xi Snow Review

[SteelBlueXI]

I looked out the window this morning and it was SNOWING!!! :redspot

I have been waiting since I got my car to test out the AWD in the snow and luckily there was still a fresh layer that the plows hadn't gotten to yet.

I hopped in and fired her up. I'm still running my OEM all season Conti's. First I tried cruising around normally... no real difference. Then I tried some manuevers I knew would really test the system.

First I gassed it hard in a slight turn and felt the back end start to kick out. That's the 68% RWD. The trac turned on and spoiled my fun. Tried again with the trac off and gave it a little more juice when I felt the back kick out and the car started to drift, but for the most part pulled itself through the turn nicely. That must have been the 32% FWD.

I threw the car around a little more this morning and for the most part it wasn't as planted as my old Explorer in the snow, but was def. more than capable. :cool:

In the rain this car is a road magnet. Two inches of water on the ground may as well be dry pavement. Snow, however, really reminds you that it is a Bimmer with RWD tendancies.

Verdict: An AWD car trapped in a RWD car's body.

[SilverStreak]

Have fun, be careful, I'm stuck home on snow days.... :D

[Kevlar]

Originally posted by SilverStreak
Have fun, be careful, I'm stuck home on snow days.... :D

:lol:

only time i see snow is if i empty my crushed ice on the sidewalk after i'm done with my drink.

[themadhatter]

Originally posted by SilverStreak
Have fun, be careful, I'm stuck home on snow days.... :D

snow? what's that? powerdery stuff associated with water? We have something like that but it's always at the beach where it's 85-100 degrees. :D :confused: :( :complain

ah the life in West Africa :help

-Ron

[SilverStreak]

Well, the sad part is that I work from home 95% of the time, so if it snows, even 3 feet at one time like last year, I don't get a day off, I get a full work day plus snow removal.... :)

[mitchelrl]

only problem i had yesterday was getting up my steep driveway.

[themadhatter]

Originally posted by Kevlar
:lol:

only time i see snow is if i empty my crushed ice on the sidewalk after i'm done with my drink.

I gotta move to Florida.

[JRyan]

Drove my 92 325is with lsd home in the snow late last night. My winter tires are coming in the mail soon. I passed a Cherokee in a ditch. I've always thought, and still do think, that's it more the driver than the car. (I can't wait for the snow tires though!)

[SteelBlueXI]

Originally posted by JRyan
Drove my 92 325is with lsd home in the snow late last night. My winter tires are coming in the mail soon. I passed a Cherokee in a ditch. I've always thought, and still do think, that's it more the driver than the car. (I can't wait for the snow tires though!)

Sometimes people with SUVs get cocky. I've had an Expedition blow by me on the highway, doing probably around 90, in heavy snow once. A half hour later, I saw him rolled in a ditch between the highway and an exit ramp.

[themadhatter]

Originally posted by NappyD1136
Sometimes people with SUVs get cocky. I've had an Expedition blow by me on the highway, doing probably around 90, in heavy snow once. A half hour later, I saw him rolled in a ditch between the highway and an exit ramp.

reminds me of the exact same that with an Audi A4 (S4?) a couple of years ago. rt280 left lane - dude was flying compared to everyone else then he disappeared into the median in a huge cloud of snow thrown up into the air. after the snow settled, he had all 4 wheels facing the sky. :rolleyes:

AWD/4WD will get you home, not a trophy.

-Ron

[not a motorist]

i was surprised how my 318ic with asc did with the snow we had last year in dc. i went to a club 1 nite and by the time the club let out, more than 3 inches fell. i got in and fired it up and drove more than 30 miles home in unplowed snow.

[marinakorp]

because you have performance tires (I'm onlt guessing) is the reason it handles... different than your explorer...

throw a devent set on snows on there and use the explorer for towing...

[LinearX]

I enjoyed spinning off the highway for basically no reason last winter in the 328. A set of snows would have helped a great deal. Now I have my beater Camry for the really bad days. Ah, skinny tires.. Also, it really helps to keep a full tank of gas in your RWD or AWD car, increases the pounds of pressure per square inch on the tire contact patch, helps counteract the plow of our somewhat wide tires.

[bostongreen18]

i read a test article on different vehicles driving in the snow. they had awd, fwd, rwd.

the findings were that good snow tires make the most difference, and that rwd with good snows and a competent driver would be better than awd with snow tires and average driver. I don't know how they rate the drivers, but the point they made was that its all in the tires

[Heckler&Koch]

I heard a story about some guys who go over the closed mountain passes every year in Jeeps. They air down their wide offroad tires and average about 4 miles an hour, but they ride on top of several feet of snow. Hardcore.

[Mikey52]

Since this topic came up I was wondering, how much tire pressure do you guys have in your snow tires? Im using snow tires this year, last year was hell with 18" Kuhmo 712's (crappy tires in the dry), and want to know how to get the most out of the tires.

Anyone know how the E30 325xi stands up? How was the AWD system back then?

