[Coo/S]

There has been a lot of discussion on how the DSC or rather the ASC+T are too intruisive to people's taste. I didn't feel that the ASC+T element of my DSC was being too intruisive when the road was dry and I had my 17" S-spokes on. Unfortunately I didn't get to try to really push it as I was still on my break-in period when I had those wheels on. When I finally managed to break in the car I had already my studded winter tires on and with them there is naturally enough power in the car even in dry conditions to get the ASC+T on even without trying. For the studs I guess this is only a good thing.

Anyway, to the issue itself...

Now that we get some snow in Finland I took the car to a large empty car park to test the DSC as well as the ASC+T. In these snowy conditions the ASC+T is working fine, it does not seem to be too intruisvie, and it actually just balances the power supply to be smooth under these conditions unless you really provoke it. With the ASC+T off the car feels uncontrolled if you really pushing it, and even when not pushing it requires more attention to drive with the system off. I don't think people can actually easily (safely) try out the DSC element (correcting yaw) in dry conditions. I took for me couple of tries to make that part kick in, but when it did it worked really nicely; you come in to a corner with a speed just too fast, start to corner and just when you start to understeer the DSC kicks in. It feels funny as the car simply breaks for you and suddenly you realise you are again "on track". The difference to ASC+T is that the DSC kicks in even when you have your foot off the gas pedal. Now one shouldn't of course rely on this feature and it can only help you if you are within the range, but it certainly kicks in to help you if you have missed a slippery corner. For winter I find the DSC really helpful.

[Silakka]

I'm allso having studded wintertires and the ASC+T really helps to protect the studs. It's not too intrusive at all, it gives you a smooth acceleration without wheelspin.
Summertime with summertires, the ASC+T is really annoying. If you happen to spin your tires at an acceleration you will have that "smack your teeths in the steeringwheel"-effect.

Now when we have snowy roads I got out to test how the ASC+T works. Notice, I only have ASC+T on my Cooper S, not DSC. ASC+T should be somekind of a limited Stability control which should prevent over(and/or?)understeer.

Now I found it to be nothing else but a traction control, Ok. it helps when accelerating through a corner so that it won't understeer, but that's it?

Could someone explain how ASC+T and the Corner Brake Control (CBC) works and how to take advantage of them, the ASC+T doesen't seem to activate in other situations except accelerations...

- Mikael

[Theo]

I have DSC on my 3-Series as well as the new MCS. Last winter I found the DSC in the BMW was great for the snow...except when starting out from a stop in slippery conditions...even with the Dunlop snows.

If I remember correctly the ASC portion of the system senses rotational differences among the wheels (wheel spin) and decellerates the motor while applying corrective braking to the individual wheels (correct me here if am misunderstanding the operation). I found that I could not avoid a certain amount of wheelspin in icy conditions when starting. The DSC would kick in and I couldn't get going very well. Switching DSC off in that situation allowed the slipping wheels to spin without the decelleration/braking. Taking-off from a stop was much improved.

However, once I got going, I switched DSC on right away. It works well in the BMW and I am expecting the same experience in the MCS.

Theo

'04 MCS

[stryder]

The FAQ on all the Three Letter Acronyms is here: (Scroll a bit farther down the page, the link isn't exact)

http://www.mini2.com/forum/faq.php?f..._faq_terms_abs

[Spookyfish]

This is good info:
http://www.esceducation.org/about_es...n_action.shtml

[HarryHBMCC]

ASC+T works in other situations than just accelerating. If you take a corner too fast in neutral and the wheels skid it will apply brakes to the wheels -- you can hear and feel it. I know this works in the wet for sure (just had it happen the other night) and likely in snow too. ASC+T doesn't have a yaw sensor so it doesn't pick it up at the same time as DSC, the front wheels really have to spin or slip before it will kick in but it does.

Also, if you downshift too hard and the wheels approach lockup, ASC+T will give a bit of gas to prevent the lockup. This is essentially the opposite of ABS.

CBC is separate. Brake loads are balanced so that you get no understeer or oversteer under braking. ASC+T works while accelerating or coasting while CBC, EBD and ABS work under braking.

Harry

[Coo/S]

Quote: Originally Posted by HarryIndiBlue

ASC+T works in other situations than just accelerating. If you take a corner too fast in neutral and the wheels skid it will apply brakes to the wheels -- you can hear and feel it. I know this works in the wet for sure (just had it happen the other night) and likely in snow too. ASC+T doesn't have a yaw sensor so it doesn't pick it up at the same time as DSC, the front wheels really have to spin or slip before it will kick in but it does.

Also, if you downshift too hard and the wheels approach lockup, ASC+T will give a bit of gas to prevent the lockup. This is essentially the opposite of ABS.

CBC is separate. Brake loads are balanced so that you get no understeer or oversteer under braking. ASC+T works while accelerating or coasting while CBC, EBD and ABS work under braking.

