. Public roads are entirely different. Driver aids are there to assist in emergency situations.....the need to slam on brakes as hard as possible while taking emergency evading action......catching the back end when tyres suddenly encounter spilled fuel, reducing power when traction is reduced. On a track, the driver must concentrate on car control, dosing throttle, brake and steering to keep the car going forward quickly. On public roads, the driver may be too busy avoiding oncoming vehicles, kerbs, roadside signs and lamposts to give a lot of thought to cadence braking, controlling under steer etc. If the track driver fails, he spins off while the road driver may kill himself of others if he makes a mistake. In view of the above I'm sure you'll agree that turning off driver aids on a public road is a very foolish thing to do. You may be a excellent driver with outstanding car control, but even you can't react fast enough to changes that happen in split seconds. Driver aids can detect and rectify a problem far quicker than even the best drivers.....typically by the time a driver has detected a problem, the on-board electronics would have already instigated the fix. Thus a driver can brake, swerve and concentrate on missing other vehicles and roadside objects without having to simultaneously try to control a resulting skid. In essence, driver aids aren't only compensating for mistakes....they're preventing sensory overload and reacting to dangerous situations far quicker than any driver can. They are not there for the expected....rather for the unexpected. Given that you therefore can't predict when you'll need them, leaving them on all the time is the only sensible solution. Last edited by SteveC; 12-19-2015 at 04:05 AM.. |
Appreciate
0
|
12-19-2015, 04:23 AM | #28 |
Brigadier General
266
Rep 3,290
Posts |
I agree with SteveC. DSC Off is for recreational driving only. Sport+ (or DTC mode) is however useful for snow driving, as the traction control is otherwise too aggressive to provide optimum traction.
On public roads, I do most of my driving in Comfort Mode. |
Appreciate
0
|
12-21-2015, 02:26 AM | #29 | |
Private First Class
14
Rep 111
Posts |
Quote:
Actually I was meant to ask you, does the electronic diff kick in in 1st gear? If I give it some in 1st gear, it's more difficult to get the rear end out than in 2nd gear. Seems like the electronic diff works much better when you're in 2nd gear. Although I have got the rear end out in 1st before, but I think the road was wet from rain. |
|
Appreciate
0
|
12-21-2015, 02:38 AM | #30 | |
Brigadier General
266
Rep 3,290
Posts |
Quote:
Actually first gear is the most important gear for this feature, as it enables you to start from a standstill going uphill when the load on the rear wheels is not equal. This is typically the case if you have to stop and restart in a corner on the way up an incline in the winter. With an open differential, the torque to the driven wheels will always be equal. If one wheel has no traction (lifted off ground or standing on black ice), the other wheel will also receive zero torque, and the car is stuck. The electronic differential brake will notice the spinning wheel, brake it individually, and the brake torque will also go the other wheel, which has some traction. Two wheel drive instead of one wheel drive. |
|
Appreciate
0
|
12-30-2015, 08:15 AM | #31 |
Private First Class
14
Rep 111
Posts |
Hi mate, I have not been at work so forgot to check back. Thanks for replying.
I'm finding in my 8 speed auto that 1st gear doesnt seem to have a differential brake. I'm not able to get the back end out as easy but I have done it before. Example, I get the car washed at the hand car wash and they put the tyre shine on the tyres and immediately outside on the main road a lot of this stuff comes off and makes the road slippery even in the best conditions. It's the same in the UK. A couple months ago, I activated DSC Off and engaged manual gear mode and 1st gear. When I came out and accelerated, there was wheel slip but the back end didnt seem to slide out. I assume it was one wheel. Today I got the car washed at the same place and did the same test but today started off in M2 (2nd gear). On only half throttle, the wheels slipped and I was nicely drifting out with about 1/8th a turn on the steering (so not much). Is there a better way for me to check if this is working in 1st gear? I find sometimes this works excellently, and sometimes it doesn't seem to work. I wonder if it's a limitation on the electronics or possibly I'm missing something. I also found the park assist sometimes didnt work, meaning that it would start to steer the car into a space and then it would just give up and I'd need to do it manually. I think this may have been because I was not indicating, as I tried this yesterday and I noticed a message come up saying to use the indicator to use park assist. So, I guess this was "pilot error" |
Appreciate
0
|
12-30-2015, 08:42 AM | #32 |
Brigadier General
266
Rep 3,290
Posts |
It is easier to check if you park on an incline, with the car leaning to one side. Then the rear end will slide downhill when you launch with some wheelspin.
|
Appreciate
0
|
12-31-2015, 12:40 PM | #33 |
Private
17
Rep 58
Posts |
Getting back to the topic of the 50:50 weight distribution, I think BMW has pretty much succeeded in stablishing a "trademark" dynamics by keeping the same weight distribution criteria through all of its range(except for the X and the 2 van). So once you started driving a bmw regardless of what series, and you started enjoying the pilot experience of a FR car, plus the elegance of the car, you are pretty much into beeing loyal to the brand, knowing that even a bigger car will behave very similar, and no other brand offers you the same driving feeling.
|
Appreciate
0
|
Post Reply |
Bookmarks |
|
|