[SteelBlueXI]

Originally posted by Mikey52
Since this topic came up I was wondering, how much tire pressure do you guys have in your snow tires? Im using snow tires this year, last year was hell with 18" Kuhmo 712's (crappy tires in the dry), and want to know how to get the most out of the tires.

Anyone know how the E30 325xi stands up? How was the AWD system back then?

From what I understand, the E30 325xi AWD system is the same as the current E46 AWD system. It's certainly not the best compared to, say, Audi's, but it gets the job done. Now, the new system, X-Drive, sounds really cool but that's only available on the new X5's right now.

[LinearX]

The 325ix's AWD system couldn't be like the E46s, could it? I thought the E46 system relied on DSC-X, which certainly wasn't out in the E30 days.

[Kevlar]

Originally posted by NappyD1136
From what I understand, the E30 325xi AWD system is the same as the current E46 AWD system. It's certainly not the best compared to, say, Audi's, but it gets the job done. Now, the new system, X-Drive, sounds really cool but that's only available on the new X5's right now.

The E30 AWD system was based on a mechanical set of gears and limited slip differentials. A perfect example would be to jack all four tires up in the air. You can put the car in gear and run thru all the gear and in theory redline the last gear with all four tires blazing away.

The E46 AWD system (prior to xDrive) is based on an electronic system with open differentials. A quick note... with an open differential, all the power goes to the wheel with the least amount of traction (dumb, yes I know). So back to the previous example. If you put the car in the air (ignoring the center differential for the time being), all the power goes by default to the passenger rear tire. The comptuer freaks out and says... oOps, no traction. It applies the brake. That means that tire now has all the traction (or so the differential thinks). The power shifts to the other side of the car driver's rear. Car says, oOh, no traction their either... brake gets applied to that wheel too. Now the center differential. By default, it is open, but has some gearing to always put some power to the front wheels. Now, with brakes in the rear being applied, more power gets shifted forward. Front wheels experience the same things the rears did.

Now... with all four tires spinning and the brakes being applied, shuffled and pulsed to try and move power around, the car says, something isn't right and starts to reduce engine power. So, in theory... if you have no traction, you are limited to crawling speed. The computers always allow for some slippage... but in theory if all tires were in the air, ground speed (in theory here) would be limited to 2-3 mph because the engine power would be reduced and all the brakes would being going crazy.

I tried to make this short... no such luck.

[LinearX]

In other words, the current BMW AWD system is not performance orientated, at least, that is what I have collected, but the 325xi's was. It's depressing for a marque that is built around the sport sedan image.

[SteelBlueXI]

Wow, thanks for the awesome clarification. If DSC was disabled would the engine management still limit your speed on the E46 system?

[toddman35]

I would guess it wouldn't but I don't have any personal experience with the system to tell you for sure.

[Kevlar]

Originally posted by NappyD1136
Wow, thanks for the awesome clarification. If DSC was disabled would the engine management still limit your speed on the E46 system?

I believe it would not... with DSC off. This is in theory now as I never thought to really test a AWD system with the DSC off.

But... if I am correct on how the system should work...

68% of the power will be sent to the rear wheels and the other 32% will be sent to the front wheels. The power will then automatically go to the wheel with the least amount of traction both front/rear. Braking forces will not be applied to help move power from the slipping wheel to the other side. The center differential does the power splitting so some power goes rear, some goes front.


the current BMW AWD system is not performance orientated,

No... not performance oriented. It's designed to keep you on the road... even if it means slowing you down to a crawl. This electronic AWD system is also cheaper and lighter... but it does significantly wear down the brake pads if you frequently drive on unstable surfaces.

[LinearX]

I'd assume that negates the ability to do a nice AWD launch then?

[SteelBlueXI]

Originally posted by LinearX
I'd assume that negates the ability to do a nice AWD launch then?

I've had a few great ones with DSC off. Tried it with DSC on once. The engine almost stalled. It was less than impressive.

[Kevlar]

Originally posted by LinearX
I'd assume that negates the ability to do a nice AWD launch then?

It will launch slightly better than a typical RWD car as it has the front wheels doing some work by default.

However... if you were looking to spin all four tires a la Skyline or Subaru, it won't happen. The AWD system in the E46 is weak in comparision.

I had played with the theory of turbocharging a AWD E46 to get neck snapping launches and performance like my friends in the Turbo Subaru world. I found out that with any significant power increase in the E46 AWD setup... it would pretty much chew up the AWD components and spit them out the rear of the car in a pile flaming drivetrain bits.

[SteelBlueXI]

Originally posted by Kevlar
It will launch slightly better than a typical RWD car as it has the front wheels doing some work by default.

However... if you were looking to spin all four tires a la Skyline or Subaru, it won't happen. The AWD system in the E46 is weak in comparision.

