[IraXI]

I am getting rid of my 330XI before winter and getting a 335I. Ive been driving around a G35 coupe for 2 winters with snows and no problems at all and I plan to add winters to my 335I as well but the big difference will be the 335I doesnt have LSD. How will this effect winter driving? Will my 335I be as good in the snow as my G35 was? I don't want to get nervous for no reason but id like to know up front if im in for a suprise.. or am I just thinking way to much into it?





Matt

[Bimmerista]

As I understand it, an LSD allows one wheel to spinn independently of the other.

With our open diffs, this is not possible, so DSC kicks in to slow down the offending (spinning) wheel. However, the system does allow for a little spinn bvefore kicking in in standard mode (DSC/DTC button not activated, all systems on). If you push the DSC/DTC button once, the system will allow for more spinn before kicking in. But from what I gather, NOT one wheel alone, rather both.

So the result would be the same in winter as with the G35, if one wheel has traction, the open diff system would not permit the other wheel from spinning and the car stays stable and gets out. If both wheels loose some traction, the system allows both to spinn somewhat to create some forward momentum and then as traction is gained the DTC stops the spinning. In the first example, the G35 LSD would permit the wheel without traction to spinn but the G35s traction control would activate to stop it from spinning (the G35s traction control would achieve the same result that our open diff does without the intervention of the DTC).

Hope this makes any sense.

[Hotan Braskey]

Originally Posted by Bimmerista

As I understand it, an LSD allows one wheel to spinn independently of the other.

With our open diffs, this is not possible, so DSC kicks in to slow down the offending (spinning) wheel. However, the system does allow for a little spinn bvefore kicking in in standard mode (DSC/DTC button not activated, all systems on). If you push the DSC/DTC button once, the system will allow for more spinn before kicking in. But from what I gather, NOT one wheel alone, rather both.

So the result would be the same in winter as with the G35, if one wheel has traction, the open diff system would not permit the other wheel from spinning and the car stays stable and gets out. If both wheels loose some traction, the system allows both to spinn somewhat to create some forward momentum and then as traction is gained the DTC stops the spinning. In the first example, the G35 LSD would permit the wheel without traction to spinn but the G35s traction control would activate to stop it from spinning (the G35s traction control would achieve the same result that our open diff does without the intervention of the DTC).

Hope this makes any sense.

Bimmerista, I think you have some info correct, and some info a little confused. In a RWD car with a LSD, if a rear wheel begins to slip, more power is transferred to the wheel with more traction, thus lessening the spin from the wheel with less traction. I am not sure what you mean when you say that a car with an open diff would remain stable in snow. A car with a LSD should be able to generate more grip than an identical car with an open diff, so I would think that a LSD would be helpful in the snow to some degree.

[subframe]

This link explains how open and limited slip differentials work.

http://auto.howstuffworks.com/differential.htm

[Bimmerista]

Originally Posted by Hotan Braskey

Bimmerista, I think you have some info correct, and some info a little confused. In a RWD car with a LSD, if a rear wheel begins to slip, more power is transferred to the wheel with more traction, thus lessening the spin from the wheel with less traction. I am not sure what you mean when you say that a car with an open diff would remain stable in snow. A car with a LSD should be able to generate more grip than an identical car with an open diff, so I would think that a LSD would be helpful in the snow to some degree.

Thanks, I am still on a learning curve on the LSD front. So our system wil not tranfer power but rather use the brakes to slow down the spinning wheel. The wheel with the traction still gets power though, so the difference in fact is ?

Does our system achieve the same end result as an mechanical LSD using electronics (and "borrowing" the brakes to do so) ?

[IraXI]

I guess I dont really need a highly in depth explaintion... but in short all I need to know is will the 335I perform in the winter like my G35 coupe did? When roads were bad and I kept the rpms under 2k I never had a prob. I just don't know if LSD helped the car perform in the snow better or will the 335I be the same granted I do the same thing with the RPM's?

[jeftrz]

Differentials 101:
A differential allows the left and right hand driven wheels on a vehicle spin at different rates. If you didn't have a differential and tried to turn your car, one of your driven wheels would have to slip since the wheel on the inside of the turn travels a shorter distance than the outside wheel.

