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      06-07-2016, 07:32 AM   #1
SchmullisBob
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Limited Slip Differential vs. Open Differential?

After reading about the Dinan and other tuning options, my impression is that they are nice, but not earth-shattering, but $ 3,000 (Engine tune 2 & CAI) is alot of green for marginal improvement which also reduces engine life by at least 50K miles (per thread with Steve Dinan's opinion).

That said, it seems that the LSD is probably a better use of $ 3,000.

Has anyone done the upgrade to LSD from Open D? If yes, was there a signficant difference? I bought my M235 and plan on keeping it 10 years, so no tracking, racing, or beating it. Just (sporty) daily driving and zooming around curvy back roads kind of driving.

Thanks for feedback!
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      06-07-2016, 08:51 AM   #2
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I doubt you will notice much difference without a trip to the drag strip or track. My vote is to invest the $3000 in hookers and blow.
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      06-07-2016, 09:05 AM   #3
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more the track, less the drag strip, no? my layperson's understanding is that it is better for the twisties b/c of power transfer to the wheel w/ more grip in a turn?
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      06-07-2016, 09:08 AM   #4
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Thanks. I guess if I move from FL to somewhere that there's snow, then it could make sense.
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      06-07-2016, 09:15 AM   #5
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I've been wanting an LSD also, but I'm not sure I really need it. From what I understand, it only makes a real noticeable difference when you're on the track. It also would be nice in winter weather, fitted with the proper tires; but it doesn't snow a lot where I live.

They're selling the LSD (for the 2 series) on Turner motorsport for $2500.00 I had not seen that mentioned on some of the older threads about the LSD.
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      06-07-2016, 09:58 AM   #6
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I would hope that your daily driving style would not warrant an LSD. Is your dSC light constantly blinking when you drive out of corners?

Each driver is a little different. Some would spend the money on rims and tires. Others on a suspension kit. Look at what would keep you excited for 10 years....and do it.
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      06-07-2016, 10:13 AM   #7
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Quote:
Originally Posted by caycep View Post
more the track, less the drag strip, no? my layperson's understanding is that it is better for the twisties b/c of power transfer to the wheel w/ more grip in a turn?
It helps on any condition when at least one of the wheels has traction....

Mostly on turns where all the load goes to one side and the unloaded wheel will spin more freely.... also helps in the rain...

Might help some on the drag strip but probably not so much...

I doubt you will see much benefit for daily driving except when it rains or if you take corners at 40mph
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      06-07-2016, 10:55 AM   #8
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Meh, I don't have it, in DD scenario, I can't notice a difference compared to my Miata equipped with LSD, even in spirited driving. On the track, however, another story.
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      06-07-2016, 11:46 AM   #9
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First off folks, don't pay over $2,000 for the BMW differential!! There is a BMW dealership in Mechanicsburg, and others, that sell them for less than $2,000.

Second, per BMW, installation should not be more than 2.5 hours of shop time. For those of you who are mathematically challenged just multiply 2.5 by the hourly charge rate at your favorite independent BMW repair shop. If you live in Eufaula, Alabama that's about $56/hour, if you live in San Francisco, California it's about $156/hour. YMMV

Third, if you're not sure you need a limited slip differential you probably can live without one. In regular driving in dry conditions the only advantage is in accelerating hard out of a low speed tight turn, with dynamic traction control on the computer doesn't do a very good job using the brakes to "limit the slip" and the rear end gets skittish. In less than ideal traction conditions this zone of instability is wider. If you drive without any of the nanny controls on (hopefully only on the track) then you really should have a LSD.
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      06-07-2016, 12:23 PM   #10
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The reality is if you are driving on the street in DSC off and breaking traction often enough that an LSD starts to become valuable, you are probably a jerk.

The car with the eLSD or Sport+ is already extremely capable near the limits. For the track, the mechanical LSD is certainly extremely valuable for being able to better control the rear end through the corners and have it more predictable than the electronics.

If you have the cash to burn and feel like you want it, then I wouldn't stop you, but you need to be pushing the car very hard to start gaining the benefit. At that point I would suggest just moving up to a stickier class of tire which would improve traction at all 4 corners when paired with the eLSD.
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      06-07-2016, 01:07 PM   #11
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Not sure about M235i, but I used to have 335i and S2000. 335i always had traction problems and light blinking, on S2000 you can clearly feel LSD working even on dry roads
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      06-07-2016, 02:12 PM   #12
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I've run both. I've had 10+ days on track with the "open" diff, and then several more with a LSD.

