[e36jakeo]

Originally Posted by Jonn335

This is a very good point which anyone wishing to add an LSD of any sort needs to consider.

How an LSD works with the stability and traction control is a bit of a head-scratcher. It seems like the stability control will brake one wheel or another to stabilize the car, but ultimately will not cause the wheel to change speed dramatically in comparison to the other wheels. The braking forces applied cause restabiliation of the car onto its intended path (to correct the oversteer or understeer). An LSD would not dramatically effect this action of the DSC.

In the case of traction control, as others have stated the LSD would prevent the need of the computer to slow a spinning rear wheel (compared to the other rear wheel) since that is the whole job of the LSD. Turning off the tractions control would allow just stability control and prevent your tire spinning from looping the car.

Any other comments from folks who know more than I do on this topic? it is a huge consideration in buying the 335i vs. the upcoming M3 (I HATE open diffs).

[npavlo]

Originally Posted by e36jakeo

How an LSD works with the stability and traction control is a bit of a head-scratcher. It seems like the stability control will brake one wheel or another to stabilize the car, but ultimately will not cause the wheel to change speed dramatically in comparison to the other wheels. The braking forces applied cause restabiliation of the car onto its intended path (to correct the oversteer or understeer). An LSD would not dramatically effect this action of the DSC.

In the case of traction control, as others have stated the LSD would prevent the need of the computer to slow a spinning rear wheel (compared to the other rear wheel) since that is the whole job of the LSD. Turning off the tractions control would allow just stability control and prevent your tire spinning from looping the car.

Any other comments from folks who know more than I do on this topic? it is a huge consideration in buying the 335i vs. the upcoming M3 (I HATE open diffs).

If you ask me the problem with DSC is not that it cant lock the open differential,
the problem is WHEN it does this, it KILLS the engine power. Reduces it to pretty much nothing.
I can see what some of you mean by, the DSC being affected in a handling situation, not acceleration. Can the Clutch style LSD (with static lock) prevent the DSC from braking rear wheels individually? Doubtful if you ask me. Most differentials are setup with a static lock that can be overcome by an average person on a lift. So if you ask me, in a non-accelerated state, im sure the DSC can still work. Its not on my list of things to worry about.
Like i said, most of your typical differential builders can custom tailor your off throttle differential behavior with ramp angles, and % of static lock (for a clutch style ramp/pin style LSD).
I don't know the best way to explain if DSC wont work, or not... is to actually look at the M cars. ALL the M cars have clutch style LSDs, and they have DSC, and it works fine.

there is DTC and DSC. in the first stage of deactivation of traction control (DTC), the wheels are allowed to spin more, but as soon as the yaw angle changes at all, FULL DSC interviens. like you said, prevents the car from "looping around".

I wont lie, in my ZHP with a 30/90 ramped LSD, with the DSC all the way on, if i accelerate hard on say a hairpin (with DSC off, the car would be doing smoking donuts maybe?), the DSC interviens still, and it cuts back engine power to prevent this. It still works as it should.
BMW so far, has never made or supported a LSD differential (of any type), that is designed to co-exist with the DSC (ie, the usage of DSC activates LSD). I guess youll have to try one.
I know if I pick a 335 up (contemplating), that will be my first mod.

as far as which one. Several are offered, as said. The Torsen/Quaife styles, the Viscous Clutch diffs (like the newer M diffs), and the varying lock clutch diffs (also called 1.5 way by some).

unofficially, i know all are available.

[e36jakeo]

Diffsonline has a bunch of different types, just not the Quaife. The Honda S2000 has a torsen-style which I like because it helps turn the car (eliminates understeer in slow corners).

I'd want the diff to be transparent to the driver (no clunking like clutch types) so it can remain just like stock until you want to do some ass-out slides!:rocks:

[npavlo]

Originally Posted by e36jakeo

Diffsonline has a bunch of different types, just not the Quaife. The Honda S2000 has a torsen-style which I like because it helps turn the car (eliminates understeer in slow corners).

I'd want the diff to be transparent to the driver (no clunking like clutch types) so it can remain just like stock until you want to do some ass-out slides!:rocks:

Instead of beating around the bush, im actually the differential engineer for diffsonline. Since were not a supporting vendor, i cant really offer specific information pertaining to what we offer (and what others don't), as it would be unfair to the paying vendors for this site. This is why im trying to keep this as general as possible.

