One Wheel Spinning in Snow, Help!

[yata]

'93 525I stuck this morning parked outside 3-5" snow. Been snowing past few days, managed in and out same parking unplowed. Today car would only budge a little. Had to get a ride from someone else.

First in reverse (auto) heard engine rev and wheel spinning. Opened door and find driver side wheel not spinning at all no matter how far push gas pedal, only passenger rear wheel spinning.

Is this because of the differential (just read online before posting this)?
Is this a problem in my Beemer I have to fix ($$)?
Tried sticking tree branch under spinning wheel but won't catch, what other way to get it going, shovel?

Any help and insight is greatly needed.

Regards,
Steve
Chicago

[bimmerd00d]

you just have an open differential, not a limited slip unit. it is NOT a problem, simply how the car was optioned when bought. Most automatic 525's did not come with a limited slip differential. Your best bet is to find a set of snow tires for winter.

[DueyT]

Yata, a trick to help open differentials is to lightly apply the hand brake and will slow the spinning wheel and transfer some torque to the stationary wheel.

I have an open 2.93 on my 540i, and even though I have ASC+T, all that does is chop power to keep the wheel from spinning....I either have to:

a) use the handbrake, or

b) a little-known ASC+T trick...hold the ASC switch for > 10 secs, which retains the ABS-assisted traction but does not reduce engine power through the DME...that means you can apply power, the spinning wheel will be slowed by the ASC/ABS controller and power will be transferred through the open diff to the stationary wheel.

Cheers,
Duey

[yata]

Thanks a lot bimmerd00d. Got worried, didn't know differential can shut one wheel completely off. I will check the tire shop for snow tires. Also put some weight in the trunk. Thanks again.

[bahnstormer]

junk in the trunk is a good way to go =]

[tim s]

tim s.

[632 Regal]

http://www.semperit.com/generator/www/de/de/semperit/automobil/themen/reifentest/reifentest_de.html

[Russell]

Mine seems very stable in ice and snow. as I have ASC+T traction control, It seems to shift power to the other non slipping wheel to ensure traction. is that correct as I cannot see what is happening while driving?

Just curious? TIA



'93 525I stuck this morning parked outside 3-5" snow. Been snowing past few days, managed in and out same parking unplowed. Today car would only budge a little. Had to get a ride from someone else.

First in reverse (auto) heard engine rev and wheel spinning. Opened door and find driver side wheel not spinning at all no matter how far push gas pedal, only passenger rear wheel spinning.

Is this because of the differential (just read online before posting this)?
Is this a problem in my Beemer I have to fix ($$)?
Tried sticking tree branch under spinning wheel but won't catch, what other way to get it going, shovel?

Any help and insight is greatly needed.

Regards,
Steve
Chicago

[yata]

Russell, are you asking members that replied to me? They know. After what happened I found:

http://www.cartalk.com/content/columns/Archive/1995/October/03.html

http://www.unofficialbmw.com/all/drivetrain/all_limited_slip_explained.html

Differential is designed and std. in all cars (?) for turning regardless of snow. Traction control works similarly I believe, a feature($$) working in conjuction.

[Russell]

Still, does straction control shift power to the non spinning wheel to gain traction or does it reduce power to the spinning wheel unitl traction is regained. Not sure??

Thanks for the reply



Russell, are you asking members that replied to me? They know. After what happened I found:

http://www.cartalk.com/content/columns/Archive/1995/October/03.html

http://www.unofficialbmw.com/all/drivetrain/all_limited_slip_explained.html

Differential is designed and std. in all cars (?) for turning regardless of snow. Traction control works similarly I believe, a feature($$) working in conjuction.

[bimmerd00d]

Still, does straction control shift power to the non spinning wheel to gain traction or does it reduce power to the spinning wheel unitl traction is regained. Not sure??
Thanks for the reply

nah that's essentially what a limited slip unit does, transfer it to spinning wheel. Or one of those active diffs Subaru and Mistubishi use on those rice burners. (sorry josh gore :D)

[black_bird_blue]

ASC+T uses brakes and ignition timing to both transfer torque from one side to the other and reduce overall torque in system. In principle it:

a) measures front wheel speeds
b) compares rear wheel speeds to front wheel speeds
c) if one wheel is spinning, applies that brake until they both go at the same* speed
d) when both wheels are going at the same speed, reduce engine torque until both wheels are going at the same* speed as the fronts.