Unfortunately with a standard differential (non LSD and without DTC) the torque from the engine is applied to both wheels equally. Because of this, if one of the wheels has no traction and the other has traction the no-traction wheel will spin and the wheel with traction will not.

Basically, an LSD allows for some slip between the two wheels, but will lock the differential to transfer torque to the non-slipping wheel if too much slip is detected in the other wheel.

DTC's function is similar, however instead of a mechanical system in the differential the car's computer applies the brakes to the slipping tire to stop the slip. This increases the torque required to spin that tire, and hopefully transfers the torque back to the non-slipping tire.

So, to answer your question:
Yes, an LSD would help in the snow as would DTC.
A good DTC system could potentially work as well as an LSD.

A car with both may be best.

JT2

[inTgr8r]

Originally Posted by IraXI

I guess I dont really need a highly in depth explaintion... but in short all I need to know is will the 335I perform in the winter like my G35 coupe did? When roads were bad and I kept the rpms under 2k I never had a prob. I just don't know if LSD helped the car perform in the snow better or will the 335I be the same granted I do the same thing with the RPM's?

Hey Matt,
I can relate to your G35.....
I have (for now) a G35 AT sedan, it comes w/o LSD. (like the 335)
It was great in the winter;
I'm in North Toronto, with 4 snows I had no problems at all

Snow tires are the key factor in winter driving.
all seasons = NO season as far as I'm concerned.

[IraXI]

Thanks guys, your response made me feel better

[Bimmerista]

Originally Posted by jeftrz

Differentials 101:
A differential allows the left and right hand driven wheels on a vehicle spin at different rates. If you didn't have a differential and tried to turn your car, one of your driven wheels would have to slip since the wheel on the inside of the turn travels a shorter distance than the outside wheel.

Unfortunately with a standard differential (non LSD and without DTC) the torque from the engine is applied to both wheels equally. Because of this, if one of the wheels has no traction and the other has traction the no-traction wheel will spin and the wheel with traction will not.

Basically, an LSD allows for some slip between the two wheels, but will lock the differential to transfer torque to the non-slipping wheel if too much slip is detected in the other wheel.

DTC's function is similar, however instead of a mechanical system in the differential the car's computer applies the brakes to the slipping tire to stop the slip. This increases the torque required to spin that tire, and hopefully transfers the torque back to the non-slipping tire.

So, to answer your question:
Yes, an LSD would help in the snow as would DTC.
A good DTC system could potentially work as well as an LSD.

A car with both may be best.

JT2

Thanks for explanation-confirms what I thought I knew.

[ward]

LSD wont' help you turn or stop

[BK]

Originally Posted by jeftrz

DTC's function is similar, however instead of a mechanical system in the differential the car's computer applies the brakes to the slipping tire to stop the slip. This increases the torque required to spin that tire, and hopefully transfers the torque back to the non-slipping tire.

Excellent explanation. I just wanted to add that Wikipedia tells me that if DTC is braking a spinning tire, torque transfer to the other tire should not be "hopeful" but automatic. Having DTC apply the brakes to a spinning wheel (for example, on rear wheel on ice) raises the reaction torque at that wheel, so the differential compensates by transmitting more torque automatically to the other wheel.

Based on my limited understanding of how this stuff works, an LSD is extremely beneficial when exiting corners while stomping on the gas. DTC is extremely beneficial when losing traction due to road conditions. But neither does the other's job nearly as well.

[silvrevo]

Im glad somone asked this question. So dtc will act like a car with lsd. So why is it that the 335i cant lay down 2 tire marks, only one? I think that is with dtc off. With it left on will it do this?

The whole idea of no lsd has me looking forward to the 335ix. Now with awd, winter time has a different spin on it. I look forward to snow in my current ride. Its just a blast to go out and tear it up!!!

As far as all season tires not worth it,,, try the conti's exteme contacts, or sport contacts, not sure which I had previous, but they were really good all round.

Im looking forward to hearing how people with the 335i deal with winter.

[LEDZEP]

I find that taking LSD helps my driving in any conditions! I really enjoy the traffic lights - they really freak me out!!