I had played with the theory of turbocharging a AWD E46 to get neck snapping launches and performance like my friends in the Turbo Subaru world. I found out that with any significant power increase in the E46 AWD setup... it would pretty much chew up the AWD components and spit them out the rear of the car in a pile flaming drivetrain bits.

AA claims their S/C kits are E46 AWD safe. And there's a guy over at e46fanatics.com who has a S/C (ESS kit I believe) on a 330xi.

[Kevlar]

Originally posted by NappyD1136
AA claims their S/C kits are E46 AWD safe. And there's a guy over at e46fanatics.com who has a S/C (ESS kit I believe) on a 330xi.

Yeah... supercharger delivers power differently than a turbocharger does. Remember, superchargers offer linear power. You really aren't given the drivetrain a super shock of power/torque.

Turbochargers provide a huge surge or torque as boost start to build. That huge surge of torque is the key to the problem as it destroys most drivetrains... the AWD system I do not believe could take it.

[SteelBlueXI]

Originally posted by Kevlar
Yeah... supercharger delivers power differently than a turbocharger does. Remember, superchargers offer linear power. You really aren't given the drivetrain a super shock of power/torque.

Turbochargers provide a huge surge or torque as boost start to build. That huge surge of torque is the key to the problem as it destroys most drivetrains... the AWD system I do not believe could take it.

Okay, I get it now. Thanks. :wave:

[SteelBlueXI]

Just for you Kevlar...

Four inches of fresh snow hit last night so I went and found an empty parking lot. I turned DSC off and hit redline in 1st, 2nd and 3rd... I wasn't doing more than 30 or 40.

So apparently with DSC off, just like you guessed, you can spin the tires at any rate you want.

[CYBER PETE]

Originally posted by NappyD1136
Just for you Kevlar...

Four inches of fresh snow hit last night so I went and found an empty parking lot. I turned DSC off and hit redline in 1st, 2nd and 3rd... I wasn't doing more than 30 or 40.

So apparently with DSC off, just like you guessed, you can spin the tires at any rate you want.

Awsome! I'm glad to hear that. I live in Buffalo and the storm totally missed us! I'm so pissed. Nappy did you get any action shots of your car in the snow!?? Quit slackin and post some pics. :

[badbadm]

Originally posted by Kevlar
The E30 AWD system was based on a mechanical set of gears and limited slip differentials. A perfect example would be to jack all four tires up in the air. You can put the car in gear and run thru all the gear and in theory redline the last gear with all four tires blazing away.

The E46 AWD system (prior to xDrive) is based on an electronic system with open differentials. A quick note... with an open differential, all the power goes to the wheel with the least amount of traction (dumb, yes I know). So back to the previous example. If you put the car in the air (ignoring the center differential for the time being), all the power goes by default to the passenger rear tire. The comptuer freaks out and says... oOps, no traction. It applies the brake. That means that tire now has all the traction (or so the differential thinks). The power shifts to the other side of the car driver's rear. Car says, oOh, no traction their either... brake gets applied to that wheel too. Now the center differential. By default, it is open, but has some gearing to always put some power to the front wheels. Now, with brakes in the rear being applied, more power gets shifted forward. Front wheels experience the same things the rears did.

Now... with all four tires spinning and the brakes being applied, shuffled and pulsed to try and move power around, the car says, something isn't right and starts to reduce engine power. So, in theory... if you have no traction, you are limited to crawling speed. The computers always allow for some slippage... but in theory if all tires were in the air, ground speed (in theory here) would be limited to 2-3 mph because the engine power would be reduced and all the brakes would being going crazy.

I tried to make this short... no such luck.

That is very accurate. And as a result, enter the xDrive all-wheel-drive system for '04 models. xDrive still uses data from the DSC-X system, but it really is a mechanical all-wheel-drive system that can transfer power on a more-immediate (read: short notice) basis. Think of it as a more traditional awd system that will operate with the enhanced "intelligence" of DSC-X.

For those of you who are too young to know: the E30 all-wheel-drive model was designated 325iX (not xi).

[LinearX]

In other words, the new ones are similar to the HICAS AWD system?

[Kevlar]

Originally posted by LinearX
In other words, the new ones are similar to the HICAS AWD system?

Not quite sure, I have not done enough research on the new system xDrive and the HICAS systems compared to the systems that are currently in place to give a good answer.

[PBalla]

i've been thinking of getting a 325xi for my winters

the e30 has handled well, but thats with 3 bags of sand in the trunk...

now I see it is worth it, but should I wait for X-drive to hit the e46s?..or possibly next gen 3 series?

I'm also afraid that'll raise the price...did the X5 get a price increase with X-drive?

I am having trouble reading, the old AWD systems transferred power, but the current e46 systems just applied brake to the area with less traction?

[toddman35]

Originally posted by Pharshballa
I am having trouble reading, the old AWD systems transferred power, but the current e46 systems just applied brake to the area with less traction?

Yup, the e30 iX's used lsd's with no electronics, while the new Xi's use open front and rear diffs and electronics to control the brakes when it senses a lack of traction.