* ish.

There are all sorts of wrinkles and details but that's the essence of it. What BMW call ASC+T (or ASC, or AST) is what Bosch call TCS (or ASR) - check out http://rb-k.bosch.de/en/start/product_s_CS_03_BR_WW.html for details of the current product.

Damian

PS if teasing the handbrake doesn't work, try letting half the air out of your tyres. Pump them up before you go back on a freeway, though.

[Russell]

Everything I have read on ASC+T "seems" to imply that power is shifted from the spinning rear wheel to non spinning rear wheel AFTER is uses ABS braking to try to reduce spinning as a first stage. Then it shifts the power to the other rear wheel. This is when the dash light flashes to show it is working at stage two, not stage one. Finally power is reduced to all driving wheels when wheel slip is very high such as glare ice situations.

ASC+t is IMO one of the best safety options on an already safe car. Would not buy a BMW without it. FYI, I had a 528e and it was one of the worst cars I have seen on ice. Could not drive in the winter without Blizzacks on the rear.

Just my opinion. :)



nah that's essentially what a limited slip unit does, transfer it to spinning wheel. Or one of those active diffs Subaru and Mistubishi use on those rice burners. (sorry josh gore :D)

[winfred]

help i seem to have problems spinning both rear wheels on dry asphalt :D
http://members.cox.net/wdixon27/burnout.gif

[JonE]

help i seem to have problems spinning both rear wheels on dry asphalt :D
http://members.cox.net/wdixon27/burnout.gif

Ahhh, Mr. 4.27 "posi" lsd must be having fun down there. Winfred, does that thing go like heck now vs. the 3.91?
Jon

[winfred]

it's a fair amount snappyer and it's still a hair below 3k at 70 (stood on it while on a empty xmas holliday highway till 135 and it still had plenty of ass) unless it's wet the 535s stuck down good now, the 325 will light em up good though, every turn at full throttle in 1st or 2nd is a potential doughnut


Ahhh, Mr. 4.27 "posi" lsd must be having fun down there. Winfred, does that thing go like heck now vs. the 3.91?
Jon

[wengenstein]

Cool! I knew holding it down did something but I wasn't quite sure what. I'll try that out during the snow storm tomorrow, before they plow... :)


b) a little-known ASC+T trick...hold the ASC switch for > 10 secs, which retains the ABS-assisted traction but does not reduce engine power through the DME...that means you can apply power, the spinning wheel will be slowed by the ASC/ABS controller and power will be transferred through the open diff to the stationary wheel.

[DueyT]

Cool! I knew holding it down did something but I wasn't quite sure what. I'll try that out during the snow storm tomorrow, before they plow... :)
W, I can't remember where I found that tidbit, but it dure does work. I had to use it last night as a matter of fact. You hold the ASC button for ~10 seconds...the ASC light will go out....you're now in "brakes-only" mode...that's what you need for very, very low traction situations (ice, hard packed snow with light powder dusting on top, etc... )

My real-world observations on ASC+T:
- in general, I'm amazed at how quickly it works to keep the car in line
- it's very effective in correcting any oversteer condition where any power is applied
- sometimes I'll hear the ABS "groaning" on the rear without the ASC light.
- "above" happens only for a few seconds...if I apply gas any longer, the light flashes.
- Don't know if my imagination but it seems to engage sometimes as I'm releasing the clutch but don't experience any wheelspin (OK, with a fair bit of power and torque, mind you...maybe it's just way ahead of me?)

Ironically, I rarely turn of the ASC -- usually only to do power slides on my street to skid and line up perfectly with my driveway (my nephew always says, "Sweet! That's sick!" :D )

I hadn't really though about how much torque and power the M60B40 has until recently (just before the snow and still with my summer tires on) when I had turned the ASC+T off just to experiment. Although an open 2.93 diff, the 540i broke both rears loose then changed to a single wheel about 100' down the road...these were 255's in the back too...holy crap it took off like a scorched cat!

ASC sure keeps alot of control over the power hiding under the hood of the Beast.

