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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Tracking, Autocrossing, Dragstrip, Driving Techniques > Do our cars have a form of Limited Slip?



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      10-25-2007, 05:10 PM   #1
NPDAN
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Do our cars have a form of Limited Slip?

I got into a friendly argument today with my SA that has now become a freind of mine. He's insistent that our cars have partial Limited Slip Differential. He claims that if Im in 1st and mash out, I'll lay down 2 sets of tread, that both wheels will spin equally? (As long as Im going straight) I have tried this and only see one each time I try. Is this true and I could have something wrong or is he wrong?
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      10-25-2007, 05:27 PM   #2
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Partial LSD? Your SA is funny and uninformed. An open diff will spin both wheels when the traction is equal. Try turning right and punching it. You know that left wheel will not be smoking like the right one.

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Mark
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      10-25-2007, 05:29 PM   #3
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No..that is why I bought a quaife LSD.
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      10-25-2007, 05:31 PM   #4
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Quote:
Originally Posted by JetskiMark View Post
Partial LSD? Your SA is funny and uninformed. An open diff will spin both wheels when the traction is equal. Try turning right and punching it. You know that left wheel will not be smoking like the right one.

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Mark
ha ha ha What are you doing Chiming in?
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      10-25-2007, 05:32 PM   #5
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Quote:
Originally Posted by S4to335 View Post
No..that is why I bought a quaife LSD.
yep, that's why im buying the quaife...
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      10-25-2007, 05:58 PM   #6
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Quote:
Originally Posted by NPDAN View Post
ha ha ha What are you doing Chiming in?
That was just too funny to pass up. Partial LSD, I know why you were arguing with your SA. I never realized my POS car had a Partial LSD. It spins both rear tires in the dirt. It also has Partial ABS. The brakes are so crappy, they don't lock up.

There are advantages to having a crappy car. I never lock it, wash it or worry about it getting damaged or stolen. You also don't have to slow down for speed bumps, dips or refrigerators.

Here is a short crappy video I shot in it.

Regards,
Mark
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      10-25-2007, 06:00 PM   #7
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Quote:
Originally Posted by JetskiMark View Post
That was just too funny to pass up. Partial LSD, I know why you were arguing with your SA. I never realized my POS car had a Partial LSD. It spins both rear tires in the dirt. It also has Partial ABS. The brakes are so crappy, they don't lock up.

There are advantages to having a crappy car. I never lock it, wash it or worry about it getting damaged or stolen. You also don't have to slow down for speed bumps, dips or refrigerators.

Here is a short crappy video I shot in it.

Regards,
Mark
Your a f'n nut
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      10-25-2007, 06:19 PM   #8
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Your a f'n nut
Thanks. It takes one to know one.

When you get your Quaife, are you going to get the 3.46 ring & pinion from the auto?

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Mark
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      10-25-2007, 06:25 PM   #9
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Post march production 335's have an "Electronic Limited Slip" differential. It's really just a fancier version of DSC, but it might be marginally better than pre-March production cars. It's actually described on the 1-series mini site, but it is also on the 335's now. It may now be described as standard for the 2008's, but it has been included in the car since march.
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      10-25-2007, 06:57 PM   #10
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Quote:
Originally Posted by ToddPhilly View Post
Post march production 335's have an "Electronic Limited Slip" differential. It's really just a fancier version of DSC, but it might be marginally better than pre-March production cars. It's actually described on the 1-series mini site, but it is also on the 335's now. It may now be described as standard for the 2008's, but it has been included in the car since march.
hmmm Mine is a March 07 build.
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      10-25-2007, 11:47 PM   #11
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      10-25-2007, 11:58 PM   #12
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dealers are full of it man... get him drunk and he'll tell u the truth
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      10-26-2007, 12:13 AM   #13
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I think he's talking about the electronic LSD.

don't quote me but I believe that leaving all nannies on will cut engine power when excessive slip is detected. Hitting the button once will engage brakes on the offending tire but not cut engine power.

Generally on the track, I run with everything completely off. I have done some sessions with one push of the button and boy the rear brakes heat up bigtime.
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      10-26-2007, 01:17 AM   #14
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Quote:
Originally Posted by leftcoastman View Post
I think he's talking about the electronic LSD.

don't quote me but I believe that leaving all nannies on will cut engine power when excessive slip is detected. Hitting the button once will engage brakes on the offending tire but not cut engine power.
I can confirm the engine power cutting out. I accidentally left DSC on during one autocross run, and the power kept cutting out on me at various points, even with the gas pedal down. I wondered if it was fuel starvation until I realized I forgot to deactivate the traction control. No problems on subsequent runs (with everything off) and better times.
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      10-26-2007, 03:11 PM   #15
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In reading the OM, under the Dynamic Traction Control section: "in the same way as with a differential interlock, even if DTC is activated, brake actions are still performed on the rear axle to enhance output if the drive wheels experience a significant loss of traction."
This statement is also listed under deactivating DSC.

So how much difference is there between this and a full blown LSD? (I'm still waiting to track my car, so I haven't felt this yet)

BTW-It still kills me that I have an LSD from the factory on my MINI but can't even get one on this beast.
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      10-26-2007, 04:01 PM   #16
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Probably b/c they want to sell some M3s next year... It really should be an option. I was really shocked when the Cayman people told they me they don't get one either.
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      10-26-2007, 05:12 PM   #17
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Quote:
Originally Posted by flyga3 View Post
In reading the OM, under the Dynamic Traction Control section: "in the same way as with a differential interlock, even if DTC is activated, brake actions are still performed on the rear axle to enhance output if the drive wheels experience a significant loss of traction."
This statement is also listed under deactivating DSC.

So how much difference is there between this and a full blown LSD? (I'm still waiting to track my car, so I haven't felt this yet)

BTW-It still kills me that I have an LSD from the factory on my MINI but can't even get one on this beast.

Maybe with DTC on it brakes the spinning wheel only until the locked wheel has more potential to spin and then as it begins to spin it lets up on the brake for the other wheel?

Not sure. Crazy we did not get LSD as standard. Is there an option for us that have the welded diff?
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      11-14-2007, 04:18 PM   #18
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I tried the "DTC" option at the track recently to see if it truly acted like an LSD.

It definitely kills wheelspin, which is nice, but also removes your ability to effectively throttle steer.

I see it this way. With everything off, I shouldn't light up my tires if I want fast times, but sometimes a little throttle steer will help you get around tight corners.

With DTC (one click), you can hammer the throttle on corner exit - it's just that nothing will happen until you get good traction. DTC will brake or cut power until you stop spinning. Throttle steering is all but impossible.

If DTC action wasn't so slow to "disengage" once you get traction, I'd say that it isn't a bad system. But as long as your right foot has fine motor control, you're likely faster without it on.
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      09-06-2010, 06:25 PM   #19
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this e92 seemd to leave 2 rubber strips when it exits a hairpin 30 seconds into the video

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      09-10-2010, 04:29 AM   #20
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it will never come close to a proper LSD as a LSD will devert power to the wheel with the most traction, a e-diff brakes the spinning (inner) wheel... I have a Drexler LSD and the difference is night and day. You are being rocketed out of a corner, oversteer is much more controlable, and no xmas tree anymore on the dash
Disadvantage of DCT is that by apllying the brakes it creates understeer and secondly it smokes the rearbrakes. with a LSD you do not have these issues.

Last edited by marcel b; 09-10-2010 at 04:37 AM..
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