On street (I have about 24k miles on the car), there is a difference, but it isn't massive. The car is much more "chuckable" wth the LSD, and traction control doesn't interfere quite as much. I assume if you do power mods, it will become more noticeable (my engine is still stock).

On the track, it's night and day. The back end of this car can get seriously harry on higher speed turns without the LSD, and it is very hard to counter steer the car out of oversteer without it (back end becomes unpredictable).

If you are keeping the engine stock and not tracking, you don't need it. If you are increasing power or plan on tracking, it's a good investment.
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      06-07-2016, 02:32 PM   #13
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I would have to agree with the majority.

The driving you are talking about doesn't seem to warrant LSD especially at the cost.

From LSD to your mention of Dinan products and long lasting of a car, it sounds like you want to keep that warranty and also not push the car too hard to where it would prob last 10 years.

I would say go with the stage 2 tune and CAI. I love it. and yeah you can push your car faster for far less, but I for one do not know how reliable those tunes are over a 10 year span. Even dinan is limited in the warranty per years.

perhaps you might want to just upgrade some suspension aspects of your m235i such as sport springs, etc. instead of dropping 2k +.
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      06-08-2016, 09:47 AM   #14
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Just adding my rant here (ie no info of any value). You have paid almost (or more than) $50,000 for the "Ultimate Driving Machine" whether you use it or not, you should at least have a differential as good as the one found in a Nissan Juke RS! .



To quote ERIC TINGWALL's Car and Driver Article:
"We should note the distinction between the differentials we’re discussing here and brake-based torque vectoring, the dollar-store variety that’s increasingly found on economy cars and crossovers. Brake-based systems selectively squeeze individual brake calipers to slow the inside wheels and increase torque to the outside wheels in turns. Automakers use this setup because it’s lighter and cheaper than ponying up for the more complex hardware while still creating a useful yaw moment. But it doesn’t take a race engineer to recognize the paradox in using the brakes to go faster."

OK, I'll crawl back into my hole now and shut up.
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      06-08-2016, 10:31 AM   #15
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Quote:
Originally Posted by mdputnam View Post
Just adding my rant here (ie no info of any value). You have paid almost (or more than) $50,000 for the "Ultimate Driving Machine" whether you use it or not, you should at least have a differential as good as the one found in a Nissan Juke RS! .



To quote ERIC TINGWALL's Car and Driver Article:
"We should note the distinction between the differentials we’re discussing here and brake-based torque vectoring, the dollar-store variety that’s increasingly found on economy cars and crossovers. Brake-based systems selectively squeeze individual brake calipers to slow the inside wheels and increase torque to the outside wheels in turns. Automakers use this setup because it’s lighter and cheaper than ponying up for the more complex hardware while still creating a useful yaw moment. But it doesn’t take a race engineer to recognize the paradox in using the brakes to go faster."

OK, I'll crawl back into my hole now and shut up.

Jesus, someone kill that thing before it reproduces!
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      06-08-2016, 02:45 PM   #16
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Quote:
Originally Posted by mdputnam View Post
First off folks, don't pay over $2,000 for the BMW differential!! There is a BMW dealership in Mechanicsburg, and others, that sell them for less than $2,000.

Second, per BMW, installation should not be more than 2.5 hours of shop time. For those of you who are mathematically challenged just multiply 2.5 by the hourly charge rate at your favorite independent BMW repair shop. If you live in Eufaula, Alabama that's about $56/hour, if you live in San Francisco, California it's about $156/hour. YMMV

Third, if you're not sure you need a limited slip differential you probably can live without one. In regular driving in dry conditions the only advantage is in accelerating hard out of a low speed tight turn, with dynamic traction control on the computer doesn't do a very good job using the brakes to "limit the slip" and the rear end gets skittish. In less than ideal traction conditions this zone of instability is wider. If you drive without any of the nanny controls on (hopefully only on the track) then you really should have a LSD.
Quote:
Originally Posted by Cyberdemon View Post
The reality is if you are driving on the street in DSC off and breaking traction often enough that an LSD starts to become valuable, you are probably a jerk.

The car with the eLSD or Sport+ is already extremely capable near the limits. For the track, the mechanical LSD is certainly extremely valuable for being able to better control the rear end through the corners and have it more predictable than the electronics.

If you have the cash to burn and feel like you want it, then I wouldn't stop you, but you need to be pushing the car very hard to start gaining the benefit. At that point I would suggest just moving up to a stickier class of tire which would improve traction at all 4 corners when paired with the eLSD.
Quote:
Originally Posted by Liquidpaper View Post
I've run both. I've had 10+ days on track with the "open" diff, and then several more with a LSD.