Cheers,
Duey

[Qsilver7]

Everything I have read on ASC+T "seems" to imply that power is shifted from the spinning rear wheel to non spinning rear wheel AFTER is uses ABS braking to try to reduce spinning as a first stage. Then it shifts the power to the other rear wheel. This is when the dash light flashes to show it is working at stage two, not stage one. Finally power is reduced to all driving wheels when wheel slip is very high such as glare ice situations.

ASC+t is IMO one of the best safety options on an already safe car. Would not buy a BMW without it. FYI, I had a 528e and it was one of the worst cars I have seen on ice. Could not drive in the winter without Blizzacks on the rear.

Just my opinion. :)

I'm not sure if other car manufacturers traction control systems works the same...but BMW's ASC+T reduces engine throttle first, then will apply brakes to the spinning (rear) wheel(s) if reduction in engine throttle does not produce enough traction to accelerate. DSC (dynamic stability control) which is a step up from ASC+T that some e39s have will detect slip and apply the brakes to any/all four wheels.

The BMW's ASC+T system is explained at this link: http://www.bmwworld.com/technology/asct.htm

[wengenstein]

I just got back from getting lunch and while I was out I used the little ASC trick and it worked as expected. Its still snowing up here and the roads were nice and white. :)

Before holding the button down I turned off ASC for a second while I slid around the corner near my house. But after setting "brakes-only" mode I found I wasn't able to turn the ASC off again. Whats up with that?


Ironically, I rarely turn of the ASC -- usually only to do power slides on my street to skid and line up perfectly with my driveway (my nephew always says, "Sweet! That's sick!" :D )

[DueyT]

That right, W...once you use the secret-mode, you'll have to recycle the ignition to return to normal mode.

Duey

[drum2430]

it's a fair amount snappyer and it's still a hair below 3k at 70 (stood on it while on a empty xmas holliday highway till 135 and it still had plenty of ass) unless it's wet the 535s stuck down good now, the 325 will light em up good though, every turn at full throttle in 1st or 2nd is a potential doughnut


Hey Winfred,

How difficult and expensive was that change out? Is it something a decent shade tree mechanic can do in his garage or should I be asking my local shop to do it? Is there enough extra snap to make it worth doing?

Blessings,

G.

[winfred]

i work at a bmw salvage yard so it cost me nothing, with a lift, air tools and the know how it takes about a half hour to 45 minutes to swap, used diffs go for $250-500 depending on ratio ls or open and seller, just about any shade tree should be able to swap one in a hour or two with hand tools. it's hard to say if it's really worth it as one man's meat is another man's poison, i like it, i can't remember who but somebody in the last couple weeks was selling several diffs at decent prices on the board


Hey Winfred,

How difficult and expensive was that change out? Is it something a decent shade tree mechanic can do in his garage or should I be asking my local shop to do it? Is there enough extra snap to make it worth doing?

Blessings,

G.

[JonE]

I think the "rig" had some but I didn't see a 4.27 lsd. I heard Gale of E32 fame has one for sale, though.

[Jon K]

The limited slip diff is all the traction control i need/want

[632 Regal]

USD was a bad standard option (unlimited slip differential) or...unitrack or pansitrack...etc my atc dont work so I try not to get stuck this time of year. Parking brake makes the right rear spinn more too, gonna have to double check the parking brakes when I change out all the rotors in the spring.

[TimGinCentralNJ]

...on Friday re: a set of studded Nokian Hakkapeliita 1's (they're mounted on BMW steel rims) which I'm trying to get out of my garage. I just sold my E34, so I no longer need them.

Let me know if you have any interest.

Rgds,
Tim G.


'93 525I stuck this morning parked outside 3-5" snow. Been snowing past few days, managed in and out same parking unplowed. Today car would only budge a little. Had to get a ride from someone else.

First in reverse (auto) heard engine rev and wheel spinning. Opened door and find driver side wheel not spinning at all no matter how far push gas pedal, only passenger rear wheel spinning.

Is this because of the differential (just read online before posting this)?
Is this a problem in my Beemer I have to fix ($$)?
Tried sticking tree branch under spinning wheel but won't catch, what other way to get it going, shovel?

Any help and insight is greatly needed.

Regards,
Steve
Chicago