I'm more interested in discussing the possible solutions for this car, since i agree with you - the lack of any type of LSD is an abomination.

Diffsonline sells quaifes, trust me. You'll just have to ask them.

The clutch diff i have, unlocks more under deceleration, to prevent understeer n slow corners, great for autocrossing, and there is no clunking, etc. Can't even tell its there.

Typically, all racing teams, in everyones experiance, use the clutch type differentials. It's becasue of they're ability to customize the locking action on accelration/deceleration.

With the advancements in modern materials, they've (even factory BMW clutch LSDs) been able to use the clutch differentials with no compromise on the street.

[npavlo]

p.s.
with my ramped diff, on a hard throttle snap, the LSD locks and power oversteer is extremly easy and predictable!

[Coyot]

Please correct me if I 'm mistaken:
I think that Torsen-type LSDs are better for general (non - racing dedicated) use and possibly best DSC-compatible, because of their real-time continuously variable engagement up to their maximum torque-biasing ratio.

Lock clutch type ones' operation is somewhat closer to an "on-off" mode.

Off course, there is also the viscous-coupled clutch-type M diff, which thus (ie through viscous-coupling) offers a gradual engagement and variable lock degree.
I was told that the latter is also ECU-slaved in terms of DSC compatibility, but another member here seriously questioned the truth of this, and I can only take his view too into account.

PS: Questions about DSC-compatibility translate into fears about DSC-effect maximization (over-reaction), excessive brake wear and possible diff damage.
PPS: Let's keep this technical. I (and many other members too, I presume) have a lot to learn.

[ducati955]

400 hp as a daily driver is all i need for me, 12's all day, hahhah

[e36jakeo]

Originally Posted by npavlo

Instead of beating around the bush, im actually the differential engineer for diffsonline. Since were not a supporting vendor, i cant really offer specific information pertaining to what we offer (and what others don't), as it would be unfair to the paying vendors for this site. This is why im trying to keep this as general as possible.

I'm more interested in discussing the possible solutions for this car, since i agree with you - the lack of any type of LSD is an abomination.

Diffsonline sells quaifes, trust me. You'll just have to ask them.

The clutch diff i have, unlocks more under deceleration, to prevent understeer n slow corners, great for autocrossing, and there is no clunking, etc. Can't even tell its there.

Typically, all racing teams, in everyones experiance, use the clutch type differentials. It's becasue of they're ability to customize the locking action on accelration/deceleration.

With the advancements in modern materials, they've (even factory BMW clutch LSDs) been able to use the clutch differentials with no compromise on the street.

npavlo, you should encourage diffsonline to sponsor the site, especially with the amount of business folks with 335is and 400 HP will bring you

I do not yet have a 335i, but Shiv's most recent advances with the XEDE tuning have the car now above 350 WHP and 400 Wtq. As cool as the new M3 will be, taking a 335i and tuning the whole car to fit your needs is even cooler.

So I will definitely need an LSD when I get the 335i. I want it to be reliable, quiet (unperceptable under normal conditions) but durable for racing and helpful for slow and fast corners. What are the limitations of the torsen-style Quaife in any of these categories, and what about clutch-type? With clutch, what are the pros and cons of going from a 40% to 60% to 75%, etc. lockup? What are the advantages of the ramped diff (30-90) and how exactly does that work?

I also want it to not damage or be damaged by the DSC or DTC.

Have you driven many 330i or 335is with either type? Will the diff make the car understeer more or make it more neutral? Work OK with DSC?

THanks in advance (from all of us!)

[npavlo]

Originally Posted by Coyot

Please correct me if I 'm mistaken:
I think that Torsen-type LSDs are better for general (non - racing dedicated) use and possibly best DSC-compatible, because of their real-time continuously variable engagement up to their maximum torque-biasing ratio.

Lock clutch type ones' operation is somewhat closer to an "on-off" mode.

Off course, there is also the viscous-coupled clutch-type M diff, which thus (ie through viscous-coupling) offers a gradual engagement and variable lock degree.
I was told that the latter is also ECU-slaved in terms of DSC compatibility, but another member here seriously questioned the truth of this, and I can only take his view too into account.

PS: Questions about DSC-compatibility translate into fears about DSC-effect maximization (over-reaction), excessive brake wear and possible diff damage.
PPS: Let's keep this technical. I (and many other members too, I presume) have a lot to learn.