On street (I have about 24k miles on the car), there is a difference, but it isn't massive. The car is much more "chuckable" wth the LSD, and traction control doesn't interfere quite as much. I assume if you do power mods, it will become more noticeable (my engine is still stock).

On the track, it's night and day. The back end of this car can get seriously harry on higher speed turns without the LSD, and it is very hard to counter steer the car out of oversteer without it (back end becomes unpredictable).

If you are keeping the engine stock and not tracking, you don't need it. If you are increasing power or plan on tracking, it's a good investment.
Pretty good advice right here.
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      06-08-2016, 03:11 PM   #17
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Quote:
Originally Posted by mdputnam View Post
Just adding my rant here (ie no info of any value). You have paid almost (or more than) $50,000 for the "Ultimate Driving Machine" whether you use it or not, you should at least have a differential as good as the one found in a Nissan Juke RS! .



To quote ERIC TINGWALL's Car and Driver Article:
"We should note the distinction between the differentials we’re discussing here and brake-based torque vectoring, the dollar-store variety that’s increasingly found on economy cars and crossovers. Brake-based systems selectively squeeze individual brake calipers to slow the inside wheels and increase torque to the outside wheels in turns. Automakers use this setup because it’s lighter and cheaper than ponying up for the more complex hardware while still creating a useful yaw moment. But it doesn’t take a race engineer to recognize the paradox in using the brakes to go faster."

OK, I'll crawl back into my hole now and shut up.
McLaren would disagree with you. The 650S, 675LT, and P1 have open differentials -- they use brake based torque vectoring only. A much better version than most cars, but still, brake based torque vectoring.
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      06-08-2016, 04:14 PM   #18
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I'll refer to the article that just got posted re: 228/235/M2 - on a tight race track, the M2 with it's fancy diff, extra horsepower and bigger tires was less than a half second faster than a M235i with it's eLSD.

At the limit the mechanical LSD is more predictable, but functionally the eLSD does what it needs to by properly sorting out calculations dynamically hundreds of times a second, rather than a mechanical LSD which has very specific behavior characteristics which are static.

The newer torque vectoring diffs use clutch packs on the diff to provide that computer level control to each wheel, which is arguably the best of both the mechanical and computerized worlds.
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      06-08-2016, 04:45 PM   #19
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Quote:
Originally Posted by Cyberdemon View Post
I'll refer to the article that just got posted re: 228/235/M2 - on a tight race track, the M2 with it's fancy diff, extra horsepower and bigger tires was less than a half second faster than a M235i with it's eLSD.

At the limit the mechanical LSD is more predictable, but functionally the eLSD does what it needs to by properly sorting out calculations dynamically hundreds of times a second, rather than a mechanical LSD which has very specific behavior characteristics which are static.

The newer torque vectoring diffs use clutch packs on the diff to provide that computer level control to each wheel, which is arguably the best of both the mechanical and computerized worlds.
Too bad the M235i is a Buick.
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      06-08-2016, 07:32 PM   #20
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Quote:
Originally Posted by SchmullisBob
After reading about the Dinan and other tuning options, my impression is that they are nice, but not earth-shattering, but $ 3,000 (Engine tune 2 & CAI) is alot of green for marginal improvement which also reduces engine life by at least 50K miles (per thread with Steve Dinan's opinion).

That said, it seems that the LSD is probably a better use of $ 3,000.

Has anyone done the upgrade to LSD from Open D? If yes, was there a signficant difference? I bought my M235 and plan on keeping it 10 years, so no tracking, racing, or beating it. Just (sporty) daily driving and zooming around curvy back roads kind of driving.

Thanks for feedback!
Margianal improvement is an understatement at stg 2 tune and if it reduces engine life by somewhere in the neiborhood of 50,000 miles then i guess my stellar N55 will only net me 950,000 miles... Damn it..!
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      06-09-2016, 10:21 AM   #21
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Quote:
Originally Posted by Liquidpaper View Post
McLaren would disagree with you.
I guess they have their reasons. But when I become King, all Regular BMW's will be required to come with LSD and all M cars must be equipped with electrically controlled torque vectoring differentials. Anyone who disagrees with the King will be sentenced to drive a Nissan Juke for the rest of their lives!!!
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      06-09-2016, 10:50 AM   #22
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Quote:
Originally Posted by Liquidpaper View Post
Too bad the M235i is a Buick.
Don't feel too bad about that. It's R&T after all, they have to be the lone voice opinion in the sea of positive reviews of M235i in order to make them stand out so to speak..I am not sure if Randy Probst would call a nose heavy Buick the most balanced BMW he has driven in a long time..
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