BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

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      07-11-2007, 11:12 PM   #1
Mahlzeit
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135 diff = 335 diff?

The NA press release states the diff is performance oriented (implies LSD to me), but then states the “electronic rear brake management is used to simulate differential lock” (implies 335 open diff).

When one disables the DSC, does one also disable that which ‘simulates differential lock’?

If so, then I envision embarrassing 1-legged burnouts during spirited driving. Hate to say it, but a bit of tail-out action is just so irresistible in my e36 M3.

-Mahlzeit


From the NA press release:


….The DSC system on the 135i Coupe is designed specifically for performance-oriented driving. For instance, the accelerator pedal has a quicker response rate and electronic rear brake management is used to simulate a differential lock for stronger acceleration in turns.


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      07-11-2007, 11:25 PM   #2
TheoIam
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I cant wait to drive it. I am coming from an E36 M3 as well.

I wont have an LSD.
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      07-12-2007, 02:10 AM   #3
bradford
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Quote:
Originally Posted by Mahlzeit View Post
The NA press release states the diff is performance oriented (implies LSD to me), but then states the “electronic rear brake management is used to simulate differential lock” (implies 335 open diff).

When one disables the DSC, does one also disable that which ‘simulates differential lock’?

-Mahlzeit
Sounds like what Audi uses in the Quattro system to distribute power from side to side. When the ABS sensors detect wheelspin they brake the spinning wheel to send power to the other side. Audi calls it EDL for Electronic Differential Lock.

In the Audi system, when you turn off ESP (Electronic Stability Protection), it does NOT disable EDL.
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      07-12-2007, 07:08 AM   #4
larryn
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At least it doesn't retard the engine power, like my e90's electronic nannies do.

I'll still wait to see how it performs before ordering calling diffsonline.
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      07-12-2007, 09:51 AM   #5
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I fully expect to be installing a Quaife out back within a few months of delivery. The promise of Tiff-esque tail-outtery is too tantalizing to pass up.
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      07-12-2007, 11:33 AM   #6
Mahlzeit
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Quote:
Originally Posted by larryn View Post
At least it doesn't retard the engine power, like my e90's electronic nannies do.

I'll still wait to see how it performs before ordering calling diffsonline.
Isn't applying brake just about the same effect? The system still retards something (throttle or inertia) to control the spin, rather than re-direct power.

If the 335 has the same diff, then we could drive that car to get a sense of what it's like.

BTW the e90post.com folks did get Quaife to build and LSD, which Vishnu Tuning's car has installed. I believe the part cost is near $1.5k, no idea what the install would be.

-Mahlzeit
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      07-12-2007, 11:41 AM   #7
bradford
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Quote:
Originally Posted by Mahlzeit View Post
Isn't applying brake just about the same effect? The system still retards something (throttle or inertia) to control the spin, rather than re-direct power.
If you're talking about the differential, the system applies the brakes to the spinning wheel to make the diff send power to the OTHER side. Therefore, you still have usable power to put down.

...as opposed to say, a traction control system which retards ignition in order to just get the car back under control.

One is a safety system and the other is a performance tool. It's simply a way of using existing electronics (ABS equipment) to accomplish a similar task to a LSD (though not as skillfully)
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      07-12-2007, 11:46 AM   #8
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Quote:
Originally Posted by bradford View Post
If you're talking about the differential, the system applies the brakes to the spinning wheel to make the diff send power to the OTHER side. Therefore, you still have usable power to put down.

...as opposed to say, a traction control system which retards ignition in order to just get the car back under control.
Bingo! That's what I meant by it bettering the e90 system by a large margin. I've mistakenly left the traction control either engaged or partially engaged during autocross runs, adn the car just bogs down. This 1er system should allow full throttle, and keep the inside rear tire from spinning.

What I wonder about is if it would allow for equal power distribution, and letting the rear step out, like a true locker would allow you to do.
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      07-12-2007, 11:56 AM   #9
Mahlzeit
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w/out the power being transfered to the outside wheel, and the inside just getting slowed down by the brakes, I get the impression that indeed the 135 would bog,... instead of stepping its tail out.

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      07-12-2007, 12:02 PM   #10
Mahlzeit
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Quote:
Originally Posted by bradford View Post
If you're talking about the differential, the system applies the brakes to the spinning wheel to make the diff send power to the OTHER side. Therefore, you still have usable power to put down.
Sorry missed this point. Perhaps I don't know enough about differentials, but how does slowing the inside wheel force the diff to send power to the outside wheel?

I get the feeling the press release is just a carefully crafted piece of marketing designed to make an inferior (in terms of fun) electronic solution sound as good or better than the best solution (mechanical LSD).
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      07-12-2007, 01:07 PM   #11
larryn
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Open differentials send power to both wheels equally in flat equal traction situations, but if one wheel loses traction, it will just spin that wheel faster. Add traction control (like the e90's) into the equation and you'll have the system sensing the spinning wheel and retards the ignition (bogging the motor).

This new system replaces the "engine bogging" with applying the brake to the spinning wheel, and allows you to continue accellerating with the other gripping wheel. In theory, it is certainly better than the existing open diff/DSC system, but probably isn't as good as a real locking differential.

Your question about disabling DSC is certainly a valid one, and I wonder if this is a third level of DSC to disable.
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      07-13-2007, 12:43 AM   #12
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Quote:
Originally Posted by Mahlzeit View Post
does slowing the inside wheel force the diff to send power to the outside wheel?
Yup, that is the basic idea in a nutshell.

Audi has been doing it for over a decade. It's not optimal, but it works WAY better than no LSD...
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      07-13-2007, 11:30 AM   #13
Mahlzeit
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So this is a different system than what's in the 335i? I searched while for the 335i's NA press release to see what that diff's description was/is. Does anyone have it?

This is highly encouraging! I really, really hope diabling DSC doesn't disable the 135i diff's performance-orientation!
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