Yes, the Torsen/Quaife are constantly varying. Its all personal preference. Lock up is not consistant with them, which is most often the reason why people dont use them for racing. There are a lot of options. Anything can be made to work. Im not sure about the DSC being programmed to work with a rear LSD, honestly I don't think so. Any clutch style differential has a static lock/breakaway torque that can be easily overcome by an actuating brake of a rear wheel (durring DSC operation).

Again, personal preference prevails!

[npavlo]

Originally Posted by e36jakeo

npavlo, you should encourage diffsonline to sponsor the site, especially with the amount of business folks with 335is and 400 HP will bring you

I do not yet have a 335i, but Shiv's most recent advances with the XEDE tuning have the car now above 350 WHP and 400 Wtq. As cool as the new M3 will be, taking a 335i and tuning the whole car to fit your needs is even cooler.

So I will definitely need an LSD when I get the 335i. I want it to be reliable, quiet (unperceptable under normal conditions) but durable for racing and helpful for slow and fast corners. What are the limitations of the torsen-style Quaife in any of these categories, and what about clutch-type? With clutch, what are the pros and cons of going from a 40% to 60% to 75%, etc. lockup? What are the advantages of the ramped diff (30-90) and how exactly does that work?

I also want it to not damage or be damaged by the DSC or DTC.

Have you driven many 330i or 335is with either type? Will the diff make the car understeer more or make it more neutral? Work OK with DSC?

THanks in advance (from all of us!)

Torsen/Quaife have varying lockup, depnding on the input torque, and the traction given. If there is low traction, then no matter what kind of input torque, the lockup threoretically can be LESS. Because of all these variables, the lock up is seldom consistant. Its hard to predict, compared to clutch styles.

Clutch styles, there are 2 that most people offer (factory and aftermarket). There are varying lock clutch diffs using mechanical advantage, and varying lock clutch diffs using viscous methods.
The mechanical locking differentials can either use spider gear action to increase force on the clutch areas, or even a ramp action to increase force. This can be done many different ways. Using a ramp-pin style carrier, the ramping action can be varied to adjust the increase-decrease in lock up durring particular situations.
The only viscous clutch differential BMW uses, is for the M diffs. Even those differentials are setup with static lock though, and the more slippage present, the tighter the lockup becomes. There is a sheer pump that presses against the clutches. The difference between L/R wheel speeds in the rear end is what increases pressure in the pump. This works, but again, sometimes inconsistant, based upon the requirement of slippage between the wheels to increase lockup. Also, becasue of all the moving parts, there has to be a lot of LSD slack inside, which causes them to be noisy and clunk on/off the gas. Most M drivers know what I'm talking about.

25/40/60/75% lockup... the difference? Most of the time, this means what the static lockup the differential is set at. Say depending on the vehicles weight, traction limitations, etc. 25% has a certain static breakaway torque. Increasing this static percentage will increase the ammount of torque required for L/R breakaway (turn indpendantlyt). This is what people are talking about when the differentials affect the handling. If you drive around with a 100% lock differential, the car won't turn, especially in slow corners.
You can get mechanical LSD diffs that are setup for 40%, or 60% (depending on the car you have, you can customize this). This will basicallly make the differential very consistant on the street/track (just like factory). Anything over 40% on the street, you will notice slow speed understeer. I used to run a 4 clutch static lock 75% in my E36 325, it was useless at autoX.
A lot of club racers use these, because they're very predicatable and consistant though (similar lock up, at all times, same ramps accel/decel, etc).

For street cars, you can maximize the best of both worlds by setting a streetable static lock, but changing the ramp angles in a ramp-pin LSD. This can increase the lockup under acceleration, to provide maximum traction. This is a great autox diff. 30/90 for example, for a DOL diff, means that on acceleration, the angle has been increased from 45-30, and on deceleration, from 45-90. This makes the differential unlock all the way to the static lock setting on DECEL (the 90), and lock up more than the stock ramp on ACCEL (the 30).