[Bimmerista]

Originally Posted by LEDZEP

I find that taking LSD helps my driving in any conditions! I really enjoy the traffic lights - they really freak me out!!

Its the 21st century now my friend - LSD is out.

[Pedal2Floor]

Originally Posted by silvrevo

Im looking forward to hearing how people with the 335i deal with winter.

As with all things car related, the most important piece of equipment is the one between your ears.

The LSD equiped cars from my experience will slip less on take off. The DTC does not react as fast in my experience and you will be a little more tail happy on starts. In all cases for RWD, you should have real winter tires.

As someone else posted above, in snow LSD will not help you to stop. And if you go to fast and start to plow, nothing will help you turn.

In the wet, LSD will definately help you vs DTC. As some of the 335 reviews by mags and other have pointed out, 300lb/ft of torque is nothing to play with in the wet. An LSD will help in the wet.

In the dry, when you take a turn hard, an LSD will prevent the inside wheel from spinning and getting the classic sqealing tire around the corner. One of the 335i mag reviews pointed out that DTC was not responsive enough and questioned the decision of BMW not including an LSD.

All in all, more people have driven without any of this for many winters past without issue. Use your head and go slow, brake early and in a straight line and don't punch out of turns in the snow. If you used your head you will not have an issue.

[Griff330Ci]

The title is hilarious. Anyone who deosn't know what the initials LSD mean would think you were asking if its easier to drive in the snow while on acid.

[goldminer]

Originally Posted by silvrevo

Im glad somone asked this question. So dtc will act like a car with lsd. So why is it that the 335i cant lay down 2 tire marks, only one? I think that is with dtc off. With it left on will it do this?

Please re-read Jeftrz's and BK's posts. They really did not say that they will act the same.

An lsd-equipped car will deliver torque to both wheels at the same time. Torsen and clutch pack type lsd's will always spin both wheels because the differential speed allowed between the 2 wheels is not infinite (unlike an open differential). It is usually limited to a max percentage difference. (Although in a Torsen differential the wheels see an open diff but the engine sees a a locked rear end because of very high ramp angles in its worm and roller gear set up).

Viscous coupled lsd's require some single wheel spinning to occur before the diff starts to lock up and spin both wheels.

BMW's DTC is still an open differential. The wheel with the least traction will get most of the power and will spin. DTC will then quickly intervene with that wheel's brake and transfer the torque to the other side. The wheel must loose traction first before DTC will intervene. This transfer of torque back and forth makes a 2-wheel burnout unlikely. One complaint about BMW's system is that when applying full power out of a tight corner the 335i does not put its power down smoothly and quickly.

This is why BK said:

"Based on my limited understanding of how this stuff works, an LSD is extremely beneficial when exiting corners while stomping on the gas. DTC is extremely beneficial when losing traction due to road conditions. But neither does the other's job nearly as well."

[inTgr8r]

Originally Posted by Griff330Ci

The title is hilarious. Anyone who deosn't know what the initials LSD mean would think you were asking if its easier to drive in the snow while on acid.

LOL... well?

[agarbati]

Originally Posted by inTgr8r

LOL... well?

I think Meth usually works better.

[Tony]

I'm confused My 2001 330i was stuck in the snow one day. Funny thing about it is that only one side of the car was in the snow. The other side including the right rear tire and front tire was on dry pavement. All that was needed to get my car out of the snow was for the differential to put the power to the wheel that was on the "DRY" pavement. That didn't happen. All the diff did was put 100% of the power to the wheel that was stuck spinning in the snow. Would an LSD be any different in this case?

[Tony]

Originally Posted by goldminer

BMW's DTC is still an open differential. The wheel with the least traction will get most of the power and will spin. DTC will then quickly intervene with that wheel's brake and transfer the torque to the other side. The wheel must loose traction first before DTC will intervene. This transfer of torque back and forth makes a 2-wheel burnout unlikely. One complaint about BMW's system is that when applying full power out of a tight corner the 335i does not put its power down smoothly and quickly.

I guess this is where DSC differs from DTC (post above). My 2001 330i has only the DSC. If DTC does eventualy put the power down to the wheel with grip then I wouldn't have been stuck? Thanks