Harry

Interesting...the downshift part I knew already, but I do not quite understand how it would work in the situation when you are in neutral. How does it sense slip (not skid)?

[HarryHBMCC]

Under cornering inside and outside wheels go at different speeds which is handled by the differential. If you carry too much speed, the difference can cause slippage. It detects wheelslip there the same as all other times, using the ABS wheelspin sensors.

Harry

[Coo/S]

Quote: Originally Posted by HarryIndiBlue

Under cornering inside and outside wheels go at different speeds which is handled by the differential. If you carry too much speed, the difference can cause slippage. It detects wheelslip there the same as all other times, using the ABS wheelspin sensors.

Harry

I see. Interestingly I never noticed that with my BMW (had only ASC+T), but with the MINI and DSC it's far more apparent. Maybe I wasn't trying hard enough to experience it with my BMW. Anyway, what is important is that it works - no matter how.

[HarryHBMCC]

BMW steers with front wheels and drives with the rears so I wonder if the ASC+T uses the wheelspin sensors on the front wheels on the Bimmer? If not then it wouldn't notice the cornering case.

Harry

[DeniseK]

Thanks - I really appreciated this discussion. I'm a snow weenie. As soon as it snows and freezes, I stop driving. I wish I knew how to drive in snow, but I don't.

[HarryHBMCC]

You live in New Mexico, Denise. How much snow do you get???

Harry

[Theo]

Quote:

BMW steers with front wheels and drives with the rears so I wonder if the ASC+T uses the wheelspin sensors on the front wheels on the Bimmer? If not then it wouldn't notice the cornering case.

Harry

BMWs ASC/DSC utilizes (among other bits and pteces) wheel spin sensors at all four wheels. The wheel sensors are also used as input to the ABS system. On the E46 3-Series (and E36 methinks) the front wheel sensors are at each front steering arm and the rear sensors are at each wheel hub.

For those of you who have or can get access to the Bentley E46 Service Manual, there is excellent documentation of the ABS/ASC/DSC systems. There are also numerous illustrations and diagrams explaining the systems' operation.

One of the most interesting descriptions is that of DSC. As I understand it, DSC expands the ABS/ASC 2-dimensional operation, which operates in only the acceleration and deceleration "dimensions", to a 3-dimensional system which adds cornering stability operations based on rotational acceleration, and lateral acceleration (left/right "g" force). The added dimension is provided by (a) the "yaw" sensor which measures the vehicle's rotation about its axis (as in "swapping ends"), (b) a lateral acceleration sensor which measures left and right "g" force and (c) a steering angle sensor which indicates the driver's intended path. If the "third dimension" sensors trigger an actual stability "warning" as predicted by the vehicle's intended path, the DSC control module uses the "two dimensional" system to reduce the yaw and/or g forces. Pretty sophisticated!

For my taste, the most intelligent part of ASC//DSC systems is the "On/Off" switch. Don't get me wrong, I normally drive with DSC on...but...when I am driving for "fun", I live in the land of the orange triangle!

My two pence,

Theo

[nonsequitur]

This is a pretty cool thread. Thanks guys! I like the "live in the land of the orange triangle!" statement.

The DSC system seems very effective on the MINI. It's more noticable than I thought it would be in the dry but the control situation it's dealing with is more dramatic than in the wet or snow. Definite pulsed feedback through the steering wheel.

DSC manages through quick corrections of the steering wheel (to regain front grip) precisely. I worried that you might be able to "confuse it" or "get ahead" of the computer with inputs but we haven't found that to happen in track day conditions with DSC switched on.

We've got our Dunlops mounted and ready, and I've tentatively signed up for a school at the Pass this winter. Should be a kick.

[Rick38]

Hi I am taking part in a rally (no speed rally) in februari 2004.
Car is a Cooper S on 17" at the moment. Trip starts from Holland, through Germany, Denmark, Sweden and Finland. Back through Estland, Letland, Lithouwania, Poland, Netherlands. 6 days. Non stop to Kuusamo Finland. 1.5 day rest , non stop back.

Wich wheel size and tyres would you recommend??!!

[OregonCooper]

Quote: Originally Posted by Rick38

Hi I am taking part in a rally (no speed rally) in februari 2004.
Car is a Cooper S on 17" at the moment. Trip starts from Holland, through Germany, Denmark, Sweden and Finland. Back through Estland, Letland, Lithouwania, Poland, Netherlands. 6 days. Non stop to Kuusamo Finland. 1.5 day rest , non stop back.

Wich wheel size and tyres would you recommend??!!

15" & Blizzaks.

[Rick38]

Blizzaks stands for Bridgestone Blizzak?

[stryder]

Quote: Originally Posted by Rick38

Blizzaks stands for Bridgestone Blizzak?

Yes... Read the FAQ on Winter snow tires - it has the full names and sizes of the tires.