Setting a normal/streetable static lock will provide you with noiseless/seemless operation. You have to watch what you buy, becasue there are so many factors. Most providers (including us), knwo what you guys are looking for, and wouldn't provide you with a jeep style mechanical locker for the street. Some LSDs (such as Kaaz), are setup with metal style clutches, that can be grooved to grab into each other, etc. These LSDs are ON/OFF (pretty much 100% - 0%). Very VERY noisy, and difficult to drive (most purpose built drifting cars use KAAZ)

DSC will not break a LSD diff with clutches. The braking action of DSC can overcome the static lock of the differentials clutches (as long as theyre LIMITED slip). I verified this TONGIHT driving my 330 around in slippery new england weather. Understeering the car will cause the DSC to actuate each rear wheel individually to pull the front end around, this worked fine, and was seemless.

Unfortunately, I do not have personal experiance with driving an E9X 335 with the LSD (although we've built a few). Understand that most of our business is export.


whew.
I hope this doesn't confuse you all. Sometimes less information is better. I say you call your favorite diff provider, and tell them what you want.

p.s. Ill talk to the rest of the company about possibly becoming a supporting vendor.

[e36jakeo]

Wow npavlo, great stuff! My E36 M3 has the factory 25% diff, and I have been plenty happy with that. Basically I want to be able to have both tires break traction at the same time so I can:

1) Do tail out slides at u-turns (quicker and more fun:rocks: )

2) Have more predictable handling in the corners (random spinning wheels SUCK)

3) Put the power down on the track when coming out of corners.

My friend got a Nismo diff for his 350z and, while helpful for track use and ass-out slides it is obnoxiously clunky on the street.

I'd guess on a 335i with the XEDE's 450 lbs torque a 40% clutch type would be about right for most of my needs. That would be strong enough for that torque but still be quiet and streetable and would work fine with the DSC/DTC.

Thanks for your expertise!

[npavlo]

Originally Posted by e36jakeo

Wow npavlo, great stuff! My E36 M3 has the factory 25% diff, and I have been plenty happy with that. Basically I want to be able to have both tires break traction at the same time so I can:

1) Do tail out slides at u-turns (quicker and more fun:rocks: )

2) Have more predictable handling in the corners (random spinning wheels SUCK)

3) Put the power down on the track when coming out of corners.

My friend got a Nismo diff for his 350z and, while helpful for track use and ass-out slides it is obnoxiously clunky on the street.

I'd guess on a 335i with the XEDE's 450 lbs torque a 40% clutch type would be about right for most of my needs. That would be strong enough for that torque but still be quiet and streetable and would work fine with the DSC/DTC.

Thanks for your expertise!

Your buddys Nismo diff probally uses metal style clutches (like the kaaz), thats why its so loud.

Is your E36 diff loud/clunk? You will recieve the same type of quality as factory.

[BMWPower06]

any chance for BMW to put an LSD in upcoming 335s such as 2008 or 2009 models?

[jayjay]

Originally Posted by BizKid

no one?
what about LSD? i cannot belive BMW produced a turbo car in the 300hp range with a 1 legger! are their LSD upgrades??

I don't think it is needed. There are alot of high hp cars and even sports cars that have no LSD and still do alright at the track and the strip.....like all AMG cars, porsches (some 911, cayman etc) or lotus (esprit turbo)

[Adham]

it is true that an LSD is not NEEDED to go fast around the track. However, the LSD gives the car such a true feel, and the feel is what im all about.

npalvo, thanks for all that great information. I had a Turner Motorsport built 3.46 w LSD in my ZHP, it was quiet at low speeds and felt very good on track. I was wondering if you knew exactly what kind of LSD they use.

the LSD would be the very first thing i would do to a 335. it transforms the behavior of the car. To come out of a corner and feel both wheels working is an intoxicating feeling. Put 360whp behind them and were in business!



<< kind of like that

[npavlo]

Originally Posted by Adham

I had a Turner Motorsport built 3.46 w LSD in my ZHP, it was quiet at low speeds and felt very good on track. I was wondering if you knew exactly what kind of LSD they use.

They offer a few differnet options now a days - Depending on when you had it, you might have had what they installed in their project zhp :

http://www.turnermotorsport.com/html/330.shtml

and here is the LSD they used. It uses alot of parts nice parts, and is quiet (clutch material is nice/factoryish), with ramps too! It can be setup many ways, by reconfiguring the internals. Its big bank for just the LSD.

http://www.turnermotorsport.com/html...DUCT_ID=LSDTMS

[Adham]

yeah i did have the one from the project ZHP ... it was an amazing unit. :rocks: