Can you experts out there explain the difference between DSC and a limited slip differential (to be offered in 2005)?

Which one of these would be better for snow?

Thank you

 

DSC kills power
Limited slip transfers power

I never have DSC engaged in the snow

 

DSC is electronic management of "stability control." It uses active braking at the wheels AND the engine to control traction.

An LSD is mechanical and simply transfers power away from a wheel that is slipping to the wheel that still has traction.

As far as I understand it, an LSD would provide some degree of safety versus no traction control at all, it's much more oriented toward performance and autocross or track usage. DSC is not really designed for performance driving, it's for safety.

 

Could somebody shed light on the ASC (standard Cooper S) vs LSD in the winter, say on snow and ice? The ASC did not seem to help my car get through the snow and slush last year.

I'm considering the LSD mostly for performance reasons but wondered if it helped in winter conditions too.

_________________
'03 Cooper S JCW Pure Silver/Black - PP, CWP, Space Cloth, Fogs, 16" R90s, K&N, 35% tint


'02 S2000 Spa Yellow/Black - HKS exhaust, OEM hardtop, Infinity rears

 

Snow tires would help more in snow than a limited slip diff would. The problem is that with an LSD, you can wind up spinning both wheels instead of just one.

However, LSD's are the cat's meow for autocross. This could really make the Cooper S into a much meaner stock class autocross car.

 

>>Could somebody shed light on the ASC (standard Cooper S) vs LSD in the winter, say on snow and ice? The ASC did not seem to help my car get through the snow and slush last year.
>>
>>I'm considering the LSD mostly for performance reasons but wondered if it helped in winter conditions too.
>>
>>_________________
>>'03 Cooper S JCW Pure Silver/Black - PP, CWP, Space Cloth, Fogs, 16" R90s, K&N, 35% tint
>>
>>
>>'02 S2000 Spa Yellow/Black - HKS exhaust, OEM hardtop, Infinity rears

LSD would help you more, but again that is relative. Just like these 4WD maniacs who drive in the snow. It doesn't matter if you have 4 wheels driving or one wheel, they all spin on ice.

With that said, the LSD is what I would call a proactive device. It is always working and therefore is always providing extra traction. The electronic controls are not always working, but are always monitoring. They are going to help cut things out to eliminate problems, (i.e. engine power, braking). The electronic aids are going to remove power from certain areas to prevent sliding, skidding.... The LSD will always be attempting to provide you with more traction.

I find the electronic aids often cut in to frequently and sometimes unexpectently.

 

I had a limited slip on the '88 BMW 325is I owned a few years back. It makes all the difference in the world in snow and slush...there was a huge hill on the road I had to take to get anywhere from my house, and I just went straight up it in 3" of snow and slush. No drama, no spin, just even throttle and motored right up. SUVs were having trouble, getting sideways, etc...but I went up it in a RWD Bimmer with all-season tires on it.

I recommend it for both performance and inclement weather if you can wait till the '05s come around.

 

Think of DSC as being electronic which uses braking to help maintain traction when traction is being lost. It helps to slow you down before you loose control so it provides some safety. When we do performance driving as in driving school we don't want the car slowing down automatically so we turn DSC off.

With a LSD it is passive and on all the time to provide a mechanical advantage to transfer as much power as possible to the driving front wheels. When loosing traction more power goes to the wheel that has traction until more traction is possible on both wheels then traction is evenly transfered to both wheels. This helps in all driving conditions where traction is being lost. It doesn't increase traction if the tires or road surface doesn't allow it so you do need the advantage of snow tires if possible.

Therefore while LSD helps immensely in autocross and on the track it does also provide for safety in street driving during inclement weather or road conditions (again you'd still need good tires to help).

So is the LSD option for the 2005 MCS worth the cost? Definitely. Also higher resale value and cheaper (worth about $2200) and less hassle than adding it aftermarket not to mention warranty.

 

DSC is an electronic attempt at making an open differential perform like a limited slip. Additionally, as it controls all 4 wheels it can maintain stability in a slide or skid and can greatly affect the overall handling of a car.

Don't confuse DSC with antilock braking. While the system may be the same the goal of the programing is different.

An open differential allows the wheel with the LEAST amount of traction to spin. When the DSC senses a spinning wheel it very rapidly applys braking to that wheel thereby fooling the differential into transfering torque to the other wheel. It will continue to do that for a time (depending on the programming) and then begin to shut down power in an attempt to regain traction. When seeking high performance, braking and power shutdown are not preferred over a mechanical torque distributing system like you have in a true limited slip. Additionally, having both wheels on an axle spinning is preferable when you are trying to steer with the throttle. I can actually place where I want the nose to be in a turn with the right pedal and with a lift I can then place the tail. DSC won't allow you to do that.

That being said a performance oriented DSC can go a long way toward making a car more stable at high speeds and can actually take advantage of an aggressive chassis design or high power situation. Just as computers allow the newest jet fighters to perform far better and be designed with more efficient (and less stable) components, computers can sense and react to situations far quicker than humans. The newest Mercedes and Corvettes have DSC systems that actually improve the performance of the cars for most drivers. That's not to say that the best drivers couldn't best the times without the computer but they may be able to have more consistant lap times or take lines they couldn't have taken before without it.

The only problem is that ours sucks! Therefore, I have it programmed to be off all the time (call Ian Cull for his magic board) and only turn it on so I can relax in the rain or snow.

Snow? Snow? Azenis don't go in the @%$&^*! snow!

 

Thank you all for your fascinating input.
Much appreciated!

-Marc (approx. March '05 club)

 

I remember rear wheel drive "posi-traction" or rear ends using clutches that apply nearly equal drive to each wheel. Newer "Limited slip" would stall the spinning wheel and drive the other. This became a conventional differential for years.

We wanted the posi style to hook-up and go fast in a straight line so posi's and Ford 9" lockers were trick. 4-wheel hardcores want locking power driving all wheels. I have driven both styles in winter snow conditions and liked the posi way better than limited slip. Often you can drive out of a situation where the LSD gives it up.

This was rear wheel drive world so I'm not sure if it even applys to MC. Guys racing these buggers may get a treat from the option but can the basic street driver tell? When it comes to winter driving will LSD be a blast from the past? ... carry sand in the boot mate.

 

>>DSC is an electronic attempt at making an open differential perform like a limited slip. Additionally, as it controls all 4 wheels it can maintain stability in a slide or skid and can greatly affect the overall handling of a car.
>>
>>Don't confuse DSC with antilock braking. While the system may be the same the goal of the programing is different.
>>
>>An open differential allows the wheel with the LEAST amount of traction to spin. When the DSC senses a spinning wheel it very rapidly applys braking to that wheel thereby fooling the differential into transfering torque to the other wheel. It will continue to do that for a time (depending on the programming) and then begin to shut down power in an attempt to regain traction. When seeking high performance, braking and power shutdown are not preferred over a mechanical torque distributing system like you have in a true limited slip. Additionally, having both wheels on an axle spinning is preferable when you are trying to steer with the throttle. I can actually place where I want the nose to be in a turn with the right pedal and with a lift I can then place the tail. DSC won't allow you to do that.
>>
>>That being said a performance oriented DSC can go a long way toward making a car more stable at high speeds and can actually take advantage of an aggressive chassis design or high power situation. Just as computers allow the newest jet fighters to perform far better and be designed with more efficient (and less stable) components, computers can sense and react to situations far quicker than humans. The newest Mercedes and Corvettes have DSC systems that actually improve the performance of the cars for most drivers. That's not to say that the best drivers couldn't best the times without the computer but they may be able to have more consistant lap times or take lines they couldn't have taken before without it.
>>
>>The only problem is that ours sucks! Therefore, I have it programmed to be off all the time (call Ian Cull for his magic board) and only turn it on so I can relax in the rain or snow.
>>
>>Snow? Snow? Azenis don't go in the @%$&^*! snow!



Who is Ian Cull and how do I contact him?